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Old 08-22-2001, 08:48 PM   #1
phatride01
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Default Anyone bore out the throttle body?

Hello all,
back again, I am, to gain some more knowledge.

I was wondering if anyone, whether it be 2.5 RS's, WRX's, or any other's (legacy's, obs's, etc.) have had the chance to bore ot the throttle bodies in your respective vehicles?

If so, would u please provide some spec's, in terms of prices, actual benefits/disadvantages, power gains, downtime associated with it?

That would be much appreciated, for any and ALL advice.

Thanks,
phat.
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Old 08-22-2001, 09:12 PM   #2
Keiho
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I've had mine done.

Same specs as Cobb's TB...64mm.

Downtime was approximately a day at the shop.

Power gains..haven't dyno'd the car yet.

Advantages: car responds a heck of a lot faster (I have an auto, every bit of throttle response counts BIG!) and the engine inhaling air through the intake is a lot more noticeable.

Disadvantages: none really, save for the few friends who keep wanting to swap TBs with me to try it out!

Price: Not that much, though if you're in the States and have no one really experienced, just get it from Cobb. They know what they're doing. I was going to go with Cobb too but I found a guy here who's good at it so I went with him instead.
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Old 08-23-2001, 09:42 AM   #3
phatride01
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Talking that sounds awesome...

I know a machinist here in new rochelle, who does all sorts of crazy stuff with motors, porting/polishing, and everything else. Maybe, if I take a week or so off for vacation (goodness knows it's due), then I can prolly take it out, and present it to him to bore out, and polish it.

I think it would be a great thing, considering I do not have TONS of money to do what some people on the board have done.

Thanks for the advice Keiho,
phat

Last edited by phatride01; 08-23-2001 at 09:47 AM.
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Old 08-23-2001, 01:17 PM   #4
phatride01
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Question Anyone else?

Has anyone with a MT done this to their vehicle's, and noticed more response?

I would like to know how satisfied you were with the whole system? I know it probably feels like a world of a difference on an AT, but what about us people with MT's?

By the way, I am almost going to assume that this will negate the factory warranty on certain parts? or all? Curious, is all.

later,
phat.
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Old 08-23-2001, 02:05 PM   #5
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Also, by his sig, Keiho has a 00RS. Would a bigger TB help the WRX at all ? I don't know if it would help a turbo as much as it would the NA engine.
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Old 08-23-2001, 02:07 PM   #6
Keiho
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Actually, the common rule of thumb is that whatever mods that help out an NA setup will see even greater results on a turbo car.

Phat: Just remember to get the machinist to get you a new butterfly plate in the TB.
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Old 08-23-2001, 02:11 PM   #7
phatride01
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Thumbs up right on...

considering that the bore of the TB will be bigger, I would assume that the butterfly would have to be bigger, since there is "more" surface area to be covered.

Thanks for the advice. I will talk to the guy this weekend, and see what he is willing to charge to do it. Plus, I would agree with Keiho, since increasing size in something that is allowing for more combustion/fuel flow, would also help out the turbo, without dealing with up-pipes/turbo-back exhausts, etc.

Please correct me if I am wrong here?

later,
phat.
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Old 08-23-2001, 03:32 PM   #8
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I have a friend who is a machinest, Just havent had the time to bring it to him. He is in Santa Cruz-about 60+ miles from me.

Ken
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Old 08-23-2001, 04:41 PM   #9
phatride01
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Unhappy too bad...

I do not live on that side of the country.

Otherwise, I would be all over that situation.

Oh well, like I stated, I will check with the machinist here in New RO. cause I have seen him doing tons of work within his tiny little "hidden" shop. The guy seems pretty experienced, and hopefully, he can hook the TB up.

