Power gains from milling?

**Speed_kills_WS6** · 03-02-2011, 07:24 PM

I've decided between PRC 227's or LS6 Stage 2.5's for my car along with a few other goodies. I'm currently running the Torquer 3 in my car, so I can only mill down to about 61cc. What happens to my torque and horsepower from leaving the stock 64cc alone to milling down to 61cc? Is there a decent amount of power gain by milling? I'd like to pick up a good amount of torque, which head will really help with that? Basically I'm not sure that the PRC227 will be worth $800 more than the Stage 2.5's. Any help or knowledge would be appreciated.

**mark21742** · 03-03-2011, 07:17 AM

For every full point of added compression (going from 10:1 to 11:1) you can expect about a 3-4% gain in torque and hp

**Speed_kills_WS6** · 03-05-2011, 02:54 PM

What are the cons of milling? I'd like to make a substantial amount of torque. Looking for the right combination.

**bills98ta** · 03-06-2011, 02:26 AM

Originally Posted by Speed_kills_WS6

What are the cons of milling? I'd like to make a substantial amount of torque. Looking for the right combination.

The more you mill, the longer your push rods will be. Just have to check them, or get an adjustable rocker assembly.

**predator** · 03-06-2011, 03:20 PM

Originally Posted by mark21742

For every full point of added compression (going from 10:1 to 11:1) you can expect about a 3-4% gain in torque and hp

I am NOOOOOOOO expert on this, but this seems on the low side. Going from 10:1 to 11:1 is a 10% increase in compression... The flow in and out of the cylinder should be the same because your BDC volume is near exactly the same and your final gas volume should be the same... Assuming you throw the limits of detonation out the window why would you only get a 35% gain by doubling your compression as opposed to a 100% gain?

-me

**mark21742** · 03-06-2011, 05:33 PM

Good question Predator, that is just the formula I know...there must be losses somewhere, maybe the strain on the bottomend having more "counter force" to rotating maas due to the extra pressure?

**bills98ta** · 03-06-2011, 05:35 PM

Since I'm 14:1 CR... I should be up 400% ??? LOL !!!
It sounded good....

**Firebirdjones** · 03-06-2011, 05:54 PM

Originally Posted by Speed_kills_WS6

What are the cons of milling? I'd like to make a substantial amount of torque. Looking for the right combination.

There are a few cons.

If you mill the heads so far, the intake will have to be milled as well. Once that is done, you have a combination that can't easily be swapped around.
Meaning,,,,that intake is milled for that amount of head milling (what ever that might be) and can't be used on another engine.
Not sure how you would go about that on these plastic intakes since they are so thin wall to begin with. Not sure if the injector sticking into the intake track may also pose a problem here as well.
You get even more in depth with this head/intake issue if you decide to angle mill the heads. That's another can of worms.

You also get into valvetrain geometry that Bill mentioned. Pushrod lengths will have to be checked, geometry checked, piston to valve clearance checked. It all changes when heads are milled.

Another draw back on some designs, you end up shrouding the valves in the combustion chamber and it costs flow. Generally this is remedied with most aftermarket heads though, CNC chambers etc...