StreetStangs.net - Must read on race fuel stoich points

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Must read on race fuel stoich points

Great info from Eric Brooks on modularfords

Quote:

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:
Eric - 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.

so me running VP110 it needs to be 15.09?????:think:

.....EDITED this post.......

another quote

Quote:

Some of the race gas like C16 has a similiar stoich point, so there is little change.

If the stoich is numerically lower than pump gas, it will run leaner.

EDIT.. Here is the original thread Joe http://www.modularfords.com/forums/s...d.php?t=132632
EDITED again...disregard original post I was wrong in my thinking.

Quote:

Originally Posted by joecoupe (Post 181445)

so me running VP110 it needs to be 15.09?????:think:

a few variables come into play here alot depends on the blue print of the engine such as is block sqaured decked is is engine set up for quench aluminum vs cast heads are all the chambers cc'd the exact, are all injectors performing exact same,valve adjustments, ring gaps,are intake runners flowing exact same etc etc. one misconception is sometimes or alot of the time when afr is set at the perfect stoich the engine will mis or vibrate and people think it is detonation when in reality it is opposite cylinders are making different amounts of power that is one of the reasons you will see tuners run to the rich side to smooth things out. as such was learned from airplane techs way back when.lol it takes alot of careful machining and planning to produce an engine that will run at or near perfect stoich. one key tool would be to have a sensor on each individual cylinder.lada da da da da! enough said for now.but it is good to know the stoich of each fuel as such to get as close as possible and still run smooth. but what do i know?jmo.lmao budlight time. brain needs a break.

Quote:

Originally Posted by waypastcrazy (Post 181523)

so i could lean on mine a little more with vp110

Quote:

Originally Posted by joecoupe (Post 181524)

so i could lean on mine a little more with vp110

yes you can

Quote:

Originally Posted by waypastcrazy (Post 181523)

one key tool would be to have a sensor on each individual cylinder.....

l would think this would be very beneficial when tuning a carb motor, right?

Quote:

Originally Posted by QWKSNKE (Post 181529)

l would think this would be very beneficial when tuning a carb motor, right?

it depends on how much a person knows about setting up a carb for tuning and how well balanced the intake runners are but yes it definitely will show just how much a copy cat knock off intake or out of the box carb is way off on afr from cylinder to cylinder.very few people take the time to study and learn how to tune a carb i have met 0 that have.fuel injection is far easier but myself i enjoy the learning process of both.if i get into carbs we will be here for a while lol iab,mab,tc,iam,etc,etc:boxer:

something i will start on sat!!! another learning curve.:banghead: