I was wondering what the highest compression ratio you can go on pump gas with the 440 kit. Wiseco offers a 11:1 and also a 12.5:1 compression piston. I live in Wisconsin and our highest octane rateings are 91 to 93 depending on the gas station.

 

I was reading at exriders.com that a 11:1 piston is acually less then that. This is a quote from exriders.com from mickey dunlap "Right now the piston is about .043 too low and you are not getting a true compression ratio as advertised by most piston companies. For instance, a 440 11:1 flat top piston advertised is really only about 9.75:1 if you measured the volume correctly." If this is true counld'nt you run a 12.5:1 compression on pump gas sinse it will only be about 11.5:1?

 

I would not go 11.5:1 or higher. A 11:1 or 10.75:1 is as high as I would go on 93 octane.

 

Thanks for all your help

 

I've got a 10.8:1 JE Piston, and my motor will "ping" if I don't at least add an octane boost to 93 octane gas. I'm better off doing a 50/50 mix of race gas with high octane pump gas. It burns alot better.

 

I too read that article on exrider.com. I would believe that the advertised compression is much less than 11:1. From everything else I have read to stay reliable with the 400EX you don't want to go over 11:1. So I would go with the 11:1 kit over the 12.5:1. In fact, I am planning on going with the 440 11:1 kit and Hotcam next month. Good luck!!

 

Let me know how the 440 kit is and what stage cam are you going with? i have the stage 2 hotcam which i hear is awsome with the 440 kit. also are you upgradeing your carb? i plan on upgradeing to the 440 kit next winter. i was thinking of getting the edelbrock 440 carb but i havent heard much about it wheather it is good or bad.

 

I don't know on the jap quads, but I have a 14-1 piston in my Dale. Wade who built my motor and designed the piston and has a Cozworth guy do the headwork says I am safe running 100 octane. He recommends Unical 100, but Sonoco w/ 4% oxygen mixed 50/50 w/ pump gas. Would a retarded EFI map affect why we can run lower octane.. Wade was an engineer in Acura's and BMW's R&D I don't doubt his word.

 

Stay away from the Weisco piston. They are not a true compression, run a JE piston they are the closest you can get.

 

I wanted to stick with just pump gas because i dont have the time or money to be running around getting race fuel. But does JE offer a 440 kit or is it only the 415cc i saw on some website. IF someone could give me a link to the JE site and if they offer a 440 kit it would help a lot.
thanks