99-01 Mustang Cobra FAQ……Supercharging
Q. What supercharger kits are available for my 99/01 Cobra?
A: There are several popular kits available for the 99 up 4.6 4 valve engine. Ati Procharger(P1SC, D1SC), Vortech(E, S trim), Paxton(novi 1000&2000), Powerdyne(XB1A), and Kenne Bell all offer one, if not several kits to fit these cars.
These kits offer a variety of accessories, and are all a little bit different.
Q: What is the difference between a positive displacement and centrifugal supercharger?
A: So far, Kenne Bell is the only manufacturer to produce a positive displacement supercharger for these cobras. The rest of the companies listed above produce gear driven centrifugal units. There are two types of positive displacement blowers. One is a roots type, such as the Eaton unit found on stock 03/04 cobras. These are the least efficient and essentially just move air. The twin screw design, like the KB uses two rotors that compress the air before it is fed to the cylinders. The twin screw is a more efficient design and will make more power. Centrifugal superchargers use an impellar to compress incoming air before it flows into the intake manifold. Both are belt driven, but they differ in mounting location and driving characteristics. The pos. displacement superchargers replace the upper intake and sit “in the V”. The advantage to this type of unit is that boost is available at any rpm, as soon as you press the throttle. This means a lot of low end torque. This type of blower is good for light to light type of driving and makes the engine feel like it has a lot more cubes (something our little 281s could use). The downside is that at higher rpm levels, they aren’t as efficient and the boost level will not increase, so peak numbers may be lower. The centrifugal mount on the front of the passenger side of the engine and add boost as the engine revs. They usually start making boost around 2500-3000rpm (depending on size and internal step up ratio) and continue to increase boost all the way to redline, in accordance with rpm. For a road racer or dedicated drag car, this often fits better because the car spends the majority of the time at high rpms. For an engine like the 4v 4.6 that loves to rev, it basically accentuates the stock torque curve. Either one can definitely boost the hp level by a large percentage.
Q: Can I easily bolt up the eaton m112 from an 03/04 onto my 99/01.
A: Well, yes and no. Physically it will bolt up, but its not that simple. You will need a lot of parts, such as the blower, the intercooler, the heat exchanger, the intercooler pump, the secondary blower belt bracket, the crank pulley and bracket, another tensioner, all the bolts and brackets, and a way to relocate the alternator. Its not an easy bolt on. It will work, and make good power, but by the time you are done (even if you get the blower for steal) you will be up to the cost of the vortech, and you will still have an inefficient blower that pushes nothing but hot air about 14 psi. Also, the instant boost from a roots blower combined with the 9.85 compression may be difficult to tune for and could be hard on the stock bottom end.
Q: What comes with my supercharger kit, and can I install it myself?
A: Most entry level kits come complete with the head unit, the mounting bracket, the belt, additional pulleys, fuel components, a chip, and the necessary hardware. Certain kits, usually named “Tuner” kits do not include the fuel components or the chip.
The install varies by type and brand. Prochargers offer an easier install because they self contain their oil and no oil feed and return lines must be installed. The install is usually not difficult, just time consuming. The directions that come with the kits are awful, so it helps if you have someone who has done it before to help. Most kits can easily be installed in a weekend.
Q: How much boost is safe for a stock engine?
A: That is a difficult question to answer because some engines may blow with 8 psi, and others will last for years at 14. For a daily driven car, 8 to 10 psi is the most common limit. The tune (including both conservative timing and a/f) is also very critical because the pistons do not tolerate detonation. Also, higher boost levels can possibly be too much for the stock rods. If so, it will get ugly if the rod breaks. If you plan to supercharge your cobra, be sure that you have the funds, downtime, and mental stability () necessary to do a rebuild, because it is possible for the motor to fail quickly. The best thing to do is to have a compression test done before installing the blower to make sure your engine is healthy to begin with. From there, being sensible with the tune and boost figures will ensure that you have done all you can to prevent engine failure. In addition, how you drive your supercharged cobra also has a lot to do with how long it lasts. Wait for it to completely warm up before adding significant load to the engine. Try to avoid high speed runs where you stay in boost for long periods of time. Also, going wot at every stoplight is probably not the best for longevity either.
Q: What fuel/ignition/computer modifications must be done to safely run a blower?
A: The 99/01 cobra have a returnless fuel system. Therefore things such as Fuel management Units and fuel pressure regulators will not work. Fuel pressure is controlled by the computer and the fuel rail pressure sensor. The computer sees the manifold pressure, and adjusts fuel pressure accordingly, by varying voltage to the fuel pump. Therefore, the only way to ensure adequate fuel supply is to install a larger pump and injectors, along with a computer chip and calibrated mass air flow sensor.
Since this is a different system, parts that older cobras use will not be effective. The first is the Walbro line of fuel pumps. They are designed to run at 100% voltage at all times, because that is how the older style cobras worked. They are not designed to have the voltage constantly adjusted. They will work, but they burn out quickly. This is not ideal since having enough fuel is very important. If your supercharger kit comes with one of these, I would strongly consider replacing it with a returnless pump. Currently there are a few options for returnless pumps. The first is the 03 cobra pump and tank. As of right now that is really the best option. The other ones are Focus or aviator single pumps. For under 500rear wheel hp, the focus or aviator should be adequate. Above that, the 03 setup is the way to go. The focus and aviator pumps will drop into the stock tank with little difficulty. The 03 setup will fit in the stock tank but you will need to remove a bucket in the tank. Its also better to get the 03 tank if you can afford it because it comes with a baffle that will keep fuel at the pick up even at lower fuel levels and hard cornering.
Fuel injectors are also important. Most basic kits come with 42 lb green topped Bosch injectors. These are excellent injectors and will handle around 475rwhp easily. Most kits also come with the adapter to make these injectors work with the stock wiring harness. IF they don’t, they can be purchased at CPR or pauls high performance for around $130.
These injectors are high impedance. The stock computer can only run high impedance injectors, so unless you want to purchase an injector driver box, they are your only option. Currently high impedance injectors are available up to 65lb per hour which should hold around 800rwhp.
The computer can not properly work with the new injectors or pump without tuning. So a chip will have to be burned. A reputable tuner will put your car on the dyno and check to make sure the timing and air to fuel ratio are safe, and then either burn a chip, or reflash your computer.
The mass airflow sensor measures the amount of airflow entering the engine. Most kits come with a lightning maf. This should be good for about 480rwhp. It does not come calibrated so the computer must be corrected for the size of the injectors for it to work properly. Aftermarket MAFs also exist. The most popular is Pro M which offers many that will work well on these cars. Once MAF voltage hits 5(pegged) , you no longer have the ability to measure the additional airflow. Once that maf is pegged, revving any further is dangerous because the tune will only be safe if the conditions are exactly the same as the day it was tuned. If the air is cooler and you see more boost, it could run lean. A lot of tuners can get around this by adding a ton more fuel and reducing timing, but the car won’t run as well. The bottom line is that instead of getting around a pegged maf, you should just replace it with one able to hold more power. Zone 5 industries has an MAF extender that can manipulate how much voltage the maf sees, extending the range. It works well and is cheaper than a new maf.
