size of sti throttle body - Perth-WRX.com

trainwrex · #1 11-10-2007, 09:16 PM

hey guys,

Just wondering wot the standard throttle body size is on a sti manifold??

WRXTASY · #2 11-10-2007, 10:30 PM

Internal Diameter in mm:

Intercooler to throttle 65mm
Throttle to manifold 60mm

Sethor · #3 12-10-2007, 12:13 AM

Yeah from what ive heard its 65mm.

While on the subject at what sorta HP does the stock throttle body become a restriction?

I have seen these 70mm throttle bodies on ebay for about $300-400ish (when they appear on the Australian ebay) from the other auctions they state they are made in Thailand. http://cgi.ebay.com.au/70mm-Throttle...QQcmdZViewItem

trainwrex · #4 12-10-2007, 07:40 AM

hmm okay...

lewis it becomes a restriction at around 400-500 hp atw.. so only when chasing high power..

The only problem i see with that TB is that yes it may be bigger but wot about the manifold.. You cant port the manifold out to the same diameter as the the bolts which fix the manifold are closely surrounding the casing???

So there would really be no benefit??

Sethor · #5 12-10-2007, 07:47 AM

That ad states that Doluck make one which is about USD$800 have you seen these?

Edit- found the Doluck ones they only have them for the GC8 which has a 60mm throtttle body.

http://www.do-luck.com/throttlebody.html

Translation of text-
It expands normal throttle diameter 60 φ to 65 φ, just replaces at entire area both power & torque the aluminum which it improves to start shaving, the big throttle. The throttle linkage transplanting normal that way, in order to use, either accelerator feeling did not change, low cost, actualized high performance.

The throttle body for EJ20K
* IMPREZA Vr.3 - 4 65 φ XXYEN 60,900 (substance price XXYEN 58,000)
* IMPREZA Vr.5 - 6 65 φ XXYEN 68,250 (substance price XXYEN 65,000)

trainwrex · #6 12-10-2007, 07:51 AM

no i havent..

The guys in the U.S are getting them for fords appartently... You might as well buy a custom manifold for that sort of dollars..

GTLeggy · #7 12-10-2007, 08:17 AM

Just about all the subaru EJ20 TB`s are 60mm where it counts(some are a touch smaller from early tt`s etc....but none are bigger) !! at the butterfly/where its the smallest.

The ford XF TB`s(a common upgrade/custom set-up thats been done to death) is a 66mm TB, its for BIG hp and may be a little too big if your not making 450+hp.
And yes the manifolds all have a 60mm hole in them so porting that out is a must to use anything bigger.

I have had several TB`s ported and new butterfly`s/throttle plates made, the most you can take a 99 on TB out to is around 64mm otherwise you`ll hit iac galleries etc etc. Early ones can go a a touch further....thats if you really want to(or need to) !

I have a spare TB I got done on the last run of 64mm`s.....its a 02 sti TB originally, I`ll sell it if anyone wants to buy it PM me !

Cheers

trainwrex · #8 12-10-2007, 08:47 AM

how far can u port the manifolds out to?? 66mm to accomodate the xfs TB? how much are they second hand if u know? And are they readily avaliavble?

tuna · #9 12-10-2007, 09:30 AM

oversized tb's are a waste of time with a factory inlet manifold, factory head ports, factory valves.

whole lot of expense for next to little gain, the air still has all the original restrictions.

97RA · #10 12-10-2007, 10:25 AM

Quote:

Originally Posted by tuna

oversized tb's are a waste of time with a factory inlet manifold.

Very true, you can probally get the same or more usable gains from having somone skilled in porting work on the standard stuff from inlet to exhaust.

Still wouldn't be cheap, but the whole XF EEC4 TB swap is a lot of work for not much gain unless you have a VL turbo.

I've had 2 of these TB's and the work involved isn't worth the gains, and yes you can find them at wreckers if you're determined to use one.