426 MagnaCharger-Dyno Sheet

Didn't that guy have heads and cam also?

 

I will "eventually" call you and we have to get together for a test ride!

Tell me about it!! Thanks....I agree about the VP109

 

Chad it was me that trapped 110mph with a custom VP109 tune I think on that pass I ran a 12.25 after richening up the tune from the previous pass, I went from 108.66 to 110.21 which is a pretty good pick up in MHP in less than 15 minutes

 

Lets assume your jeep has a nice tune that gives a perfect 11.8 AFR under WOT with pump gas.

So now it is race day. We add some timing to our tune, drain the fuel tank, and fill up with some high octane unleaded VP109.

We go for a blast down the 1/4 mile while datalogging and see the A/F is reading 12.8 then make a quick trip to the bathroom only to find out they are out of toilet paper (just seeing if your awake)

There are a few factors here to consider.

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. For the most part a safe lambda value is .80 to .82 for a forced induction jeep. I prefer .80

So we take VP109 stoich of 13.41 x .80 lambda = 10.73 AFR
This is the AFR (10.73) I am tuning for.

Keep in mind this is not what will display on your wide band as it is programmed to 14.7 stoich. You must convert the AFR.

AFR/Race Gas Stoich*Wide Band Stoich

10.73/13.41*14.7 = 11.76 AFR is what I want to see on my wideband when running VP109.

Just to reiterate 11.7 on the AFR display with VP 109 is really a 10.7 AFR.

Ok so hopefully you are not totally confused.
Some AFR modules may be able to be programed to the correct stoich.
Or leave the stoich in the tune and wideband at 14.64 and calcualte what AFR you need to read on the wideband for the fuel that is used.

This is why you have to exercise caution when mixing race gas and pump gas as you do not know the true stoich of the mixture.

More:

Race Gas Stoich Ratings

Sunoco MO2X UL – 14.5
Sunoco 260 GTX – 14.4
Sunoco 260 GT – 13.9
Sunoco 260 GT Plus – 13.7
Sunoco Standard – 14.8
Sunoco Supreme – 14.9
Sunoco MO2X – 14.5
Sunoco HCR Plus – 14.8
Sunoco Maximal – 15.0
Sunoco MaxNOS – 14.9

Turbo Blue Unleaded (100 octane) -13.9
Turbo Blue Unleaded Plus (104 octane) - 13.7
Turbo Blue 110 - 14.7
Turbo Blue Advantage - 14.9
Turbo Blue Extreme - 15.0

VP Street Blaze 100 - 14.16
VP C10 -14.53
VP C16 - 14.77
VP 110 - 15.09
VP MS109 - 13.41

 

I was talking about the magnacharger.

 

Chad you may be right on that then I don't recall, I do know his tune (well considering where he went for it) is probably not anywhere near close to being optimal.

 

He had a few supporting mods.....

So went with the 6.3psi Magnacharger S/C
Fastlane custom grind 607 cam & springs
American Racing headers with Cats
Borla S cat back
2800 stall converter

 

Yeah , I was just taking it easy on Wade making sure he had his facts straight.