WTB- 83mm throttle body

[The Radium King]

if you are tuning for midrange torque you want an intake that gradually decreases in diameter. this serves to accelerate the incoming air charge and facilitate the filling of the cylinders on the intake stroke.

if you are tuning for max hp at max rpm then you want as little resistance as possible to the large volume of incoming air.

street cars are tuned to be useable at low and mid rpms, and on you boxster you will find an intake system that decreases in diameter as you move from airbox to throttle body to the plenum. the gt3 is a track car designed to live at high rpm. as such the intake system is as wide open as possible.

you can put a gt3 throttle body on your car, but it only means anything if you have removed all the other restrictions from your intake system. otherwise the air will restict at the airbox, then expand when it reaches the throttle body, then constrict again when it hits the plenum. that's a lot of useless work that your engine has to perform.

a larger throttle body will also change the performance characteristics of your throttle. think about the 1/2" tap on your sink. say it is attached to a 1/2" water pipe. open the valve halfway and you have half flow. open it fully and you have full flow. now put a 3/4" valve on the 1/2" pipe. open the valve halfway and you get 75% flow, open it two thirds and you get full flow. so, power comes on sooner with a larger throttle body.

the real question is - say you have a 3/4" pipe with a 1/2" valve - even fully open the valve isn't letting all the water through - did porsche leave any power on the table with the 986? jake says not in this case.

sorry for hijack.

[Jake Raby]

It's real easy to get "big throttle body syndrome" with these engines if they are stock or near stock.

What the OP is needing this throttle body for, is about as far removed from stock as possible.

[Pdwight]

I had seen this tried on BMW E36 cars and saw the actual Dyno information and the result was always in my mind just not there.

I always like straight answers and you guys give good ones.

Happy THanksgiving

Dwight

[Jake Raby]

The "bigger is better" crowd is always the easiest to beat.

[jaykay]

Are you tell me the 74mm tb on my 3.2 is no bueno?

[rfuerst911sc]

The cat is partially out of the bag but I'm not saying anymore as I have been sworn to secrecy As stated above my motor is being " built " over the next few months and the end result will be a engine that can be docile as a daily driver or a beast if you put your foot in it.........nothing like anything currently out there to my knowledge. As far removed from stock as can be without being a dedicated race engine. Happy Thanksgiving !

[Jake Raby]

Originally Posted by jaykay

Are you tell me the 74mm tb on my 3.2 is no bueno?

Did I say that? Nope. We're talking 82.5 (83) mm here.

I leave stock displacement engines stock.

Size doesn't matter- its all in the combo.

BTW- Stop PM'ing me asking if Rfurerst911sc is getting my 4.1L! He is not. The 4.1 is a hell of a lot easier to create than what he is getting; which is smaller than even a 4 liter. Nothing that it takes to create this engine is off the shelf.

[jaykay]

[QUOTE=BTW- Stop PM'ing me asking if Rfurerst911sc is getting my 4.1L! He is not. The 4.1 is a hell of a lot easier to create than what he is getting; which is smaller than even a 4 liter. Nothing that it takes to create this engine is off the shelf.[/QUOTE]

Wasn't me man....err em who is getting it?