Is there anything to be gained by boring out the throttle body? It would be the first thing on my list if it were a NA engine.

I am also thinking, reduce the thickness of the throttle spindle where the butterfly goes through it, and dress the screws to be flush, fit with loctite.

Also turn a proper taper on inlet and outlet.

Obviously this would need a new butterfly to be made too.

Paul

 

I wouldnt bore it out to that extent... but they knife edge bits and grind other bits over the pond... do a search on IClub.

David

 

I see the I-club thread going at the moment, and Jorges pictures of his mod. But I wonder if it was only taken that far due to a lack of a lathe.

I would be looking to bore out 1-2mm, new butterfly, thinner spindle, csk screws and taper both ends.

Paul

 

I think there are greater gains to be had by concentrating on the high velocity areas ie where the air is flowing at atmospheric pressure such as turbo inlet and induction system. The intercooler pipework is also far more restrictive than the throttle body. Approx 40 mm v 70 mm that's less than 1/3rd of the CSA therefore 3x velocity, drag, pressure loss etc

 

Age old carburettor tricks, but I think the throttle plate is already a good size. Any gains would be pretty small, considering the pipe coming out of the turbocharger is generally only 2", it is about the smallest pipe/hole in the intake system. The subaru throttle plate is a lot bigger than a cossie one, and they seem to be able to get a wee bit of power. Well, power claims anyway.

 

Fairy snuff.

Might just taper the ends then, save all the hassle of making a new butterfly.

Paul

 

what are the advantages of tapering the ends... do you have a link to the iclub thread?

David

 

http://forums.i-club.com/forums/show...hreadid=214601

cArLoS h.

[Edited by carlos_hiraoka - 7/15/2002 3:27:03 PM]

 

Well it certainly looks nice and shiny, Im sure loads will want it...but he does only state, that is 'seemed' or 'think' that it made a difference. People generally do seem and think things after spending time/money on some mods. I have seen people spend a fortune on their car, 'tuning' it, only to find standard cars are quicker.
Worth a try, if its free, but some tricky machining involved, and you could very easily mess things up. The polishing would not help the airflow one bit, despite what anyone says. Smooth yes, mirror polished, especially when you cant see it...a total waste of time.

 

I am not a polisher. But it might be useful to get rid of any sharp lips in the whole throttle body/intercooler hose assembly.

Paul

 

cant say Im convinced on this one... however I dont have any tuning background or degree's to support my theory... so Ill shut up..

David

 

It's my belief that the fuel will puddle and drop out of it's atomised state if you get it tooooooo shiny in there. as Stevie turbo said smooth yes, mirror no.

 

I looked at the shiney thing on I-club, LOL!

He hasn't touched the obviously large throttle splindle, hasn't touched the bore size wise, yet claims a significant improvement.

Bring out he brasso.

I am sure if all that time spent polished went into turning it properly there could be an improvement.

I might see about putting in some differetial pressure sensors somewhere, and check this lot out (pre turbo stuff and all).

Paul