Raising static compression

[Turbo6PGT]

If I were to take a DE or E engine and mill the head .005" or .010" does anyone know what the static c/r would raise to? I would be doing this purely for the power gains because its a race only motor. I know everyone will say "get the SR motor, boost the car etc etc". Im racing in a class where you must use a stock n/a engine. So the only real thing I can get away with is changing the c/r. And milling the head is the most cost affective way to do it. I really dont want to pull the block apart or buy new pistons/rods to do it. Im sure someone around here has milled a head or block on a rebuild and would know what the c/r changed to. If anyone can give me some technical help on how to figure out the compression change Id appreciate it mucho! Thanks

[cdlong]

CR is just (displacement+head volume)/head volume. just subtract the volume of the amount milled from the head and recalculate. i don't really feel like doing the calculations right now, but i bet someone else will.

now, if you mill the head down, it's not really stock anymore. i'm not sure what type of racing you're doing, but it's probably not legal. and a side note, half assing stuff never works out well. do it right the first time.

[TheWolf]

on average with a 60cc chamber and a 3.5" bore. (I'm to lazy to do the calcs) you'll see a .1 increase for every .010" you mill off. So you "Deck" a head .040" you can go from 9.5:1 to 9.9:1. It is a racing advantage ;) but not much of one... and you'll need an adjustable cam gear as you'll have walked about 2 degrees of retard into the cam by lowering it.

[cdlong]

i found this handy calculator http://www.csgnetwork.com/compcalc.html
and it will calculate the combustion chamber volume. if you set the head gasket thickness at 2.54mm (0.1 inch), find the combustion chamber volume, then set the headgasket to 0 and have it calculate the compression ratio it will give you 11.97:1. pretty high for a KA. you can play around with it to get the ratio you want. 11:1 is a pretty good point to shoot for.

[Turbo6PGT]

Thanks for the links and help. That at least helps me figure out what I could do. As for the racing legality stuff, its not "illegal" to shave a head. Anyone rebuilding a motor is allowed the basics like this but the pistons/rods and valve stuff is supposed to remain oem. I rear somewhere that it is possible to slap a DE head on an E block, it might have been on this forum, but the person had yet to get it running in the thread. But thats way more work than its worth. Im just trying to make sure the engine is running as fresh as possible given than it has old pistons and rods with a tired old head. But I cant dump money into it because we have a claim rule that says another racer can walk away with your car for like $1200. So if I were to win a lot someone else can claim Im cheating and leave with my car on his trailor for $1200. Doesnt do much good to rebuild a motor "the right way" only to lose it all!

[DJ_Sunrise]

In that case don't break any rules. Throw in an S14 SR20DE N/A motor.. Decent price, good power.

-Bart

[cdlong]

how does that work out to be under $1200 or have more power than a modified KA?