Raise C/r On Stock Car???
Thread Starter
Launching!
Joined: Aug 2004
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Raise C/r On Stock Car??? i was thinking about running a full bolt-on car, with stock internals, but i was thinking if it was possible to mill the stock heads to bump up the compression ratio a bit, and maybe run some high octane (100+) to see if it would be possible to scavange a few extra HP.
-is this possible?
-how much extra HP do you think would be obtained?
THANKS.
-is this possible?
-how much extra HP do you think would be obtained?
THANKS.
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From: Tomball
Yes you can mill the stock heads. I would recommend going with a cam first before milling the heads because in the future you might run into piston to valve clearance. You might also want to get the heads ported if you going to mill the heads also, but you might lose some torque with out a cam helping the heads. If your sticking with your stock cam, milling the heads will definatly give you some power, but not as much power as a cam with ported and milled heads. I also doubt you would benefit running race gas unless you car really needs it which would be a high compression motor. The one way you will need race gas is if you car cannot run on 91/93 octane in your area. Just my opinion, hope this helps...
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From: BFE
What I've done in the past is to use thinner Cometic gaskets .040>.045 depending on my piston/hole position to improve quench, which BTW also lifts CR a little.
That and portmatching helps a little a (cheap because I did it all).
When you mill heads, you are loosing flow.
So as said above milling to raise CR should be accompanied by porting.
That and portmatching helps a little a (cheap because I did it all).
When you mill heads, you are loosing flow.
So as said above milling to raise CR should be accompanied by porting.
Thread Starter
Launching!
Joined: Aug 2004
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right, i want to utilize the stock heads/cam to its utmost full potential, so if i had the stock heads milled down to achieve 11-1 C/R or so, running some good octane, how much HP do you think it will add retaining stock unported heads and its stock cam?
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From: BFE
Originally Posted by jaredwayt
right, i want to utilize the stock heads/cam to its utmost full potential, so if i had the stock heads milled down to achieve 11-1 C/R or so, running some good octane, how much HP do you think it will add retaining stock unported heads and its stock cam?
~average 4% per full point of CR.
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From: Tomball
In other words, its not worth the money to just mill the heads by themselves. There is other power to get out of the car than to just mill the heads. Like I said before, if your planning on going with a cam dont touch the heads because you might run into P/V clearance with a nice size cam...
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Thread Starter
Launching!
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ok, that makes sence, i am going to be putting togther a full bolt-on, the best of the best, kooks/lsx/etc., im not worried about down the road head/cam, it dosnt matter, i just want to make the most out of a full bolt-on, and it will also be sprayed eventually, but i would be happy with 10-15rwhp extra. how much would i have to mill the heads to achieve 11-1 C/R? OR perhaps how much could i go safely to raise the C/R above 11-1?
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From: Tomball
You would need 61.07cc chambers...I think you would have to mill the heads quite a bit. Talk who ever is going to mill the heads for you on pricing, I have a feeling it will be quite a bit of money for the power you are going to get out of it...
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From: BFE
Not really, milling is around $100.
Like I said before, decide on the gasket you will run (Cometic) for quench desired and mill accordingly to reach 11.0:1 SCR
Shouldn't be that much mill, would think ~ .030
Like I said before, decide on the gasket you will run (Cometic) for quench desired and mill accordingly to reach 11.0:1 SCR
Shouldn't be that much mill, would think ~ .030
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From: Australia
IMHO you are stretching the boundaries of what is a full bolt-on car. If you have to remove the heads and modify them that should count as a modified car - equivalent to bolt-on+heads.
I dont know how strict you guys are with regard to classification but over here in OZ there are people who are mental about car classifications. Otherwise workshops are claim fastest NA bolt-ons that compete with CAM cars for extra business but cannot be achieved with bolt-ons only.
Just food for thought...
I dont know how strict you guys are with regard to classification but over here in OZ there are people who are mental about car classifications. Otherwise workshops are claim fastest NA bolt-ons that compete with CAM cars for extra business but cannot be achieved with bolt-ons only.
Just food for thought...