For the ignition, the only thing that should be needed is a colder set of spark plugs. Aswfa-22c plugs are an excellent choice, as well as Autolite 764s. They should be gapped around .035. If the car misses, the gap may need to be closed. Since plugs are cheap they should be changed often.
Q: How much rwhp can I expect out of a base blower kit?
A: On a stock car or one with minor bolt-ons, you should expect to see anywhere from 410 to 450rwhp on 8 psi. Torque numbers are dependant on the type of blower, the tune, and whether your kit is intercooled or not. the higher the boost, the riskier the tune, and the more modifications, the higher the numbers will go. Above 500rwhp, the engine is not very safe because of the connecting rods, so making that kind of power on the stock engine is an “at your own risk” type of endeavor.
Q: Do I need an intercooler?
A: No, an intercooler is not necessary to run a kit. The tune will have to be very conservative, but it is not imperative. However, for maximum performance and consistency, an intercooler is recommended. There are two types, Air to Air(Paxton, procharger), and Air to water(vortech). Both are effective, but for a daily driven car, the A/A will likely be the better option. For a mostly track car, the A/W is good because you can add ice to further cool down the intake air.
Q: What are the benefits of intercoolers?
A: A great reduction in intake temperatures in which An 85° - 200° drop in air temperature (dependent upon application) results in a more dense, powerful fuel/air charge, greatly reduces exposure to detonation, and virtually eliminates the "power fade" felt in back-to-back runs and extended pulls without intercooling. This reduction in temperature allows you to run factory (or close to factory) timing, and avoids the substantial horsepower loss inflicted by excessively retarded ignition timing. The intercooler also acts as a passive wastegate, flattening the boost curve at higher rpm's and allowing more boost to be dialed in at lower rpm's. Full timing and forced induction keep the engine pulling hard to redline. Not only will you experience the above benefits at any boost level, you can also safely run substantially more boost when intercooled!
Q: What should I expect to pay for the average kit with everything needed? (courtesy of Blown01Cobra)
A: The average non intercooled kit will cost about 3800. For an intercooled kit, its closer to 4800. Obviously that depends on the manufacturer and the options that come with the kit. To have it installed would probably cost around 600, and with tune and chip, about 1100 for labor. So around 6000 would be a good ballpark.
Q: Will my traction control damage anything?
A: Since this car did not originally come supercharged, the traction control will dump fuel, but not boost. That creates a lean condition and can lead to engine damage….quickly. Therefore it is a good idea to turn the traction control off when you plan to drive the car hard.
Q: Do I need additional gauges?
A: No they are not necessary, however they are very helpful and informative. At the least, you should really think about a boost and fuel pressure gauge. Things such as EGT and a wideband aren’t needed but can tell a more accurate story about the a/f mixture. Having the most information about your engine is a definite plus when dealing with this much power.
Q: Is there anything else I should know about supercharging my 99/01 Cobra?
A: there are a few things. The 99 and 01 belt routing are different so unless you are a good fabricator, only buy the kit that fits your car. Also, by adding around 120 to 160rwhp to your car, you place additional strain on other components such as the clutch, transmission, and rearend. These components were not built for this kind of power, and you must keep in mind that they can fail if they aren’t treated properly. That means no 6000rpm launches and powershifts on the stock clutch, T45 and IRS. Maintenance should not be drastically different. Changing the oil at 3000 miles is a good idea, and using synthetic oil is recommended. The plugs will need to be changed more often, along with the serpentine belt. The final thing is to use common sense. If the car is not running well, don’t get into boost and drive it hard. If it doesn’t feel right, it probably isn’t. The car should accelerate smoothly and without hesitation or misses. If this is not the case, have it fixed immediately because it can lead to other problems.
Q: Any problems I should look for?
A: Yes. If your boost doesn’t come up like it once did or drops as rpms increase, your belt is most likely slipping. For the most part, the only thing you can do is replace it. A tight belt is important, but an overly tight one can do damage. If the car seems to fall on its face, the car may be detonating and pulling timing. If this is the case, have the car checked out immediately. IF it misses or runs rough, the spark plugs may need to be changed or regapped. Again, using common sense, finding problems before they become serious is important. An ounce of prevention is worth a pound of cure in these situations.
Some info on prochargers for those looking into them courtesy of Blown01cobra
Procharger also know as ATI sells both tuner and complete kits. All Procharger kits are setup as a blow threw MAF setup but can be easily converted to suck threw setup. The First and most popular kit is the P1-SC w/ 2-core intercooler kit (30PSI max boost). It comes complete with all piping, intercooler, MAF, Injectors, brackets, bypass valve, hardware, chip, and fuel pump. The second most popular kit is the P1-SC w/ 3-core kit. This kit is more of an upgrade from the first consisting of the same parts except for the upgraded intercooler. There is also another upgrade consisting of a 3-core sheet metal intercooler with larger inlet and exit sizes (3 IN, 3.5 IN, and also a 4 IN race size). The next two kits are more for race setups than for streetcars with the first setup being a D1-SC serpentine race kit (32PSI max boost). This kit is a tuner kit it comes with no fuel pump, no injectors, no MAF, and no chip. This kit is not wanted if you are still on stock internals being that on a cobra the stock pulley that comes with the kit push 14 PSI. This kit does come with the 3-core intercooler, all piping, brackets, and hardware. The last setup is for straight up racecar or built motor weekend warriors it is the F-1R it is capable of boost level of 38 PSI and isn’t recommended for a streetcar. This kit can come the same way as the D1-SC kit or as a custom race setup. ATI also produces a host of other supporting parts air-to-air intercoolers custom or premade. They also have air-to-water intercoolers for race application up to 2000+ HP.
Q: How good is the fuel pump that comes with the kit?
A: The fuel pump they send with the kit isn’t designed for the returnless fuel systems of the 99+ cobras and will eventually burn out. Now with that being said if you are driving when it fails this could be a huge problem especially if you are at half throttle or more.
Q: What size blowoff will I need?
A: Well a blowoff is for turbo not for centrifugal blowers. It is actually called a bypass valve and feeds metered or unmetered air back into the intake or to the atmosphere when you let off the throttle. If you have a suck threw style MAF setup It returns the metered air back into the intake so the PCM doesn’t sense that there is getting more air than is actually there. Now with the blow threw style MAF being the maf is after the intercooler you can vent to the atmosphere without a problem, because you are dumping unmetered air.
As for the size of the bypass you will need one that is suited for your application. The one that comes with the P1-SC kits is good for boost levels below 12PSI anything above this level should look into getting a race bypass.
Q: What does SC mean?
