Head Porting gains tech
Thread Starter
Joined: May 2009
Posts: 1,539
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From: columbus,ohio
Head Porting gains tech Like to get some input from experienced head porters on certain areas that gain good returns. The area in question is the intake port floor and wall
just preceding ssr . Are there any gains in this area , buy moving the straight wall out and knocking down the floor slightly ?
just preceding ssr . Are there any gains in this area , buy moving the straight wall out and knocking down the floor slightly ?
Thread Starter
Joined: May 2009
Posts: 1,539
Likes: 26
From: columbus,ohio
In general the floor is a area not to mess with, agreed. But I've read some guys have seen flow gains in the area encircled in green .
Keeping the mixture atomized on its way to the cylinder is what burns cleaner faster and makes more power.
Lowering or hogging out the port floor can show gains on a flow bench in some cases however that almost never translates into an actual hp gain on the dyno according to an old friend that ported beads.
If one was to go back to the early LS days in 1997-2001 one could find certain shops that lowered the floor to pump up flow numbers.
If one was to go back to the early LS days in 1997-2001 one could find certain shops that lowered the floor to pump up flow numbers.
Thread Starter
Joined: May 2009
Posts: 1,539
Likes: 26
From: columbus,ohio
Well here is a quote from the past , a experienced porter' on here.
"Jantzer98SS , 12-07-2006 03:33 AM
Focus on the straight side especially around the ramp area and up into short side. That side shows a lot of gains the 2" before the short turn. Pull the ramp down, but don't try to remove as it will get thin. You'll see huge gains there. Also the front rocker bump can be removed, I'm sure you know that. I would do chamber work on the 5.3's as well. Unshroud the valves and roll over the sparkplug boss."
"Jantzer98SS , 12-07-2006 03:33 AM
Focus on the straight side especially around the ramp area and up into short side. That side shows a lot of gains the 2" before the short turn. Pull the ramp down, but don't try to remove as it will get thin. You'll see huge gains there. Also the front rocker bump can be removed, I'm sure you know that. I would do chamber work on the 5.3's as well. Unshroud the valves and roll over the sparkplug boss."
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I knew some head porters that swore flattening out the SSR there helped, but I don't know if they were talking about gains on the flowbench or dyno.
There is a lot of power in reshaping the short turn, but you can shoot yourself in the foot if you don't know what you're doing. I was taught that that part of the port has what we call a "bias", meaning that the port leans one way or another with respect the the valve centerline. The air is going to flow though the port and try to turn to the center of the bore as it approaches the valve. In your picture of the port, the air will be turning towards the bottom left area of the port.
The idea here is that if you have a flat SSR with a tight radius corner, the air will crowd there and cause very high localized velocities, which is bad. However, if you bias the port and lean that port floor, the air will spread out and remain stable to higher average air speeds. It's kind of like the embankments on a NASCAR oval track.
There is a lot of power in reshaping the short turn, but you can shoot yourself in the foot if you don't know what you're doing. I was taught that that part of the port has what we call a "bias", meaning that the port leans one way or another with respect the the valve centerline. The air is going to flow though the port and try to turn to the center of the bore as it approaches the valve. In your picture of the port, the air will be turning towards the bottom left area of the port.
The idea here is that if you have a flat SSR with a tight radius corner, the air will crowd there and cause very high localized velocities, which is bad. However, if you bias the port and lean that port floor, the air will spread out and remain stable to higher average air speeds. It's kind of like the embankments on a NASCAR oval track.
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Verdad Gallardo Even removing the intake bowl ramp does spike flow numbers but dramatically changes what the engineers were trying to achieve. Carl Wagner here in Wisconsin has done an awful lot with the LS stuff over the years and right from his mouth was "I simply can't get 300 CFM from a cathedral head while keeping the swirl ramp. I modify it but refuse to remove it"
Even removing the intake bowl ramp does spike flow numbers but dramatically changes what the engineers were trying to achieve. Carl Wagner here in Wisconsin has done an awful lot with the LS stuff over the years and right from his mouth was "I simply can't get 300 CFM from a cathedral head while keeping the swirl ramp. I modify it but refuse to remove it"