Race fuel

[FireFighterI]

ok my question is how does race fuel work? I just put in a 13:1 je piston in.. what is the benefit of running race fuel? what makes it better then just running premiem pump gas? if someone could explain how it works and why it is needed for higher compression pistons? lol I know I sound like an idiot

[tfuchs]

First off as you raise your compression you need a higher octane fuel. The reason is pre-detonation. The higher the compression the quicker a lower octane fuel will ignite. If you dont run a fuel with a high enough octane than the gases in the combustion chamber will explode before they are suposed to causing major engine problems. With 13.1 compression ratio you will should run at least a 110 octane fuel.

[FireFighterI]

Originally posted by tfuchs
First off as you raise your compression you need a higher octane fuel. The reason is pre-detonation. The higher the compression the quicker a lower octane fuel will ignite. If you dont run a fuel with a high enough octane than the gases in the combustion chamber will explode before they are suposed to causing major engine problems. With 13.1 compression ratio you will should run at least a 110 octane fuel.

Ok.. so I just finished the project last night.. 13:1 piston and a hotcam 2.. I have not even started it yet. I was thinking of running a 50/50 mix of race fuel and pump gas. but that probably still wont put me up at 110 octane cause the race fuel its self is only 110. do you think I should run straight race fuel or will 50/50 be fine? thanks for the reply

[sandmanblue]

Originally posted by FireFighterI
Ok.. so I just finished the project last night.. 13:1 piston and a hotcam 2.. I have not even started it yet. I was thinking of running a 50/50 mix of race fuel and pump gas. but that probably still wont put me up at 110 octane cause the race fuel its self is only 110. do you think I should run straight race fuel or will 50/50 be fine? thanks for the reply

With only 13:1, you might be just fine with a 50/50 mix of something like VP110 and 92 Pump gas. BUT.... What are you really saving in not running straight 110? If the 110 is $7/gal and 92 is $3.00/gal, it will cost you about $16 and the hassle of mixing fuels each time to fill your tank. In addition, you will probably get the ratios mixed up when you mix them a 2nd and 3rd or more times. If you run straight 110, you'll spend about $22.50 to fill up (3.2 gallons). So you spent $6.5 dollars more, but didn't run around to two different places and have a consistent fuel to boot.

I just can't understand why anyone would spend $500+ to hop up their motor, and then they won't spend another $6 to fill their tank with the right fuel.


The other option is to use some of the lesser expensive race fuels found at pumps like the 100 octane unleadeds from Union 76 and VP. They run about $6/gal.


Whatever you decide, get the jetting dialed on a dyno and don't change fuels all the time (like a lot of ppl do). You need to jet for a specific fuel. Changes in different fuels can affect jetting as much as 2 - 3 jet sizes - so you're gambling if you switch.


I have mine specifically jetted for two race fuels - VP C12 and Sunoco MO2X Oxy fuel. They both use the same jetting, verified on a dyno. The oxy makes another 0.5 hp - FWIW. Oh - and the tank gets drained after a riding weekend and the fuels get put back into sealed metal cans to preserve them.

[MX MaNiAc 06]

Originally posted by sandmanblue
Oh - and the tank gets drained after a riding weekend and the fuels get put back into sealed metal cans to preserve them.

I keep my Klotz in a plastic 5 gallon can. The little air thing closed and i shove a balled up napkin in the top. Is it sealed up good enough?

[450R-156]

If you dont want to spend the money on race fuel try using avtiation fuel its 100 octane and up instead of race fuel is just an average of 110 octane. The aviation gas has a lot higher standards and it only costs me around 4 dollars a gallon. Ran it iwith 13.1 compression all year with no problems

[GPracer2500]

Originally posted by MX MaNiAc 06
I keep my Klotz in a plastic 5 gallon can. The little air thing closed and i shove a balled up napkin in the top. Is it sealed up good enough?

I can't tell if that's a joke or not. ;)

Assuming you're serious--no that's not good enough. At a very minimum it should be in an AIR TIGHT container. If the container doesn't pressurize itself if it gets hot than it's not air tight.

[GPracer2500]

Originally posted by tfuchs
....The reason is pre-detonation....

Just an FYI: the term is detonation. Pre-detonation is a nonsense word. The a/f mixture does not detonate at all under normal circumstances--it deflagrates. Deflagration = burn and it is the good kind of combustion; detonation = explode and it is the bad kind of combustion.

[sandmanblue]

Originally posted by 450R-156
If you dont want to spend the money on race fuel try using avtiation fuel its 100 octane and up instead of race fuel is just an average of 110 octane. The aviation gas has a lot higher standards and it only costs me around 4 dollars a gallon. Ran it iwith 13.1 compression all year with no problems

I know a lot of ppl say to use av-gas, but it is a fact that this fuel is not meant for anything but high altitude, low rpm engines in a relatively mild state of tune being used at low ambient temperatures. While the octane may be high enough, that alone is not justification to run a fuel meant for a very different engine than a 10,000 rpm small displacement engine used at sea level... I think it's worth just saying that you should do some research on this. Problems associated with av-gas are power output and throttle response. I wouldn't recommend it at all.....

