Bigger Throttle Body...???
Thread Starter
Racer
Joined: Oct 2006
Posts: 335
Likes: 14
From: Houston, Tx
Bigger Throttle Body...???
FVD and possibly others offer a bigger throttle body for the 993, both for NVR and VR motors. As far as I know, FVD bore out a standard throttle body, from 68mm to 71mm on the NVR and from 65mm to 70mm for the VR, and install a new butterfly accordingly. To me this looks like a job any carburator shop could do for a fraction of the price.
For the NVR increase from 68mm to 71mm gives a 6% increase in throttle body area, and in theory a 6% increased air flow, that again in theory should give a 6% increase in HP as long as the air/fuel mix is still correct. Also, in theory each 1mm increased bore should give around 2% air flow increase.
My question is; are there anyone out there that can bore out the throttle body to let's say 75mm, and install a new butterfly flap to match?
For the NVR increase from 68mm to 71mm gives a 6% increase in throttle body area, and in theory a 6% increased air flow, that again in theory should give a 6% increase in HP as long as the air/fuel mix is still correct. Also, in theory each 1mm increased bore should give around 2% air flow increase.
My question is; are there anyone out there that can bore out the throttle body to let's say 75mm, and install a new butterfly flap to match?
Nordschleife Master
Joined: Oct 2007
Posts: 5,471
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From: Tacoma, WA
Well, unless other things are done on the motor, you most likely will see 0hp increase, or only slight increase at the last range in the RPM. But if you have cams, exhaust & other stuff, it might give you a little bit.
You might loose some low end torque, & you will totally change the throttle modulation. Your A/F will be fine, & the ECU will keep it in the happy zone.
I've built a few motors, the TB is usually one of the last things you do. I had a fully built BMW engine, increase bore, big head, big cams, race header, etc. I then went & put on a $5000 set of bigger TB's (there were 4) I gained like 4hp from it. You only get the HP if the TB's are getting maxed out currently & are the bottle neck.
You might loose some low end torque, & you will totally change the throttle modulation. Your A/F will be fine, & the ECU will keep it in the happy zone.
I've built a few motors, the TB is usually one of the last things you do. I had a fully built BMW engine, increase bore, big head, big cams, race header, etc. I then went & put on a $5000 set of bigger TB's (there were 4) I gained like 4hp from it. You only get the HP if the TB's are getting maxed out currently & are the bottle neck.
Nordschleife Master
Joined: Feb 2007
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From: Torrance, CA USA
I had the throttle body on my SC bored out by Ed Mazula (lives a few blocks from me, used to advertise in Excellence, not sure if he still does throttle body work or not)
I had it done when my engine was apart, and honestly, I don't know that it made much of a difference. I think it would have been beneficial in conjunction with other mods, like higher compression P/Cs or larger displacement, but in and of itself, I didn't notice a bump in power, but the engine did seem to run smoother.
On another note, I thought that the 993 throttle body used a hot wire set up and didn't use a butterfly valve?
If Ed is still doing these, (Don't see him advertised in Excellence anymore) he is a good option, I was pleased with the customer service, quality of work etc... Not to mention he had a sweet Shelby Cobra. his number used to be (800) 792-9338.
I had it done when my engine was apart, and honestly, I don't know that it made much of a difference. I think it would have been beneficial in conjunction with other mods, like higher compression P/Cs or larger displacement, but in and of itself, I didn't notice a bump in power, but the engine did seem to run smoother.
On another note, I thought that the 993 throttle body used a hot wire set up and didn't use a butterfly valve?
If Ed is still doing these, (Don't see him advertised in Excellence anymore) he is a good option, I was pleased with the customer service, quality of work etc... Not to mention he had a sweet Shelby Cobra. his number used to be (800) 792-9338.
Rennlist Member
Joined: Nov 2002
Posts: 12,229
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From: Chicago
I would expect pretty modest gains, and only at high rpms, from this mod.
Remember, there are MANY sources of air restriction. The throttle body is just one of them. Perhaps it's a major contributor, so I'd like to hear experiences with this mod. Hopefully one of our engine experts will chime in.
Remember, there are MANY sources of air restriction. The throttle body is just one of them. Perhaps it's a major contributor, so I'd like to hear experiences with this mod. Hopefully one of our engine experts will chime in.
Nordschleife Master
Joined: Oct 2007
Posts: 5,471
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From: Tacoma, WA
Of course all the engines, have a TB, but I also thought on the 96+ cars there are a primary TB with a small secondary TB?
Rennlist Member
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From: Chicago
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Three Wheelin'
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Nordschleife Master
Joined: Oct 2007
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From: Tacoma, WA
Banned
Joined: Jun 2005
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From: NJ but from Boston
I considered this mod until the guy's at 9M noted & loss in power with just the throttle body on a stock motor!!.
They reccomended ECU/X-Pipe,or lightweight flywheel for doccumented gains.
Next would be cams & the throttle body.
They reccomended ECU/X-Pipe,or lightweight flywheel for doccumented gains.
Next would be cams & the throttle body.
Last edited by RDS928S; Jul 15, 2010 at 01:43 PM.
Three Wheelin'
Joined: May 2005
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From: Reston, VA
Pisses off about 1/2 the fellow owners I meet though. Oh well.
Nordschleife Master
Joined: Oct 2007
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From: Tacoma, WA
LOL, yea, I kept the S14, invested around $30k, & had 305hp (crank). But I learned a ton, & know what works, & what doesn't.
Nordschleife Master
Joined: Oct 2007
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From: Tacoma, WA
