100 octane? 14:1

[Toyorider]

think up picking up this 450r with Baldwin racing piston, hotstage cam II, and port and polishing. he said he has a 14:1 compression. will it run off 100 octane. thats what readily avaliable in my area without buying vp race fuel. otherwise how much and how hard is it to step the compression down and what ratio (12-13:1)?

[medicdude]

110.

[lundgrener02]

well i'm running 100 octain in my 450r with 13.5.1 compression piston. i know alot of guys with new 07's running 14.1 and they are using 100 octain and they are all honda techs at the local dealer where i live. so not saying its good but they have been doing it with thier bikes and no problems and they work on them all day.

[FHKracingZ]

you will be fine at 100. 50/50 race mix will run 14:1 fine without getting to hot. 112 + 93 = 205 divide by 2 102.5 , i think u will be fine.

[GPracer2500]

Originally posted by FHKracingZ
...112 + 93 = 205 divide by 2 102.5....
The final octane rating of a leaded/unleaded mix can't be figured that way. It becomes a non-linear function of lead response....blah blah blah....point is you'll never know for sure what octane rating you're actually ending up with. It could be higher or lower than the average of the two numbers.

I'm not saying mixes don't have their place. I'm just saying the actual octane number will be unknown. All you can do is give a mix a pass/fail regarding octane rating for any particular engine.



When I talk about fuels I don't bother listing the octane rating type (RON, MON, or [R+M]/2 ) for normal pump fuel because pump fuel is always reported in (R+M)/2 in the US and Canada. But with any other fuel I always specify which rating system I'm talking about. With racing fuels MON is the most common but some companies advertise with RON (RON is always the highest so it looks better) and some fuels (especially "street" fuels) use (R+M)/2.

MON is the best one to use as it is the most accurate measure of deto resistence in our engines. But whichever one is used, you've got to stick with only one system when comparing. Apples to apples so to speak.