I'm pretty sure the stock compression is 9.7:1 right? So 11.5:1 is quite a bump from stock. So, I'm wondering how much power is gained and WHERE in the power band... I know it will help bottom end a lot but I also wanna know how much is gained in mid range and top end. I'm talking JUST the piston because I know cams will help quite a bit WITH the piston but for now I just wanna know how much is gained and where from the bump in compression to 11.5:1..... stock bore remember.... thanks[img]i/expressions/face-icon-small-happy.gif[/img]

 

Compression is the cheapest horsepower available...its free
If you gotta buy a piston a high comp model shouldn't cost you any more than standard
The power gains will be throught the entire pulling range of the motor...
the motor will be more responsive(snappy)

A high comp piston alone in a 400ex will eassily take it past a KFX

Compression can also have disadvantages if not dealt with properly such as heat/detonation

 

Thanks bunches for the info!!! And that's why I will be only going to 11.5:1 so I can stay on premium....... And the price is right from who I'm getting it from....... I just have to wait a while longer though...

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You might possilby loose on top. Thats why they do cams. HC pistons are good on the bottom but worse on top. Cams are good on top but worse on the bottom. The kinda cancel each others bad spots... Thats why most people do both. If your not worried about topend then just get the piston.. Keep in mind I dont know this for sure.. I had to get cams, I broke mine [img]i/expressions/face-icon-small-smile.gif[/img]

 

More compression helps EVERYWHERE, down low AND up top. The only down side is detonation/preignition due to too much comp for the type of gas one is using.
Bigger cams get more air in and out. To get more air in, the cams hold the valve open longer, which reduces the effects of compression. THIS is why one adds compression when adding cams...[img]i/expressions/face-icon-small-smile.gif[/img]

 

If i remember correctly, raising compression gains the same at all rpms. IE: go up to 12:1 from 10:1 gains you say 5ft/lbs of tq at 3000rpm, 6000rpm, and 8000rpm. Pretty much the same everywhere.

 

my vortex CDI raised lowend a lot!

 

Winston Cup cars run over 13:1 pistons and they are all about peak power. I don't think hi-compression hurts the top end at all.JMO

 

I saw the curves that were programmed for you and I will tell you this, for only haveing a 8.xxx piston, I bet you have GREAT low end!!!

The wonders of technology!!!!

DuneDevil

 

Could someone decipher the above post for me. Seriously