LT4: matching intake manifold ports to intake gasket - comments?
#1
Drifting
Thread Starter
LT4: matching intake manifold ports to intake gasket - comments?
According to Jim Mason (96 Grand Sport fame) this is a mod that is beneficial to a slightly modded LT4.
http://www.hashmarks.com/techtips/in...ke_porting.htm
I need to replace my intake manifold gaskets. A little bit of seepage at the rear.
While I have my intake off, I was thinking of porting the intake manifold to the size of the intake gasket. Time consuming but this would be the ideal time to do this.
Anyone have any thoughts or tips?
http://www.hashmarks.com/techtips/in...ke_porting.htm
I need to replace my intake manifold gaskets. A little bit of seepage at the rear.
While I have my intake off, I was thinking of porting the intake manifold to the size of the intake gasket. Time consuming but this would be the ideal time to do this.
Anyone have any thoughts or tips?
#2
Typically, gasket matching results in minimal gains. I would not think that paying someone $100+ an hr would make it worth it, but if you are doing it yourself, it is a great deal. You may only get 2-3 hp. Then again, 203 is not a bad deal. You could get a few more if you are lucky. Get grindin
#3
Le Mans Master
Originally Posted by Pete K
Typically, gasket matching results in minimal gains. I would not think that paying someone $100+ an hr would make it worth it, but if you are doing it yourself, it is a great deal. You may only get 2-3 hp. Then again, 203 is not a bad deal. You could get a few more if you are lucky. Get grindin
Sounds like a perfect time to pull the heads and send both the heads and intake off for a full matching port job!
Otherwise, I doubt you'll see any real gain from only matching the gasket alone. If you do it yourself, good luck, and be careful as the oem lt4 intakes are getting hard to find and are $$$. I would definitely not pay someone to do the intake gasket matching port work alone.
#4
Melting Slicks
What's being described in that article isn't full gasket matching. He's just matching the top of the ports (intake) to the stock head port's shape.
When I fully matched mine it was with a 12367777 gasket both on the intake and heads. There is a considerable amount of material to take out of both to do this. Originally I was just going to do the port matching but after some reading I discovered it didn't do much without some further bowl cleanup and further porting.
So in the end the end I went a full port job and what is supposed to be a 5 angle cut.
Here's the numbers with JUST a Hot Cam and tune. Everything else is stock from the exhaust manifolds back.
When I fully matched mine it was with a 12367777 gasket both on the intake and heads. There is a considerable amount of material to take out of both to do this. Originally I was just going to do the port matching but after some reading I discovered it didn't do much without some further bowl cleanup and further porting.
So in the end the end I went a full port job and what is supposed to be a 5 angle cut.
Here's the numbers with JUST a Hot Cam and tune. Everything else is stock from the exhaust manifolds back.
#5
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Originally Posted by TorchRedlt4man
I was thinking of porting the intake manifold to the size of the intake gasket. Anyone have any thoughts or tips?
I say, "What's the point?" Do it right....full, professional porting job. Won't give you much, but will help when you add the other stuff like cam/headers/etc.
Larry
code5coupe
Last edited by rocco16; 09-06-2006 at 04:03 PM.
#6
Safety Car
Originally Posted by TorchRedlt4man
According to Jim Mason (96 Grand Sport fame) this is a mod that is beneficial to a slightly modded LT4.
http://www.hashmarks.com/techtips/in...ke_porting.htm
I need to replace my intake manifold gaskets. A little bit of seepage at the rear.
While I have my intake off, I was thinking of porting the intake manifold to the size of the intake gasket. Time consuming but this would be the ideal time to do this.
Anyone have any thoughts or tips?
http://www.hashmarks.com/techtips/in...ke_porting.htm
I need to replace my intake manifold gaskets. A little bit of seepage at the rear.
While I have my intake off, I was thinking of porting the intake manifold to the size of the intake gasket. Time consuming but this would be the ideal time to do this.
Anyone have any thoughts or tips?
Jim Mason knows what he is talking about!!!!!
Also Doug Rippie promoted this mod way back....and others
It just makes sense to correct any mismatch if you after maximum performance.....
#7
Le Mans Master
Originally Posted by LT4BUD
I matched mine to the ....777 intake gaskets.....
Jim Mason knows what he is talking about!!!!!
Also Doug Rippie promoted this mod way back....and others
It just makes sense to correct any mismatch if you after maximum performance.....
Jim Mason knows what he is talking about!!!!!
Also Doug Rippie promoted this mod way back....and others
It just makes sense to correct any mismatch if you after maximum performance.....
I don't know how much gain you'll see, but Jim Mason knows what he is talking about, I've seen him go past me to many times on the track to disagree with him.
#8
Melting Slicks
Here's what it looks like when you fully match the heads to a 12367777 gasket, quite different from the Jim Mason page.
Then look here and find LT4's with just a Hot Cam and see if they're making the same power. Some are but they have headers also. I'm positive this is where my low torque number is coming from. Still it's a substantial gain from a bit of porting.
So I'm anxious to see what happens with a full exhaust. Priorities keep getting in the way though.
I was always under the impression that's why the LT4 intake was different, so that when the time came you could use the extra material to fully match the ports. Frankly I thought it was common knowledge.
Then look here and find LT4's with just a Hot Cam and see if they're making the same power. Some are but they have headers also. I'm positive this is where my low torque number is coming from. Still it's a substantial gain from a bit of porting.
So I'm anxious to see what happens with a full exhaust. Priorities keep getting in the way though.
I was always under the impression that's why the LT4 intake was different, so that when the time came you could use the extra material to fully match the ports. Frankly I thought it was common knowledge.
#9
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Originally Posted by ALLT4
Then look here and find LT4's with just a Hot Cam and see if they're making the same power. Still it's a substantial gain from a bit of porting.
