Ported 99-01 lower intake manifold opinions

[Poolman]

Anyone out there have any experience with a ported 99 lower intake?

I am building an open track car, engine was running when I got the car, but was tired. Anyway, overhauling the engine, all forged internals, will run N/A for the track, but I am used to boost, so trying to squeeze as much out of it as I can.

Engine is .020 over, has 03 Cobra heads with some polish (not ported), Ford Racing hi lift cam kit, long tubes, and I have the 1/2" intake spacer kit for the 99 intake. Engine long block together, working on the car this winter.

If anyone has spent the money on porting the intake, let me know if you think it was worth it. I know about Sean Hylands porting and I think Steigmeir does it as well. Maybe there are others.

thanks

 

[trxcobra]

I have a ported short runner intake manifold that i will most likely be selling within the next month or so if your interested. Definately worth it

Anyone out there have any experience with a ported 99 lower intake?

I am building an open track car, engine was running when I got the car, but was tired. Anyway, overhauling the engine, all forged internals, will run N/A for the track, but I am used to boost, so trying to squeeze as much out of it as I can.

Engine is .020 over, has 03 Cobra heads with some polish (not ported), Ford Racing hi lift cam kit, long tubes, and I have the 1/2" intake spacer kit for the 99 intake. Engine long block together, working on the car this winter.

If anyone has spent the money on porting the intake, let me know if you think it was worth it. I know about Sean Hylands porting and I think Steigmeir does it as well. Maybe there are others.

thanks

 

[...01CobRa...]

ill take it from u ^^^^

 

[na svt]

Anyone out there have any experience with a ported 99 lower intake?

A ported stock runner length intake is only worth a few hp throughout the powerband. A 9-10" short runner will be far better for open track.

 

[Un4GivN]

A ported stock runner length intake is only worth a few hp throughout the powerband. A 9-10" short runner will be far better for open track.

How does one determine what runner length is best for their application?

 

[99cobra302]

How does one determine what runner length is best for their application?

short runner for high rpm power

long runner for down low grunt

 

[Un4GivN]

short runner for high rpm power

long runner for down low grunt

I understand this, but how does one determine actual runner length?

 

[na svt]

I understand this, but how does one determine actual runner length?

experience

 

[Un4GivN]

experience

PM on the way.

 

[tmhutch]

I understand this, but how does one determine actual runner length?

The general rule of thumb is an additional 200 RPM for every 1" of reduced runner length. Other considerations are the camshafts RPM capability and airflow capabilities of the intake manifold, and cylinder heads. When reducing runner length a person also has to know that the intake manifold and cylinder heads can flow the air needed to perform at the specified RPM. They also have to know if the cams are up to the task.

The 4.6 DOHC is a perfect example of these relationships. The stock intake from 99 - 04 has airflow limitations that prohibit peak performance starting around 5200 and become a real problem past 6500 RPM so the ideal runner length for that intake is in the 10" range.

The cylinder head in stock form is strong into the 7000 RPM range. Camshafts vary between the 99 - 01 cars and the 03 - 04 cars. The smaller cams of 03 -04 are done by 6500 RPM no matter how short the runners are whereas the 99 - 01 cams will run to almost 7000 RPM with just a couple inches removed. They wont pick up power much beyond 6500 but they will hold power almost flat.

Port the heads, put cams in or both and the limitations of the stock intake can be stretched but the problem usually boils down to short block, transmission or computer RPM limitations before induction limitations.

Since the DOHC will make peak power well into the 7500 RPM range with tiny 209 degree duration cams and 5" runners it is best to think more in terms of the beginning of the power band VS where it will stop making power. To figure this out we first need to settle on the maximum RPM we want to spin the engine, than work backwards from there.

So, a typical maximum RPM based on transmission shifting capabilities or computer ignition limitation is 7200. Figure an average 2200 RPM drop between gears and this gives us a 5000 RPM bottom for our power band in which we want to produce maximum power. In this case you would choose the runner length (10") that makes the most power starting at 5000 RPM. This may sacrifice a little power below that.

So 10" is a reasonable starting point. Move your RPM band up 200 RPM to 7400, remove another inch. If the given combo has big cams and ported heads that really start to come on strong at 6000 RPM than the sacrifice in power at 5000 RPM from an 8" runner can be outwayed by the increases produced at the top of the powerband even if limited to 7200 RPM. The average power is what needs to be considered and sometimes this will take a little experimentation if a person wants every last ounce of power available.

 

[01strokersnake]

Awesome explanation

 

[Poolman]

Awesome explanation

Yes, thanks eveyone for the input, especially TMHutch, if you were a little closer to the Carolina coast would take you to dinner, I'm sure I could learn some more. Think about coming to Mustang Week in Myrtle Beach...great time.

