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View Full Version : Good HP gains - High Compression HG or Mill



maxxedsx
10-22-2005, 09:41 PM
Since most people seem to have good gains running 9.0.1 compression pistons, I was wondering if anyone tried running the thinner headgasket on a stock bottom end. From what I am told that gasket will bring you to 8.8.1 rather than the stock 8.5.1 compression.

-or-

My other thought is to just mill the head (and add cam gears to correct timing) to bring it to 9.0.1 compression.

Thoughts? http://forums.freshalloy.com/images/graemlins/grin.gif

Enthalpy
10-23-2005, 12:18 PM
here's the general rule of thumb...

1.0 point of compression ratio increase (static) will yeild 3.0% power increase.

so bumping form 8.5 to 9.0 will only yeild 1.5% power increase....not worth all the hassle.

sspikey
10-23-2005, 12:28 PM
so 9.0 compression only yields better throttle response and not so much power by what your saying

tErbobOOst
10-23-2005, 03:19 PM
so 9.0 compression only yields better throttle response and not so much power by what your saying



and more prone to detonation. up the boost 2 lbs and you'll more than make up for it http://forums.freshalloy.com/images/graemlins/wink.gif

Papa Lazarou
10-23-2005, 06:11 PM
Higher compression gives better thermal efficiency, which results in more power, but I'm not sure it would have an impact on throttle response. Thats more to do with other factors I'd say.

_Def_
10-23-2005, 07:09 PM
Higher compression gives better thermal efficiency, which results in more power, but I'm not sure it would have an impact on throttle response. Thats more to do with other factors I'd say.



Agreed.

killjoy
10-23-2005, 07:13 PM
But Scott, when building a motor you recommend to go to 9.0 right? I think we talked about this before.

Wazowski
10-23-2005, 10:32 PM
9.0:1 with 0.8mm HG is the cool.

MottoOkii
10-24-2005, 01:31 PM
My other thought is to just mill the head (and add cam gears to correct timing) to bring it to 9.0.1 compression.



This is the very worst way to increase compression. By milling the head you change the size, shape and squish area of the combustion chamber... That is a HUGE no no! It would be far better to mill the block, same results with none of the negative side effects encountered with the milled head.

Just my 2

s13SRmadness
10-24-2005, 06:54 PM
9.0:1 with 0.8mm HG is the cool.


why not 9:1 with the stock 1.1mm hg?