[slowbird]

Those of you that have a head what do you think of the exhaust port? Seen it mentioned that to make more power the exhaust side is going to need more work.

[cgeise]

Jim -- the pics are great - -ty - Don -- I hear what you are saying-- IMO -- If the head can be done in a 450 to 465 cfm configuation - and duplicated in a CNC setup --I think we wil have a winner no welding - no epoxy - ext. Jims port is giving me a little stiffy - jk

Good luck all

[blaktopr]

Slowbird, remember the valves are pushed off the X axis opposite directions and the centerline is measured off the X axis, giving more between the valves.

I think these should be done focusing beyond what we have now. I see 470+ potential and 8000+ RPM 535's. And I wouldn't even consider the Victor even at 440CFM levels.

[BruceWilkie]

Originally Posted by slowbird

Those of you that have a head what do you think of the exhaust port? Seen it mentioned that to make more power the exhaust side is going to need more work.

I hope there are new opportunities there myself. For a long time I've been of the opinion that our "traditional" layout poses some limitations. If we can get better balance percentages than what we usually see it should help us. If we get same percentages I dont think it hurts us. Worse percentages would not be good and I dont think that will occur.

[slowbird]

Originally Posted by BruceWilkie

I hope there are new opportunities there myself. For a long time I've been of the opinion that our "traditional" layout poses some limitations. If we can get better balance percentages than what we usually see it should help us. If we get same percentages I dont think it hurts us. Worse percentages would not be good and I dont think that will occur.

Wilke what kind of ratio do you think is, 75%?

[pastry_chef]

Originally Posted by BruceWilkie

I hope there are new opportunities there myself. For a long time I've been of the opinion that our "traditional" layout poses some limitations. If we can get better balance percentages than what we usually see it should help us. If we get same percentages I dont think it hurts us. Worse percentages would not be good and I dont think that will occur.

I will disagree

better/maintaining I/E flow ratio "percentages" should not be "looked at", even if you are less than 70 percent

[BruceWilkie]

Originally Posted by pastry_chef

I will disagree

better/maintaining I/E flow ratio "percentages" should not be "looked at", even if you are less than 70 percent

There can be a point where a deficient exhaust chokes the potential of the intake flow capabilities. You can only crutch around exhaust deficiencies with ex valve movement(open/close factors) header and intake tuning to a point.

Yes actual flow capacity matters and balance is an important part . Sure, I could improve percentage on a D port, or any other head, and not gain if I dont take advantage of it elsewhere.

??? You seem to be implying that better balance cant be used to improve VE.

If you are improving the intake capability by "x" percentage flow gain should you not be trying to improve your exhaust capability by the same percentage gain??? Could a little more be useful??? Aiding blowdown isnt desirable??? Cutting exhaust pumping losses arent beneficial???

Please explain if you were not playing word games.

FWIW I dont "feel" there is an "ideal" balance percentage. Simply I'd rather have more exhaust capacity than I need or at least as much as I could get.

[cfmcnc]

Some of our Fastest Running Down The track Exhaust ports flow considerable less than some of our Flow bench bragging rights exhaust ports,We like to see real high air speed at the crack of the exhaust valve opening and enough area to not be restrictive.Some of the most refined NA cylinder heads are 55-60% ratio,ieNHRA Pro-Stock.If the 11 pro-port intake can get to 450-470cfm ,with correct air speed and crossectionals and good CFM to MCSA ,we would not be to concerned if the exhaust did not go 70-75%.Bill C.