OK, so we need 9 to 10 inch runner length, where would you guys have that done? And does the inside of the casting need some cleanup or polishing or does that really matter?

If you want to keep recommendations private, then PM me.

Great discussion for me, thanks again. :beer:

 

[na svt]

Since the DOHC will make peak power well into the 7500 RPM range with tiny 209 degree duration cams and 5" runners it is best to think more in terms of the beginning of the power band VS where it will stop making power.

209 degree intake cams will peak below 7k with a 5" runner. In fact, Bob Cosby's combo with 212deg cams peaked right or a little below 7krpm.

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I have 5" runner intakes on 204 deg cobra cammed combos and the peak occurs near 6500 and flattens out afterwards; not a good match with these cams.

I often get asked the question of which runner length to run. I base my opinion on the the following:

I suggest a stock runner length intake if:
- the shift point is 6500 or below
- max mid range power is the goal
- max torque is the goal
- the intake cams are of the 03/04 type
- the combo has an auto trans

I recommend a 9.5" short runner only if:
- shift point is above 6500 and the combo has at least 99/01 (200deg) cobra cams
- the average power (between shifts) provided by the short runner would be higher than that provided by teh stock runner length intake

I recommend a 5" runner if:
- the combo will see RPMs above 7200 but for some centri and turbo applications operating in that range a longer runner is preferred due to it's higher pre-boost power potential.

The Cobra computers are good for more tha 7200rpm, unlike those Mach. However, a stock shortblock or a built shortblock and stock cams probably won't see that RPMs that high anyway.

The design of the C head intake is one that doesn't respond well to having it's runners shortened. Removing 1" does little to change the powerband and peak is almost unaffected. Removing 2" results in a greater change but peak is still not increased as much when removing 1.5" from the runners of a B head intake. The tight turn at the top of the runners, the shrouded entrance of the end runners and the small cross section of the front runner are the three constraints to making big power. There are ways to improve these shortcomings, 1) shorten the runners so that the curve is effectively removed, 2) enlarge the entrance of the "end" runners through a bit of creativity and 3) enlarging the cross section of the "front" runner through a drilled access port or by the use of acid.

 

[tmhutch]

Awesome explanation

Yes, thanks eveyone for the input, especially TMHutch, if you were a little closer to the Carolina coast would take you to dinner, I'm sure I could learn some more. Think about coming to Mustang Week in Myrtle Beach...great time.

OK, so we need 9 to 10 inch runner length, where would you guys have that done? And does the inside of the casting need some cleanup or polishing or does that really matter?

If you want to keep recommendations private, then PM me.

Great discussion for me, thanks again. :beer:

Right on. Glad you guys found it useful. I remember what it was like 10 years ago when I was trying to figure this stuff out. Like pulling teeth.

No worries on the dinner, lol. If I had to buy everyone dinner who shared valuable information with me on these forums I'd be broke. As far as PM's, let's keep it public just in case someone else can use the info.

The inside of the casting doesnt really benefit from much cleanup unless were talking about the 6 feeder holes. They benefit greatly from some port work. In terms of the lower plenum, the runner shortening process will entail all the cleanup neccessary.

As far as who does short runners, I do them once in awhile when I have time but that doesnt happen very often. NA SVT seems to be the most consistent about being able to deliver a product when someone wants one.

209 degree intake cams will peak below 7k with a 5" runner. In fact, Bob Cosby's combo with 212deg cams peaked right or a little below 7krpm.

This is a perfect example of how important it is to consider the entire combo when deciding on runner length. If you look close at the graph you'll see that Bob's engine is actually peaking at 7100 before it begins to drop off. Impressive considering he's running shorty headers and catted X pipe. Not ideal for high RPM but not a huge problem compared to the fact that he was running out of injector starting at 6500 and critically lean by 7000. With enough fuel he would have pulled well beyond 7100.

There are no hard and fast rules when it comes to runner length, cam timing, head flow. It seems all engines have a bit of personality all their own but the guidelines I layed out above are a good foundation to start with.

Heres a great example of a couple combos performing well beyond the expected capabilities of the camshaft:

Joe Charles Mach 1 with stock 186 degree Mach cams and 5" runner intake peaking at 6700 RPM:

Jesters Mach 1 with stock 186 degree cams and 5" runner intake peaking around 6300 and then again around 6700. This is on a stock shortblock.

Both of the above vehicles perform slightly beyond the camshafts expectations.

Below is a typical 209 duration cam (FR500) 5" runner intake combo. As you can see the run stops at 7250 RPM because of the stock shortblock limitations but the engine is still pulling.

All in all it's not that difficult to get the right combination of runner length for the intended application and more often than not it boils down to how much torque were willing to sacrifice below 5000 RPM.

 

[na svt]

All in all it's not that difficult to get the right combination of runner length for the intended application and more often than not it boils down to how much torque were willing to sacrifice below 5000 RPM.

