So my buddy wants me to fab him a intake manifold for his GSX-R 750 engine...its in a sandrail so clearances aren't a concern. The plan is to turbo it, so we are kicking around the idea of building a intake manifold rather than building a bonet/plenum for the throttle bodies. We know we will loose a little throttle response with the conversion. Anyone want to help us out with the pros vs cons? or have you seen this conversion before?

 

manifolds usually work better for boost than ITBs. Under boost since there is so much air flow 1 large throttle body causes less flow disturbances than 4 smaller ones. A good rule of thumb is plenum size should be 2X engine displacement.

a turbo sandrail...better have one hell of a cooling system in that girl!!

 

Formula SAE teams put manifolds on GSX-R's all the time. The benifits are less rubber couplings to go loose and a smoother power band from low to high throottle angles. Resonance inside itb setups dont help flow for lower end, by eliminating them to one tb and plenum you will help low/mid range. At wot 1 or 4 tb's wont make a difference, but they will dependent on your intake runner and plenum sizing. With that said I would go 1 tb for an overall optimizer.

What year is yours I have IM flanges on file that I make if you want to get started on one.