A: It stands for Self contained (SC) and means that there is not tapping into the oil pan for a return or having to run lines to feed the blower with motor oil. ATI is the only centrifugal supercharger company that has this setup. The only downside to this is instead of being able to just change you oil and being done with it the oil has to be sourced from ATI and needs to be changed every 6000 miles but sooner is better (I changed mine every 4000 miles).
Q: How strong are the brackets that comes with the kit?
A: they are very strong but tend to flex because of the design of them some people have claimed to see as much as 1/8th inch of flex when under WOT. This can be fixed easily with a custom made bracket that bolts to the Alternator and to the back of the procharger (I don’t have any pictures or a website it is one of those homemade things that any machine shop can build). In addition the 99 cobras belt routing and the 01 cobras belt routing are different so makes sure you have the right manual for the install.
Q: How long does it take for the average Joe to do the install?
A: If you have are a good back yard mechanic this can be done in 8 hours or less now if you are a beginner it is best to get some help and look over and through all instruction completely (I can’t express this enough so take notice and read completely) and expect for at least 12hours of work.
Forged Internals for your Modular Cobra.
Often when one runs any form of forced induction on a stock motored 99/01 cobra, after a while the engine may be damaged. This may be a result of too much rpm or boost or a bad tune. It is also possible to spin a bearing (usually a rod bearing) if you run your engine low on oil.
Q. What can I do to avoid having to rebuild my engine?
A. The first thing you can do is not drive like an idiot. Be reasonable with how much you get into boost, and if you plan to do things like roadracing where you are in boost often, prepare for a rebuild. It is inevitable. You have to pay to play. However, for the average person, driving in a sane manner, combined with checking oil and coolant levels frequently, doing proper maintenance(oil changes, fuel filters, spark plugs) and making sure the tune is conservative will all make it less likely for you to have engine failure.
Q. My blown cobra smokes like a train, whats the problem?
A. If it is smoking badly and you notice the smoke is blueish, you most likely cracked a ringland on the piston, or broke a ring. While you can still drive your car like this, it will perform poorly and eat oil like crazy. Not to mention its embarrassing to trail smoke for 500 yards every time you touch the gas pedal. With a compression test, if you notice a cylinder that is very low compared to the rest, you have most likely found your bad cylinder. usually a cracked ringland or ring will show anywhere from 60 to 90 psi, compared to 180 for the rest.
Q. I was getting on it, I heard a bang and there is oil all over the place, wtf?
A. Time to start looking for extra holes in your block because you most likely just broke or “threw” a rod and it made a nice little window in your snazzy aluminum block. At this point, the motor is pretty much trashed. This will most likely damage the heads as well because of the debris that are flying around in there.
Q. Now that im sure my motor is blown and I want to rebuild it for more boost, what do I do?
A. The absolute FIRST thing you must do is decide what plans you have for your vehicle and you absolutely must be realistic
1. Do you plan to keep it a street car, transform it into a race car, or use it as a daily driver?
2. How many miles do you drive it a week and is driveability important to you?
3. What type of hp/tq are you looking to make, and at what rpm?
4. Where do you want your powerband to be?
5. Are you willing to give up some power for safety?
6. How much money do I want to spend?
Once you start answering these questions you can get an idea of where you will need to go, and what parts you will need to buy.
FORGED INTERNALS
Q. What brands of pistons should I look at?
A. There are a number of very good brands that offer different advantages. The two strongest (shelf, ie not custom) piston brands are CP and DIAMOND. These pistons have huge top ringlands and beefy construction. Quality control is also excellent and in .020 overbore, they are still light (360grams). However, you pay a price for quality and these two are the most expensive pistons out there, with CP leading the charge. If you aren’t ready to spend 850 dollars for pistons and rings, there are still plenty of good alternatives that will be totally fine for a street/race engine. These are JE, ROSS, WEISCO, MANLEY and to a lesser degree PROBE. Probe pistons, while definitely adequate, are not necessarily the strongest out there. While they are light, they probably shouldn’t be used for a motor that will see over 15 psi. Another option for a daily driven vehicle that isn’t going to see over 10 psi, is MAHLE. They are a well known german manufacturer that makes piston for Ferrari and F1 teams. Very well designed and quality made piston, but unfortunately they are made from 4032 alloy, which isn’t as strong as the 2618 that the other brands are made from.
Q. What is the difference between 4032 and 2618 alloy?
A. The metallurgy is a bit complex, but the end result is that the 2618 is a stronger piston, but it also expands more when coming up to temperature. Factory forged pistons, such as those in the 03/04 cobra are 4032. They are still a huge step up from the hypereutectic pistons that are stock in the 99/01. They can be setup tighter, for reduced noise, and for a street car that won’t see a large amount of boost (over 12 or so psi) a 4032 piston is an ok choice. The price difference also exists. However, you only want to have to rebuild the engine once, so buy the best parts you can afford. Since the pistons see the brunt of the combustion, you want the highest quality piece you can get there. (I personally run CP pistons as I have found them to be the most beefy, and have absolutely spectacular machining work.)
Q. Some forged engines I have heard sound like diesels when they are cold, why?
A. Forged pistons expand a greater amount than the stock pistons in the 99/01. For this reason, when the engine is built, the piston to wall clearance (bore size-piston diameter) must be larger to account for the piston expanding. Running this p/w clearance too tight can cause scoring of the piston and cylinder bore. For this reason, when the engine is cold the piston is slightly loose in the bore and can rock around when the piston is at the bottom of the bore, causing this piston slap. The noise should fully go away when the engine is warm. DIAMOND pistons currently have offset wrist pins to in order to reduce this problem. While this is very common, and not necessarily a bad thing, some engines don’t have slap, either because of how they were setup or the piston. (again, my engine with CP has a very very slight slap that can only be heard with the hood up and your head by the alternator.)
Q. I plan on running nitrous or a supercharger, what should my ring gaps be?
A. With the higher cylinder pressure associated with a poweradder, the gap should be larger than an NA setup. Most rings are file to fit, so you need to square a ring in its bore(upside piston works great for this) and check the gap a few inches down the bore. Then file it to the gap you are looking for. Remember that your gaps should not be on the same size of the piston. Have the gaps 180 degrees from each other.
Q. Connecting rods, what are my choices?
A. 4340 Forged H beam rods are a GREAT choice for the street/strip poweradder rebuild. These rods have been proven countless times, and routinely exceed their recommended power level. They are good until about 800hp, and 8000rpm, but again, they have been taken above that. EAGLE and MANLEY are the only manufacturers I would look at when dealing with these rods. Both are forged in the same facility, and they are machined here in the US. While some say one brand is better, they are both fantastic. They should both ship with the ARP 2000 rod bolts, but make sure of that with any set of manleys you buy because they didn’t use to. If you get a set that’s been on a shelf for a few years, you may run into a problem. Just double check with your parts supplier. These rods are 500 dollars and weigh in right around 600 grams or so and are absolutely worth the money.
