Closing up the squish band clearance on my modified head! My testing continues....

[zedicus]

Re: Closing up the squish band clearance on my modified head! My testing continues...

you know a lot of the crotch rockets use quite high compression ratios and fairly tight squish. how do you think they are getting 150hp out of 600cc in a 4-stroke? those things are coming from the factory with 13:1 and the understanding that not all fuel is the same and that some cheap bastard is gunna dump 87 octaine in it at some point.

110 oct fuels are so consistant that they could be tuned for ragged edge. the margin on it would be something that could be ruled out. unlike pump gas where you don't even know how much water is in your fuel from state to state.

 

[joeak47]

Re: Closing up the squish band clearance on my modified head! My testing continues...

Results of .017 squish ,was that I was detecting DETONATION!

I did one quick hard pull and..... there wasn't any more power than my original head (head #1) that I cut to the DT200 specs that "BEST" posted in another thread.

My original head (head #1 DT200 specs) originally had .066 to .072 thousandths squish clearance. It worked AWESOME!
However,I was on the "outside" of being in the "optimum" range for squish clearance ,so thats when I "step cut" the sealing surface .031 thousandths,so I could bring the copper head gasket dead even with the outer edge of the squish band. This reduced the squish band clearance into
the .035/.041 thousandths range.

When I did this,the engine CAME ALIVE!!!

It went from working "AWSOME" to working

PHENOMINAL!

Thats why I've determined that when you get the squish in the .035 to .045 range (with the DT200 specs),you are pretty much where you want to be!!!

Anything past that,and you start hitting the "point of diminishing returns" and DETONATION

The reason I State that my squish distance is between .035 and .041 is because when I checked it with solder on both sides you get more of a difference with a cast piston,because of its cast top compared to a forged piston (not my favorite) that is machined on top.
If you want an average on my squish clearance it would be .038

.035 + .041 divided by 2 = .038 thousandths.

I LOVE my DT200 spec head!

Here's the head next to a stock one. This is before I step cut it.