Patman

I'm curious if anyone has figured out (through dyno tuning) as to an approximate horsepower gain for every degree of timing you're able to run when you're doing dyno tuning? I would assume it's slightly different depending on the level of the mods, so let's just say it's for a relatively stock LS1.

jimmyblue

iTrader: (11)

Torque Loss % vs Spark Retard might be an indication.
One thing it says to me, is -6degrees and you're still
at 99%.

<I attached a .gif of this table but is is not showing?>

Patman

The reason I ask is because when I initially had my car dyno tuned, it was summertime and I was running 94 octane. This time around, since it's cold out here, I am running 89 octane. So we had to take out some timing in order to get rid of the KR. But it was only about 50 degrees in the dyno room. So I feel 89 octane in 50 degree weather is safe, since I now run mostly 91 octane in the summer. So even though I could be down on some power, it's a safer tune now. In reality, I was probably losing a lot of power on the street when running 91 octane in the summer with a tune based on 94.

But if there was actually a big power loss, I would consider getting it re dyno tuned and going back to 94 octane.

We ended up getting the car to 290rwhp this time, vs 291 the previous time. But I also had a Vararam installed too. So it's not a direct comparison for me. I believe my timing is now set up around 26 degrees at WOT in the upper rpms.

SideStep

89 Octane

Why???

GuitsBoy

iTrader: (4)

Sell off some of your GC stockpile and youll be able to afford premium

jay_99z

iTrader: (5)

Lol!

Spends a premium on oil and oil testing yet runs 89 octane......

Patman

I run 89 octane in the winter because it's not necessary to run premium when it's fricken freezing outside. (besides, it's not often I get to go full throttle in the winter)

Seriously though, an engine's appetite for octane is a lot lower in the winter than in the summer. Running 89 octane in the winter is equivalent to running 91 in the summer. It wouldn't have made much sense to dyno tune with 91 octane in the tank when the temperature was only 50F that day, because then anytime it would be warmer than 50F I'd end up getting knock retard. I want this engine to last, not detonate itself to death!

Anyhow, I talked to the tuner just now and he informed me the total advance is 22 degrees, not 26.

Dixit

iTrader: (1)

Well Im probably going to **** off a few folks, but when the gas price hit $3+ dollars I basically starting filly 87 and just put in my tune that I had from awhile back where I got the timing set low enough that it wouldnt ping or knock on 87. It works just fine, just a good loss of power, but like Patman said, in winter the cold azz air makes up for it. It almost feels as good as premium in summer.

Dixit

jay_99z

iTrader: (5)

Lol! I was just kidding man. Winter here in South Carolina is a little different than Canada....

Bombguy99z28

I guess its a trade-off, you get lower combustion chamber temps but more air density in the cylinder... kinda like run leaner with less timing or richer with more timing, but since its cheaper to run with lower octane I'd do it over the winter, you probably won't see too much if any performance difference in a normal setup, and I doubt the vararam would make much of a difference on the dyno anyway, at speed I'm sure but static I dunno.

I only see about 22* of timing in my stock vette on 91 cali gas. Don't know why, but I've spent hours upon hours trying different things and thats all it wants. Since thats what it wants I'm gonna leave it alone.

DaleMX

iTrader: (4)

I'm at 28 with 93 octane and 10.8 CR and no knock. Of course thats only at certian places on the high octane table. 28 might be killing HP though. Only the dyno knows for sure.