The port will transfer more of the exhaust gasses throughout the valve action. This larger port will flow more at its initial opening when pressures are the highest. Taking advantage of the overlap. You will also be able to use a shorter duration, or earlier valve timing. The flow bench remains constant for reading. But does not replicate pressure of the running combo. This would yield higher power numbers on a dyno.
Area is important. Velocity is important, but the exhaust side is odd. When John Kaase developed his new SR71 head, he left the exhaust the same size as the huge SCJ port. He admitted on a bench that when filled, it flowed more CFM but lost 30 HP on the dyno.
I've been preaching for years, I don't care what the exhaust flows on the bench... it goes supersonic on a running engine. Bench is good to make sure the port isn't tripping somewhere in the curve but that's about it. Once I finally let go of the flow numbers and started just giving the exhaust some area and shape my life got a lot easier. My stuff normally runs better than i expect it to.
@@servediocylinderheadsno, don't like the valve job, throat is too big for it. When I say I give it area, I mean I open up the throats, widen and lay back the short side, work the guide boss and send it. I'll only enlarge the port itself if it's high rpm, nitrous or on methanol. I've found methanol stuff likes a bigger exhaust port. On production heads I usually end up at 1.350"ish with a 1.6, works out really nice with my valve job. Aftermarket heads i'll get into 1.400"+.
0.20 lift isn't minus? I think is a winner as it has got better flow from 0.20 lift on and it tops out way better. I wonder would you like to test the theory and try to fill the floor with some clay
As soon as you raised the roof I knew the air would separate. That's a healthy gain though. This would be a good candidate for DV anti reversion plate in the exhaust header. How much of the bottom of the port can you cover up before it drops cfm?
Awesome stuff! you mentioned that you wouldnt braze these cheaper heads but would you braze say a big block Olds head on the floor to mimic the edelbrock olds exhaust port shape? if you google it its roughly 1/2" raised on the floor. anti reversion too with a rectangle header port flange? thanks. Wish i could post pics to make it easier for you to answer. I know your time is valuable
@@robtdougherty Depending on the application and how much I think it could be improved I would consider it. Everything needs to be trued up after brazing due to heat warping. Keep that in mind.
The port will transfer more of the exhaust gasses throughout the valve action. This larger port will flow more at its initial opening when pressures are the highest. Taking advantage of the overlap. You will also be able to use a shorter duration, or earlier valve timing.
The flow bench remains constant for reading. But does not replicate pressure of the running combo. This would yield higher power numbers on a dyno.
@@approachingtarget.4503 I agree. Good info.
Area is important. Velocity is important, but the exhaust side is odd. When John Kaase developed his new SR71 head, he left the exhaust the same size as the huge SCJ port. He admitted on a bench that when filled, it flowed more CFM but lost 30 HP on the dyno.
@@lucascb750 Good info.
Thanks
Thank you for taking the time to explain
@@clarkmcmahan1595 You are welcome.
I've been preaching for years, I don't care what the exhaust flows on the bench... it goes supersonic on a running engine. Bench is good to make sure the port isn't tripping somewhere in the curve but that's about it. Once I finally let go of the flow numbers and started just giving the exhaust some area and shape my life got a lot easier. My stuff normally runs better than i expect it to.
@@dirtfan05 So you like this port?
@@servediocylinderheadsno, don't like the valve job, throat is too big for it. When I say I give it area, I mean I open up the throats, widen and lay back the short side, work the guide boss and send it. I'll only enlarge the port itself if it's high rpm, nitrous or on methanol. I've found methanol stuff likes a bigger exhaust port. On production heads I usually end up at 1.350"ish with a 1.6, works out really nice with my valve job. Aftermarket heads i'll get into 1.400"+.
@@dirtfan05 Good info. Thanks
It flows more, but may not work as well during overlap.
0.20 lift isn't minus? I think is a winner as it has got better flow from 0.20 lift on and it tops out way better. I wonder would you like to test the theory and try to fill the floor with some clay
@@mikkokuorttinen3113 eh
................impressive design and shape,,,,,,,,,,,,,,,,,,,,i'd keep the same only smaller............................................
@@ThomasELeClair Depends on application. Thanks
This good stuff 😊😊,,,,
@@jeremystory6981 Thanks
As soon as you raised the roof I knew the air would separate. That's a healthy gain though. This would be a good candidate for DV anti reversion plate in the exhaust header. How much of the bottom of the port can you cover up before it drops cfm?
@@chrisstavro4698 I didn't try but the air speed is low on the bottom. Thanks
Would a seat angle change fix the noisy issue and improve the low lift flow??
@@clarkmcmahan1595 It might.
Sheeeeesh
@@vestal2245 Is that good?
Awesome stuff! you mentioned that you wouldnt braze these cheaper heads but would you braze say a big block Olds head on the floor to mimic the edelbrock olds exhaust port shape? if you google it its roughly 1/2" raised on the floor. anti reversion too with a rectangle header port flange? thanks. Wish i could post pics to make it easier for you to answer. I know your time is valuable
@@robtdougherty Depending on the application and how much I think it could be improved I would consider it. Everything needs to be trued up after brazing due to heat warping. Keep that in mind.