Anyone care to help if I run VP MS109 = 13.41 stoich and my stoich is 14.7 on pump gas with a 12.5 A/F at WOT, where would my WOT A/F need to be at on the VP 109? 1.3 LOWER at 11.2??? Ever wonder if your airfuel will change with race gas? The answer is yes.... Real gasoline has various different stoich points due to the blend, how much ethanol is in it, etc. It is somewhere between 14.1 and 14.7 though. Finding the information on race gas isn't easy. It is not posted anywhere on the internet that I have found. VP does not publish it, nor does Sunoco (TurboBlue) Several weeks ago I got in touch with the chemist at VP and got all the stoich points of their fuels. Last week I got in touch with a Sunoco chemist and got the data from him as well. When I asked the guy from Sunoco why they don't publish the information on the TurboBlue website he said - Quote: You're right, stoichiometry is important. Fact is many people have no idea what it is - kudos to you for knowing. Unfortunately many folks we talk to think the stoichiometric air/fuel ratio is where they should set their fuel system at wide open throttle. So we are torn about posting or not posting stoichiometry data because of that potential problem. Shocking right? Especially when you see how different the fuels are... Here is a list of the ones I have gathered. 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): 13.9:1 Turbo Blue Unleaded Plus (104 octane): 13.7:1 Turbo Blue 110: 14.7:1 Turbo Blue Advantage: 14.9:1 Turbo Blue Extreme: 15.0:1 VP Street Blaze 100 = 14.16 VP C10 = 14.53 VP 110 = 15.09 VP C16 = 14.77 VP MS109 = 13.41 Back to pump gas.... While I had the Sunoco guy's ear, I tried to get an answer about the stoich of their fuel and to find out how much actual Ethanol is in it, when the label says up to 10%... Here are his comments... Quote: I know plenty about pump gas, enough to say that there is no useful stoichiometry data on pump gas. Composition varies WAY too much, regardless of brand/refinery/etc... especially on the lower octane grades. But I can tell you that Sunoco 94, which is very hard to find these days, will contain some ethanol. Per the first sentence, it will depend on the blend though. I would go out on a limb and say it is nearly 10% most of the time (keep in mind 10% is the max allowed by law). Street gas blends change all the time thanks to environmental requirements (fed/state/local), seasonal adjustments, and price pressures. Really makes you wonder if what is common knowledge of what is the 'right' a/f is completely wrong. stoichimetric ratio for various other fuels: Gas (Reg=14.8...Prem=14.7) Iso-octane=15.2 Diesel=14.5 Methanol=6.47 Ethanol=9 E85=9.87 Propane=15.67 Hydrogen=34.3 Methane=17.2 Kerosene=14.5 Benzene=13.3 Toluene=13.4 LPG=15.5
Wow, good stuff Wade! I guess you'd want to be careful to avoid the ones with a stoich below 14.7. As long as you're at 14.7 or above you're going to be running fine or on the rich side at part throttle.
Sure, I'd think so. How much, I don't know... I'm thinking if Stoich was .2 different then you'd want to adjust your WOT by .2. Maybe not. Part of that enrichment is for cooling and the cats if you have them. Don't know if that would change linearly with the stoich.
if you are going to run race gas at the track and pump gas on the street you should have two different tunes. your timing can be different snd the amount of fuel or a/f ratio can be different your tuner should be able to help you with it. i am going to say this running race gas compaired to pump gas can in some casses let you run more timing than with pump gas there are a lot of factors to determine exactly what your tune will be but just so you know i have different tunes for different ways i run ex. pump gas, race gas tune and nitrous tune.
Thanks but way ahead of ya on that info this track tune is for VP 109 only I have a good tuner we've been working on this for a while. Can't give out all my secerets:bigwink:
