Head question LT1vsLT4
Thread Starter
Melting Slicks
Joined: Apr 2001
Posts: 2,877
Likes: 7
Head question LT1vsLT4
I am looking into doing a progressive engine build up and I need some advice/opinions on what heads.
I have decieded to build a 383/396(not sure which yet) and was going to updgrade the heads to LT4 castings. I was wondering If I should just buy bare LT4 heads and then have them ported or go with the AFR 195 or 210 LT4 heads with their competition porting package. Or, for that matter should I just get my existing LT1 heads done with a stage 3 type porting. I want to get the most power (425+rwhp) I can out of this and because I am going to do this over time I can absorb some of the higher dollar avenues, fully forged bottom end, splayed caps, maybe some titanium valves to spin this baby to 7000rpms, etc.
Any advice is greatly appreciated, especially from those running similiar setups.
I have decieded to build a 383/396(not sure which yet) and was going to updgrade the heads to LT4 castings. I was wondering If I should just buy bare LT4 heads and then have them ported or go with the AFR 195 or 210 LT4 heads with their competition porting package. Or, for that matter should I just get my existing LT1 heads done with a stage 3 type porting. I want to get the most power (425+rwhp) I can out of this and because I am going to do this over time I can absorb some of the higher dollar avenues, fully forged bottom end, splayed caps, maybe some titanium valves to spin this baby to 7000rpms, etc.
Any advice is greatly appreciated, especially from those running similiar setups.
Thread Starter
Melting Slicks
Joined: Apr 2001
Posts: 2,877
Likes: 7
Re: Head question LT1vsLT4 (Ruby6spd)
No one has any input on this,, how about all you guys with ported LT1 heads..
With good porting are you able to acheive equal numbers to ported LT4 or is the LT4 always going to put a few more horsepower down??
[Modified by Ruby6spd, 3:59 PM 6/26/2002]
With good porting are you able to acheive equal numbers to ported LT4 or is the LT4 always going to put a few more horsepower down??
[Modified by Ruby6spd, 3:59 PM 6/26/2002]
Burning Brakes
Joined: Apr 2002
Posts: 934
Likes: 0
From: MO
Re: Head question LT1vsLT4 (Ruby6spd)
I'm going with LT4 heads/intake. You can put bigger valves in them over
the LT1 heads and get a little more flow as well. I don't think you can buy
LT4 heads as bare castings new however. There is a set for sale on the forum with some porting done already.
the LT1 heads and get a little more flow as well. I don't think you can buy
LT4 heads as bare castings new however. There is a set for sale on the forum with some porting done already.
Thread Starter
Melting Slicks
Joined: Apr 2001
Posts: 2,877
Likes: 7
Re: Head question LT1vsLT4 (James94LT1)
I saw a set of new LT4's with valves/springs etc, for 600each. It's to bad you can't shave a few dollars from that because with a big cam and valves you will be replacing it all anyway
Burning Brakes
Joined: Apr 2002
Posts: 934
Likes: 0
From: MO
Re: Head question LT1vsLT4 (Ruby6spd)
I saw a set of new LT4's with valves/springs etc, for 600each. It's to bad you can't shave a few dollars from that because with a big cam and valves you will be replacing it all anyway
Safety Car
Joined: Jul 2001
Posts: 4,178
Likes: 2
From: Windermere FL
Re: Head question LT1vsLT4 (James94LT1)
I'm doing the same thing and wish I knew more also. I was looking at AFR LT-4 heads with CNC. I don't know what one I need yet. I want a 383 stroker build with an LT-4 intake, also CNC ported/polished.
Safety Car
Joined: Mar 2000
Posts: 3,620
Likes: 2
From: Hillsboro OR
Re: Head question LT1vsLT4 (Ruby6spd)
Its possible to get to 425 rwhp (500 crank) with AFR 180 heads. Go with those unless you want to get the heads comp ported in which case the 190s would be a better choice. I would not use the 195s unless you were upgrading an LT4 enigne and already had the LT4 intake.
