LT4 Head porting results are in
Thread Starter
Safety Car
Joined: Jun 1999
Posts: 3,570
Likes: 3
From: Austin, Singapore, Kuala Lumpur, Houston, Dallas, Hong Kong, Elgin, etc.. Texas
LT4 Head porting results are in
Below are the most recent Dyno runs for my LT4. The first one was done on July 7 with the only modifications being the throttle body by-pass and K & N air filter. Peak was 300 rwhp and 305 rwtq.
The November 17 run showed 22 more horse power as a result of a Stage I head porting that consisted of pocket porting, 3 angle valve job, combustion chamber polishing, head port gasket match to the new GM gasket for LT4 (part# 12367777), and intake manifold gasket match.
What is interesting is just this virtually stock LT4 picked up 22 hp with just a simple, basic head and intake port work. Mechanically, otherwise it is original including the cam, exhaust system, and air intake system (except for K&N filter). The slight dips in the upper RPM range are the knock sensors taking the timing down a few degrees. A boost in octane would stop it.
[Modified by Mez, 6:12 PM 11/19/2001]
The November 17 run showed 22 more horse power as a result of a Stage I head porting that consisted of pocket porting, 3 angle valve job, combustion chamber polishing, head port gasket match to the new GM gasket for LT4 (part# 12367777), and intake manifold gasket match.
What is interesting is just this virtually stock LT4 picked up 22 hp with just a simple, basic head and intake port work. Mechanically, otherwise it is original including the cam, exhaust system, and air intake system (except for K&N filter). The slight dips in the upper RPM range are the knock sensors taking the timing down a few degrees. A boost in octane would stop it.
[Modified by Mez, 6:12 PM 11/19/2001]
Burning Brakes
Joined: Aug 2000
Posts: 984
Likes: 1
From: Cincinnati OH
Re: LT4 Head porting results are in (Mez)
This is great info. I've never seen pure head head work results documented for an LT1 or LT4 car without any other changes before but was always curious. Looks good.
Drifting
Joined: Aug 2001
Posts: 1,823
Likes: 1
From: Arlington TN
Re: LT4 Head porting results are in (Mez)
What was the rough cost of your work, if you dont mind our asking....Looking to lay out my projects down the road (next winter????)
This winter is new wheels and exhaust.
Thanks
:cheers:
This winter is new wheels and exhaust.
Thanks
:cheers:
Thread Starter
Safety Car
Joined: Jun 1999
Posts: 3,570
Likes: 3
From: Austin, Singapore, Kuala Lumpur, Houston, Dallas, Hong Kong, Elgin, etc.. Texas
Re: LT4 Head porting results are in (BrentDev)
The cost was not that much. With head and intake gaskets, new head bolts, belt, and other odds and ends you should be able get this done for about $600 (of course, excluding disassembly and reassembly labor).
I must stress that my objective was to maximize the factory set up including stock cam, exhaust system, and air intake assembly. I have not even change cut out the air cleaner lid. For more HP, the next step is to buy a new Cam, a free flow exhaust system, and paid for more work on the heads. Probably another $1500 which was not in my budget. Also, I was not willing to live with a louder exhaust or a less smooth idle.
I must stress that my objective was to maximize the factory set up including stock cam, exhaust system, and air intake assembly. I have not even change cut out the air cleaner lid. For more HP, the next step is to buy a new Cam, a free flow exhaust system, and paid for more work on the heads. Probably another $1500 which was not in my budget. Also, I was not willing to live with a louder exhaust or a less smooth idle.
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