Later, will let ya all know what happens over the weekend.

phat.
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Old 08-23-2001, 09:39 PM   #10
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RC engineering dose it they do realy good work there the best in my book
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Old 08-23-2001, 10:17 PM   #11
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Guys, I have a great machinist who can do it. The problem is, as he told me, that there is some tooling required. The butterfly will have to be made. It is not a plane circle. It is eleptic. So, if I have about 10 people interested, I will talk to him and see how much he can do it for. He has the bench-flower or whatever the hell that thing is called. I will show the CFM flow rates before and after so no BS claims.

Lets see how many people are willing to test this out.

-Alex
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Old 08-23-2001, 11:38 PM   #12
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Question Sounds interesting.

So, would this mod be more beneficial for modified WRXs? Like for example, you have added a larger turbo, exhaust, and now need more flow through the TB? Will the stock ECU handle the increase in flow? Definately and interesting idea. Alex, I'd be interested in finding out more.

Thanks,

Matt
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Old 08-23-2001, 11:55 PM   #13
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Just a thought here guys, in order for a bored out throttle body to make more power on an engine, the throttle body needs to be the most restrictive point in the intake tract. A larger throttle body will feel more responsive because you are effectivly getting more throttle opening for a given movement of your foot. Looking at the rex's intake system (and I could be wrong here) it seems to me that the intake pipe from the MAF to the turbo, and the lines from turbo to the intercooler are the most restrictive, maybe after these were upgraded, a bored out throttlebody would be more effective. JMO - Chris
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Old 08-24-2001, 12:44 AM   #14
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Quote:
Originally posted by WRX216
Just a thought here guys, in order for a bored out throttle body to make more power on an engine, the throttle body needs to be the most restrictive point in the intake tract. A larger throttle body will feel more responsive because you are effectivly getting more throttle opening for a given movement of your foot. Looking at the rex's intake system (and I could be wrong here) it seems to me that the intake pipe from the MAF to the turbo, and the lines from turbo to the intercooler are the most restrictive, maybe after these were upgraded, a bored out throttlebody would be more effective. JMO - Chris
I would tend to agree with you here. Those two restrictions are much worse than the TB, but if you fit a larger inlet pipe, and better intercooler hoses, a bored out TB might give some gains.

I would be interested in knowing what the stock TB can flow... my guess is that it is far and away more than the stock turbo can push and likely more air than the heads can flow. So it might not do anything at all. What we need is to get some of this stuff on the flow bench and really find out what can be done.

I bet a set of ported and polished heads, with a better inlet pipe and a bored TB would do awesome things on this car.

-Nathan
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Old 08-24-2001, 02:40 AM   #15
Andrew
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cobb's TB claims a 20% flow increase. has anyone done this to an Automatic RS-T.


also for someone who is runnining high EGTs due to too little of fuel wouldnt this be a BAD mod, because this would incrase the air/fuel ratio. or am i looking at it wrong?
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Old 08-24-2001, 10:37 AM   #16
phatride01
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Default well,

what if someone, like myself, has NO mods, as of yet, but are thinking of increasing the diameter of the throttle body to the 63mm that Cobb does it?

Would this provide any gains? Or would it make it worse overall?

IMO, and as I have previously seen, is that a better intake (on an N/A car, never seen it on a turbo) and better exhaust would provide effecient enough A/F ratios and that would account for the production of more power. In turn, this would not really cause abnormal EGT's, but again, it was not on a turbo'd car. Neither did I see any CEL's.

Therefore, in my questioning, if I were to bore out the throttle body, without any significant mods, would it have any benefit? Given that it's a turbo, which I am new to, I would not be too sure, which is why I ask. I suppose that I could ask the machinist, here in new rochelle, and see what he may have to say?!

Fishguy, I would attempt to use your machinist, but sending out the TB would cause me significant downtime, as this is the only car I have to get to and from anywhere. If it did not require me sending it, and if I did not have to work (), that would be cool..and I suppose that it would take about a day??? to have done?

