4BBL Junkyard TBI?

[McRoth]

Just wondering if there is a 4bbl GM tbi? I've got a stock 4bbl manifold that I'm going to put on my offroad Wag & the plan is to put a junkyard tbi on it. Is there a 4bbl tbi version that will take better advantage of the manifold? All of the tbi pics I've seen only have two injectors that I noticed.

[steven79]

The 4 bbl tbi will be tooooo much for a 360 2 bbl is plenty air and gas for a stock to pritty wild 360.

[J10Mike]

to answer the question, a 4 bl tbi came on the chevy 454. the only problem with that is finding that set up. they are somewhat rare. but, you never know what you may find in a junkyard.
also, like steve said, it would be too much for a 360. and probably too much for my 401. but, should one fall in my lap, i may try it out.

[Spectre]

Depending on the version of GM's TBI unit that you get, the two barrels are the equivalent of 580-750cfm carbs.

The two-barrel Holley TBIs are typically rated at 670cfm.

[derf]

I've never seen a stock factory 4bbl TBI setup on any 454.

The TBI setup I got from a 454 uses a 750cfm 2bbl throttle body. It's a lot like the ones off the 4.3/5.0/5.7 but with bigger throttle bores and bigger injectors.

[J10Mike]

Derf,
I'm not an engine guru. So, I won't dispute your comment. However, another local FSJ guy in my area was surprised to find a 4 B throttle body on a 454. He too thought that the 454 TBI was a 2 B as well until he saw it with his own eyes.
Is there a chance that he saw an aftermarket 4 Barrel throttle body set up for the 454? I haven't looked for it on the web. But, I will...Now, I'm curious.

[Spectre]

Holley makes at least two aftermarket 4bbl TBI systems - the Pro-Jection 4 series, and the Commander 950. They also, I believe, offer 4bbl TBI units as an upgrade for stock GM units.

[McRoth]

Thanks for all the info guys!!! I don't know much about these kinds of things & I just figured that a 4bbl tbi would work better on a 4bbl manifold. I'll just stick with the 2bbl tbi & adapt it to the 4bbl manifold then.

[tgreese]

I'm not sure that it matters whether it's 2 or 4 barrel for an injection system. The 4Vs (with secondaries) are used to keep the air velocity up at low speed on a big engine where the venturi size is large. You need the velocity to give a usable vacuum signal for vacuum-driven systems of a carburetor.

FI uses more than the vacuum signal to control the mixture and atomization, so there may be no need to split the low-speed and high-speed operation between primaries and secondaries. A bigger 2V may be fine for larger displacements.

[derf]

Derf,
I'm not an engine guru. So, I won't dispute your comment. However, another local FSJ guy in my area was surprised to find a 4 B throttle body on a 454. He too thought that the 454 TBI was a 2 B as well until he saw it with his own eyes.
Is there a chance that he saw an aftermarket 4 Barrel throttle body set up for the 454? I haven't looked for it on the web. But, I will...Now, I'm curious.

I'm not saying there isn't one. Just that in all my research, I've never seen one that is factory stock.

I have seen the Holley Commander 950 4bbl system.