If you are looking to do an NA rebuild, a set of forged I beam rods from manley is a great choice. They are lighter than h beams and therefore will save reciprocating weight, giving you more power. They are fairly cheap and can handle about 600bhp. I wouldn’t recommend them for a poweradder motor since the h beams are so well tested and cheap.
If you plan to really make over 800hp, stepping up to a set of billet I beams from Carillo, Oliver or Manley is a good piece of insurance. While the forged h beams have held above 800, you don’t want to break a rod. These billets are usually around 1200 dollars, but for a serious race motor they are worth it. They are rated to about 1400hp, so they are definitely serious pieces.
Aluminum rods should not be used in a street motor.
Q. Crankshaft choices, what do I need?
A. The stock forged crankshaft in your cobra is fantastic. 6 second race cars making over 1500 hp use the same crank(albeit modified). Its fully counterweighted, internally balanced, and able to handle over 8000rpm. For most people, this crank will be all you will ever need. A new one runs about 600 these days, but unless you really spun a bearing or possibly threw a rod, your crank should be useable. Polishing or turning a crank to get rid of imperfections is a good idea if your car has higher mileage, although if it is turned, you will need undersized bearings. A good rule of thumb is that if your finger nail catches a scratch on the journal, it needs to be turned or at least polished.
For those very serious, there are billet options out there. They are expensive ($2000) and unnecessary for a street strip motor.
There are also some stroker kits out there that will increase displacement to about 305ci. There are also kits that will offset grind the stock crank and increase the throw that way.
If it were my motor, id want a crank that was designed with a longer stroke, not a modified stock crank, but they have been working ok it seems. That’s something to do at your own risk. The increased stroke will increase low end torque, but will slightly limit rpm potential and slight increase wear on the thrust side of the piston and wall. A viable option for those who want a better low end but want to retain stock gears.
Q. Bearings, should I use the stock ones?
A. You can use the stock ones, but when fantastic options are so cheap it doesn’t make sense to. Federal Mogul Hi performance bearings are available for 160 dollars for both mains and rods, so there is absolutely no reason to use anything else. Clevite, Ford, and King make good bearings for stockfish rebuilds, but you will spend close to 90 for them so do yourself a favor and get the FM hi performance ones. If you have your crank turned you will need bearings that will fit the crank. They are usually available in .010, or .020 undersized for mod motors.
Q. Fasteners, TTY or ARP
A. You are spending thousands of dollars to build a quality engine, so there is no reason not to use ARP STUDS from the main caps. They redistribute the clamping force and help to ensure the main caps don’t walk. They are about 150 dollars and absolutely worth the money. For a blown car, the head studs are needed as well, to prevent head lift. (note, this makes it just about impossible to pull the heads in the car) the head studs are also about 150 dollars. The 99/01 has no jack screw and a larger side bolt for the main caps. As much as it stings, these bolts are Torque To Yield, so they must be replaced every time. However, they work well and are only about $100 or so. Replace them, no questions asked.
Q. How do I pick a machine shop?
A. the shop you choose absolutely MUST have modular experience. While they can convince you all day long that a modular block is like a 350 chevy, its NOT. The shop must bore the block with torque plates. This is a plate that botls to the block to simulate the load of a head being on there. This assures that when your heads are bolted down, the bore is perfectly round. The aluminum block distorts a lot, so its necessary to do this. If you plan on using head studs on your motor, use them when boring. The shop should also demand your piston spec sheet and ask what piston to wall clearance you want so they can bore/hone the bore properly. Other things they should do is check the decks side to side to make sure they are even, and that the head mating surface is 100% flat. They should also check the main bores to make sure they are the same size, and align hone them if they are not. This can run anywhere from 200 to 400 depending on what needs to be done, and who does the work.
You will also want your machine shop to balance your rotating assembly. That means they will need your pistons, rods and crank. they should balance it to half a gram. Don't let them tell you that 1 gram imbalance is ok, because that 1 gram can turn into lbs at rpm. .5 grams is the standard. This usually runs about 175 on top of the other machine work.
Do not skimp here, good machine work is vital.
Q. Bigbore, how does it work and are there any problems?
A. To do this, your block will be resleeved. The blocks are aluminum with iron liners or sleeves. The sleeve is bored till its very thin, and then crack and removed. The actual aluminum block itself is then bored, and a larger liner is installed. This usually adds about 1000 to the cost of machine work. This gives you about 305 cubic inches and unshrouds the valves. The bore size is now 3.7 inches. You will need a piston that fits obviously. While there is very very little material between the liners, there don’t seem to be any problems with this type of setup. Has been shown to hold high boost without problems as well. There is something else, called the Darton MID setup which removes the area inside the block and replaces it with wet liners. This is expensive and relatively new, although it has been working very well on high powered Honda 4 cylinders. Id stay away from this for right now, till these motors get more miles on them.
Q. Does my low mile block need to be bored?
A. Yes. The stock bore is hardly ever perfectly round, and they don’t use torque plates. If there is minimal damage on the cylinder walls, have it bored .020 over. The service limit for these blocks is .030. At that point you either need new sleeves or a new block.
Q. Windsor aluminum plant block, vs the Teksid block?
A. The WAP block is weaker and you can identify it by the ribbing in the valley. The teksid block is a good bit stronger and only 5lbs heavier. It is the one to get if your stocker is trashed. Either one will hold 600rwhp pretty easily though, so for the average rebuild either is fine. (I run a WAP) 96-98 cobras definitely had the teksid block, and they can be used with 99 heads, and vice versa. 99/01s had either the wap or teksid and can be identified by the ribs in the valley.
Q. What head gasket should I use?
A. The stock one is the way to go. Fairly cheap and can handle huge amounts of power/boost. For 120 dollars, it’s a great option. Other choices are Felpro and Cometic.
Q. What else do I need to replace?
A. The oil pump needs to be replaced. If any metal goes through it, just replace it, its dirt cheap (50 or so). If you had a lot of metal running through the oil, such as the case of a spun bearing or thrown rod, replace the oil cooler. Its expensive but practically impossible to clean entirely. Don’t trash a new motor over 200 dollars. Oil pump gears should be replaced as well. It’s the most boring 280 dollars you will ever spend, but it will ensure you don’t lose a motor to a broken set of gears on that big 1 to 2 powershift. Its worth the piece of mind. Also replace the seals and gaskets if they don’t look to be in good shape. Also, strongly consider getting a drivers side head cooling kit from apten or LDC.
Q. Can I rebuild this myself?
A. If you have experience, a set of good tools (micrometers, dial indicator, etc), you can sure as hell try. Its still an internal combustion engine and there really is no voodoo in the shortblock. There isn't even a cam to worry about. However, the parts are very expensive and if you aren't 100% sure you trust yourself to take a motor you built to 7500rpm, let someone else build it. The extra cost is minimal when considering the piece of mind.
i need to add some stuff still, but i figure its a good start.
