Plenum volume

[brngrhd]

Hello I found this site a long time ago and have been reading everything that I can find that has to do with what I’m about to ask, so please don't tell me to use the search button.

What I have is a 2.4 liter turbo charged engine and what I would like to know is what the required plenum volume for such an animal is. I’m going to be running an hp54 turbo and running as high as 28psi of boost. I will also be using direct port nitrous. I have found that runner length is not as important as it is with an N/A engine since it changes with boost pressure. So is that the same as plenum volume? What would be too big or too little? The engine is like I said 2.4l that runs an 87.5mm bore and 101mm stroke, and max of 6200rpm. Your help is greatly appreciated. Thanks Steve

 

[brngrhd]

is there some type of help that someone can give? a site that might have some more info for me to read. a basic rule of thumb that says plenum volume shold be the same as engine volum, anything?

 

[patprimmer]

There is no "required volume" there are compromises that change with plenum volume. The bigger the plenum, the more potential power, but as usual, there is a law of diminishing returns.

The smaller the volume, the quicker the response or less lag.

I would think one cylinder full to be the absolute minimum and one engine full to be to much. The are in between depends on many things, not the least of which is number of cylinders or importance of response vs maximum power output.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[brngrhd]

thanks i guess that 1/2 engine volume is a good place to start. i found some other info that said that but it was talking on a non turbocharged engine. here is what i found on grapeaperacing.com


"Plenum Volume
There is not going to be a simple answer to
the needed plenum volume for a given application or
rpm range. The good thing about plenum volume is
that there is a pretty wide range that it can be and
still be effective, so general rules work well. The
following guidelines are for engine operating in the
5000-6000 rpm rage.
V8's with one large plenum feeding all 8
cylinders does not work all that well as far as the
Helmholtz resonator goes, but if this is the case,
plenum volume should be about 40-50% of total
cylinder displacement. On a four cylinder engine 50-
60% works well."

so i don't know if that even applies to a "boosted" engine. max power is part of what i'm looking for but i want a manifold that will supply enough air to all runners and not so big htat it induces a bunch of lag. is it going ot be a guessing game?