Quote:
Originally Posted by Tinker
Craig, this build is awesome to follow. You definitely have some mechanical skills and a keen sense for engineering. I hope the worst phase of the project is behind you so you can stay driven to see your vision to it's completion.
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Thanks. Yes, had to walk away from it for a little bit, but back on it.
Quote:
Originally Posted by Tinker
Just a question on the header flanges, which look fantastic. Are you familiar with reversion? In my experience (which includes according to my wife "way too much time" working with my flowbench) the trend is to make the exhaust tube larger than the head exit. Usually the upper 2/3 of the port will match for high speed flow, but if the tube is left round, there will be a step at the floor of the tube. During operation, the exhaust pulses will travel down the exhaust tube, reach the end and turn around (over and over diminishing). This is reversion, and these pulses can carry spent gasses back into the chamber reducing VE. The step helps block these pulses from re-entering the cylinder. Is this not a concern for turbo cars, or are you more concerned about WOT performance?
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Yes, reversion is a big deal on turbo cars! I've been working with Burn's Stainless on the header size/length and shape. They recommended a smooth transition from port to primary with no step or lip.
I believe the long primaries are more key in the reversion scenario, but does go against conventional wisdom for turbo headers. I trust that they know best, it's what they do, and I've seen the data on spool time with short vs. long primaries. Just look at the Mazda turbo road car, high compression turbo car that only works because of a long tube primary manifold.