Lemme know, and thanks for the answers/insight.

phat.
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Old 02-08-2002, 11:39 AM   #17
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Just resurrecting this thread...

has anyone had the WRX throttle body bored out yet? Any input as to power gains, price, current state of modification, etc?

Also, what is the size of the tb stock?

I spoke to Cobb Tuning, they told me they would bore over ~6mm, knife edge the inlet ridge, and grind down the screws on the butterfly plate, but that's about as far as they could go with it.

What is a good price for that type of work?
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Old 02-08-2002, 12:11 PM   #18
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Thanks, but I'm not referring to knife edging. I knew about that DIY already. I only mentioned that as it is one of the things Cobb would do while it was there (as well as the screws which I could also do myself).

I'm more concerned with boring it out. Has anyone done this, or replaced with a brand new TB for that matter?

If so, how much did it cost, what kind of gains did you get, and how much modification does your car have (one would only assume a bored tb would benefit a highly modified car more than your average stock)

Additionally does anyone know the diameter of the stock TB?
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Old 02-08-2002, 04:55 PM   #19
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First off, I realize this thread is about boring, not knife-edging.

But... I thought I would throw in my $0.02 on the knife-edging that I did.

With the difference that my seat-o'-the pants tells me, I would say that boring it would show a good gain in flow.

With all of the "edges" or "steps" that the air sees removed (TB, IC elbows, turbo inlet, etc.), I can tell an appreciable difference in the upper-RPM breathing capabilities of the car. I don't want to go on and on, but it's pretty amazing. These porting mods plus the silicone IC hoses made much more difference that I would have ever expeted, and I'm running the TD04!

This weekend, my Unichip arrives, tuned for my setup and now I can actually crank the boost back up. The car is faster now, using the stock EBC, than it was before with a MBC set at 16 psig! I know it can handle more boost now, so I'll really get a chance to see what this setup will do this weekend.

FYI - I also installed the Samco inlet hose when I did the aforementioned mods. So, I can't really tell what made the most difference, although I suspect it was the porting.
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Old 09-26-2002, 02:59 PM   #20
phatride01
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Question Well, here I am bringing this back alive...

I am still curious if anyone has attempted this, and added a new "butterfly" to their TB?

Now that we have people with some 'insane' mods. done to their vehicles, is there ANYONE that has attempted this? I wonder if it would help people in the 'big leagues' (for lack of a better notion) gain that extra couple of tenth's when they are at the strip?

Also, anyone with a stock turbo car attempt this at all? Thanks again to all that replied earlier!

later,
phat.
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Old 09-26-2002, 03:28 PM   #21
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I would be a lot more interested in using the older style plenum on the new age car, the older plenums has a larfe box on top (like the one modified on the WRC car) while in the last few years the shape of the plenum and TB has changed a bit I have heard from my friends over seas that the older style is a better shape but they changed it for reason, yet they still use that style on the WRC car. Just a little food for thought.
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Old 09-26-2002, 03:30 PM   #22
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I forgot to add that I think that hte most restrictive part in the intake system is the lower plenum that houses the TGVs even wide open it is more restrictive then my RA spec c lower plenums that do not have the TGVs perhaps TGV removal would lead to more gains I have not installed mine.
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Old 09-26-2002, 03:38 PM   #23
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I forgot to add that I think that hte most restrictive part in the intake system is the lower plenum that houses the TGVs even wide open it is more restrictive then my RA spec c lower plenums that do not have the TGVs perhaps TGV removal would lead to more gains I have not installed mine.
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Old 09-26-2002, 05:54 PM   #24
phatride01
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Unhappy anyone else?

I guess the issue about TGV's may be right, but would it even be possible to use an older version of the TGV/TB and apply it to the new WRX's? I Figure if the rally car drivers are able to, then WRX owners should be able to as well.

Yet, the question still lurks about whether anyone has modified a stock TB, and realized any gains. If anyone has, please let the rest of us WRX owners know.

Thanks.
phat
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