rhesus

86 951 with the following mods:
Guru Chips (no shim on the stock WG), Reliaboost set to 15 psi, 3-bar FPR, removed CV, test pipe.

I was expecting it to be rich on the upper end and it was. I seem to have a lean spot around 3500 RPM's, I'm guess it's due to a slight spike in the boost. My next mod will be a WG with MBC. Comments are welcome. The pull was in 4th.

rhesus

Sheet #2:

Tomas L

Hejsan Björn.

Then lean spot is probably intentional and the purpose is to build boost faster.

Tomas

Sean Hall

Clean up that fuel curve and you'll gain another 20HP or so. One problem with chips is that one size doesn't fit all...

Here's my dyno runs from several years ago. Fuel curve in the mid range was too rich, but "okay" in the higher RPMs. I had APE stage II chips, ARC2 MAF, running 17 PSI boost. Fuel pressure was set to 47 PSI with stock injectors. Cat bypass pipe installed.

turbo944

Yes, I would definitely think cleaning up the A/F ratio should net you quite a few ponies and I think having a good wastegate would help you a lot. I'm betting you're losing quite a few ponies due to the wastegate opening prematurely to some degree once you get into a good bit of boost. My 86 951 was dynoed at 101k by a PO and got 201RWHP totally stock. I'd think you'd get 240RWHP or so with the A/F cleaned up and a good wastegate.

Can't wait to see what you get once you get that done!

Are you running that regular 3 bar FPR that comes with the chips or an adjustable one?

rhesus

Regular 3 bar FPR included in the kit

Thanks for the input guys

Jake951

I had a very similar A/F curve with my Guru MAP right out of the box. I found I actually lost power by trying to richen the "lean" spot around 3500 by tuning the AFMLink box. 13:1 was about optimal for me in that region. Around 5000 rpm where I was rich like you, I gained only 5 hp by leaning out to about 12:1. Without the WG shim, you are probably dropping a bit of boost on the top end. Put in the shim and you will pick up 1-2 psi boost, which will probably lean out the top end to about optimal.

Danno

Yeah, that lean spot before max-boost is intentional to get hotter exhaust gases to spool up the turbo quicker and reduce turbo lag. However, the trend towards richness with increasing RPMs is getting too rich. Most likely due to dropping boost in the upper-RPMs. Go ahead and install the wastegate shims to pick up another 2psi or so in the upper RPMs

porshhhh951

wait......i thought it was the higher the number the leaner??? and the lower the number the richer???
Am I smoking crack! I have yet to dyno my car.(might be nice to actually know how to read it)

adrial

Thats correct.

And on the dyno sheets above, the a/f ratio drops a bit lower than 10.9:1 in the higher rpm ranges...wayy rich. 12.5:1 is a good number to aim for on a 951. Maybe a bit richer than 12.5:1 for a track car where EGT's start getting out of hand.

porshhhh951

this was the statement that confused me

Sach951

If you look at the dyno chart he's down in the 10:1 range circa 5000 RPM. Moving to 12:1 would be leaning out the a/f ratio.