race fuel info requested

[stony]

A buddy and I are tuning his Z32. He built up a vg pretty strong and it running ceramic coated forged pistons, hks rods and balanced crank. Stock heads (well stock appearing :>), ported and extrude honed stock exh manifolds, stock extrude honed upper intake manifold, a set of the new HKS gtrs turbos. he is producing 550rwhp and 480ft lbs of torque.

 

he is running 106 race fuel. egt doesn’t get above 580C, total timing is at 30 degrees, air inlet temps are in the low 140s, A/F is rock steady at 11.5 all the way thru to 6200 rpm.

 

My question is I have heard that with race gas you will not detonate you will just not make anymore power if you put too much timing into it.

 

The problem is right now at about 5000RPM the torque curve takes a dive till about 5500 rpm and then starts rising again till about 6000 rpm

 

In the pic below (not the actual dyno chart) the black line is the original run and the red line is the run after several runs of advancing the timing in that area to try and get a nice curve with one peak.

 

Anyone care to comment on what else can be done to fix this curve. I was thinking since we have hit the limit on what timing will do.... leaning it out in that same area is the next step. We are being very conservative with the tune to stay as safe as possible and still hit the 600rwhp goal.

 

Also what are safe A/F ratios when using 106 unleaded race gas.

[stony]

Oh yea what we are shooting for is a curve like this yellow line in the pic below

 

 

This will also obviously increase HP also if the curve is worked out.

 

I originally thought that the VG30's exh or intakes lack of flow (myth or fact) is what was causing it but since the timing adjustments started to fix it....I guess I was wrong. Anyways any help or suggestions would be appreciated. We will be hitting it again tomorrow night. Might even take some video if it get close enough to the goal of 600RWHP at 19 PSI

[Guest JAMIE T]

I would start leaning out the fuel in that area slightly. 550hp on GTRS' huh... I should easily be able to hit my 600whp goal with my HKS GT2540's then. I was starting to question it. They are supposedly good to 750(probably flywheel). I'm looking forward to having the tuning problems, because then at least the car will be running.

[Clifton]

You can detonate on any octane of fuel. It will just take a little more boost and or timing but you are never safe. Is he running standalone? Is he controlling the VVT? Could be coming on too late. That kind of torque I would think he is running atleast 18- 20 psi. 30* is alot of timing.

[stony]

He is running HKS Vpro stand alone system. The same system i will be running its very impressive and almost has too many inputs

 

 

UPDATE:

 

As suspected it was a little too rich in that rpm range. He leaned it out and the torque curve is almost perfect now and its making 599.6rwhp with 530ftlbs of torque!!!! and this is at 21 psi. egt is still real low af ratio in the hi 11s and the air inlet temps are still in the low 140s. still hasnt reached his goal of 600 though so we are going to try and tweak a little more tomorro. and also tweak on teh midrange to try and get the lowend to come on a little earlier. if anyone is interested i will post a viceo or 2 later.

 

I was pretty impressed that the VG could make power like that. maybe that will be my next build

[stony]

Well almost done....fixed the dip in the torque curve..... it hits it's peak torque at 4500rpm (510ft lbs) and carries it all the way out to 6500 rpm and hp peaks at 602 all this at 21 PSI. should get above 620 easy once the goal 24 PSI is reached.

 

I must say with a bigger set of turbos and a custom intake 800+rwhp would be real easy on this motor. anyone considering a vg swap.... Im thinking it could be done cheaper then a RB26 swap. and the fact that parts are valable in the us makes it even more tempting.

 

Oh yea the idle is cool as hell. a vg with 272 cams has a good rumble to it