At What Point Would The Standard Inlet Manifold Be A Restriction?

[TAG 25 1 Cars]

Hello there,

As road rally regs state that the standard inlet manifold has to be used, i was curious if anybody knew at what point the mani would be a restriction?

 

Say if the engine spec was 1.9 engine, 1.6 pistons, lumpy stick, double valve springs, mild porting. On throttle bodies and management, i would have thought this would see ~170hp as a conservative estimate. I'd be curious to then see what it would make on the standard manifold, does anyone have any idea?

 

Thanks,

Tom

Edited April 4, 2015 by TAG

[hoodygoodwood 71 3 Cars]

Will be interested to see what people think , i know there have been 8v engines built on aftermarket management but retaining the std plenum - Anthony did one .

This is exactly what i want to build , 1905 cc 8v , Piper 285 cam , Magnex ,std inlet manifold , modified throttle body to flow more air , AFM and std inlet piping removed . Possibly 1.6 pistons as well or head skimmed at least , all running on Emerald or similar management and ignition .

At the moment it seems everyone has an untouched or very near std engine on original Bosch management or a fully modified engine on throttle bodies or twin 40's . There must be room for something in the middle before the original inlet manifold becomes the restriction .