[FireFighterI]

Originally posted by sandmanblue
With only 13:1, you might be just fine with a 50/50 mix of something like VP110 and 92 Pump gas. BUT.... What are you really saving in not running straight 110? If the 110 is $7/gal and 92 is $3.00/gal, it will cost you about $16 and the hassle of mixing fuels each time to fill your tank. In addition, you will probably get the ratios mixed up when you mix them a 2nd and 3rd or more times. If you run straight 110, you'll spend about $22.50 to fill up (3.2 gallons). So you spent $6.5 dollars more, but didn't run around to two different places and have a consistent fuel to boot.

I just can't understand why anyone would spend $500+ to hop up their motor, and then they won't spend another $6 to fill their tank with the right fuel.


The other option is to use some of the lesser expensive race fuels found at pumps like the 100 octane unleadeds from Union 76 and VP. They run about $6/gal.


Whatever you decide, get the jetting dialed on a dyno and don't change fuels all the time (like a lot of ppl do). You need to jet for a specific fuel. Changes in different fuels can affect jetting as much as 2 - 3 jet sizes - so you're gambling if you switch.


I have mine specifically jetted for two race fuels - VP C12 and Sunoco MO2X Oxy fuel. They both use the same jetting, verified on a dyno. The oxy makes another 0.5 hp - FWIW. Oh - and the tank gets drained after a riding weekend and the fuels get put back into sealed metal cans to preserve them.


So I can run straight 110 race fuel in at and it wont hurt it at all? my jetting was perfect before I put in the piston and came in... i am running a 185 main and 52 pilot... do you typically have to change the jetting after putting in a higher compression piston and changing the cam?

[IMSROLL450R]

Originally posted by tfuchs
With 13.1 compression ratio you will should run at least a 110 octane fuel.

I dont think thats right. With the stock 06 R at 12:1 compression Honda recommends 91 or better. Why would only a jump in 1 compression require a jump in 19 octane. You could use something lower than 110 and be perfectly fine and if you are doing a lot of riding that $6 you save by mixing every tank will add up quick, which is a big deal to people without a bottomless wallet.

[tfuchs]

I sell Sunoco Race Gas and their recomendation is 110 for up to 13.1 compression and 112 for anything up to 15.1

[MX MaNiAc 06]

Originally posted by GPracer2500
I can't tell if that's a joke or not. ;)

Assuming you're serious--no that's not good enough. At a very minimum it should be in an AIR TIGHT container. If the container doesn't pressurize itself if it gets hot than it's not air tight.

Where could i get an air tight container? The metal 5 gallon cans they come in are air tight right?

[GPracer2500]

The newer plastic CARB approved cans are air tight. Even lots of older cans are air tight--it just depends on how well the caps seal.

Metal cans are better. The 5 gallon mini-barrels that race gas normally comes in are air tight until the plastic "pull-up" spout starts to deteriorate (which will happen after you pull them up and push them down enough times). I usually don't get more than 1 re-fill out of those barrels before the spout develops a crack. I really wish they'd make those 5 gallon barrels with a normal 2" bung. :mad:

Good metal gas cans can be hard to come by. It might be easiest to just order a couple on-line. They're not especially cheap either. You can try checking a local army surplus store. I've been told that Home Depot or Lowes has 5 gallon metal gas cans but have never seen them there (haven't looked that hard though).

It's always a good idea to store fuel in a cool, dry place out of the sun. This is especially important if your getting by with plastic jugs.

[JJs450r]

i have a 13:1 piston and it seemed like on cooler days it ran better on 110, but on hot days seemed it ran better on 75/25 but c&d had my piston thermal coated so it was safe 2 run 50/50 mix

[sandmanblue]

Originally posted by FireFighterI
So I can run straight 110 race fuel in at and it wont hurt it at all? my jetting was perfect before I put in the piston and came in... i am running a 185 main and 52 pilot... do you typically have to change the jetting after putting in a higher compression piston and changing the cam?

Straight 110 isn't going to "hurt it" at all...

Your jetting was "perfect"? Was this tuned on a dyno or just by trial and error? While you might be pretty close with those jets, unless you've actually tuned it on a dyno (with AFR) then you can't really say it's dialed in properly. But, maybe it's fine. If it was, then in MY experience, the cam and piston won't make that much of a difference when you are using the same FUEL! But, you won't be. That's where the jetting changes will likely come from - the fuel, not the compression and the cam.

If you're going to play the home jetting game, then you have to start somewhere and what you have in there is as good as guess as any. Like I said - just make sure you don't start playing with different fuels. Settle on one (or two) and be done with it.


BTW
Originally posted by tfuchs I sell Sunoco Race Gas and their recomendation is 110 for up to 13.1 compression and 112 for anything up to 15.1

Sunoco's recommendations are very likely in reference to automobile engines that have a very different bore/stroke/cam/rpm arrangement. Bikes/quads can run a lot higher compression for the same fuel....