Race gas

383stroker

383stroker

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ontario
Wondering what my squish should be to run 112 race gas?


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if ya need race gas, or gonna need race gas, i assume your gonna have your heads cut. yes this will change your sqiush and raise your compression. if your looking for a cut off number, where ya need race fuel, its gonna depend on how much your heads are modified and your squish area is changed. just guessing, i would say any squish area changed to under .040 is starting to get to good fuel area. 3:16 (yammie tony)
 
That's what I thought. The heads were to be cut for race gas.


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I ran essentially those same numbers in a 780 on non ethanol 91 with torch accelerator at 8 ounces to 5 gallons of fuel for 4 years without any fuel issues.
 
theres alot of factors that go into a engine as far as what octane it needs. compression, squish clearance, timing advance, the actual port timing on the exhaust port. There is no advantage to running race gas, its just what you need to keep the engine alive. The more octane you have the less volitile the fuel is so remember, you can make the utmost power on 87 octane vs 112 octane, however the engine wont live long due to detonation, so just because you run your engine on 93 pumpgas doesnt make it a low output motor.

It seems to suprise guys when they build a heavily modded engine and it will make awesome power on only 96-97 octane, and low 102-104 octane on imp and pro stock engines. It all about how the engine is "set up" as to what fuel youll need.
 
I understand. Running 116 fuel is probably a lot on the safe side. Could go back to 102 and still not hurt anything.


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using more octane then what is needed makes you lose power. I dont know anyhting about your engine specs but you might be suprised at how well a pumpgas and small mixture of race gas will work. like say a 70/30 ratio,70% 91-93 octane and 30% mix of race gas and then start watching the piston wash, you basicly can jet the sled by changing the mixture of the gas, the more race gas you use the richer it will run with the same jets in the carbs!
 
So octane just changes the ignition timing. More octane less timing?


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no... the octane doest change the timing it just makes the fuel more resistant to burn. More octane is a slower burning fuel with less heat. By adding race gas to say a bone stock srx or any snowmobile youll automaticly make the engine run richer without even touching the carb settings. The more octane you have, the richer the engine runs if nothing else is changed.

the "octane" is the fuels ability to NOT burn, so if you have ever tried to start a race sled in the winter with race gas its almost impossible because the fuel doesnt want to burn or explode, pumpgas will start right up ,make more power but the engine will usually need more octane because you added compression, or added ign timing. ign. timing.

In a 2 stroke engine,adding ignition timing adds heat to the piston, so when you add a crank offset key or a cdi with more advance your putting more heat into the piston crown of the engine. To combat this heat youll increase the jetting or increase the octane because it will be more resistant to burn and will allow it to cool the crown.
 
How much squish would you suggest with 780 turning 9700rpm running a 1/4 on tar? We plan on running 112 or 116.


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383stroker said:
How much squish would you suggest with 780 turning 9700rpm running a 1/4 on tar? We plan on running 112 or 116.


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kinda tough to give you a set number because i dont know any specs on your engine such as exh port timing, ign. timing,etc.

Seeing your turning high rpm your gonna wanna be generally around .052-.055" squish but would use a 10.5 degree angle for a race engine.
 
Thanks for the info. I had them cut to .053 squish. We will see how it works now


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