Why no gains after head install?
Thread Starter
Joined: Sep 2005
Posts: 741
Likes: 1
From: North Little Rock, Ar
Why no gains after head install? Recently installed some PRC stage 1 ls6 heads that were milled to 62cc and used a .045 head gasket. When I went to the track this last weekend my car ran the same MPH as when it was cam only. The weather conditions were pretty much the same as before. Since running cam only car received a k-member and I went back to 3.23 gears from 3.73? I was hoping the car would run at least 116mph. I do all of my own tuning and feel the tune is pretty good. I can post it up if someone wants to look.
EDIT: Final Dyno pull attached.
EDIT: Final Dyno pull attached.
Last edited by LeftySS; Oct 4, 2011 at 08:40 PM.
Did you recheck your pushrods length with the new heads? Did you run at the same track? DA the same, temp?
I take it you had 241 heads before?
I know you said you tuned it but has it been on a dyno? What's your AFR and spark look like?
I take it you had 241 heads before?
I know you said you tuned it but has it been on a dyno? What's your AFR and spark look like?
Thread Starter
Joined: Sep 2005
Posts: 741
Likes: 1
From: North Little Rock, Ar
No I had the 853s. No dyno tune just a street tune. As far as spark goes I am not sure if I am getting false knock or real knock. But don't see anymore than 2 deg pulled a WOT, that puts me at about 24 deg total. Is that too high for 11:2 CR with 91 octane?
Thread Starter
Joined: Sep 2005
Posts: 741
Likes: 1
From: North Little Rock, Ar
Thread Starter
Joined: Sep 2005
Posts: 741
Likes: 1
From: North Little Rock, Ar
Yes. Will gears make that much of a difference? Lets say I still had the 3.73 gear what should the car run? Just trying to figure out if the car is down on power, bad tune, or it is where it should be with the 3.23 gear.
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Verdad Gallardo Gears make a significant difference and render the before/after comparison meaningless other than to indicate the gear change is roughly equal to the head change.
Thread Starter
Joined: Sep 2005
Posts: 741
Likes: 1
From: North Little Rock, Ar
Ok, feeling a little better i guess. I didnt think about it being lower in the rpms at higher speeds and not being able to pull quite as hard. What kind of mph could i expect with 373s?
Thread Starter
Joined: Sep 2005
Posts: 741
Likes: 1
From: North Little Rock, Ar
It is a little hard for me to swallow a gear set being worth the same gain as a nice set of heads. I mean $1500 for no gain??
Last edited by LeftySS; Sep 12, 2011 at 03:15 PM.
Thread Starter
Joined: Sep 2005
Posts: 741
Likes: 1
From: North Little Rock, Ar
I feel the same way. I will post up my tune and a log i took yesterday, when i get home from work. Hopefully someone can point me in the right direction.
Of course something is wrong............why use the same cam with a new set of heads? They have to be matched together if you want to get that ~40 RWHP out of them thats still on the table. Heads that breath more need a cam to allow it......
You obviously gained a little through simply having better flowing heads, lost a LITTLE bit with the gear change. But you should have seen a big difference....with a new cam.
.
You obviously gained a little through simply having better flowing heads, lost a LITTLE bit with the gear change. But you should have seen a big difference....with a new cam.
.
Well a 228R shouldn't be that far out of line with ported 243s.
Gears should not make enough difference to negate the gain from ls1 heads to ported 243s, especially not on an automatic car.
If you find out what it was be sure to post up!
Gears should not make enough difference to negate the gain from ls1 heads to ported 243s, especially not on an automatic car.
If you find out what it was be sure to post up!
Joined: Aug 2007
Posts: 24,241
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From: Turnin' Wrenches Infractions: 005
OP, something is wrong. Your 60 should be better, you ET should be better, and your mph should be better.