MPI throttle body options

[1project2many]

Jeep used a 4bbl TB??? I never knew.

I used a monoblade TB with a homemade adapter on my 4bbl smallblock Vortec intake.


The TB is from a 350 Vortec engine. The 4bbl intake to TB adapter is made from a piece of 1/2" aluminum plate I picked up from a local scrap metal guy. The TB is bolted to a 1" TB spacer purchased from Ebay. The manifold inlet has 4 smaller holes instead of one large opening so the spacer provides room for the throttle plate to open and also allows the throttle linkage to pivot without hitting the adapter plate. A big block L29 TB wouldn't work because the cable angle is all wrong for my application. Can't say much regarding the LSx TB but the 5.7 TB was a very nice fit.

The area of a circle is pi r squared. r is radius, 1/2 of diameter, so two 50mm TB blades provide 3927mm squared while a single blade 75mm TB provides 4419 square mm of area. This is also true of exhaust... one 3" pipe will provide better flow than two 2.25" pipes. Anyway, there are a few other considerations for TB. When opening throttle plates, the first 20 degrees of throttle angle provides something like a 35% change in airflow. With large monoblade TB's this means a little throttle can make big power changes. The Vortec truck TB uses a progressive linkage under the throttle cable to slow the throttle opening from idle to maybe mid throttle. This is nice if you don't want to light the tires up at every light, and it's great if you're a serious wheeler and need good throttle control at low speed. Also, the IAC tapers are different so you might have to play with a few IAC parameters to get idle speed correction to be a smooth process.

Edit: Accell has a pretty neat (but pricey) 90 deg adapter for TB to 4bbl carb pattern. For the monoblade TB, GM has three different 90 degree intake air elbows which fit the top of the TB. First is from an S10 blazer from 96+. This one is angled to the driver's side of the engine. Second is from a fullsize pickup 96+, it's angled toward the passenger side of the engine. Third is from a 97+ G van with 5.7 which is aimed straight forward.
Here's an aftermarket elbow but you get the idea:
DSC09349.jpg

[JeepsAndGuns]

For the monoblade TB, GM has three different 90 degree intake air elbows which fit the top of the TB. First is from an S10 blazer from 96+. This one is angled to the driver's side of the engine. Second is from a fullsize pickup 96+, it's angled toward the passenger side of the engine. Third is from a 97+ G van with 5.7 which is aimed straight forward.

There was a few of those vortec S10 blazers at the local pull a part. No trucks or tahoes/burbs/etc with the V8's though. So I will probably have to source one on ebay or somewhere like that. Unless eaglemark wants to sell the one he has for cheap

[JeepsAndGuns]

Here's an aftermarket elbow but you get the idea:
DSC09349.jpg

Bringing this thread back up just to ask one question. Where can you get this elbow? I have been searching online but havent really come up with anything like that one. You dont happen to know who made this one do you?
I looked at a few of the factory ones and didnt care anything for them. One like the one pictured above would be pretty much perfect for me.