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Q. What supercharger kits are available for my 99/01 Cobra?
A: There are several popular kits available for the 99 up 4.6 4 valve engine. Ati Procharger(P1SC, D1SC), Vortech(E, S trim), Paxton(novi 1000&2000), Powerdyne(XB1A), and Kenne Bell all offer one, if not several kits to fit these cars.
These kits offer a variety of accessories, and are all a little bit different.
Q: What is the difference between a positive displacement and centrifugal supercharger?
A: So far, Kenne Bell is the only manufacturer to produce a positive displacement supercharger for these cobras. The rest of the companies listed above produce gear driven centrifugal units. There are two types of positive displacement blowers. One is a roots type, such as the Eaton unit found on stock 03/04 cobras. These are the least efficient and essentially just move air. The twin screw design, like the KB uses two rotors that compress the air before it is fed to the cylinders. The twin screw is a more efficient design and will make more power. Centrifugal superchargers use an impellar to compress incoming air before it flows into the intake manifold. Both are belt driven, but they differ in mounting location and driving characteristics. The pos. displacement superchargers replace the upper intake and sit “in the V”. The advantage to this type of unit is that boost is available at any rpm, as soon as you press the throttle. This means a lot of low end torque. This type of blower is good for light to light type of driving and makes the engine feel like it has a lot more cubes (something our little 281s could use). The downside is that at higher rpm levels, they aren’t as efficient and the boost level will not increase, so peak numbers may be lower. The centrifugal mount on the front of the passenger side of the engine and add boost as the engine revs. They usually start making boost around 2500-3000rpm (depending on size and internal step up ratio) and continue to increase boost all the way to redline, in accordance with rpm. For a road racer or dedicated drag car, this often fits better because the car spends the majority of the time at high rpms. For an engine like the 4v 4.6 that loves to rev, it basically accentuates the stock torque curve. Either one can definitely boost the hp level by a large percentage.
Q: Can I easily bolt up the eaton m112 from an 03/04 onto my 99/01.
A: Well, yes and no. Physically it will bolt up, but its not that simple. You will need a lot of parts, such as the blower, the intercooler, the heat exchanger, the intercooler pump, the secondary blower belt bracket, the crank pulley and bracket, another tensioner, all the bolts and brackets, and a way to relocate the alternator. Its not an easy bolt on. It will work, and make good power, but by the time you are done (even if you get the blower for steal) you will be up to the cost of the vortech, and you will still have an inefficient blower that pushes nothing but hot air about 14 psi. Also, the instant boost from a roots blower combined with the 9.85 compression may be difficult to tune for and could be hard on the stock bottom end.
Q: What comes with my supercharger kit, and can I install it myself?
A: Most entry level kits come complete with the head unit, the mounting bracket, the belt, additional pulleys, fuel components, a chip, and the necessary hardware. Certain kits, usually named “Tuner” kits do not include the fuel components or the chip.
The install varies by type and brand. Prochargers offer an easier install because they self contain their oil and no oil feed and return lines must be installed. The install is usually not difficult, just time consuming. The directions that come with the kits are awful, so it helps if you have someone who has done it before to help. Most kits can easily be installed in a weekend.
Q: How much boost is safe for a stock engine?
A: That is a difficult question to answer because some engines may blow with 8 psi, and others will last for years at 14. For a daily driven car, 8 to 10 psi is the most common limit. The tune (including both conservative timing and a/f) is also very critical because the pistons do not tolerate detonation. Also, higher boost levels can possibly be too much for the stock rods. If so, it will get ugly if the rod breaks. If you plan to supercharge your cobra, be sure that you have the funds, downtime, and mental stability () necessary to do a rebuild, because it is possible for the motor to fail quickly. The best thing to do is to have a compression test done before installing the blower to make sure your engine is healthy to begin with. From there, being sensible with the tune and boost figures will ensure that you have done all you can to prevent engine failure. In addition, how you drive your supercharged cobra also has a lot to do with how long it lasts. Wait for it to completely warm up before adding significant load to the engine. Try to avoid high speed runs where you stay in boost for long periods of time. Also, going wot at every stoplight is probably not the best for longevity either.
Q: What fuel/ignition/computer modifications must be done to safely run a blower?
A: The 99/01 cobra have a returnless fuel system. Therefore things such as Fuel management Units and fuel pressure regulators will not work. Fuel pressure is controlled by the computer and the fuel rail pressure sensor. The computer sees the manifold pressure, and adjusts fuel pressure accordingly, by varying voltage to the fuel pump. Therefore, the only way to ensure adequate fuel supply is to install a larger pump and injectors, along with a computer chip and calibrated mass air flow sensor.
Since this is a different system, parts that older cobras use will not be effective. The first is the Walbro line of fuel pumps. They are designed to run at 100% voltage at all times, because that is how the older style cobras worked. They are not designed to have the voltage constantly adjusted. They will work, but they burn out quickly. This is not ideal since having enough fuel is very important. If your supercharger kit comes with one of these, I would strongly consider replacing it with a returnless pump. Currently there are a few options for returnless pumps. The first is the 03 cobra pump and tank. As of right now that is really the best option. The other ones are Focus or aviator single pumps. For under 500rear wheel hp, the focus or aviator should be adequate. Above that, the 03 setup is the way to go. The focus and aviator pumps will drop into the stock tank with little difficulty. The 03 setup will fit in the stock tank but you will need to remove a bucket in the tank. Its also better to get the 03 tank if you can afford it because it comes with a baffle that will keep fuel at the pick up even at lower fuel levels and hard cornering.
Fuel injectors are also important. Most basic kits come with 42 lb green topped Bosch injectors. These are excellent injectors and will handle around 475rwhp easily. Most kits also come with the adapter to make these injectors work with the stock wiring harness. IF they don’t, they can be purchased at CPR or pauls high performance for around $130.
These injectors are high impedance. The stock computer can only run high impedance injectors, so unless you want to purchase an injector driver box, they are your only option. Currently high impedance injectors are available up to 65lb per hour which should hold around 800rwhp.
The computer can not properly work with the new injectors or pump without tuning. So a chip will have to be burned. A reputable tuner will put your car on the dyno and check to make sure the timing and air to fuel ratio are safe, and then either burn a chip, or reflash your computer.
The mass airflow sensor measures the amount of airflow entering the engine. Most kits come with a lightning maf. This should be good for about 480rwhp. It does not come calibrated so the computer must be corrected for the size of the injectors for it to work properly. Aftermarket MAFs also exist. The most popular is Pro M which offers many that will work well on these cars. Once MAF voltage hits 5(pegged) , you no longer have the ability to measure the additional airflow. Once that maf is pegged, revving any further is dangerous because the tune will only be safe if the conditions are exactly the same as the day it was tuned. If the air is cooler and you see more boost, it could run lean. A lot of tuners can get around this by adding a ton more fuel and reducing timing, but the car won’t run as well. The bottom line is that instead of getting around a pegged maf, you should just replace it with one able to hold more power. Zone 5 industries has an MAF extender that can manipulate how much voltage the maf sees, extending the range. It works well and is cheaper than a new maf.
