GuitsBoy

iTrader: (4)

Hi all -

I have access to an aerospace machine shop and I am concidering milling the heads down .030 when I install my TR224. What gains do people typically see from going from 10.1 CR up to 10.8 - 11? Is it worth the agrivation of pulling the heads? The machine shop dosnt have the capability to do much more than mill the heads down since they build airplane parts, not race engines. I dont really want to spend the money to send the heads out to have them ported / polished, and Ive come to understand that porting them yourself is a big mistake. Should I bother milling or no?

Thanks,
-Tony

Cstraub

iTrader: (1)

Good rule of thumb is around 5 to 7% gain in power based on CID displacement. Example 346CID engin would be a gain of 17 to 24 HP. This comes from reference with engine builders and first hand knowledge of a 283 mule that we tried this with back in the 80's. Pull, take apart, shave, assemble, pull, take apart. . .etc.

Cstraub

iTrader: (1)

Good rule of thumb is around 5 to 7% gain in power based on CID displacement. Example 346CID engin would be a gain of 17 to 24 HP. This comes from reference with engine builders and first hand knowledge of a 283 mule that we tried this with back in the 80's. Pull, take apart, shave, assemble, pull, take apart. . .etc.
Sorry, per point gained over 10 to 1.

Colonel

It depends on what CR you're starting from. You'll get a very nice gain if going from 8-10:1 but comparatively little when going from 13-15:1, for example.

I'll guess that going from 10.1-10.8:1 would be worth about 7-8 RWHP.