blundar

I need a bigger TB than the 58mm that came stock with my b16a1.
The engine it will be going onto:
B18A1 block, 89K
PR3 Pistons
PORTED PR3 head (exhaust ports enlarged to B20 headgasket, intake ports enlarged + cleaned up, valve seats cleaned up, casting marks removed, combustion chambers cleaned + reworked...)
Stock headgasket (~11.5:1 compression)
Skunk2 Intake manifold
JDM ITR 4-1 header w/ 2.5" collector
Stock A1 cams for now, prob JUN3s later

I'm going to be squirting a lot of juice at this engine (direct port fogger system).

I want a bigger than stock TB. So far the choices I have come up with:
1. 60mm 92+ B series
2. 62mm ITR
3. 62mm H22A
4. JG 65mm http://www.edelbrock.com/automotive/...ttle_body.html
5. Erick's Racing 70mm http://www.modacar.com/Merchant2/mer...nda&Carb=Civic
6. Holley 68mm TB (supposedly uses stock TPS + IACV)
7. BBK 70 mm TB http://store.summitracing.com/partde...5,'BBK1547'
8. Proflow overbored http://www.proflowdesign.com/throttlebodies.html
9. Boring the 58mm as big as it can go, using a 64mm Mustang butterfly
10. Boring a 60mm as big as it can go, using a 64 mm Mustang butterfly

If anyone has any first hand experience, post away!

Thanks in advance,
-Dave


[Modified by blundar, 12:27 AM 6/17/2002]

Jonathan_ED3

well wouldn't you first need to determine what your optimum size would be?

speeddave

good question! i'm interested in this as well. my setup is very much like yours and i've been contemplating which tb to use. i have another question; which inj and management are you using for your setup? thanks

blundar

Not to sound too much like an idiot, but how do you determine the optimum size?
I know the basics - too small and you lose top end, too big and you lose low end torque. I don't know how to figure out the "optimum" based on the information I have. Is it anything like doing flow map calculations for turbo sizing? I vaguely remember how to do that... You need to take your engine's displacement and multiply it by the number of RPMs and some other stuff to come up with some kind of figure for the volume of air the engine is going to need.
Any/all help appreciated
-Dave

Finest

I don't see why the stock TB isn't sufficient enough for you? You're shooting nitrous, which introduces oxygen in itself...there's no need for such a big bore, unless you're trying to cram more air into the cylinders with boost or something. Also, how much of the time are you planning on running w/o the bottle?

11.5:1 CR with nitrous? I hope you have a new motor waiting to drop in?

743power

inlinefour.com sells overbore throttle bodies for $255 plus a core. It's a really nice TB too. The butterfly is 68mm tapered down from 70mm. I believe the spoon one is like 62 or 64mm up to 70mm. I'd say that the inline four is the best deal I've seen though. It's got the largest bore possible on a stock honda core.

blundar

only n2o use will be track or when some ********* in a 5.slow is beating me
Figure 80-90% of the time NA. I'm trying to be very concerned with NA performance. The nitrous is intended to be a surprise, not what the car relies on to be fast.

Blowing engines: I dont think that the eagle rods are going to go. I'm guessing that I'm going to kill this engine by shoving a piston through a cylinder wall or cracking a sleeve. The LS crank is not known for a happy R/S ratio. I have a spare b18 longblock lined up - they're worth peanuts around here and a a friend works for a yard so that makes them cheaper. I plan on tuning the car thuroughly before beating it, with a wideband o2. At a minimum, I want to make 100% sure that I have the jetting right on the fogger system so that I am running about a 12:1 A/F ratio while on the bottle. Additionally, I want to make sure the MSD box is retarding the timing at least 12 degrees. I hope to have this engine last 1-2 race seasons with 2-3 weekends/month of racing. It is not going to ever be a daily driver except for a month or so when I'm tearing apart my 1st gen ZC to turbo it.

More feedback is good feedback! Thanks again everybody!

blundar

the guys at inline4 seemed really helpful. thanks for the suggestion. They say they can take a ITR to 70mm, a GSR to 68mm and a B16a1 to 64mm. I'll prob scrounge up a GSR to send em... Waiting to hear back from proflow.... Anyone ued a proflow?

_unknown_

Don't even bother with Inlinefour. They just send the TB's out to RC Engineering ...

Go to RC and get it done cheaper. Or try Leitner & Bush. I think they are cheaper than RC...

RC quoted me $60 for taper boring the ITR tb. Basically boring the tb to Spoon specs...

HTH

Jason kiDD

Website or phone number would help greatly, this is some good information..

_unknown_

Here are some links...

http://www.leitnerbush.com/

http://www.rceng.com/

Jason kiDD

Good man..

blundar

on the off-the-shelf note, I spoke to a friend that has hands-on experience with some of hte big throttlebodies.
Apparently the 68mm holley does not close/seal very well
Apparently the 70mm BBK is the highest quailty piece overall but has a poor return spring that should be upgraded to a much stiffer spring. I'm leaning this way...