For the ignition, the only thing that should be needed is a colder set of spark plugs. Aswfa-22c plugs are an excellent choice, as well as Autolite 764s. They should be gapped around .035. If the car misses, the gap may need to be closed. Since plugs are cheap they should be changed often.
Q: How much rwhp can I expect out of a base blower kit?
A: On a stock car or one with minor bolt-ons, you should expect to see anywhere from 410 to 450rwhp on 8 psi. Torque numbers are dependant on the type of blower, the tune, and whether your kit is intercooled or not. the higher the boost, the riskier the tune, and the more modifications, the higher the numbers will go. Above 500rwhp, the engine is not very safe because of the connecting rods, so making that kind of power on the stock engine is an “at your own risk” type of endeavor.
Q: Do I need an intercooler?
A: No, an intercooler is not necessary to run a kit. The tune will have to be very conservative, but it is not imperative. However, for maximum performance and consistency, an intercooler is recommended. There are two types, Air to Air(Paxton, procharger), and Air to water(vortech). Both are effective, but for a daily driven car, the A/A will likely be the better option. For a mostly track car, the A/W is good because you can add ice to further cool down the intake air.
Q: What are the benefits of intercoolers?
A: A great reduction in intake temperatures in which An 85° - 200° drop in air temperature (dependent upon application) results in a more dense, powerful fuel/air charge, greatly reduces exposure to detonation, and virtually eliminates the "power fade" felt in back-to-back runs and extended pulls without intercooling. This reduction in temperature allows you to run factory (or close to factory) timing, and avoids the substantial horsepower loss inflicted by excessively retarded ignition timing. The intercooler also acts as a passive wastegate, flattening the boost curve at higher rpm's and allowing more boost to be dialed in at lower rpm's. Full timing and forced induction keep the engine pulling hard to redline. Not only will you experience the above benefits at any boost level, you can also safely run substantially more boost when intercooled!
Q: What should I expect to pay for the average kit with everything needed? (courtesy of Blown01Cobra)
A: The average non intercooled kit will cost about 3800. For an intercooled kit, its closer to 4800. Obviously that depends on the manufacturer and the options that come with the kit. To have it installed would probably cost around 600, and with tune and chip, about 1100 for labor. So around 6000 would be a good ballpark.
Q: Will my traction control damage anything?
A: Since this car did not originally come supercharged, the traction control will dump fuel, but not boost. That creates a lean condition and can lead to engine damage….quickly. Therefore it is a good idea to turn the traction control off when you plan to drive the car hard.
Q: Do I need additional gauges?
A: No they are not necessary, however they are very helpful and informative. At the least, you should really think about a boost and fuel pressure gauge. Things such as EGT and a wideband aren’t needed but can tell a more accurate story about the a/f mixture. Having the most information about your engine is a definite plus when dealing with this much power.
Q: Is there anything else I should know about supercharging my 99/01 Cobra?
A: there are a few things. The 99 and 01 belt routing are different so unless you are a good fabricator, only buy the kit that fits your car. Also, by adding around 120 to 160rwhp to your car, you place additional strain on other components such as the clutch, transmission, and rearend. These components were not built for this kind of power, and you must keep in mind that they can fail if they aren’t treated properly. That means no 6000rpm launches and powershifts on the stock clutch, T45 and IRS. Maintenance should not be drastically different. Changing the oil at 3000 miles is a good idea, and using synthetic oil is recommended. The plugs will need to be changed more often, along with the serpentine belt. The final thing is to use common sense. If the car is not running well, don’t get into boost and drive it hard. If it doesn’t feel right, it probably isn’t. The car should accelerate smoothly and without hesitation or misses. If this is not the case, have it fixed immediately because it can lead to other problems.
Q: Any problems I should look for?
A: Yes. If your boost doesn’t come up like it once did or drops as rpms increase, your belt is most likely slipping. For the most part, the only thing you can do is replace it. A tight belt is important, but an overly tight one can do damage. If the car seems to fall on its face, the car may be detonating and pulling timing. If this is the case, have the car checked out immediately. IF it misses or runs rough, the spark plugs may need to be changed or regapped. Again, using common sense, finding problems before they become serious is important. An ounce of prevention is worth a pound of cure in these situations.
Some info on prochargers for those looking into them courtesy of Blown01cobra
Procharger also know as ATI sells both tuner and complete kits. All Procharger kits are setup as a blow threw MAF setup but can be easily converted to suck threw setup. The First and most popular kit is the P1-SC w/ 2-core intercooler kit (30PSI max boost). It comes complete with all piping, intercooler, MAF, Injectors, brackets, bypass valve, hardware, chip, and fuel pump. The second most popular kit is the P1-SC w/ 3-core kit. This kit is more of an upgrade from the first consisting of the same parts except for the upgraded intercooler. There is also another upgrade consisting of a 3-core sheet metal intercooler with larger inlet and exit sizes (3 IN, 3.5 IN, and also a 4 IN race size). The next two kits are more for race setups than for streetcars with the first setup being a D1-SC serpentine race kit (32PSI max boost). This kit is a tuner kit it comes with no fuel pump, no injectors, no MAF, and no chip. This kit is not wanted if you are still on stock internals being that on a cobra the stock pulley that comes with the kit push 14 PSI. This kit does come with the 3-core intercooler, all piping, brackets, and hardware. The last setup is for straight up racecar or built motor weekend warriors it is the F-1R it is capable of boost level of 38 PSI and isn’t recommended for a streetcar. This kit can come the same way as the D1-SC kit or as a custom race setup. ATI also produces a host of other supporting parts air-to-air intercoolers custom or premade. They also have air-to-water intercoolers for race application up to 2000+ HP.
Q: How good is the fuel pump that comes with the kit?
A: The fuel pump they send with the kit isn’t designed for the returnless fuel systems of the 99+ cobras and will eventually burn out. Now with that being said if you are driving when it fails this could be a huge problem especially if you are at half throttle or more.
Q: What size blowoff will I need?
A: Well a blowoff is for turbo not for centrifugal blowers. It is actually called a bypass valve and feeds metered or unmetered air back into the intake or to the atmosphere when you let off the throttle. If you have a suck threw style MAF setup It returns the metered air back into the intake so the PCM doesn’t sense that there is getting more air than is actually there. Now with the blow threw style MAF being the maf is after the intercooler you can vent to the atmosphere without a problem, because you are dumping unmetered air.
As for the size of the bypass you will need one that is suited for your application. The one that comes with the P1-SC kits is good for boost levels below 12PSI anything above this level should look into getting a race bypass.
Q: What does SC mean?
