Just put a trail mod head on my 4x4. My compression went from 125 to 165. The rest of the engine is stock except for a hpd trail pipe and boysen reeds.
I took it down the road today to see how it acts.. I think I got some detonation going on here. It sounds real "tinny- pingy" And it also runs real eratic at 1/2 throttle. Is this what detonation acts like?
I think there was some low test gas left in my tank. Im gonna fil it up with super next time out. I hope it helps.
How much comp can you get before race gas is needed? What is 165 considered, 12:1?
Thanks for any input.

 

165 is around what the race mod is, there is more than just cranking psi to take into consideration, but I'd say you need to run race gas with that much compression!

 

You need race gas or a mixture ofrace gas and high test fuel to run that compression. 150psi is max on high test pump gas. You will burn a hole in the piston if you keep running it. who's head did you put on?
AZ BAD BOYZ (Dennis)

 

The head is from Rick Ritter. I talked to him today and he said that my guage may be off.
Im going to borrow another guage and test it again. Im going to mix up a fresh tank of super this weekend, and see how it acts then.
If that dosent work hes gonna send me another.
I tell ya what.. the sound this motor had, was making the hair stand up on my neck.

 

Welp fellas.. It was the guage. I borrowed another guage from a friend, and I got a reading of 149 psi.
Gonna mix up some super this weekend and giver he11!
Thanks for the help.[img]i/expressions/face-icon-small-smile.gif[/img]