my mate is about to put a 100mm throttle body on his 3L 2JZ which atm has 440 rwhp so i mean 100mm shouldnt be too overkill for a 4L falcon right ?

mayby if it had a large turbo pushing alot of boost..

busso, how many NA falcons do you know that are pushing 440rwhp, or 320rwkw!??? there wouldnt be any... pushing for 200rwkw is a big task on its own, 70mm is still probably overkill...

imo there is no need to go any bigger than the intercooler piping diameter.

I personally would make sure I had the right size throttle body then make sure the intercooler pipes are the same size.

You can't directly relate a turbo and atmo engine the way mentioned above when you are talking about throttle body size.

For example compare a 200 hp atmo engine and a 400hp turbo engine running 2 bar of boost. They both have the same "volumetric flowrate" (cfm) of air going into them. (assuming the intercooler is cooling air to near ambient). This means the air speed through the throttle body is the same for both engines.

The difference is that the turbo engine has twice the "Mass Flow" (lb/min) of air going into it because the air is compressed to be twice as dense.

It is mass flow that makes power. This is why all turbo maps are given in lb/min.

The volumetric flow and high air speeds that cause the limits of engine intake. So if you reach the volumetric limit of your engine then the only thing left is to improve volumetric efficiency by porting, bigger valve, higher revs, biggerruners etc. If that is not enough for you then you need to squeeze the air with some boost to get the air mass you need to make the power.

fast-xr mate i was assuming that even tho this falcon motor wouldnt be pushing the same horsepower, because it has an extra litre then it would take an almost equivalently sized t/b ?

ive seen an FJ20 push 500hp plus and run a full bodied escort down teh 1/4 in less the 10sec at about 138mph using a 50mm TB

my question to you is what makes you think you need such a stupidly large TB