[/quote]

Take note of the dynos used, MD and a superflow, both routinely place peak power and/or tq at RPMs not normally seen on Dynojets. The Superflow also produces higher than normal results, hence Naz's higher than normal numbers...well that and the higher octane German gas he was using.


BTW, the FR500 cams I've checked had 212 deg dur.

All in all it's not that difficult to get the right combination of runner length for the intended application and more often than not it boils down to how much torque were willing to sacrifice below 5000 RPM.

A loss of torque routinely follows the addition of a short runner. However, the loss of torque can be reduced through changes in cam timing. On combos wtih 9-10" sort runners, these changes quite often result in increased average power and sometimes even further peak gains. At a minumum I recommend advancing the stock intake cams to an LC of 108, sometimes even further.

The c head intake can have it's runners shortened to approximately 9" while still maintaing clear entry to the runners. Going shorter, between 9" and 5", will result in runner entrances that are shrouded thereby limiting hp. Shortening the runners only 1"-1.5" is more work than it's worth. So basically the options are stock, 9"-10.5" and 5-5.5" runners.

 

[tmhutch]

Take note of the dynos used, an MD and a superflow, both routinely place peak power at RPMs not normally seen on Dynojets. The superflow also read quite high, hence Naz's higher than normal numbers...well that and the higher octane German gas.

I dont agree that it is routine but more importantly I think we are starting to split hairs here.

BTW, the FR500 cams I've checked had 212 deg dur.

They seem to have some variability. Al P. checked a set that came in at 214 i and 204 on the exhaust. Typical of any cam manufacturer.

 

[na svt]

I dont agree that it is routine but more importantly I think we are starting to split hairs here.
They seem to have some variability. Al P. checked a set that came in at 214 i and 204 on the exhaust. Typical of any cam manufacturer.

I agree on the cams, they can be off spec. Ford specs have them at 212/208, 109 LSA. I've checked 4 sets, all the intakes were 211-212 but the LCs were not consistent.

The reason I brought up the dynos is that I did a short runner for a B headed engine which was tuned on a mustang dyno. It made peak power at 6700, about 200 rpm higher than normal. He took it to another MD and it peaked at only 5700 but the power was the same as the first dyno. The second dyno also had much higher tq. He went to a third dyno, a dynojet, and peak occured at 6550, right where other similar combos have been.

Just saying, dynos are great tools but terrible for comparison between types.

 

[TD91GT]

great post!!!!!!!! thanks so much

 

[tmhutch]

I agree that they can have problems, especially Mustang Dynos. In terms of what I posted, the Mustang dyno shows the same peak as the dynojet that is posted with identical combos. The Superflow 5" runner intake is layed over the top of a ported stock intake which is accurately peaking at 6250 RPM, so the calibration is accurate and happens to be indicative of what my experiences have been.

I especially appreciate your hands on measurements of various camshafts. It has been very interesting.

 

[Poolman]

BTW, the FR500 cams I've checked had 212 deg dur.

A loss of torque routinely follows the addition of a short runner. However, the loss of torque can be reduced through changes in cam timing. On combos wtih 9-10" sort runners, these changes quite often result in increased average power and sometimes even further peak gains. At a minumum I recommend advancing the stock intake cams to an LC of 108, sometimes even further.

The c head intake can have it's runners shortened to approximately 9" while still maintaing clear entry to the runners. Going shorter, between 9" and 5", will result in runner entrances that are shrouded thereby limiting hp. Shortening the runners only 1"-1.5" is more work than it's worth. So basically the options are stock, 9"-10.5" and 5-5.5" runners.[/QUOTE]

NA SVT:

Looked up my purchase of the FR500 cam kit and I bought them from you in Nov 09. Appreciate all your input in this thread. I have read through these posts a couple of times trying to digest the info and make a decision.

Let me run through exactly what I have for your review:
99 Cobra Short block is built, Manley I beams, forged Malhe pistons, full professional machine work and assembly, all new parts, no problem with 7200+ rpm.
I will have the shift light at 6800, sometimes it will go to 7000.
FR500 cam kit in 03 heads with some polishing in the heads by engine builder, not ported. Heads installed, stock timing chains and cam gear sets.
Long tube headers
I have one of the aluminum intake spacers that goes between the upper and lower manifold.
5 speed, car built for track use, 5-6 events per year

I am inclined to do something to the intake, maybe the 5-5.5 runner length for the higher rpm power, even if torque drops off at lower rpm, this morning I was more inclined to do the 9" version. Looking at the dyno graphs maybe short runners and cam degree kit would be helpful, not to late for that.
So what would you do if it were your engine? Are you willing to do the work on the intake? No rush, car is 3 months to be ready.

thanks Dennis