Larger throttle bodies

[aelred]

For those people who are increasing their BHP and running large intercoolers.

I am having the original throttle bodies modified by increasing their size to 70mm, with a S/S butterfly. Everything remains the same, mountings, spindle etc.

I can supply these on a exchange basis ONLY or modify your own.

I have tried a large aftermarket throttle and I had nothing but problems, you cannot beat the original one unless you go for the Sport one but the cost of it makes unrealistic.

For those people that always want pictutes I will post some tomorrow but to be honest it will look the same as the standard one just with a larger diameter and larger butterfly.

Please PM me if you want your moded.

[HPmuirt]

Can I ask what effect it would have to a car which is nearer to standard?

My car is stock apart from an RS2 airbox, but will hopefully soon be chipped (when I am in the country for long enough). Longer term, I have an RS2 EM and injectors and plan to upgarde the IC and turbo to match.

So I guess my question is, at what point is the TB the bottle neck in the airflow and therefore worth enlarging?

Cheers n

Si

[S2central.net]

Haven't we seen the 500bhp brigade on here running no problems with stock S2/RS2 throttle bodies already ?

I would also expect a little less smoothness with a larger throttle body at the low-mid rev ranges but that's not a major concern for the monster big power outputs that I suspect are made possible (partly) by the larger TB.

Paul

[HPmuirt]

Ah hah. Paul, if I remember back to the good ole days of carbs and airflow, the recommendation there was to run the smallest possible bore which would allow enough air into the engine, therefore giving the fastest air speed.

Are you saying that the same is true for our more modern engines? If so, then I guess the larger TB is a big power mod?

Cheers n

Si

[S2central.net]

Something along those lines yes. If I ever need more than 500bhp I'll bet it works out cheaper to get a larger member fitted to my nether regions and just be done with it

[aelred]

I would go along with that,
Never tried a larger TB on a moderate increase of power.
Only used it on big BHP.
Lot of the large intercooler that are used by people in their S2 have 3" inlet and outlet with 3" piping only to come down in size to a standard throttle.