Horsepower Question - Milled Heads?

Kugellager · **Posted:** Mon Jul 31, 2006 3:31 am

I'm into classic cars as well as 4-wheeling and hear of people milling their heads back a few hundreths of an inch to slightly increase the compression and with it the horsepower.

My question is...Is it possible to mill the heads in the KJ to increase the compression to say 9.8:1. If that is safely possible what kind of HP gains would we see? What other mods would be needed to realize the full potential of milling the heads?

Just something I have been wondering about for some time and have not seen it mentioned..at least not in the searches I have done.

John
];')

KY Liberty · **Joined:** Sat Jul 09, 2005 1:46 pm **Posts:** 1195

You might want to talk to KRC in Florida. They can build the 3.7 into a higher compression motor. I discussed it with them last year when I was dealing with the nightmare of a stealership engine swap. If I hadn't been lied to and told my block was cracked, and gotten stuck with a stock motor so poorly installed that I had to have my mechanics fix it or it would have destroyed the transmission, I would be running a built, high compression motor with a 120 hp direct ported N2O shot from them. They were also very interested in building a 3.7 to handle a Paxton supercharger kit for the 4.7 and adapting it.

bigp38 · **Joined:** Thu Nov 09, 2006 5:44 pm **Posts:** 23

i have heard of rings breaking with a supercharger i would be careful

Lashlarue · **Joined:** Wed Jan 31, 2007 11:11 am **Posts:** 5

If I was going to the trouble of pulling the heads, I think my 1st option would be to port the heads. With over a million of these engines already built, the junkyards ought to have plenty for sale.Also wouldn't be difficult to machine them to accept larger valves.I havent been able to find anyone grinding a high performance cam. The three cams offered by KRC are for the 4.7l engine and are made by Comp Cams. Crank could be offset ground at least one millimeter the bore increased at least the same amount.That would increase total displacement to approx. 238 ci, with forged domed pistons,headers a free flowing exhaust and a cold air intake, I think hp in the range of 240-265 would be easily obtainable.

KY Liberty · **Joined:** Sat Jul 09, 2005 1:46 pm **Posts:** 1195

Dan can make some cams for you. I'm going to get some 206's this summer from him once JBA finishes my headers. I think I'm going to get some ported heads at the same time.

http://www.thefastman.com/index.asp

Horsepower Question - Milled Heads?

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