I wanted to know whats the highest comp. piston I could get for a Raptor so I could still use 92 octane gas?

 

i have heard that 11:1 is the highest you can go on pump gas

 

I heard the same 11:1 from the guys who did my tranny rebuild and piston swap since the cases were split.

 

I had contacted JE about this same thing, and they make a 10.75:1 standard bore piston that they recommend if still running pump gas. It includes the picton, rings, pins, and clips and tha part number is 190253 for the raptor.

My question is who else makes pistons for the Raptors? Who is best?

Chris

 

I got a Wiseco 11:1 and Ive been running 87 octane without any problems.....I might try 91 and see if it helps any.

 

Are quads like cars in that if you have a high flowing exhaust, the compression decreases a tad inside the chamber? It's funny how some people say that they are running 87 octane when others are saying with the same piston they have to erun 93 octane. Other than altitude differences, what could be causing this wide difference?

Chris

 

I would think they are the same as cars, 4 strokes work the same way. Ive got an e-series pipe without a spark arrestor so its pretty much a straight pipe, dont know if it hurts compression but it sure does sound mean [img]i/expressions/face-icon-small-cool.gif[/img]

 

Yeah, see I'd bet that if you ran the stock pipe/exhaust, you'd have to run higher octane gas.

Chris

 

Many things. Some of them are:

#1. Load
#2. Ambient air temp
#3. Cam timing
#4. Cam profile
#5. Combustion chamber and piston shape
#6. Exhaust back pressure
and even air cleaner efficiency just to name a few

 

Running anything higher than a 10:1 compression you should be using at least 91 octane gas. It combusts a lot better than 87. Plus you get the added benifit of the cleaners from the gas in your engine.