Race fuel or pump gas

Kennedy_Power

New Member
Apr 8, 2008
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Rochester,Michigan
People ask me this question all the time. Should I run race fuel or pump gas. You will loose power on your bike if you run race fuel on a low compression engine. Race fuel has a slow burn rate and needs lots of compression and a different ignition timing to get the benefits from it. I have done several tests on different fuels and seen huge power drops on my own engines. We where trying to eliminate all possibility’s during testing a few years back. One test on fuel dropped the bike down 10hp and even when we pulled the timing out it was still down 8hp. When your spark plugs rattle loose, it’s from detonation, back your timing off -2
 
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Thanks for the great info ! So essentially in mild/stock motors running 93 octane would be best or would 87 be better?
 
also wondering...

and im running 91 right now. i havent checked my compression yet, i guess i should, for all i know buddy could have milled the head before me.
 
One test on fuel dropped the bike down 10hp and even when we pulled the timing out it was still down 8hp.


8-10hp on a Blaster would leave it with like, 1/2hp?? I don't see how that could be possible on a Blaster motor. Surely you would be able to feel a 8-10hp loss and I've never felt a gain or a loss when switching octanes, especially one as dramatic as an 8-10hp loss.
 
8-10hp on a Blaster would leave it with like, 1/2hp?? I don't see how that could be possible on a Blaster motor. Surely you would be able to feel a 8-10hp loss and I've never felt a gain or a loss when switching octanes, especially one as dramatic as an 8-10hp loss.
He's probably talking about a shee or something, he does all sorts of bikes not just blasters. Also hes Probably not talking stock. read some of his other posts and you'll quickly realize that he knows what he's talking about he does a lot of R&D on the dyno. So when it comes to HP numbers he would no better than most of us.
 
Well on some motors you can lose 10hp from a sparkplug change, but that's not going to be typical for a stock to lightly modded Blaster. It's kinda deceiving to say you can lose 8-10hp from running race gas because those results aren't typical and don't apply to 99% of the bikes on here. Chances are most of us would never be able to tell the difference because the loss/gain would be so minimal.
 
keep in mind that most of the people who use this forum on a regular basis are at least somewhat familiar with kennedy's back ground. And you might be suprised to know how many people on here are modified to the point that they would be affected by this. maybe not to the point of 8-10 hp but to some extent
 
Ok?

I'm sure there are a few people who have full race motors, but the majority don't. The way it sounded to me was that these are typical results for the average person, and they aren't. For the majority of us, it really doesn't matter if we run race gas, pump gas, AV gas,...etc.

I'm not doubting his knowledge or his background so I'm not sure why you keep bringing that up?
 
Ok?

I'm sure there are a few people who have full race motors, but the majority don't. The way it sounded to me was that these are typical results for the average person, and they aren't. For the majority of us, it really doesn't matter if we run race gas, pump gas, AV gas,...etc.

I'm not doubting his knowledge or his background so I'm not sure why you keep bringing that up?

well quit your bitching and just stop. he builds high performance motors.

why do you keep bringing it up and saying that its like we dont care? if you dont care or dont belive him, dont look at this f*cking thread.


Hi im the blunt guy. Whats your name?
 
if yo u are satisifed with mild compression then yes premium pump gas will be better for you than race gas in that application ,for guys wanting the best torque out of the little engine and willing to use high octane race fuel for the most benefit they will see surely see improvment ,keep in mind the race fuel itself adds only a small percentage of gain(5-7% over pumpgas ) and these race blends vary alot ..some are hardly better than the watery crap out of your local gas station . its the mods that require the anitdetonation rating are what gives the power gains like high static compression and ignition timing advancement these are the things that really help out the torque factor *but require the need for slower burning fuel types (lead and oxygen are nice power adders though too) to ward off the inevitable detonation that would occur by using said mods ,many things to think about when building an engine
 
well quit your bitching and just stop. he builds high performance motors.

why do you keep bringing it up and saying that its like we dont care? if you dont care or dont belive him, dont look at this f*cking thread.


Hi im the blunt guy. Whats your name?


Calm down. Jesus, pull the stick out of your ass.
 
I'll throw some tech and useful knowledge into the mix and you can argue and get pissy like a little girl about this all you want.

When we asked Eric Klein if we should run race gas with this motor setup, he replied, “You should always run race gas in a Blaster since it is air cooled and race gas runs cooler.”

Project Yamaha Blaster Part 3 - Holeshot Potential


You also might want to think about the difference between "pump gas" being unleaded and most "race gas" being leaded. Don't reply unless you have something of value to add to this topic. Pissing and crying because someone questions a statement doesn't solve anything, especially when you don't have ANY information to prove anything right or wrong.
 
i guess it's that time of the month again...

put 115 octane in a stock blaster and let us know what happens! i'm curious. lol. it's definately not gonna make 10 hp difference on stock blaster, he was obviously talking a race motor. if it make 10 hp less on a stock blaster it wouldn't be running. but it WILL make a difference. it is physics. octane ratings should match compression and timing, thats all there is to it. like he said, if the octane is too high, it is too hard for the poor little blaster to ignite, and it burns more slowely. making less power and maybe even a miss. on the other hand, run too low octane with too far advanced timing and too high compression, the mixture will spontaneously combust (detonate) before the piston gets to the top of the stroke, and if it's bad enough, you'll have a rod stickin out the side of your motor.
 
i've went into detail on several other threads about octane and when higher octane should be used. 90% of people on this forum will actually lose power by going higher than 91-93 octane. its 87 for me on the stock bore stroke and combustion chamber.

i could site here and type a novel on octane and all of the common misconceptions of it, but i would rather post up this nifty little web link and let you read the basics of it for yourselves.

HowStuffWorks "What does octane mean?"
 
Also running meth which has a very high octane rating on even a stock motor will absolutely give you more power, you will feel it :)
 
3 major (there are others)factors to consider for the anti detonation rating are static compression ,igntion,exhaust port design