Dorman LS2 Intake Manifold Porting
Thread Starter
Pro
Joined: Feb 2013
Posts: 535
Likes: 92
From: Raleigh NC
Dorman LS2 Intake Manifold Porting
Just curious if anyone has any experience with DIY porting of the Dorman LS2 intake manifold?
I decided to give the Dorman a try and from looking at the ports, there appears to be some areas for improvement. There's a "step" in the runner that looks like it could be removed. And probably some cleanup around the TB opening. The transition between different parts of the mold can be a little rough too.
I've got a set of TSP cnc ported 243 heads, and the intake openings measure 1.15" wide. The ports on the intake manifold are significantly smaller than that, so there could be some gains from opening those up.
The socket you see in the picture has an OD of 1.10". You can see the before and after of how that socket compares to the port opening.
I'm still experimenting some with different bits. Both the 80 grit sanding drum and the carbide bit both remove material pretty quickly. Going slow and not taking too much at a time seems to be key. Trying not to get too greedy, as I can see how you could really screw up the air flow in a hurry.
I went back and hit the port walls with an abrasive buffing wheel afterwards (240 grit?), which definitely helps smooth the walls, but I think it can be better. I've got some even higher grit buffing wheels coming.
I also bought the flex shaft attachment for my Dremel. Makes it way easier to work with, and it can get deeper in the ports too.
Any ways, just thought I'd share what I'm working on and see if anyone else had any tips or suggestions. Mine is still a work in progress but I think it's headed the right direction. I'd love to see finished pictures of what others have done.
I decided to give the Dorman a try and from looking at the ports, there appears to be some areas for improvement. There's a "step" in the runner that looks like it could be removed. And probably some cleanup around the TB opening. The transition between different parts of the mold can be a little rough too.
I've got a set of TSP cnc ported 243 heads, and the intake openings measure 1.15" wide. The ports on the intake manifold are significantly smaller than that, so there could be some gains from opening those up.
The socket you see in the picture has an OD of 1.10". You can see the before and after of how that socket compares to the port opening.
I'm still experimenting some with different bits. Both the 80 grit sanding drum and the carbide bit both remove material pretty quickly. Going slow and not taking too much at a time seems to be key. Trying not to get too greedy, as I can see how you could really screw up the air flow in a hurry.
I went back and hit the port walls with an abrasive buffing wheel afterwards (240 grit?), which definitely helps smooth the walls, but I think it can be better. I've got some even higher grit buffing wheels coming.
I also bought the flex shaft attachment for my Dremel. Makes it way easier to work with, and it can get deeper in the ports too.
Any ways, just thought I'd share what I'm working on and see if anyone else had any tips or suggestions. Mine is still a work in progress but I think it's headed the right direction. I'd love to see finished pictures of what others have done.
Racer
Joined: Mar 2008
Posts: 457
Likes: 52
From: Elkhart, Texas
Mine is similar. Took out the steps and cleaned up the inlet as well as throttle body and adapter. They are pretty clean overall. I saw a gain in airflow volume up top, hope to have the entire setup on the rollers this spring to see what it puts down.
Le Mans Master
Joined: Jun 2016
Posts: 5,431
Likes: 3,990
From: Cincinnati, OH
I want to bump this back up.
Last year I added this intake on a C5Z with LS2 TB, LS3 air bridge, speed density tune, full exhaust. Before installing I smoothed out the ridge between the two halves denoted by OP's yellow arrow. However, I did not widen the runner (port match) or smooth out the "step" leading up to the injector on the long (top) side of the runners.
Now I'm thinking about removing the intake for some more porting if it might be worth it. My goal is midrange hp/tq gains not so much at 6000+ rpm.
Last year I added this intake on a C5Z with LS2 TB, LS3 air bridge, speed density tune, full exhaust. Before installing I smoothed out the ridge between the two halves denoted by OP's yellow arrow. However, I did not widen the runner (port match) or smooth out the "step" leading up to the injector on the long (top) side of the runners.
Now I'm thinking about removing the intake for some more porting if it might be worth it. My goal is midrange hp/tq gains not so much at 6000+ rpm.
