Whhhhaaaaattttttttt are you doing with a 13.0 at 7100 rpm. That thing should be an 11.3 from the time it makes 10-15psi, and up. You're gonna melt that motor..

 

Lean is mean...
I mean lean is melting

11.3-11.5 is where I would want to be.

Or if you could add fuel over time and go from 11.5 to 11.1 if you were 5th gear cowboy mode.

Important detail to remember is that the 02 sensor is an Average of all the cylinders. Depending on how close the injectors flow, how the intake and exhaust manifold are designed its possible that some cylinders are leaner or fatter then others

 

Vacuum assist is due to electric vacuum pump installed. Red hose to silver pump in pic. Silver cylinder on strut brace is holding tank.

 

The MAP sensor immediately seeing vacuum is because the throttle plate closes. The length of time spent at WOT/in boost doesn't effect that. The vacuum pump also has no effect on this as it is attached to the crank case, not the intake manifold or any other part of air induction system.

 

 

Are you guys talking gasoline or E85?

 

Both really. Everything just stays happier in the low to mid 11's. Not worth the small gains running high 11's. You gain nothing getting into the 12's, and past 12.5 you lose power.

 

When you get richer, the EGTs in the exhaust manifold go up from unburned fuel, which may not be representative of cylinder temps, but it is indicative of what temps your exhaust valves and turbine housing are seeing. Not sure whether that is a factor to consider in road racing applications? When I was running an EGT sensor on my car and self-tuning years ago, I saw EGTs go well north of 900c when AFRs were in the high 10/low 11 range and they stayed lower around 11.4-11.5. At the time, I was trying to strike a balance between not burning a piston and not burning a valve or hurting the turbo.

 

If that were a concern, stock Evo's running low 10's would melt everything. Timing plays a big factor as well, you have to have enough of it or you'll have high EGT as well. If you left the timing the same and dropped EGT by taking fuel away, you probably needed more timing at the richer AFR. Peak EGT is going to be around stoich (14.7-15:1), higher and lower than stoich it drops, unless timing is a factor and you're running too much or too little.

My car runs slightly leaner, on pump, it seems to like an 11.7-11.8 with the combustion chamber work done by head games. E85 was happiest around 11.1-3. At no point is anything over a 12.0 really doing anything helpful. And above 12.5 you're asking to burn **** up.

What was well north of 900? Because 900 is really fine, even though it is on the higher end of fine..

 

900c = 1652 Fahrenheit doesn’t aluminum melt at like 1700 f so that seems like cutting it close no?

 

If you had air constantly flowing thru there at that temp long term it could but its essentially short duration with the air not able to actually transfer enough energy to the aluminum to melt. Think about your combustion chamber which is much higher at combustion than you get 10" past the valves at your EGT sensor.

 

gotcha that makes more sense. Thanks

 

Maybe 920ish? Not near 1000c, though I feel like I read something By PA or Element Tuning that they routinely see 1000C EGTs in their unlimited car. There really was no way to bring them down In my car with tuning. My timing is already higher than typical recommendations for 93 and my boost is only around 23 psi up top where I see those EGTs. I’ve run the tune in all kinds of conditions and never see knock at high RPMs on track, so I’m not worried at this point.

 

I'm sure your car is fine. Generally EGT/AFR/Timing doesn't universally apply. Each car needs some paying attention to see what it likes

What turbo is holding 23psi out the top?

 

English racing did a test a few years ago and ran a pretty wide range of AFRs on E85 and I remember them not really having too much change in power at all over a wide range of AFRs and all the power to be had was in timing. I dont remember what that range was but I feel it was something like 10.5-11.5.