CAMARO6 - Max Spark Timing for LT4s on E85

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- - Max Spark Timing for LT4s on E85 (https://www.camaro6.com/forums/showthread.php?t=614429)

Quote:

Originally Posted by Megahurtz (Post 11298884)

On E60+ I usually run up to 28 degrees on the LT4's before any modifiers( Humidity and IAT's) and 29 on the LT1's before any modifiers. Even in full humidity, the modifier pulls half a degree. Then if things heat up the logic will pull more timing. I choose the set this up like OEM logic. I know some tuners remove most of the logic and lock in on a lower number timing number for consistency. I'm not saying I am right or they are wrong. I just do things a little differently. I have quite a few cars running around on the street with this setup with no issues.

I've seen one reputable shop run up to 32 degrees on the dyno on the LT4's with E62. However, I'm sure they back it down once it's off the dyno. I can't imagine that living very well on the street.

If the car is boosted to the moon I'll back that number down to 26-27 depending on the setup. Cammed cars are a little different as well. So my above numbers are stock heads and stock cammed cars. Timing is ramped up on the LT4 from a lower value to a peak value at redline. The LT1's are a little different. They like more timing pre peak torque, then less timing during peak torque then more timing after peak torque. I don't desensitize the knock sensors either.

That is what I generally do except I am more conservative on the timing.

I assume when you say 29 degrees for LT1 that is NA which seems right. Just curious what kind of timing do you run for FI LT1's on E?

Quote:

Originally Posted by KingLT1 (Post 11299218)

Yes definitely NA for the LT1.

Boosted LT1's I am very conservative on timing. Like 15-16 degrees on 93 and 19-20 on E even though I feel like you could get away with 21-22. I don't do much of the boosted LT1 stuff honestly because the pistons are so weak so I am definitely not as knowledgeable here. Even with a conservative tune these things can pop and then the tuner gets blamed. I actually turn down most work if it involves a boosted LT1 with stock pistons.

Quote:

Originally Posted by Megahurtz (Post 11299254)

Me too lol. I have mine running between 19-20 on E and 12 on 93 even though I have yet to run it on 93 with FI. It's pretty much been on E its entire life even when it was NA.

What do you guys think about Lambda on E60-E70? Meaning, do any of you run leaner on E60+ than you would tune a customer car for?

I run my LT1 .82-.83. I try to keep LT4 stuff around .84-.85.

Quote:

Originally Posted by KingLT1 (Post 11299457)

I run my LT1 .82-.83. I try to keep LT4 stuff around .84-.85.

Same here. I've gone up to .86 on my LT4 without an issue on 14lbs but I moved it back to .84-.85. I get nervous about .86.

Clients LT4's I target .83-.84 unless a lot of blower/psi and meth. Then I target richer.

Quote:

Originally Posted by Megahurtz (Post 11298884)

Cammed cars are a little different as well.

Do cammed cars like more or less timing than stock cammed cars?

Thanks

Quote:

Originally Posted by ZL14ever (Post 11307148)

Do cammed cars like more or less timing than stock cammed cars?

Thanks

As a generality, typically larger cams need more timing in the lower RPM range since dynamic compression and/or efficiency is reduced vs the factory cam in that lower operating ranges. As for WOT timing, it all depends on the build. A bigger cam doesn't automatically mean it requires more timing at WOT. This is where it is beneficial to use a dyno to determine what timing the setup likes.