Don't forget the cost to clean up your heads, reassemble them onto the shortblock, and time everything together.
Rebuilds aren't cheap at all....
Rebuilds aren't cheap at all....
What Shortblock Would You Choose?
- Thread starter Rossim22
- Start date
That is a pretty general statement.
Depending on power goals, IAT's, and octane level, that argument can be 100% correct or 100% false.
Most of the time, 9.5:1 is an excellent C/R for a PD Blower combo.
Maybe you are saying it isn't enough C/R? Considering how well a Coyote 5L does with only 14PSI with a PD Blower, maybe that's what you're trying to say. :dw:
Rossim22 re-read post #7!
Great. I completely disagree with you.
But if you want to recommend bad info, thats all on you.
But if you want to recommend bad info, thats all on you.
Nothing wrong with disagreeing with me but this "bad info" thing you speak of is a little fuzzy to me :shrug: What I said was more of a "statement".
You seem to know something I don't yet you're not letting me in on it :cuss: It's not too late for me to swap out my 8.5:1 pistons. This is on a Boss 5.0 with a 2.9 running 91 pump swill :rockon:
What's is my best course of action and why?
California, 91 Octane.....yuck.
In your particular situation, mid 8's may be the better route....as far as simple is concerned.
If it were me, I would run well into the 9's. Probably 9.6:1 to be exact.
I am a firm believer in less boost, more compression, and proper cams that are also timed appropriately. A 3.7 bore combo with the right headwork and proper cams would be able to perform pretty well on a boosted combo with 91 octane and 9+ C/R.
ALL boost makes more power with more compression. As long as the IAT's are in check, you can get by with a decent amount of compression on pump gas.
On a 99+ DOHC V-8....I can say for 100% certainty that a turbo, PD, and centri combo will make the same power at 9.5:1 on 18 psi as the same exact combo with 11.0:1 and 15 psi.
In your particular situation, mid 8's may be the better route....as far as simple is concerned.
If it were me, I would run well into the 9's. Probably 9.6:1 to be exact.
I am a firm believer in less boost, more compression, and proper cams that are also timed appropriately. A 3.7 bore combo with the right headwork and proper cams would be able to perform pretty well on a boosted combo with 91 octane and 9+ C/R.
ALL boost makes more power with more compression. As long as the IAT's are in check, you can get by with a decent amount of compression on pump gas.
On a 99+ DOHC V-8....I can say for 100% certainty that a turbo, PD, and centri combo will make the same power at 9.5:1 on 18 psi as the same exact combo with 11.0:1 and 15 psi.
Why do you have to change cams when upping the compression? What if I were to keep the stock cams with 9.5:1 or even 10:1 cr?
You don't have to change the cams. Big power can be made on stock cams, but it is not as efficient, nor is it as "easy" on the engine.
Aftermarket cams have a more benefits than just adding some power. Since we are talking boost...you can effectively lower the DCR. The longer duration on the cams, the longer the intake valve takes to close....the lower the "running" compression will be on the engine.
If you want to learn more, just Google "Static Compression Dynamic Compression"
Aftermarket cams have a more benefits than just adding some power. Since we are talking boost...you can effectively lower the DCR. The longer duration on the cams, the longer the intake valve takes to close....the lower the "running" compression will be on the engine.
If you want to learn more, just Google "Static Compression Dynamic Compression"
What do you mean when you say stock cams are "not as efficient, nor is it easy on the engine"? This sounds backwards!
Aftermarket cams tend to benefit an NA engine more because they struggle to fill the cylinders. Achieving 200% volumetric efficiency on a supercharged engine is just a pulley swap away. Terminators can make big power on stock cams where an upgrade here is a very expensive way to gain a little more power at the sacrifice of fuel economy and emissions. Most people main reason for wanting radical cams is for the "lope".
To the OP:
Very few people swap out their cams in this engine. The OEM cams has a milder ramp for better valve control at higher rpm's, you will get good gas mileage and the car will pass emissions. The blower can pack more charge into the cylinder then it can handle anyhow. What I would do is get a set of springs with higher seat pressure than the 62 lb OEM springs and a set of steel retainers for an added measure of safety. Anything beyond that will get expensive and most likely won't yield any significant advantage for a car driven on the street.
Although this is not a cam thread. I was referring to utilizing a higher compression shortblock with stock cams VS aftermarket.
I can see your thinking, and don't necessarily disagree with that....but there is much more behind it than what you presented.
My point is to build a shortblock which theoretically raises the SCR....and using a larger set of cams, ground properly, and degreed properly....to put the DCR where you effectively utilize the increase in compression with gasoline at the pump. Lower boost, good power, low octane.
