compression verses timing

[mx1986]

JWow how'd u get the squish right custom domes?

[possum]

You usually have the step on the dome cut deeper to compensate for the stick out. In order to get the squish correct. I had to do the same thing.

[Wildcardracing]

Wow! 17cc domes on a 10 cub at 1k elevation. That will put you around 18.6:1 UCCR. I set mine up with 20's at 4500' assuming a cub with std deck heights. You've got way too much compression IMO. You'd be much better off to go to a larger dome and less compression. High compression motors can and will fight themselves in the higher RPM's. As you approach the peak efficiency of your pipe/porting the dynamic compression will dramatically increase well above cranking pressures. To much static compression will kill the motors ability to over-rev and can slow the motors acceleration.

[dajogejr]

Well said Brandon.

Too many people want to "just slap a dome in" and get peak performance.

 

There are too many variables...especially on a cub.

 

Gotta know if it's out of the hole, trapped volume, UCCR...

[mx1986]

Thanks helpd me a bunch.