DIY Head porting
07-20-2013, 06:37 PM
#21
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Mike
Last edited by Mikey 97Z M6; 07-21-2013 at 12:08 AM.
07-20-2013, 11:39 PM
#22
I've talked to the gearhead4life guy. He used the 3 piece summit set and a bag of 80 grit "tootsie rolls" that he bought off of eBay.
Here is his 10 part series:
How To LS1 DIY Head Porting - YouTube
It's worth the watch I think. He's not porting 317 heads in that video though.
My big question is, what all to take out? My truck isn't an all out race vehicle. I wonder how important leaving the swirl ramps in place would be for low end torque? I'm building a turbocharged 6.0L. I don't want a dog out of boost.
I understand we're improving peak flow here, especially in the upper rpms, but I don't want to sacrifice driveability. I'm considering the removal of rocker arm stud boss, but keeping the swirl ramps. Then smoothing and polishing everything up.
Advice?
Here is his 10 part series:
How To LS1 DIY Head Porting - YouTube
It's worth the watch I think. He's not porting 317 heads in that video though.
My big question is, what all to take out? My truck isn't an all out race vehicle. I wonder how important leaving the swirl ramps in place would be for low end torque? I'm building a turbocharged 6.0L. I don't want a dog out of boost.
I understand we're improving peak flow here, especially in the upper rpms, but I don't want to sacrifice driveability. I'm considering the removal of rocker arm stud boss, but keeping the swirl ramps. Then smoothing and polishing everything up.
Advice?
07-21-2013, 12:14 PM
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I havent seen any flow data or dyno sheets that support leaving that swirl hump in there. Until I do see that I will always remove them when porting. I havent seen any cnc heads leave them there either and often times those flow numbers exceed stock flow numbers even at .200" and. 300" valve lift.
Concentrate your efforts in the bowls, directly under the valves. Make that area larger and try to think in terms of how the air path moves when shaping. Sharp or abrupt edges kill velocity which will hurt flow. The factory short side radius is pretty good on most LS heads so dont try reshaping those. Just blend with cartidge rolls to help smooth and blend. Work slowly with purpose. Constantly feel the surface to make sure the shape is smooth and consistent because the lighting can be deceiving in there. Also can open up the intake port entrance a bit. Its always better to have the intake port slightly larger than the manifold port rather than the other way around. Again, think in terms of airflow direction and how an abrupt edge can hurt airflow. Obviously the opposite is true for the exhaust since you want exhaust port opening a tad smaller than the header opening. If you're super **** you can try port matching but that can be difficult to do, time consuming and usually results in little gain on a street engine.
Chances good that if you dont get too carried away with making the ports too large that yoi should pick up port velocity and flow numbers at low lift. This will help low end torque production so I wouldnt worry about it feeling sluggish down low.
Good luck and shoot me a pm if you run into trouble or have any specific questions.
Mike
I would highly suggest practicing on a set of junk heads. If you really want to learn, have them flow tested before and after to see if you're working the right areas and making improvements.
Concentrate your efforts in the bowls, directly under the valves. Make that area larger and try to think in terms of how the air path moves when shaping. Sharp or abrupt edges kill velocity which will hurt flow. The factory short side radius is pretty good on most LS heads so dont try reshaping those. Just blend with cartidge rolls to help smooth and blend. Work slowly with purpose. Constantly feel the surface to make sure the shape is smooth and consistent because the lighting can be deceiving in there. Also can open up the intake port entrance a bit. Its always better to have the intake port slightly larger than the manifold port rather than the other way around. Again, think in terms of airflow direction and how an abrupt edge can hurt airflow. Obviously the opposite is true for the exhaust since you want exhaust port opening a tad smaller than the header opening. If you're super **** you can try port matching but that can be difficult to do, time consuming and usually results in little gain on a street engine.
Chances good that if you dont get too carried away with making the ports too large that yoi should pick up port velocity and flow numbers at low lift. This will help low end torque production so I wouldnt worry about it feeling sluggish down low.
Good luck and shoot me a pm if you run into trouble or have any specific questions.
Mike
I would highly suggest practicing on a set of junk heads. If you really want to learn, have them flow tested before and after to see if you're working the right areas and making improvements.
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