In general, a set of stock cams will meet most peoples goals. I like to think outside the box though.
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SlowSVT.
Have you seen someone swap to larger cams, and gain HP without changing the pulley to re-coop the boost loss? I have.
Have you seen someone swap to larger cams, and compensate for boost with a pulley change?
Remember, if you want to see true numbers....you must run the same exact boost. one pound of boost can be tremendous, in comparison tests.
As for your comment about efficient. What is more efficient, 500rwhp with 16psi.....or 497rwhp with 13 psi?
As for the n/a comparison. I have seen a 20rwhp increase on NON S/C 4V with the addition of 1996 Cobra intake cams...and a 20rwhp increase on a 2003 Cobra with the same cams. And that is just a 20 degree bump in duration on the intake side only.
Have you seen someone swap to larger cams, and gain HP without changing the pulley to re-coop the boost loss? I have.
Have you seen someone swap to larger cams, and compensate for boost with a pulley change?
Remember, if you want to see true numbers....you must run the same exact boost. one pound of boost can be tremendous, in comparison tests.
As for your comment about efficient. What is more efficient, 500rwhp with 16psi.....or 497rwhp with 13 psi?
As for the n/a comparison. I have seen a 20rwhp increase on NON S/C 4V with the addition of 1996 Cobra intake cams...and a 20rwhp increase on a 2003 Cobra with the same cams. And that is just a 20 degree bump in duration on the intake side only.
Here are some results to ponder:
03-04 Mach 1 Engine (same as cobra, except 10.1:1)
Stock Engine + Supporting Mods + Eaton 3.4 Pulley (10 PSI)
18 Degrees Timing
458rwhp / 421rwtq
Same Combo, with Comp 106100 Cams (7.5PSI)
13 Degrees Timing
455rwhp / 426rwtq
Perfect example of what I am getting at.
03-04 Mach 1 Engine (same as cobra, except 10.1:1)
Stock Engine + Supporting Mods + Eaton 3.4 Pulley (10 PSI)
18 Degrees Timing
458rwhp / 421rwtq
Same Combo, with Comp 106100 Cams (7.5PSI)
13 Degrees Timing
455rwhp / 426rwtq
Perfect example of what I am getting at.
SlowSVT.
Have you seen someone swap to larger cams, and gain HP without changing the pulley to re-coop the boost loss? I have.
Have you seen someone swap to larger cams, and compensate for boost with a pulley change?
Remember, if you want to see true numbers....you must run the same exact boost. one pound of boost can be tremendous, in comparison tests.
As for your comment about efficient. What is more efficient, 500rwhp with 16psi.....or 497rwhp with 13 psi?
As for the n/a comparison. I have seen a 20rwhp increase on NON S/C 4V with the addition of 1996 Cobra intake cams...and a 20rwhp increase on a 2003 Cobra with the same cams. And that is just a 20 degree bump in duration on the intake side only.
Dude, he's building a street car and doesn't appear to have much experience here which is why he's asking. You got him on the topic of valve timing and static/dynamic compression ratio. This shouldn't be a science project for him.
A Terminator running 16 lbs of boost will be making a lot more then 500 hp. If not there is something very wrong. Your use of the word "efficient" is not really the correct term to use on this subject. Raising the horsepower in an engine tends to have the opposite effect on it's "efficiency" (ie: more fuel consumption).
Seeing a 20 hp increase on aftermarket cams on a blown engine is very typical and it's likely you can gain even more on an NA engine. I get very weary of claims of power increases with a component when modding an engine. Often there are other factors involved which tend to get overlooked.
The 96 Cobra cams seem to be all the rage. Are there any real comparative test results under controlled conditions available? They are not a radical departure from the OEM Terminator cams and the Ford GT cams with higher lift don't appear to offer much improvement.
An 8.5:1 Terminator engine is easily capable of making close to 600 hp running pump gas on boost alone.
And the numbers I posted would be even more biased if speaking 600rwhp :rolling:
My N/A combo (Mach 1 engine) made a best of 326rwhp, before the 1996 Cobra Intake cams.
Bolting them in, non-degreed....resulted in 346rwhp. (gain of 20rwhp)
My trap speeds went from 115 to the trap in my sig.
This was all done in similar conditions, days apart. I feel my comparison on that N/A combo were very realistic....as I modify, test, and race my combos often...not just once in a blue moon.
Lift is not going to gain HP like duration will on these engines.
Not sure what you mean by that :shrug:
Ok so 9.5:1 w/ stock cams and possibly in a Boss 302 at 5.15L w/ a ported eaton and e85 is the new goal pending on what is currently damaged... tear down begun today.
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If for sure E85....use a flat top. More efficient.
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