Absolutely no way port matching will give as much power as the Hot Cam can give. None. Nada. Zip.
Larry
code5coupe
Last edited by rocco16; 09-06-2006 at 06:07 PM.
#10
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Originally Posted by TorchRedlt4man
According to Jim Mason (96 Grand Sport fame) this is a mod that is beneficial to a slightly modded LT4.
While I have my intake off, I was thinking of porting the intake manifold to the size of the intake gasket. Time consuming but this would be the ideal time to do this.
Anyone have any thoughts or tips?
While I have my intake off, I was thinking of porting the intake manifold to the size of the intake gasket. Time consuming but this would be the ideal time to do this.
Anyone have any thoughts or tips?
Port matching has been controversial regarding power output for sure but on highly modded cars the intake is a definite restriction. GM never in their wildest dream intended these engines to make 600 hp and the intake is one area that can be improved.
The biggest restriction lies right around where the injectors sit and there is not enough metal just above the injectors to port the intake properly. If that area has additional material welded and the path straightened, then port match (really porting) adds significantly to a cars capablility of producing a lot of airflow.
At what power level this appreciately helps? Not sure, but for sure if your in the 450rwhp or above it adds at least 10 hp.
If you do your own porting make sure you remove the plate underneath the intake and clean it very well before putting the intake back on the car. One intake I had was professionally ported and the car came out way below what we expected. Then all of a sudden the car picked up on it'w own. Turns out there were shavings from the intake that got caught between the pistons and the cylinder wall and the rings were not seating. After this had cleared itself the car ran great but we didn't know why until after the teardown.
#11
Melting Slicks
Originally Posted by rocco16
Absolutely no way port matching will give as much power as the Hot Cam can give. None. Nada. Zip.
Last edited by ALLT4; 09-06-2006 at 06:26 PM.
#12
Melting Slicks
Originally Posted by d48mclain
If you do your own porting make sure you remove the plate underneath the intake and clean it very well before putting the intake back on the car. One intake I had was professionally ported and the car came out way below what we expected. Then all of a sudden the car picked up on it'w own. Turns out there were shavings from the intake that got caught between the pistons and the cylinder wall and the rings were not seating. After this had cleared itself the car ran great but we didn't know why until after the teardown.
#14
When I replaced my intakes gaskets, I went with the 777s as well. Thanks Jim Understand that there is a Huge difference btw the standard LT1 app and the 777s gaskets. I also bench sanded the intake ports myself basically just to deburr and smooth a bit, nothing major. Did all the work myself so no money spent except the parts. I WILL tell you that I noticed a SOP difference. No other mods done at the time. I don't have dyno results to post so believe it or not, that's my experience
#16
Drifting
Originally Posted by ALLT4
Here's what it looks like when you fully match the heads to a 12367777 gasket, quite different from the Jim Mason page.
Then look here and find LT4's with just a Hot Cam and see if they're making the same power. Some are but they have headers also. I'm positive this is where my low torque number is coming from. Still it's a substantial gain from a bit of porting.
So I'm anxious to see what happens with a full exhaust. Priorities keep getting in the way though.
I was always under the impression that's why the LT4 intake was different, so that when the time came you could use the extra material to fully match the ports. Frankly I thought it was common knowledge.
Then look here and find LT4's with just a Hot Cam and see if they're making the same power. Some are but they have headers also. I'm positive this is where my low torque number is coming from. Still it's a substantial gain from a bit of porting.
So I'm anxious to see what happens with a full exhaust. Priorities keep getting in the way though.
I was always under the impression that's why the LT4 intake was different, so that when the time came you could use the extra material to fully match the ports. Frankly I thought it was common knowledge.
LT4 heads available, and the ORIGINAL LT4 service parts gaskets were made with the ports upside down, the taller part of the port was on the bottom. Calling a friend in engineering, he sent me a blueprint, and it was wrong too. I corrected him, and a few months later, the proper design gaskets, with a new part number, were available.
#17
Safety Car
Originally Posted by LT1GMC
......... My theory? GM guys ran out of time developing the LT4, and didn't get time to do a new casting for the inside of the manifold, just the outside. ............
Things like the mismatched manifold give clues as to this possibility.....if you port match to the ...777gasket, then put in the LT4 hot cam...put in a 52mm throttle body......and what to you have??? 400hp..
But we will never know..
#18
Tech Contributor
Originally Posted by STL94LT1
If I remember correctly Jim Mason made 342 rwhp with just a Hot Cam, intake porting, shorty headers, and bone stock heads.
Mike mentioned I made 342rwhp with the ported intake, shorty headers, and the HOT Cam. This is correct. With nothing more than mild pocket porting of the cylinder heads and port matching the cylinder head intake runners to the intake manifold I made 363rwhp.
The bottom line....port or don't, it doesn't hurt my feelings. I had a staged plan for the engine and simply tried to document things as I went along for others to use if they found it helpful.
#19
Melting Slicks
I thought port matching was standard practice for a better breathing motor? This thread has me wondering how many folks actually do it.
Might not make much difference on stock stuff but when you start adding bigger cams and headers I think it's well worth the effort. If you're going to have the intake off, just go a bit further with taking the heads off, clean up the bowls and port match the intakes.
It's only bolts and few more gaskets, plus maybe some extra money to have someone do it if you can't do it yourself.
Might not make much difference on stock stuff but when you start adding bigger cams and headers I think it's well worth the effort. If you're going to have the intake off, just go a bit further with taking the heads off, clean up the bowls and port match the intakes.
It's only bolts and few more gaskets, plus maybe some extra money to have someone do it if you can't do it yourself.
#20
Originally Posted by ALLT4
If you're going to have the intake off, just go a bit further with taking the heads off, clean up the bowls and port match the intakes.