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Old 05-31-2001, 11:05 PM   #1
Andrew
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Post Cobb wide throttle body for a ~10psi turboed 2.5RS

I'm wondering if a wider throttle body (namely the cobb one) would do anything for me. I'm looking to push close to 10psi, right now im only at 5-6 (would it help at that amount of psi?) ...or are the gains minimal? i did a search and couldnt find anything that was conclusive...

also this wouldnt be a problem with an IC right? everything would still fit fine correct?
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Old 06-01-2001, 05:44 AM   #2
Joe Hogan
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Andrew,

The enlarged TB from Cobb eases the restriction to flow of air into the engine. The RS I drive has one and I'm running a Vishnu turbo @ 10 psi. The engine is estimated to make 300 - 325 hp. Dyno'd at approx 245 hp to the wheels.

FWIW

JH
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Old 06-01-2001, 07:57 AM   #3
dirk.gecko
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Actually, there would be an increase in power without running any more boost because overall flow would be up. In theory, at least, dunno how much. To see any real gains, you'd need to do the heads as well ( Cobb notes that the heads are a restriction long before the TB is).

dirk
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Old 06-01-2001, 09:37 AM   #4
Rich L
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Heres a question to add...
What about those of us who have a MY99/turbo with the first stock airbox??
As seen here:

<IMG SRC="http://216.242.153.40/MembersList/UserPics/1929/intercooler.jpg" border=0>

Isnt the size of the hole between the airbox and R fender ony like 2" in diameter?
So I would think a bigger TB wouldnt help much at all do to the restriction of airflow at the box. I may be wrong though. Any thoughts?
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Old 06-01-2001, 01:50 PM   #5
Andrew
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is the throttle body something that you can install in a couple minutes (sorry if that sounds dumb, i have no experience with TBs)? I dont have the money to have someone install the heads, and theres no way that I personally would open up the engine..
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Old 06-01-2001, 02:09 PM   #6
efoo
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not really, unfortunately - engine coolant is routed through the throttle body to warm it up and keep the throttle plate from sticking in really cold weather, so to get the throttle body off and on you'd have to deal with coolant. if I get around to doing this to my own car eventually (probably next summer) I will probably time it in conjunction with a coolant flush.

Rich L: I do think you'd probably want a better-flowing air intake before a wider throttle body. However, a wider throttle body may well make a bigger difference on a heavily boosted car, because you have to remember that the air in the throttle body is pressurized. So any little improvement in flow there is multiplied by the amount of boost. If the throttle body is too small then it is essentially a boost obstruction just like the intercooler is (which is why small pressure drops across well-designed intercoolers are crucial) and will cause you to build boost slower in the intake manifold, and therefore the engine.

But, this is probably of no concern to you or me at only 6-7psi. A better intake address the much bigger issue of getting air into the turbo in the first place, which is much further upstream. Why are you still using the stock airbox anyway?

-Edwin


[This message has been edited by efoo (edited June 01, 2001).]
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Old 06-01-2001, 02:21 PM   #7
kaos200
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changing out the TB isn't that hard, it took about 30-60 minutes because of the intercooler. the coolant only spilled slightly and we had rags and something to cap the line handy...
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Old 06-01-2001, 02:21 PM   #8
t.rod
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Has anyone had here TB bored. I think on a NA RS it's subpost to deliver Something like 5HP. I imagine on a Turbo'ed RS it would produce more.
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Old 06-01-2001, 02:54 PM   #9
tomrichardson
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Andrew,
I don't think Cobb carries a larger throttle body for your 2000 Yellow Lamborghini. However, with Cobb being a machinist, he could probably custom fabricate something for you since you've got so much money.

Later,
Tom

[This message has been edited by tomrichardson (edited June 01, 2001).]
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Old 06-01-2001, 04:15 PM   #10
Rich L
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Edwin,
Since I dont have a TECII, I still have a MAF issue to contend with. So my options for intake design were limited. My current set up seemed to be the "safest" intake while retaining the stock maf sensor. There is one advantage to this setup, it one of the few CAI for the MY99.
I also agree that under low boost, and stock heads... the TB is probably not going to make a big difference.

Just let me know if your going to sell that TECII for cheap! Ill buy it!

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Old 06-02-2001, 11:37 PM   #11
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That hole in the inner fender is over 3" in diameter, almost 3.5". I know that for a fact, from making CAI's for the Impreza/Legacy/Forester.

Larry
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