Quote:
Originally Posted by Pinhead
I was under the impression that the low-lift flow actually increased due to the effect it has on the boundary layer. I'm pretty sure one of his PDF's mentioned somewhere around 40% increase. In addition to helping to vaporize the fuel.
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I am sceptical of any intake
flow increase especially relating to any modification that is on top of the valve inside the chamber, and 40%, no way.
Unless you are referring to mods that are at the underside of the valve but even then I remain sceptical and again, 40%, no way.
David vizard has tried and tested (on a dyno) many theoretical profiles to get to where he is at today and has never made any unbelivable 40% claims. He has found improvements that accumulativly add up but not
40% above a properly done, modern, high flow, performance valve job.
David Vizard, I hope you read this or mabe I should post this in a different thread but it kind of fits into what were talking about -------- I realize that many nascar builders have gone to 55 degree valve seat angles and with that the port to valve centerline angles, RPM horsepower curve, and many other things contribute to the trend for this application. What application is best suited to the 30 degree valve seat angles that you had supported against the trend for a more conventional 45 degree seat. Some diesles have 30 degree seats and are low RPM but I dont know how many are currently running these angles. You have run these angles at a much higher RPM but I dont know if you continue to do so. I have built a sprayed boosted engine with 30 degree seats so I could justify a decrease in valve duration. I havent read any where of you saying anything about this but I believe the boosted low lift flow on the intake side can really get moving before the piston does and so this could allow for a smaller intake valve and hence a larger exhaust valve within the chamber space that is available. I have no scientific supporting data to confirm my guesses as to the best valve event timing for any 30 degree boosted engine and there may be drawbacks that I havent realized. Also would you
not run 30 degree seats on the exhaust valve of a sprayed motor.
matt kneen mpls, mn.