Best compression for 4.0?

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BADASYJ
I made it to triple digits!
I made it to triple digits!
Posts: 164
Joined: December 7th, 2008, 10:21 am
Stroker Displacement: 4.7

Re: Best compression for 4.0?

Post by BADASYJ »

Yes its that high. When I first restarted after build I ran 93 mixed with 103. I was a little worried about detonation. The next 3-4 fill ups were all 93 oct. Most of the time I try to mix it with race fuel but that is not always possible.
I tore the motor apart last week, dang thinh dropped a pushrod. While I was at it I decided to replace bearings n check rings. Everything looked a ok with no sign of detonation. Oh n I had another .010 removed from the head so now I have .040 removed.
Do it man, thats where the power is hiding.
racing89
I made it to triple digits!
I made it to triple digits!
Posts: 117
Joined: September 17th, 2010, 4:15 am
Stroker Displacement: 306 ci
Vehicle Year: 1988
Vehicle Make: jeep
Vehicle Model: comanche
Location: Barrington N.S.

Re: Best compression for 4.0?

Post by racing89 »

BADASYJ wrote:I zeroed the deck, took 30 from the head and it gave me roughly 10.75-11 to 1 comp. I run at least 93 oct and have not had n issue yet. Knock on wood. But I am looking for more. Get a valve job while you got the head off.
Hey 89 what are the cc's on your combustion chamber with that mutch milled from the head?
How much lift does your cam have?
52cc if I recall. (will check records @ home tonite) 512/484 lift cam. 202/ 160? mopar valves
2jxj
Noob
Noob
Posts: 11
Joined: June 16th, 2012, 12:28 am

Re: Best compression for 4.0?

Post by 2jxj »

Well,I've done the head,50 thou off,victor,hg,late model intake,swap,and it seems a bit dissapointing.It seems to run smoother,but can't feel any real performance improvement.
I'm still on normal low octane juice,and no pinging,no overheating.I haven't swapped the 2000 injectors in yet,could they make a difference? I think at this stage,I could have gone the 100 thou off,that was suggested... Do the late injectors flow more,they still have only 1 hole?
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superj
Donator
Donator
Posts: 70
Joined: May 18th, 2012, 5:12 pm
Stroker Displacement: 4.5
Vehicle Year: 1987
Vehicle Make: jeep
Vehicle Model: wrangler
Location: corpus christi, texas

Re: Best compression for 4.0?

Post by superj »

get 3.73 gears from a cherokee with the factory tow package. immediate change in acceleration.

the wife's stock 95 with 3.73 gears and an automatic would worry mustang/camaro guys light to light and totally embarrass the import guys. it was a super sleeper
We broke something, I think it was traction.
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