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Old 03-02-2011, 07:18 PM
franka franka is offline
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Location: Lakewood
 
Join Date: Jan 2006
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Mein Auto: E39 540i Sport
540alex,

In the April issue of Popular Hot Rodding (PHR) they have an article called 'Power Tricks for any Engine'. It has 10 specific things you can do while building or re-building any 200 + hp V8 to p/u over 150 hp. All w/o replacing the internals, except for the cam and rings.

One of the items that you might be interested in doing, while you have complete access to your valves, is to have your valves back-cut (I quote this part of the article below) to p/u 5-15 hp by picking-up 5-10 cfm between 0.100 to 0.500" of lift. Those numbers are right from the article and a picture with the article. And, like I already said, apply to any V8.

Quoting right from the article... "This is one of those small tricks that is worth way more than the paltry sum it usually costs for this extra step. If you have the heads apart to lap the valves, or you have them at a shop, the easiest thing to do is mark the face of the valves with layout fluid or even a Sharpie, lap the valves in, then just have your machinist gives the valves a standard 30 degree back-cut up to the edge of the lap mark - simple and worth an average of 5-10 cfm, 5-15 hp. It's worth more power than most gasket-match jobs!".

For a typical 2 valve American V8 they estimate the total cost to be apprx $ 40. Of course that would be for 16 valves and you have 32. And a shop might charge more than $ 80 if you come in for the valve cut only. Or maybe not. If you have a lathe you can do it yourself.

For those that don't know, PHR has some great in-depth articles regarding American performance engine building, which can apply to any engine make, type, country of origin, etc. They also put out another magazine called Engine Masters that is in addition to PHR. American or not, engines are engines.

Below is PHR's web site. I did a quick look and couldn't find the article, probably because it just came out in the current issue.

http://www.popularhotrodding.com/index.html
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Last edited by franka; 03-02-2011 at 07:28 PM.
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