what race gas??

[forum]

Well?? it's for my 426. My engine builder said with some race gas it could add as much as 5 hp to my 426, since the stock compression is already so high. He told me that the MR2 works really well but its oxygenated to I'll have to upjet the carb. which i don't want to do cause then I'll have to rejet when im practicing and not using race gas. He said th other kind thats good is D somthing or other. What do you guys recomend and does the oxygenated fuel really help enough to change the jets before every race.

[timewass]

I run VP C-12 in mine. 50/50 with Sonoco 94

[AndrewRRR]

I run Unocal Competition 110. Used to run VP C-14 but the specific gravity is too low to use with premix oil.
Are you at stock compression? Usually the only reason people run race gas is to avoid detonation on high compression motors. I read recently, race gas can actually decrease performance because since the higher octane fuels are harder to ignite and burn slower, the power stroke doesn't begin until too late after TDC.
I guess give it a try, but if I didn't feel a power difference (5hp on a quad is a lot! 10-20% for most), and wasn't getting detonation with pump gas, I'd just use pump and save that extra $3 or so per gallon!
Not sure what "D" race gas is, unless he's talking about Daeco. We used to run Daeco or Cam2 way back in the day with karts.

[Giz400ex]

:) I ran straight VP C-12 last year and this year I'm gonna try 50/50.

[wilkin250r]

High octane fuel and race gas are not necessarily the same thing. Alot of race gases are oxygenated More oxygen means you can burn more fuel, which results in more power. Methanol added to fuel does basically the same thing, when the methanol burns, it decomposes and actually adds a little bit of oxygen to your fuel/air mixture, meaning you can burn more fuel.

When you compress a gas (like your fuel/air mixture) it heats up (Boyle's Law) This heating can cause the fuel to ignite on the upstroke, before the spark plug fires. This is called detonation, and it is very bad for your engine. High octane fuels are not more explosive, they are more stable, which allows them to handle the higher compression. The extra power comes from the higher compression, not the fuel.

I can't see how you would gain more power if you got a race gas that was not oxygenated, which would require re-jetting. I could be wrong, go ahead and try it out, but I have my doubts.

[forum]

well this is a yz426 engine. which has 12.5:1 compression stock. They are able to run on pump 94 but are said to really be helped by race gas. The local toronto Yamaha backed factory team told my engine builder that the mr2 oxygenated VP fuel adds 4 Hp to there 426's and 450's. I was wondering how much larger main jet would i need to go to run mr2?

[lilpoppy]

Maby I'm wrong but I have alwase been told that it is the compression that you are getting the power from not the gas. The gas just helps it run cooler. If it actually does add power 5 sounds hella high.

[Big - D Racing]

I seen dynos done on a 440 with 92 octane and straight c-12 and it picked up 2 hp with the c-12.
I run the c-12 straight in my 440.

[wilkin250r]

Methanol (or some other type of alcohol) added to the fuel can actually increase HP because the alcohol will add oxygen, enabling you to burn more fuel, which results in more power.

[timewass]

Alcohol also runs much much cooler.

VP!:D

[AndrewRRR]

I switched to Unocal from VP. I'd rather pay $218 for a drum compared to $380 per drum. Keep that extra $160 in my pocket

[nick23]

cam 2...110 octaine

[29FTEX]

One of the additives you could add to your race gas is Propylene Oxide. It's like liquid nitrous. ONLY use with proper jetting and 10% or less ratio. You have to know what you're doing with it. I bought a 5 gal. can of it for $150. I ran it on 2 races, and man what a difference in the power and sound. I'm not going to run it anymore... I don't want to scatter the motor. :D