Looking at upping the compression on my 400 2-stroke...

I like using an Octane Booster but there are a lot of choices - Turner Labs, Prestone 0-60, Outlaw, 104+, Hp, etc. I'd like to hear what you all use. Typically I buy premium pump gas (In Colorado, the cheap stuff is 85 octane, middle is 87, and premium is 91) and use a 1/4 bottle of octane booster (full bottle treats 20 gallons) in every tankful. Any idea on what kind of boost I am getting? I noted the bottles don't really specify the octane boost - it varies from "up to" 3-10 points.

Can anyone educate me on Octane Booster - how it works, what to do/not to do. Or, give me an alternative idea? Thanks - Dave

 

I don't think you really understand what octane does. The higher the octane, the slower the burn. Higher octane is used to prevent pinging or detonation by slowing down the burn so that a high compression engine does'nt wear out before it's time has come. You should only use higer octane if your engine pings. Otherwise you are throwing money out the window.
[http://www.commerce.state.mn.us/page...taneFacts.htm]

 

He is right. Only use as much octane as needed to cure the problem. You are at such a high altitude, I dont think it will matter. For instance: HPD's cool head has a 12:1 chamber for pump gas. Their high altitude chamber is 13:1. That is with all other factors staying the same.If you look and read closely at the bottles of booster, when they say that they raise the points 3-10 or such, that is not raising the actual octane numbers.Some laquer thinner or plain tolulene would do about the same. It would be more economical to add a gallon of race fuel or such to a tankful if needed, but you shouldnt have a problem at all if you send your head and have it machined for pump gas. We dont have a problem even down in the lower altitude. But is does make HP. If you ride anywhere from 5-12k feet, have it machined for the lower of the 2, then you have no worries. Bubba

 

Little left to say. Many studies have been done showing too much octane robs HP. I do carry a small amount of the morroso (sp?) octane booster around for when I get stuck w/o race fuel, but that's rare. As mentioned, most folks mix tutbo-blue, or whatever 50-50 with premium. And again, ask somebody when you do the head how high a compression you can go and stay on premium pump fuel.

Or goto the airport and buy aviation fuel. Its 100 octane anyway. You'll occasionally hear a religous arguement against doing that, but I've never heard one that held water.

Why not start a thread on who's carrying how much compression and what fuel Octane's they've been successfull with? If you do limit what you listen to to the 400 2 stroke, as engines differ in the octane needs for a compression. I run my 'she @ 170 on 50/50 all the time and have no worry's. Right now I'm afraid to do that on the 400...

luck dan