lt1 vs lt4 heads
Thread Starter
Racer
Joined: Aug 2008
Posts: 457
Likes: 2
lt1 vs lt4 heads
I have a 94 396 stroker with the lt1 heads 2.02 1.60 valves and heads are fully ported.If I put on a set of fully ported GM lt4 heads how much of a horsepower increase will this be.And do you think it will be worth it.Also will putting on lt4 heads increase my compression ratio.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Comparing what you have against LT4s, I'd say NO.
From my research, here's what I found:
The LT4 heads have 195 cc intake ports but your ported LT1s may be close to that already. Stock, your LT1s were 170 ccs. In any event, if competently ported, yours are flowing more that stock LT4s.
The difference in CR between the LT1 and LT4 is due to the LT4 having smaller valve reliefs in the pistons which increases CR from 10.4 to 10.8. The CR increase is due to the difference in pistons, not the size of the combustion chambers.
The LT4 heads need a LT4 intake since the port alignment is different between the LT1 and LT4 heads is different.
Easiest way to increase CR is to go with a thinner head gasket. The stock gaskets are .051 I just mic'd my son's LT1 HGs yesterday to verify that to be correct. There are some .026 and .028 gaskets available that many guys are running.
Jake
West Point ROCKS!
From my research, here's what I found:
The LT4 heads have 195 cc intake ports but your ported LT1s may be close to that already. Stock, your LT1s were 170 ccs. In any event, if competently ported, yours are flowing more that stock LT4s.
The difference in CR between the LT1 and LT4 is due to the LT4 having smaller valve reliefs in the pistons which increases CR from 10.4 to 10.8. The CR increase is due to the difference in pistons, not the size of the combustion chambers.
The LT4 heads need a LT4 intake since the port alignment is different between the LT1 and LT4 heads is different.
Easiest way to increase CR is to go with a thinner head gasket. The stock gaskets are .051 I just mic'd my son's LT1 HGs yesterday to verify that to be correct. There are some .026 and .028 gaskets available that many guys are running.
Jake
West Point ROCKS!
Last edited by JAKE; Jun 20, 2009 at 12:49 PM.
Pro
Joined: Jan 2009
Posts: 686
Likes: 4
From: Austin Texas
I have a 94 396 stroker with the lt1 heads 2.02 1.60 valves and heads are fully ported.If I put on a set of fully ported GM lt4 heads how much of a horsepower increase will this be.And do you think it will be worth it.Also will putting on lt4 heads increase my compression ratio.
http://www.gofastnews.com/board/tech...t-volumes.html
Thread Starter
Racer
Joined: Aug 2008
Posts: 457
Likes: 2
more help
I was thinking that it would'nt be worth it too,but i wanted to hear from someone else.
If i did go with AFR heads what do you think the power increase would be.I was thinking the lt4 heads since i have a lt4 intake.210cc or 227cc heads?
If i did go with AFR heads what do you think the power increase would be.I was thinking the lt4 heads since i have a lt4 intake.210cc or 227cc heads?
Pro
Joined: Jan 2009
Posts: 686
Likes: 4
From: Austin Texas
http://www.chevyhiperformance.com/te...ild/index.html
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Team Owner
Joined: Oct 2004
Posts: 81,241
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From: altered state
St. Jude Donor '05
interesting, they give theri opinion on why the LTs spin bearings so frequently.
I agree if you pour enouhg into a factory head you can make 500hp but youll get more out of a real good aftermarket.
I agree if you pour enouhg into a factory head you can make 500hp but youll get more out of a real good aftermarket.
Pro
Joined: Jan 2009
Posts: 686
Likes: 4
From: Austin Texas
I thought it was interesting too. I'll follow his lead and open my bearing clearances up also.
