mactizen

iTrader: (1)

I've been running 94 octane pump gas (ethanol blended) and have been running 6 degrees less timing then my NA tune with fantastic results. Ive been wanting to jet up to 200 and eventually 250 but don't want to do that on pump gas for safety. So anyway, I want to start slow and stick with my 150 and get it set on the ms109 before upping the jet. I'd like to know if there is a rule of thumb for how much, if any, more timing I can run or if its all play it by ear for the conditions.

mods
ls2 w/stg 2.5 cnc 243 head hand finished, ms3, fast 102, ported z06 tb, NO plate kit
th400
3.73 gear 28x10.5ETdrag

ronn25

iTrader: (3)

I believe the only correct way to set the timing is by reading the plugs after a pass. The plug will show a timing mark on the ground strap. Do some searches on here for plug reading to get an idea.
Some of the more experienced guys will probably chime in on this.

mactizen

iTrader: (1)

I shut down at the stripe and pull plugs after every pass, was just looking for a rule of thumb type deal to get started.

Graham@NitrousOutlet

I wouldnt make any changes other than swapping the gas and making a pass. No reason to over guess it.

mactizen

iTrader: (1)

^agreed

Went out on motor and picked up 2.5 mph and a tenth in et. Hoping for good results on spray!

Ran a new best motor et and mph 10.24 @ 131.75

Carter01

iTrader: (11)

Uh? If that's the case I wouldn't touch the timing. Sounds to me the motor conditions were too hot to start with (via timing and pump gas). 2.5mph in similar weather conditions means a significant increase in power. Race Gas burns at slower rate which cools the cylinder hence protects against detonation. Treat your setup as safe as possible as if you are still running 94, reads the plugs like your doing and creep up on the 250.

owndjoo

iTrader: (2)

i ran this fuel in my old 50trim turbo talon. i picked up .5 et and 12 mph completely unchanged tuned. the fuel trims were maxed out on lean... had too big of injectors, but this fuel is badass!!

mactizen

iTrader: (1)

sorry forgot to mention I added 1 degree made a pass then added another 1 degree. I will be pulling timing when I spray as I was before, then start adding a little back in if the motor is liking it. My motor tune is now +2 degrees from where it was and loves it. I'll be pulling atleast 6 for a 150.

ATVracr

iTrader: (5)

That is an oxygenated fuel, that's why it picks up so much on motor.
Be careful with nitrous, it will burn hotter.
If it were mine I would pull more timing than normal with that fuel.

We ran Q16 for a season a couple years ago and with a lot of nitrous most dont recommend oxygenated fuel. With 150 shot you'll be ok but I would pull some extra out, maybe start with -9*

mactizen

iTrader: (1)

I have no problem starting safer, would you pull 9 from my pump gas na tune or the new tune I added timing too?
Also I'm in Canada so my 94 pump gas is up to 10% ethanol blended (oxygenated) year round. That's why I went with the MS 109 as I had good luck with it in a turbo 4 cyl car, I had almost no corrections to make on the fuel maps to get my afr's in line.

Dirty Vegas

iTrader: (12)

Something was very wrong on your tune to begin with. VP MS109 is 13.4ish stoich

The stoich rating of VP109 is 13.41.
Most wideband A/F modules are calibrated to 14.7 pump gas stoich.

So this is the formula to determine the true A/F for the run.
AFR/Wideband Stoich x Race Gas Stoich
12.8/14.7*13.41= 11.7 AFR on Race Gas

So you may think 11.7 sounds safe but we must remember the VP109 stoich is 13.41. So 11.7 AFR = .87 lambda.

So we take VP109 stoich of 13.41 x .80 lambda = 10.73 AFR