Originally Posted by Maxwell
I understand that the larger 80TB flows more air but I have my doubts about it's relevance, because the intake ports in the heads are really the restriction not the 75MM TB.
I can't find any dyno graphs from VRS, I will have to email him and see what he found. It could be he dosen't have the computer tuned to adjust for the extra incoming air.
Granted, the intakes are basically 50mm x 30mm (see photos) But lets play engineering students and say hypothetically that the SC creates a 7 psi increase over atmospheric pressure... And it runs at 12,000 rpm... And it has a 75mm hole to suck air from then cram it into a 50mm x 30mm hole... Do you think the volume of air moved through the 75mm hole would be the same as that through a 80mm hole ?
No, you would get approximately 269 ft3/min CFM more forced into the 50mm x 30mm hole... Now granted, you will have more back pressure created, but providing your SC maintains a constant 7psi, you will have an increase of air volume...
That being said, do you think I would rush out and buy a 5mm larger TB ? Absolutely NOT... I would first increase the intake and exhaust ports by 5mm and then increase the TB inlet to match...
FREE FLOWING COLD AIR is what we are looking for... And we all know that the REALLY SMART GERMAN ENGINEERS maximized this engine to balance performance, reliabiltiy and practicality... Not to mention CARB requirements...