After 5 years, finally got the Cobra tuned! Procharger F-1A

JetmechF16

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Sounds great man!! But that 6200rpm roll over is weird. Even with stock cams should be going out to Atleast 6800

Yeah we were a little stumped too, I was expecting it to make keep making power a little higher. Heads, cams, timing gear all stock except for BTR springs.
 

JetmechF16

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That is peculiar seeing the incremental data.....it was picking up ~20 every 100 rpm until about 5300 then it really slows down. 5800-6200 only a 13.5hp total gain. I would have guessed it would be steamrolling thru that range....but maybe only producing 15psi is completely out of that blowers efficiency range and things are going to change drastically at 23psi

I'm going to run it as is for now to break the motor in, then I'll take it back with a smaller pulley. I think you're on the right track though.
 

c6zhombre

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I'm going to run it as is for now to break the motor in, then I'll take it back with a smaller pulley. I think you're on the right track though.

I'm over looking at the procharger website right now....and damn, that blower will max 38psi and 74,000 impeller rpm. Lol. Ya, 15psi isn't even a blip on the radar.
 

JetmechF16

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I'm over looking at the procharger website right now....and damn, that blower will max 38psi and 74,000 impeller rpm. Lol. Ya, 15psi isn't even a blip on the radar.

When I ordered the kit I specified I was looking for 25 psi at 6800 rpm, however the receipt had 20 psi written on it when it arrived. I just went with it and never measured the pulley. Finally did after it was only hitting 15 psi yesterday, 4". Now I know why the supplied belt was too short haha.
 

01yellercobra

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When I ordered the kit I specified I was looking for 25 psi at 6800 rpm, however the receipt had 20 psi written on it when it arrived. I just went with it and never measured the pulley. Finally did after it was only hitting 15 psi yesterday, 4". Now I know why the supplied belt was too short haha.

Don't forget that their data is usually based on a stock 4.6. You've increased cubic inches and a better flowing exhaust. So all their data goes out the window. FWIW, I think I had the 3.9" blower pulley with the ATI 15% crank pulley and saw 19psi at 6500rpm. I had a ported 01 intake though so I'm sure that made a difference.
 

98 Saleen Cobra

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Ehh even with you not spinning it hard it shouldn’t roll over. Did boost fall off too? I doubt you’re floating a valve that would be weird if you did with springs like that.
 

JetmechF16

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Ehh even with you not spinning it hard it shouldn’t roll over. Did boost fall off too? I doubt you’re floating a valve that would be weird if you did with springs like that.

I was holding a manual boost gauge while he was making pulls, boost was steady at 15. He did see some valve float on one run when we ran it up past 7200 rpms. We are not sure the BTR springs I had installed are up to the task.
 

98 Saleen Cobra

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I was holding a manual boost gauge while he was making pulls, boost was steady at 15. He did see some valve float on one run when we ran it up past 7200 rpms. We are not sure the BTR springs I had installed are up to the task.
So boost stopped creeping at a certain rpm?? Did it drop at all??

I’m willing to bet you probably have valve float. I went through 4 sets of springs until we got the correct pressure before assembling my heads. Even tho they all claimed xyz after measuring them they were all less. I ended you with livernois springs after going through pac, crowed, Manley lol. All the ones we went through all claimed a certain seat pressure. All fell short when we measured.
 

JetmechF16

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So boost stopped creeping at a certain rpm?? Did it drop at all??

I’m willing to bet you probably have valve float. I went through 4 sets of springs until we got the correct pressure before assembling my heads. Even tho they all claimed xyz after measuring them they were all less. I ended you with livernois springs after going through pac, crowed, Manley lol. All the ones we went through all claimed a certain seat pressure. All fell short when we measured.
My tuner wants me to check out the springs before we try for more boost, he's thinking they aren't as strong as advertised also. From what I could tell holding a manual gauge 3 ft from a car going WOT on the dyno it pegged 15 psi and didn't move beyond it through the run.

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98 Saleen Cobra

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My tuner wants me to check out the springs before we try for more boost, he's thinking they aren't as strong as advertised also. From what I could tell holding a manual gauge 3 ft from a car going WOT on the dyno it pegged 15 psi and didn't move beyond it through the run.

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Gotcha, ya you def need to check out the springs. I'm sorry to pass that kind of news onto you man.. But you're not the first car that I know that has had spring seat pressure issues. What they advertise and what is real are 2 very different things. :( After the first 2 sets I almost just called Accufab and had them sell springs, but we tried Livernois and they were good.
 

c6zhombre

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So boost stopped creeping at a certain rpm?? Did it drop at all??

I’m willing to bet you probably have valve float. I went through 4 sets of springs until we got the correct pressure before assembling my heads. Even tho they all claimed xyz after measuring them they were all less. I ended you with livernois springs after going through pac, crowed, Manley lol. All the ones we went through all claimed a certain seat pressure. All fell short when we measured.

Good info

Might as well add some custom spec'd cams, too lol
 

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JetmechF16

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Forgot to mention, car has 3" cats in it, maybe that was choking the power in the upper rpms?

The JBA 3" catted midpipe I bought had been discontinued in 2011, I think the company I got it from had it sitting around since then. Maybe the old cats didn't like all the dyno pulls. I'll pull the midpipe off and borescope them to see if they're plugged.

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mcobra01

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I just finished my 2001 cobra f1a install a few months back. With a 4” pulley I hit 20lbs of boost. Jba headers and 2.5” exhaust with cats along with stock cams
 

98 Saleen Cobra

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Forgot to mention, car has 3" cats in it, maybe that was choking the power in the upper rpms?

The JBA 3" catted midpipe I bought had been discontinued in 2011, I think the company I got it from had it sitting around since then. Maybe the old cats didn't like all the dyno pulls. I'll pull the midpipe off and borescope them to see if they're plugged.

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You absolutely need to get rid of those immediately.
 

JetmechF16

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I just finished my 2001 cobra f1a install a few months back. With a 4” pulley I hit 20lbs of boost. Jba headers and 2.5” exhaust with cats along with stock cams

What size crank pulley/damper?

You absolutely need to get rid of those immediately.

On it! They're coming out next week when I get back in town. I completely forgot about them while we were on the dyno, I was still use to my old twin setup with almost no exhaust haha.
 

JetmechF16

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Well with a 4" upper and 8" lower my impeller rpm is right about maxed out at 7000 so I would think I should be making a good bit more boost with this combo. Now I'm wondering if I'm just getting massive belt slip?
 

98 Saleen Cobra

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Well with a 4" upper and 8" lower my impeller rpm is right about maxed out at 7000 so I would think I should be making a good bit more boost with this combo. Now I'm wondering if I'm just getting massive belt slip?
No it’s not belt slip or anything it’s the cats and likely valve stuff. Cats are a Major restriction can be blown out and I’ve heard of them damaging engines. Like I said remove them immediately. Think of the gt500 guys having tons of issues at anything really over 17psi. The lack of boost will be interesting to see though. Def not belt slip with that pulley combo
 

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