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Yeah I've done a ton of research, personally I'm going with the greddy plenum. I just like to know other peoples take on subjects, always good to have a second opinion
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“Hey, come on, its a car right? No. It’s a symbol of your history, its a thread of continuity from which you came to where you are. It’s important that you don’t want to forget who you are.” -Dr.Phil in "Love the Beast" -
Workout what you want car to do (street, racetrack, dragstrip, etc) and build engine, etc to suit.
From what I understand, the intake plenum volume, runner length, etc matches head (cams, port size, valve size), turbo size, etc that affect's the powerband (power spread across the powerband with stock ports, stock cams, small turbo's, etc or just mid to peak hp on heavily ported heads with oversized valves, aggressive cams, massive turbo, etc). Since you still have stock ports, stock cams, stock valves, stock turbo's, etc, it's a waste of time, money going with a bigger volume intake plenum than what's needed.
Cam manufacturers ask for this intake, exhaust manifold, turbo, etc info when designing head to match -
The problem with stock intake plenum is the inlet on intake plenum aims at back of intake plenum and 5th, 6th cylinders get too much air. Also the shape around 5th, 6th runners is incorrect. That's why you put highest flowing injectors into 6th, next highest flowing injector into 5th, etc. I don't think Nismo intake plenum is much better, as I remember someone mentioning it has extra places for extra injectors around 5th, 6th cylinders and still has a similar inlet angle as stock intake plenum. The shape around 5th, 6th has been changed which might help a little bit.
This is what a good intake plenum design looks like -
Note the angle of entry / throttlebody (aims towards towards 3, 4 runners / cylinders to help get a even distribution of air to all cylinders) and shape around 5th, 6th cylinder intake runners.
There's CAD flow data to back this design up (It's not perfect on all cylinders, but better than stock intake plenum and more even flow of air into each cylinder and you know where to place the highest flowing injectors, etc) -
Intercooler size is worked out by choosing your hp goal, say 500hp (combined hp of engine + turbo). Then using a simple formula 500hp x 1.67 = cfm you get the CFM. Then you take the CFM, space you have available on car and look it up in a list of intercoolers with CFM, dimensions and find the core that fits into space on car and matches the CFM.
An easier way is to look at Garrett website, as they have core size vs hp -
Most of this is not guessed, it's worked out.RESPONSE MONSTER
The most epic signature ever "epic".
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