Big Bore Throttle Body

[Paul C]

I know someone who bores out throttle bodies. Is this mod worth doing or is there no noticeable gains to be made.I did this mod on my bmw and gained about 6 bhp and gave better acceleration. Has anyone had this done before and what where the results?

[bradc]

I doubt there would be much of a differance, remember with a turbo the air is being forced into the throttle body, rather than being sucked in through a hole ;)

I would concentrate on other mods first.

[Axeboy]

Im sure Zentac done this ages ago...

He might shed some light


I have been thinking about this aswell.

[Paul C]

I thought it might help low down in the rev range

[Gly]

easiest thing to do would be to get a N/A V6 throttle body, put all the VR4 bits on it, and bore out the VR4 Plenum inlet to match,

the n/a bolts on no probs, just that the plenum inlet is to small on the VR4 plenum

[enigma]

Little known fact, the VR4 has 2 different sizes of throttle bod and inlet manifold............ You may be able to get a bigger one without needing a machine shop. Rich had his bored and its not as big as my standard one..............

[Wodjno]

Little known fact, the VR4 has 2 different sizes of throttle bod and inlet manifold............ You may be able to get a bigger one without needing a machine shop. Rich had his bored and its not as big as my standard one..............

How does 1 find out if 1 has a Big 1 or a Small 1 :happy:

Is there a number on them to differentiate ?

[enigma]

How does 1 find out if 1 has a Big 1 or a Small 1 :happy:

Is there a number on them to differentiate ?

No numbers on the inlet manifold that can be seen but I have just measured the hole in mine at 62mm - the smaller one is errrrrrr smaller.

[bradc]

never knew that either. Do you have any measurements on the smaller one Dave?

[enigma]

never knew that either. Do you have any measurements on the smaller one Dave?

No I only have 2 big ones here

[Nick Mann]

There is about 5mm in it. Of the cars I have seen, facelift cars are bigger, prefacelift smaller. I would not guarantee that is the pattern, though. Also, the design looks identical. You only realise the difference with a direct comparison.

[enigma]

Even with such a small difference the area difference is large..........

for the 'big' hole the area is 3018mm^2

and the small hole 2552mm^2

so the big one is 18% bigger...........

[bradc]

yeah that is quite a big difference. I'm just glad I've got a facelift :)

[Nutter_John]

Have heard a rumor that someone is developing a bigger inlet manifold with a large Throtle body on it .

[enigma]

Not all facelifts have the bigger hole................