I have AFR 190 heads which are in the machine shop right now and found out some things about the quality of AFRs head assembly work that is disturbing. My heads have about 10000 miles on them and needed new guides, new springs, new exhaust valves and a valve job. Apparantly, the guide work and seat work on the heads was not very good when they came from AFR. The machinest told me that this is a very common problem with aftermarket heads from all manufacturers and is not limited to AFR.
In light of this, I suggest you get bare castings and have a good machine shop do the work to complete them.
I have AFR 190 heads which are in the machine shop right now and found out some things about the quality of AFRs head assembly work that is disturbing. My heads have about 10000 miles on them and needed new guides, new springs, new exhaust valves and a valve job. Apparantly, the guide work and seat work on the heads was not very good when they came from AFR. The machinest told me that this is a very common problem with aftermarket heads from all manufacturers and is not limited to AFR.
In light of this, I suggest you get bare castings and have a good machine shop do the work to complete them.
Safety Car
Joined: Jul 2001
Posts: 4,178
Likes: 2
From: Windermere FL
Re: Head question LT1vsLT4 (AquaMetallic94LT1)
I'm replacing the intake, heads, cam, crank, pistons, rods, etc. All new. I was thinking bigger than 195 if possible. 220? I want 500+ hp/torque at the flywheel.
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Drifting
Joined: Apr 2000
Posts: 1,803
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From: PA
Re: Head question LT1vsLT4 (92TripleBlack)
Ruby,
You need to get the good CNC/More Performance article from around 1997 that was posted in an internet Corvette mag. They ran some real interesting dyno tests on the LT1 and LT4 combos. They are virtual clones to the $10K turnkey road legal setups that Lingenfelter used to bolt-in during the mid 90's. These were street legal combos with Random Tech cats and stock short block. The only "questionable" item was the cam. The CNC ported LT1 heads and unmodified, stock LT1 manifold produced 425 HP on the dyno. The IDENTICAL motor with CNC ported LT4 heads and PORTED LT4 manifold produced 435 HP. Their opinion was the LT4 heads were somewhat superior and the LT1 manifold (which requires no porting) was clearly superior. These were very streetable combos that appeared stock aside from the larger TB and shorty headers. These are good numbers from a motor that produced gobs of torque across the spectrum and peak HP below 6K RPM. These motors do not break.
You need to get the good CNC/More Performance article from around 1997 that was posted in an internet Corvette mag. They ran some real interesting dyno tests on the LT1 and LT4 combos. They are virtual clones to the $10K turnkey road legal setups that Lingenfelter used to bolt-in during the mid 90's. These were street legal combos with Random Tech cats and stock short block. The only "questionable" item was the cam. The CNC ported LT1 heads and unmodified, stock LT1 manifold produced 425 HP on the dyno. The IDENTICAL motor with CNC ported LT4 heads and PORTED LT4 manifold produced 435 HP. Their opinion was the LT4 heads were somewhat superior and the LT1 manifold (which requires no porting) was clearly superior. These were very streetable combos that appeared stock aside from the larger TB and shorty headers. These are good numbers from a motor that produced gobs of torque across the spectrum and peak HP below 6K RPM. These motors do not break.
Thread Starter
Melting Slicks
Joined: Apr 2001
Posts: 2,877
Likes: 7
Re: Head question LT1vsLT4 (Rick93Z07)
I will try to track that article down. I just wish I could find some new LT4 head that are bare rather than assembled., I am going to try to get 425+ ar the rear wheels. Since i am approaching this as a long term project I want to use best components as well as the best combinations of those components that i can get.. Also, i am interested to see what a set of AFR 195 LT4 fully ported head puts out. If anyone has used this head or know someone who has used it, pointing me in their direction would be a great help
Thanks to those who have responded
Thanks to those who have responded
Safety Car
Joined: Jul 2001
Posts: 4,178
Likes: 2
From: Windermere FL
Re: Head question LT1vsLT4 (Rick93Z07)
Melting Slicks
Joined: Dec 1999
Posts: 2,816
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From: Austin, TX
Re: Head question LT1vsLT4 (Ruby6spd)
There is a GM 'service replacement' LT4 head (bare head, no valves, studs, springs). However, the best price I've found on them new were from 18carfan (Jeff) at $590 each. Unfortunately, I don't have the part number, though.