Oxygenated Race Fuels
10-12-2014, 09:22 PM
#1
Oxygenated Race Fuels
Anyone have experience with highly oxygenated unleaded race fuels such as Sunoco 260 GT Plus? Sunoco state this fuel requires additional fuel flow. I'm assuming the tune will automatically compensate for this correct? Or do I need to make specific changes to the VE tables?
10-13-2014, 06:50 AM
#2
Safety Car
I tried it once at the track - sometimes I'd add some 103 to boost my octane a bit if I only had 91 in the tank, they were out so I tried 110 originated..... Which was all they had left....Turns out it slowed me down like my tuner said it would've ... that's been my experience with it....
10-13-2014, 08:20 AM
#3
Tech Contributor
Anyone have experience with highly oxygenated unleaded race fuels such as Sunoco 260 GT Plus? Sunoco state this fuel requires additional fuel flow. I'm assuming the tune will automatically compensate for this correct? Or do I need to make specific changes to the VE tables?
You'll need a race gas tune. When you get it, don't go changing race fuels either. That could be the recipe for disaster too.
10-13-2014, 11:09 AM
#4
The tune will compensate in closed loop while cruising around. The second you meet your power/boost enrichment requirements, you go into a fixed routine. That's the point where you get in trouble. I've had to add as much as 20% more fuel to tunes when changing to race gas.
You'll need a race gas tune. When you get it, don't go changing race fuels either. That could be the recipe for disaster too.
You'll need a race gas tune. When you get it, don't go changing race fuels either. That could be the recipe for disaster too.
The reason I am asking is that I usually run Sunoco 260 GT 100 octane. But I'm having trouble procuring this right now and I may need to run either Sunoco 260 GT Plus (104) or VP MS 109.
Last edited by Neil B; 10-13-2014 at 11:11 AM.
10-13-2014, 12:21 PM
#6
Burning Brakes
Sunoco 260 GT 100: Stoich is 14.1
Sunoco 260 GT Plus: Stoich is 13.7
VP MS 109: Stoich is 13.4
If your car is tuned for pump gas (highly likely), then for both of these you will need to add fuel or you'll be lean.
10-13-2014, 02:12 PM
#7
I checked my tune and the stoich scalar is set to 14.63. So I just need to change the stoich AFR scalar value in the tune for the desired fuel, correct? I'm assuming I would also need to rescale my wideband or use the lambda value.
10-15-2014, 08:46 AM
#8
Tech Contributor
your PE won't compensate. It's a multiplier and that's all. It was factored into your original tune and so you can expect to be lean. Using the scalar should scale your entire VE and get you there. Just ease into boost and watch your AFR's on the first hit to verify or (what I prefer to do) throw extra fuel in the boosted region of your fueling make your hit and see where you're at. I always choose to lean-to-suit when tuning. Much safer that way.
10-15-2014, 12:25 PM
#9
^^^ That's correct. Then cruise around and make sure your fuel trims are close to 0.
your PE won't compensate. It's a multiplier and that's all. It was factored into your original tune and so you can expect to be lean. Using the scalar should scale your entire VE and get you there. Just ease into boost and watch your AFR's on the first hit to verify or (what I prefer to do) throw extra fuel in the boosted region of your fueling make your hit and see where you're at. I always choose to lean-to-suit when tuning. Much safer that way.
your PE won't compensate. It's a multiplier and that's all. It was factored into your original tune and so you can expect to be lean. Using the scalar should scale your entire VE and get you there. Just ease into boost and watch your AFR's on the first hit to verify or (what I prefer to do) throw extra fuel in the boosted region of your fueling make your hit and see where you're at. I always choose to lean-to-suit when tuning. Much safer that way.