|Quote, originally posted by silvercar »|
|I believe brett@apr designed the APR unit.|
any of you fellas care to chime in on areas you feel are victory or defeat?
I did indeed design the APR manifold. First let me say that the efforts of all those involved should be applauded and I also applaud everyone that designed and/or produced a manifold for the test.
My design, the APR unit, was engineered for the absolute best performance running on an engine. I compromised as little as possible in an effort to realize this objective. I did place the throttle body in a location that was most logical for the applications that this unit would see and I did utilize the factory injector seats (for several reasons.)
The APR manifold was not designed to win a flowbench test such as the one performed (although our unit performed admirably.) As any engine designer worth his weight in salt would tell you, what is optimal on a flowbench and what is optimal on an actual engine are very different. There are several 'dynamic' design considerations on our manifold that would never be measured on a flowbench test. For starters, our plenum is large, does NOT taper, and extends beyond the last runner (I would have extended it even further if I had room.) This is critical. As an intake valve opens, the air velocity surrounding the runner gets high very quickly. This has a tendency to create low pressure in the runner. The runner needs access to higher pressure air as readily as possible. The best way to do this is to utilize a large plenum and make sure that the plenum has volume surrounding all sides of each runner inlet. THIS BECOMES EVEN MORE CRITICAL ON TURBO APPLICATIONS AS INTAKE MANIFOLD PRESSURE INCREASES. In simplified terms this is why the best manifolds are designed this way. Look at the plenums on this engine (Audi R8) ->http://gallery.audiworld.com/a...l.jpg A tapered plenum in a boosted application will have progressively worse flow as you move further down the taper (the runner on the end will be very lean.) This WILL NOT be evident on a flowbench test (in fact a flowbench test will likely show flow as nice and even.)
This is completely counterintuitive to what someone would think would be optimal by watching a flowbench all day and that's because engines do not operate like a flowbench. Based on the designs that I see here, I would expect the APR manifold to outperform every manifold here in actual engine performance (in fact, I believe it has already proven this as I have not seen any performance figures close to the gains that people have been making on our manifold.) I would expect the HOMEBREW manifold and RMR to be close seconds.