Which Junkyard Throttle Body to choose

[gregs78cam]

Soooo...... I am getting things and ideas organized in preparation of building a MultiPort Intake, I spent a few hours in SolidWorks, and have some good ideas on runners and plenum, but I wanted to ask everyone what their preferences are on throttle bodies. I want to know what vehicle I need to rob, er uh, acquire one off of. I looked briefly on Feebay, and don't want to spend $150+, but want something that will support the 425HP I have now AND have a compatible flange/bolt pattern for upgrading if/when I add a turbo or two. At this point I am not even considering a 4bbl type. Mostly monoblades.

[RobertISaar]

IIRC, the N* throttle bodies are 75mm units. you'll want a 96-up unit to get away from the ISC motor though.

not sure if that's big enough for you, in theory it should flow ~636cfm.

a twin 52mm TPI/LT1 unit flows ~850-900 cfm. twin 48 are roughly 800.

[1project2many]

Mpfi8.jpg

1100 cfm marine TB with staged blades and GM TPS/ IAC? :)

[EagleMark]

Next time your in town stop by, I have a 4 barrel holly or a big one barrel brand new like jeepsandguns is using.

Ideas I had for mounting fuel rails involved a one piece TBI adapter extended to hold fuel rails in place...

[gregs78cam]

I guess I should add a little more info. My current iteration of this is looking a bit like the RAMJET 502 intake.....with injectors mounted in the valley....

1100cfm from 2bbl. COOL, but I have no idea where to find one.

[EagleMark]

LT1 has an aftermarket 52mm and 58mm
http://www.google.com/products/catal...ed=0CFMQ8wIwAA#

You could probably machine a JY one and make new butterfly's.

[JeepsAndGuns]

IIRC, the N* throttle bodies are 75mm units. you'll want a 96-up unit to get away from the ISC motor though.

not sure if that's big enough for you, in theory it should flow ~636cfm.

a twin 52mm TPI/LT1 unit flows ~850-900 cfm. twin 48 are roughly 800.

Heres my findings when I was searching for a TB for my MPI build.

We discussed in this thread several options, and found out a single large blade flows more air than a two smaller ones.
http://www.gearhead-efi.com/Fuel-Inj...e-body-options

I took a clear easy to read ruler with me to the pull a part junk yard and measured a few TB's. I found the 99 and older cadillac northstar tb's have a 73mm blade. The 2000 and newer ones have a 75mm blade. I purchased one of the 00 northstar units witch are just a mirror image of the LS1 tb's. After some trial and error, it was just gonne be too much work to use it, with throttle cable being the biggest part.
I measured several 96+ vortec tb's and all the ones from the 4.3 were 73mm, and had a large air deflector on the underside of the blade. I did find one V8 vortec tb, I noticed the air deflector on the underside of it was half the size of the ones on the 4.3. I measured it and the blade was 75mm. I purchased this tb and I'm using it.
The tb itself has a slight taper under the blade, so I had a machine shop remove the taper so its a straight 75mm all the way through. I then removed the deflector from the blade, but was left with two large holes where it was attached. I then saw the unused northstar tb I had laying there and tried the blade out of it, it fit perfectly and had no holes in it. I just had to slightly slot the holes to match the screws in the vortec shaft.
I have a pic of mine in my "getting closer" thread in the gear heads section.

Nice intake btw.