A: It stands for Self contained (SC) and means that there is not tapping into the oil pan for a return or having to run lines to feed the blower with motor oil. ATI is the only centrifugal supercharger company that has this setup. The only downside to this is instead of being able to just change you oil and being done with it the oil has to be sourced from ATI and needs to be changed every 6000 miles but sooner is better (I changed mine every 4000 miles).
Q: How strong are the brackets that comes with the kit?
A: they are very strong but tend to flex because of the design of them some people have claimed to see as much as 1/8th inch of flex when under WOT. This can be fixed easily with a custom made bracket that bolts to the Alternator and to the back of the procharger (I don’t have any pictures or a website it is one of those homemade things that any machine shop can build). In addition the 99 cobras belt routing and the 01 cobras belt routing are different so makes sure you have the right manual for the install.
Q: How long does it take for the average Joe to do the install?
A: If you have are a good back yard mechanic this can be done in 8 hours or less now if you are a beginner it is best to get some help and look over and through all instruction completely (I can’t express this enough so take notice and read completely) and expect for at least 12hours of work.
Forged Internals for your Modular Cobra.
Often when one runs any form of forced induction on a stock motored 99/01 cobra, after a while the engine may be damaged. This may be a result of too much rpm or boost or a bad tune. It is also possible to spin a bearing (usually a rod bearing) if you run your engine low on oil.
Q. What can I do to avoid having to rebuild my engine?
A. The first thing you can do is not drive like an idiot. Be reasonable with how much you get into boost, and if you plan to do things like roadracing where you are in boost often, prepare for a rebuild. It is inevitable. You have to pay to play. However, for the average person, driving in a sane manner, combined with checking oil and coolant levels frequently, doing proper maintenance(oil changes, fuel filters, spark plugs) and making sure the tune is conservative will all make it less likely for you to have engine failure.
Q. My blown cobra smokes like a train, whats the problem?
A. If it is smoking badly and you notice the smoke is blueish, you most likely cracked a ringland on the piston, or broke a ring. While you can still drive your car like this, it will perform poorly and eat oil like crazy. Not to mention its embarrassing to trail smoke for 500 yards every time you touch the gas pedal. With a compression test, if you notice a cylinder that is very low compared to the rest, you have most likely found your bad cylinder. usually a cracked ringland or ring will show anywhere from 60 to 90 psi, compared to 180 for the rest.
Q. I was getting on it, I heard a bang and there is oil all over the place, wtf?
A. Time to start looking for extra holes in your block because you most likely just broke or “threw” a rod and it made a nice little window in your snazzy aluminum block. At this point, the motor is pretty much trashed. This will most likely damage the heads as well because of the debris that are flying around in there.
Q. Now that im sure my motor is blown and I want to rebuild it for more boost, what do I do?
A. The absolute FIRST thing you must do is decide what plans you have for your vehicle and you absolutely must be realistic
1. Do you plan to keep it a street car, transform it into a race car, or use it as a daily driver?
2. How many miles do you drive it a week and is driveability important to you?
3. What type of hp/tq are you looking to make, and at what rpm?
4. Where do you want your powerband to be?
5. Are you willing to give up some power for safety?
6. How much money do I want to spend?
Once you start answering these questions you can get an idea of where you will need to go, and what parts you will need to buy.
FORGED INTERNALS
Q. What brands of pistons should I look at?
A. There are a number of very good brands that offer different advantages. The two strongest (shelf, ie not custom) piston brands are CP and DIAMOND. These pistons have huge top ringlands and beefy construction. Quality control is also excellent and in .020 overbore, they are still light (360grams). However, you pay a price for quality and these two are the most expensive pistons out there, with CP leading the charge. If you aren’t ready to spend 850 dollars for pistons and rings, there are still plenty of good alternatives that will be totally fine for a street/race engine. These are JE, ROSS, WEISCO, MANLEY and to a lesser degree PROBE. Probe pistons, while definitely adequate, are not necessarily the strongest out there. While they are light, they probably shouldn’t be used for a motor that will see over 15 psi. Another option for a daily driven vehicle that isn’t going to see over 10 psi, is MAHLE. They are a well known german manufacturer that makes piston for Ferrari and F1 teams. Very well designed and quality made piston, but unfortunately they are made from 4032 alloy, which isn’t as strong as the 2618 that the other brands are made from.
Q. What is the difference between 4032 and 2618 alloy?
A. The metallurgy is a bit complex, but the end result is that the 2618 is a stronger piston, but it also expands more when coming up to temperature. Factory forged pistons, such as those in the 03/04 cobra are 4032. They are still a huge step up from the hypereutectic pistons that are stock in the 99/01. They can be setup tighter, for reduced noise, and for a street car that won’t see a large amount of boost (over 12 or so psi) a 4032 piston is an ok choice. The price difference also exists. However, you only want to have to rebuild the engine once, so buy the best parts you can afford. Since the pistons see the brunt of the combustion, you want the highest quality piece you can get there. (I personally run CP pistons as I have found them to be the most beefy, and have absolutely spectacular machining work.)
Q. Some forged engines I have heard sound like diesels when they are cold, why?
A. Forged pistons expand a greater amount than the stock pistons in the 99/01. For this reason, when the engine is built, the piston to wall clearance (bore size-piston diameter) must be larger to account for the piston expanding. Running this p/w clearance too tight can cause scoring of the piston and cylinder bore. For this reason, when the engine is cold the piston is slightly loose in the bore and can rock around when the piston is at the bottom of the bore, causing this piston slap. The noise should fully go away when the engine is warm. DIAMOND pistons currently have offset wrist pins to in order to reduce this problem. While this is very common, and not necessarily a bad thing, some engines don’t have slap, either because of how they were setup or the piston. (again, my engine with CP has a very very slight slap that can only be heard with the hood up and your head by the alternator.)
Q. I plan on running nitrous or a supercharger, what should my ring gaps be?
A. With the higher cylinder pressure associated with a poweradder, the gap should be larger than an NA setup. Most rings are file to fit, so you need to square a ring in its bore(upside piston works great for this) and check the gap a few inches down the bore. Then file it to the gap you are looking for. Remember that your gaps should not be on the same size of the piston. Have the gaps 180 degrees from each other.
Q. Connecting rods, what are my choices?
A. 4340 Forged H beam rods are a GREAT choice for the street/strip poweradder rebuild. These rods have been proven countless times, and routinely exceed their recommended power level. They are good until about 800hp, and 8000rpm, but again, they have been taken above that. EAGLE and MANLEY are the only manufacturers I would look at when dealing with these rods. Both are forged in the same facility, and they are machined here in the US. While some say one brand is better, they are both fantastic. They should both ship with the ARP 2000 rod bolts, but make sure of that with any set of manleys you buy because they didn’t use to. If you get a set that’s been on a shelf for a few years, you may run into a problem. Just double check with your parts supplier. These rods are 500 dollars and weigh in right around 600 grams or so and are absolutely worth the money.
