Designing plnum and runners around restrictor

[Greg5OH]

Hello, first time posting in these forums, hopefully you kind folk can point me in the right direction.

We are running a 550 cc aprilia vtwin engine for FSAE. We are required to run a 20 mm restrictor, in the order of

Throttle body - restrictor - [blower - intercooler] - plenum.

Now from my understanding and reading, it seems a large (relatively) plenum is desirable on a small restricted engine such as ours. We run the engine in a "go kart" on an autocross track, which requires rapid throttle manipulation and instant response. I was thinking of using a De Laval style nozzle for the restrictor. (basically the convergence point is the 20 mm nozzle, while the high pressure side is where the TB is located, and the low pressure high velocity side tapers out to a plenum.

For plenum design, does the typical 1-2 times the size of engine displacement apply to a restricted engine?

It would be nice to fab up an intake manifold and use multiple MAP sensors to measure and tune, however this will be done out of carbon fiber and we simply dont have the money for that.


If someone could point me in the direction of more reading regarding plenum and intake design (specifically for a restricted engine) it would be VERY much appreciated

 

[MikeHalloran]

Google will bury you in response to a query including "FSAE restrictor" without the quotes.

I'm surprised they don't require sharp-edged restrictors provided by a third party, but I guess the DeLaval nozzles keep the CFD vendors busy enough.



Mike Halloran
Pembroke Pines, FL, USA