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Originally Posted by TrinaBabe
The original design concept was taken from a 24 hour race car designed by HKS. It has changed a decent amount in me trying to get it to be perfect. Not an easy task at all  |
No doubt. A PITA, to say the least. Hopefully it will make you at least enough cash to make your time spent worthwhile!
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Originally Posted by TrinaBabe
About the runner length yes, there are a few different ways to measure the pulsing. I am assuming the one you mentioned is a helmholtz equation broken down to be simple.
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Not even that complicated. It's just a basic open-pipe oscillation equation. A CFD approach would be infinitely better, especially in the case of building a single engine with as few unknown variables as possible. But, since so many Evo's will have so many intake/cam/turbo/porting/valve arrangements with this manifold, there will be no way to predict any sort of
exact pulsetuning, making the
precision of a particular equation less and less valuable.
The Achilles Heel of my previously mentioned equation is that it doesn't consider the iterative effects of the previous engines cycles. As you pointed out, at high RPM, the wavefronts from the previous few engines cycles are still not completely damped. In reality, you'd need to compute the viscosity of the air, the effects of the shape on sound damping, the local mach number (to test for compressibility), and you'd need to take into account the linear movement of the air into the engine and its effect on pulsetuning: IE you'd need either 1) a GOOD sound-wave emulator program or, 2) a variable-length test manifold onto which you could put pressure probes.
Talk about a PITA! I wonder if the design of all those sheet metal manifolds involved any of that ...
(maybe one or two of em?
)
Truth be told, I was just curious why I hadn't even seen you mention pulsetuning thus far. No offense, but it kinda seemed like you were missing the most important aspect of the manifold! (Otherwise you'd just park the plenum at the runners with some horns to smooth the flow. You'd get badass flow numbers, but the powerband would suck.)
But, as long as you are at least
considering the pulsetuning effect, I've certainly no objection! I'm sure you'll do a fine job with all the computational and mathematical tools at your disposal!
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Originally Posted by TrinaBabe
The good news is I dont actually have to make anything to test the designs. I couldnt imagine if I just starting making things with no idea of how well they actually worked. Im sure after 5 designs that take a while to fabricate, bolt up and dyno I would get close but I will never know how well they actually do work compared to what is possible.
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That's the beauty of designing in the computer.
Also +1 for cams not being a huge deal in this case. I just mentioned it because, hey it does matter in some cases, people may as well at least be aware of it!
-Adrian