If you are looking to do an NA rebuild, a set of forged I beam rods from manley is a great choice. They are lighter than h beams and therefore will save reciprocating weight, giving you more power. They are fairly cheap and can handle about 600bhp. I wouldn’t recommend them for a poweradder motor since the h beams are so well tested and cheap.
If you plan to really make over 800hp, stepping up to a set of billet I beams from Carillo, Oliver or Manley is a good piece of insurance. While the forged h beams have held above 800, you don’t want to break a rod. These billets are usually around 1200 dollars, but for a serious race motor they are worth it. They are rated to about 1400hp, so they are definitely serious pieces.
Aluminum rods should not be used in a street motor.
Q. Crankshaft choices, what do I need?
A. The stock forged crankshaft in your cobra is fantastic. 6 second race cars making over 1500 hp use the same crank(albeit modified). Its fully counterweighted, internally balanced, and able to handle over 8000rpm. For most people, this crank will be all you will ever need. A new one runs about 600 these days, but unless you really spun a bearing or possibly threw a rod, your crank should be useable. Polishing or turning a crank to get rid of imperfections is a good idea if your car has higher mileage, although if it is turned, you will need undersized bearings. A good rule of thumb is that if your finger nail catches a scratch on the journal, it needs to be turned or at least polished.
For those very serious, there are billet options out there. They are expensive ($2000) and unnecessary for a street strip motor.
There are also some stroker kits out there that will increase displacement to about 305ci. There are also kits that will offset grind the stock crank and increase the throw that way.
If it were my motor, id want a crank that was designed with a longer stroke, not a modified stock crank, but they have been working ok it seems. That’s something to do at your own risk. The increased stroke will increase low end torque, but will slightly limit rpm potential and slight increase wear on the thrust side of the piston and wall. A viable option for those who want a better low end but want to retain stock gears.
Q. Bearings, should I use the stock ones?
A. You can use the stock ones, but when fantastic options are so cheap it doesn’t make sense to. Federal Mogul Hi performance bearings are available for 160 dollars for both mains and rods, so there is absolutely no reason to use anything else. Clevite, Ford, and King make good bearings for stockfish rebuilds, but you will spend close to 90 for them so do yourself a favor and get the FM hi performance ones. If you have your crank turned you will need bearings that will fit the crank. They are usually available in .010, or .020 undersized for mod motors.
Q. Fasteners, TTY or ARP
A. You are spending thousands of dollars to build a quality engine, so there is no reason not to use ARP STUDS from the main caps. They redistribute the clamping force and help to ensure the main caps don’t walk. They are about 150 dollars and absolutely worth the money. For a blown car, the head studs are needed as well, to prevent head lift. (note, this makes it just about impossible to pull the heads in the car) the head studs are also about 150 dollars. The 99/01 has no jack screw and a larger side bolt for the main caps. As much as it stings, these bolts are Torque To Yield, so they must be replaced every time. However, they work well and are only about $100 or so. Replace them, no questions asked.
Q. How do I pick a machine shop?
A. the shop you choose absolutely MUST have modular experience. While they can convince you all day long that a modular block is like a 350 chevy, its NOT. The shop must bore the block with torque plates. This is a plate that botls to the block to simulate the load of a head being on there. This assures that when your heads are bolted down, the bore is perfectly round. The aluminum block distorts a lot, so its necessary to do this. If you plan on using head studs on your motor, use them when boring. The shop should also demand your piston spec sheet and ask what piston to wall clearance you want so they can bore/hone the bore properly. Other things they should do is check the decks side to side to make sure they are even, and that the head mating surface is 100% flat. They should also check the main bores to make sure they are the same size, and align hone them if they are not. This can run anywhere from 200 to 400 depending on what needs to be done, and who does the work.
You will also want your machine shop to balance your rotating assembly. That means they will need your pistons, rods and crank. they should balance it to half a gram. Don't let them tell you that 1 gram imbalance is ok, because that 1 gram can turn into lbs at rpm. .5 grams is the standard. This usually runs about 175 on top of the other machine work.
Do not skimp here, good machine work is vital.
Q. Bigbore, how does it work and are there any problems?
A. To do this, your block will be resleeved. The blocks are aluminum with iron liners or sleeves. The sleeve is bored till its very thin, and then crack and removed. The actual aluminum block itself is then bored, and a larger liner is installed. This usually adds about 1000 to the cost of machine work. This gives you about 305 cubic inches and unshrouds the valves. The bore size is now 3.7 inches. You will need a piston that fits obviously. While there is very very little material between the liners, there don’t seem to be any problems with this type of setup. Has been shown to hold high boost without problems as well. There is something else, called the Darton MID setup which removes the area inside the block and replaces it with wet liners. This is expensive and relatively new, although it has been working very well on high powered Honda 4 cylinders. Id stay away from this for right now, till these motors get more miles on them.
Q. Does my low mile block need to be bored?
A. Yes. The stock bore is hardly ever perfectly round, and they don’t use torque plates. If there is minimal damage on the cylinder walls, have it bored .020 over. The service limit for these blocks is .030. At that point you either need new sleeves or a new block.
Q. Windsor aluminum plant block, vs the Teksid block?
A. The WAP block is weaker and you can identify it by the ribbing in the valley. The teksid block is a good bit stronger and only 5lbs heavier. It is the one to get if your stocker is trashed. Either one will hold 600rwhp pretty easily though, so for the average rebuild either is fine. (I run a WAP) 96-98 cobras definitely had the teksid block, and they can be used with 99 heads, and vice versa. 99/01s had either the wap or teksid and can be identified by the ribs in the valley.
Q. What head gasket should I use?
A. The stock one is the way to go. Fairly cheap and can handle huge amounts of power/boost. For 120 dollars, it’s a great option. Other choices are Felpro and Cometic.
Q. What else do I need to replace?
A. The oil pump needs to be replaced. If any metal goes through it, just replace it, its dirt cheap (50 or so). If you had a lot of metal running through the oil, such as the case of a spun bearing or thrown rod, replace the oil cooler. Its expensive but practically impossible to clean entirely. Don’t trash a new motor over 200 dollars. Oil pump gears should be replaced as well. It’s the most boring 280 dollars you will ever spend, but it will ensure you don’t lose a motor to a broken set of gears on that big 1 to 2 powershift. Its worth the piece of mind. Also replace the seals and gaskets if they don’t look to be in good shape. Also, strongly consider getting a drivers side head cooling kit from apten or LDC.
Q. Can I rebuild this myself?
A. If you have experience, a set of good tools (micrometers, dial indicator, etc), you can sure as hell try. Its still an internal combustion engine and there really is no voodoo in the shortblock. There isn't even a cam to worry about. However, the parts are very expensive and if you aren't 100% sure you trust yourself to take a motor you built to 7500rpm, let someone else build it. The extra cost is minimal when considering the piece of mind.
i need to add some stuff still, but i figure its a good start.
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