I've just seen someone get 10hp (6kW) by boring out their throttle body and inlet pipe by about 4mm. This was on an MR2 mind, but it only cost them £45. I was quite impressed.
Has anyone done this, or does anyone know if this is possible to do on an Alfa V6? Apparently if there is only 1-2mm available to use - not enough clearance - it is a waste of time taking it out and doing it.
this sounds like an old wifes tale..it doesnt matter how big you make the enterance to the throttle body because you cant change the size of the butterfly or the size of the hole around it as far as i know you can buy larger throttle bodys but if you chop up your own it will cost you ££££ if you get it wrong..you could get one from a scrappy and mess about with it to see what happens.
Higher bore throttle body would give a drop in pressure after the butterfly and possibly set up some backwash pressure wave through the butterfly?
I suppose a Q4 would blast its way through such a problem but surely the respose would lose its smoothness in normal driving conditions (as opposed to a straight drag). I imagine non-Q4s would experience a more detrimental effect.
I hear this being recommended for naturally aspirated cars quite a bit, as well as turbos. Its an idea to buy one - perhaps one off a 164 3.0 litre V6 might be bigger.
The theory I think hinges around volume per minute through the tube, although yes I have to admit I have no idea what happens once the air passes through it. But then again, what about all the sytems that force induction? That's a similar concept isn't it?
isn't it the same principle as carbs.. the bigger the better (to a point) a friend has quad 48mm throttle bodies on his 1.6 16v (nova!) - fueled correctly it goes like stink. Basically the next step to increasing air flow (filter).
I'm not sure about all this pressure wave business wink