331 dino still very dissapointing, experts help needed

[Andres2882]

331 dyno still very dissapointing, experts help needed

Ok, recently swapped in a 331 stroker motor. Have a C&L Maf calibrated for my 30lb injectors, AFR 185s with FTI upgraded spring package, Performer RPM intake, and an FTI custom cam (Gross Valve Lift: .5728 / .5632; Duration 224*/ 228*) with a powerband from 2800-6100. TPS voltage is at .97.

I've included both my dyno sheets and have some questions on what to do.

Original dyno run showed that the car was running pig rich with fuel pressure at stock levels. Dropping that fuel pressure to 35psi netted some decent gains.

On next trip, fuel pressure was dropped to 28psi and the A/F ratio got a little better but netted only 4hp more.

And the questions:

1) Given my parts, shouldn't I be expecting more out of my engine than I'm getting? I was expecting more in the 360hp range.

2) I am going to swap a Pro-M MAF in and see if that improves my A/F ratio. If my MAF is somehow off, could it be the reason that the car is not performing as well as it should? My friend said something about how even though you can compensate with the AFPR, if the MAF is off, it'll still throw the timing advance and whatnot way off. Is that true? Do I need a base fuel pressure of 40psi for everything to work optimally and then work with maf adjustments, or does it not matter as long as you get a good A/F ratio at the end

3) Do I have some sort of bottleneck or mismatch that is causing such an early and massive dropoff in power? Do I need a bigger intake?

4) I was planning on running nitrous and have a SCT chip. Will this chip and some good dyno tuning cure any problems I might be having?

Thanks!

 

[89white50]

man, you have everything 've been gathering and planning on, except the heads. I was also hoping for around 375rwhp...now im getting worried. what do you have for exhaust? also, 5spd or AOD?

 

[Aliate X]

If you look they have the smoothing set on 5 and your still showing fluctuations, I would recheck your rockers and such, looks like you might have some instability.

 

[Grn92LX]

If you look they have the smoothing set on 5 and your still showing fluctuations.

Good point.

How much timing are you running? You NEED to get that fuel pressure back up to 40 psi. Try putting the FP back to 40psi, then disconnect your battery for a while to erase the KAM (keep alive memory)

What are you running for exhaust? It should still make good power even with the smaller unported RPM intake.

 

[Andres2882]

I have full exhaust, BBK long tubes, no cats, h-pipe, ultra flows. Its a 5-speed too.

 

[Andres2882]

How much timing are you running? You NEED to get that fuel pressure back up to 40 psi. Try putting the FP back to 40psi, then disconnect your battery for a while to erase the KAM (keep alive memory)

On that note, when I switch MAFs, I want to have the fuel pressure set at stock levels. Seeing as how the fuel pressure is so low right now, is there a certain amount of time that the computer takes to compensate, or is it as easy as bumping the pressure back to 40, unhook the battery, switch MAFs and fire it up and the computer will be on track?

 

[tmoss]

Yes, if the MAF is calibrated for your injectors, you do just that. reset fuel pressure, swap out MAFs and disconnect the vbattery before you start work on ther MAF. Should be disconnected ~20 minutes or more. That resets KAM and erases your Adaptive multiplier.

Edit, if that RPM I is not ported, it will hold back some level of power on that 331 and that cam. The "CNC" match at the upper-to-lower flanges is a joke and both pieces need work there - then the lower is restrictive @ the head flange for 185 heads. If you don't want to work that intake, try an RPMII or Holley.

 

[meangreen92lx]

Should do alot better. Combo in my sig put out 311rwhp and 338rwtq. I'm hoping for a little more after I swap my upper intake for the RPM plenum. Something is not right with your fuel by the sounds of it.

 

[Rick 91GT]

Numbers are still pretty low, and I agree with Tom on the intake....

 

[Andres2882]

Numbers are still pretty low, and I agree with Tom on the intake....

I agree. I'm hoping the MAF will change things drastically.

 

[onefstsnake]

yeah the Graph is all over the place...
Should be ALOT smoother than that.

Pro M's are nice from what Ive heard. So I hope that fixes it some.

good luck

 

[jrichker]

Did you ever replace the bad Baro sensor that gave the code 22 from last time? That will seriously mess up your A/F. Do you have any new codes?

 

[Andres2882]

Yes, replaced that sensor. CEL is off now. Going to swap my friend's wideband onto the car today along with the other MAF. I'll see what happens.

 

[GTS95]

I was thinking weak valve springs and float, but in your post you said they are new..
Poss. add some timming..
L.

 

[Andres2882]

I'm hoping, looks like the intake will have to get ported or replaced.