C7 z06, did i go too hot?

[mJolnir]

The car is a 2015 c7 z06, it has a intake, headers, 18% overdrive lower pulley, flex fuel sensor and a Meth kit with a 30 gpm injector on 100% meth. The car doesn't have a wideband installed, so we used the one on the dyno, AFR goes to 0.69 on the hit and then it gradually gets leaner until redline and ends up at 0.78. The owner didn't bring any spark plugs at the end of the last pass i took one of the spark plugs out and it looked like the timing mark was before the bend but this was a 3 months old spark plugs.

dynowatermeth10 e60 680whp 797wtq.hpl
dynowatermeth11 e60 690whp 804wtq.hpl


After the 690whp pass i felt it was way too much timing and retarded 2* so it ended up with the same ignition to the 680whp pass. its my first time tuning a car with this much meth.

did i go too far on the timing?

[TriPinTaZ]

I think your instincts led you in the right direction. 2.5 degrees of additional timing only gave 10more HP. That means there is a very small increase in power per degree past the 27 degrees on your 680rwhp run but a very large step towards danger. Ethanol and Meth will beat the bearings out of the crank before you see any signs of troubling knock retard. It's not like tuning on 93 pump gas. For the record, I typically run between 25-27 degrees by redline on the LT4's dependent on Ethanol content, Meth volume, and how much the blower is over spun. This would all be on stock cam stuff. For your setup, I just tuned a ZL1 with identical mods running E75 and Meth and I settled on 26.5 degrees of Peak Timing.

One suggestion I would give you is since you're spraying meth as a fuel source and your injector duty cycle is still below 5ms, get the SOI at 360 or below. There is no sense in spraying fuel at the very end of the exhaust stroke when you have plenty of room to start injecting at TDC. The exhaust valves are still closed at SOI 370 so its not a big deal. Also LAmbda of .78 is a bit rich for a DI motor. I am for .80-.82 on a setup like this.

[mJolnir]

I think your instincts led you in the right direction. 2.5 degrees of additional timing only gave 10more HP. That means there is a very small increase in power per degree past the 27 degrees on your 680rwhp run but a very large step towards danger. Ethanol and Meth will beat the bearings out of the crank before you see any signs of troubling knock retard. It's not like tuning on 93 pump gas. For the record, I typically run between 25-27 degrees by redline on the LT4's dependent on Ethanol content, Meth volume, and how much the blower is over spun. This would all be on stock cam stuff. For your setup, I just tuned a ZL1 with identical mods running E75 and Meth and I settled on 26.5 degrees of Peak Timing.

One suggestion I would give you is since you're spraying meth as a fuel source and your injector duty cycle is still below 5ms, get the SOI at 360 or below. There is no sense in spraying fuel at the very end of the exhaust stroke when you have plenty of room to start injecting at TDC. The exhaust valves are still closed at SOI 370 so its not a big deal. Also LAmbda of .78 is a bit rich for a DI motor. I am for .80-.82 on a setup like this.

How do i go about the SOI i see that the base SOI table only goes up to 356 but in the log goes up to 372, should i take out from that table?

0.78 was the leanest i could get it without butchering the MAF table, im basically commanding 0.99 in PE to get it there.

How much power did that zl1 make?

[TriPinTaZ]

There is a SOI Alcohol Offset table you have to take into consideration now since you've enabled flex fuel. Your additional SOI is coming from that table. I have found that tuning for meth you almost always have to make weird MAF adjustments which then require torque adjustments, especially on an automatic car.

I don't recall the power of that ZL1. It made more power when tuning it again on the street so I don't really put a lot of weight into the dyno. It is certainly a great tool but many of the guys I tune for run on the street or at the track and we tune for that vs on a dyno.

[cadillactech]

Could you go the next size down on the meth nozzle to lean it out?

Best thread I have found on the SOI is here https://forum.hptuners.com/showthrea...njector-Timing

[TriPinTaZ]

^^ If he were to cut the meth a little he shouldn't run anything less than E65 with that much timing in it.

[cadillactech]

^^ If he were to cut the meth a little he shouldn't run anything less than E65 with that much timing in it.

Yes timing would need to be looked at, would be an interesting experiment to see what the power does if he gets it closer to .80 and the timing where the engine wants it.

[mJolnir]

Yes timing would need to be looked at, would be an interesting experiment to see what the power does if he gets it closer to .80 and the timing where the engine wants it.

Actually from what i have read methanol dont like being lean, and you loose very little power by being rich on meth unless you cant light it off, so im not worried on leaning it out, the owner of the car wants to go 9's so we will probably add more air instead of taking fuel away :P

[TriPinTaZ]

Actually from what i have read methanol dont like being lean, and you loose very little power by being rich on meth unless you cant light it off, so im not worried on leaning it out, the owner of the car wants to go 9's so we will probably add more air instead of taking fuel away :P

But DI motors don't like being overly rich . You're probably safe at .78 lambda though. If you go a little richer you may actually have misfires and fuel knock.

[cadillactech]

Actually from what i have read methanol dont like being lean, and you loose very little power by being rich on meth unless you cant light it off, so im not worried on leaning it out, the owner of the car wants to go 9's so we will probably add more air instead of taking fuel away :P

Yes fuel knock would be the only concern with this. the .69 at the start just seems really rich but if no fuel knock or misfires, then no problem!

[mJolnir]

we did have misfires in the beginning, but that was on the first passes where i was still commanding PE 1.20 and turned the meth on, it was so rich we had to turn the car off and leave the dyno cell until the all the meth was cleared, it was so emotive with everybody crying right there.