Am I making less power for my boost than you'd expect?

[DRK HRS]

I've been wondering about this, at peak power I'm making 486 rwhp on 14 PSI. This is with a P1SC from the Mach 1 kit. That's at like 6300 RPM or so. Apparently it keeps building more boost up until redline (17 PSI) but the blower is losing efficiency at that point and I actually make less power there. I am running an 03/04 Cobra short block so 8.5:1 compression, and the original Mach 1 heads which should be identical to Cobra heads.

When I still had the original Mach 1 block, I was making 448 rwhp at 7-8 PSI. I think it was 10.1:1 compression. Is the CR making this big of a difference, or is it a combination of that and a crappy blower? I was expecting closer to the mid 500's to the tires.

It's still a quick little DD street car, but my numbers seem off to me. This was measured on a Dynojet.

 

[DSG2003Mach1]

i know that compression ratio is hurting for sure but I dont know how much its costing you. The boost is there, is it possibly pulling timing due to IATs or something?

 

[DRK HRS]

Not sure. I am intercooled with the standard Procharger kit equipment. My tuner did say it was getting hot as it started going past 14 PSI which is why I was losing power above that.

Cobras come stock with what, 8 PSI and dyno around 370 whp? Maybe it really is just the CR and I'm around what I should be at 14. I need a D1 and I need it now!

 

[procharged 99]

Are you running pump gas?

 

[DRK HRS]

Yup, 93.

 

[black4vcobra]

Is the shortblock healthy? I would assume you did a compression check before buying, what were your numbers?

Also, is the intercooler the 2 core or the 3 core unit? If the 2 core, I'm guessing high IAT's are hurting your car's power.

 

[DRK HRS]

Is the shortblock healthy? I would assume you did a compression check before buying, what were your numbers?

Also, is the intercooler the 2 core or the 3 core unit? If the 2 core, I'm guessing high IAT's are hurting your car's power.

Im not sure if 2 or 3, the kit came installed on the car when I bought it. I'm not aware that a compression check was done when I had the engine put in, but it was an unused block. It's not burning oil or anything though at all.

 

[DRK HRS]

Aren't I making about what a pulled Cobra makes?

 

[DSG2003Mach1]

I dont get the feeling anythings wrong with the motor, to me it sounds like a combo of low compression and probably pulling timing due to IATs. Your tuner should be able to tell you what your IATs were and what peak timing was during the pull. That should narrow it down considerably

 

[Sluggie24]

Ford used a low compression ratio in those engines so it would be super safe. They didn't want to have to eat the cost of replacing thousands of engines under warrantee when people put in bad or low octane fuel. The low ratio gave them a safety buffer. That safety buffer is absolutely costing you power but it is also keeping your engine very safe even with higher boost.

If you are dead set on more power at that boost level you would have to bump the compression to 9 or 9.5 to 1 and retune. Not a cheap job but it would give you a good jump in power.

The other option I can think of is figuring out what is causing the intake temps to rise so much and correcting that. Better intercooler maybe? Then put more boost in. With 8.5 - 1 you can run more boost than you currently do.

 

[DRK HRS]

Ford used a low compression ratio in those engines so it would be super safe. They didn't want to have to eat the cost of replacing thousands of engines under warrantee when people put in bad or low octane fuel. The low ratio gave them a safety buffer. That safety buffer is absolutely costing you power but it is also keeping your engine very safe even with higher boost.

If you are dead set on more power at that boost level you would have to bump the compression to 9 or 9.5 to 1 and retune. Not a cheap job but it would give you a good jump in power.

The other option I can think of is figuring out what is causing the intake temps to rise so much and correcting that. Better intercooler maybe? Then put more boost in. With 8.5 - 1 you can run more boost than you currently do.

No, I'm not dead set on this boost level. The goal has always been more, I want to do a D1SC upgrade this summer but was budget-limited after spending all the cash on the new block. The P1SC is just left over from when I had the standard Mach 1 Procharger kit on the stock short block. Better intercooler is a good idea, and will be useful when I upgrade the blower too.

I'd like to end up around 20 PSI or a little more, or whatever it takes to make 600-650 rwhp.

 

[Sluggie24]

I'm no expert, but if i was in your position, I would upgrade the intercooler first and get a retune. See if you can resolve the intake temp issue and see if a better flowing FMIC gives the boost a bump up as well. In theory if the FMIC is restricting flow on your combo you should easily push over 500rwhp with a better one and tune not changing anything else. Then if you want to upgrade the blower and boost you already have a FMIC that can handle it.

If 20psi is your goal I hope you used good head gaskets and head studs to keep the heads from shifting. Also look into the driver side head cooling mod so you don't overheat the back cylinder on that side.

 

[Zemedici]

How does the car drive?

And how hard you wanting to lean on that P1? Hahaha

 

[DRK HRS]

The car drives awesome. I'm planning to get rid of the P1 pretty soon lol. D1 upgrade coming.

I did some live logging of the IATs and even at 6200 RPM it's only like 100 degrees so the intercooler is doing a good job.

 

[Sluggie24]

What was the ambient temp when you were seeing 100 degrees IAT? Where is your IAT sensor located?

 

[imbuggin]

Its is your compression. I have (PSC1) The same blower on the same engine as a mach 1, I run 9.5-10 LBS of boost and have a bit more power than you do. I hope that helps, you need a bigger blower with that low compression.

 

[BigFatMatt]

imbuggin, what are your numbers? Are you getting 563 whp out of a P1 at 10 psi (from your sig) ??

 

[DrumGuru]

I had a very similar setup in my 97' Cobra. 03 Cobra long block with a stage 2 P1SC. I was running 15#'s and would consistently see 17#'s on the gauge. I was making right in the 500 whp range with that boost level (intercooled as well). I found out from Procharger that I was actually over spinning the blower by 2-3k RPM, and for that reason was trashing the efficiency of the unit. I upgraded to a D1SC unit pullied at 15#'s and made 620 whp. The P1SC efficiency seems to die off drastically above 12#'s from what I have seen. Sounds like its time to upgrade. You should easily break 500 whp with a D1 unit around 10#'s.

 

[imbuggin]

imbuggin, what are your numbers? Are you getting 563 whp out of a P1 at 10 psi (from your sig) ??

I was pushing another pound of boost. I sit right around 500 at the Wheels with 10LBS and a safe tune. Headers, Exhaust and goodies.

 

[Riddick]

As you said you definitely need a D1 and feed that 03/04 short block!! If its going to be a little while you could always but a bigger pulley on the car which will make less boost but you can run more timing. Sounds like you are spinning the P1 to hard causing your IATs to rise, less boost and more timing in this case will probably yield higher numbers. How much timing is the car seeing once the boost gets over 14 psi, its prolly pulling timing at that point and your losing power.