I'm thinking of including an Edelbrock intake in my V6 buildup. Since I'm partial to fuel injection, I'd rather use a TBI unit than a carb. I've seen several 60-degree V6es with Edelbrock intake manifolds and carbs, but none with TBI units. I'm wondering if there's a reason for this (other than the "cool factor" of having a carb).

I know that some of the GM cars in the '80s had TBI V6es, so the parts are available. And I'm pretty sure Edelbrock has an adaptor plate for TBI units. So I guess I have 3 main questions here:

1) Why isn't anybody using a TBI with the Edelbrock intake?
2) Is there a TBI unit available that will flow enough air?
3) What mods (if any) have to be made to the Fiero's engine electronics to run the TBI?

Thanks in advance.

As for why more people use a carb than the TBI would be cost. Carb is $200, TBI runs around $2000.

The Holley 670 cfm 2-bbl Pro-jection system would be the way to go. You would need the Edelbrock intake with the 2-bbl riser.
The Holley system is made to bolt right on a carb'd intake so no other adapter woul be required. It comes with it's own fully adjustable
control module so tuning is easy. As for adapting an OEM set-up, You would need to get an adapter and OEM control module.
Most likely from a 4.3L engine since these had the 2-bbl TBI set-ups.

Using the Holley set-up, You would get rid of the ECM in the Fiero and use the Holley control module.
If you were going to convert to an OEM style, You are basically starting from scratch. I don't know anyone who has swapped in an OEM style.
I know of a few people who have went the Holley route (mostly the S-10 crowd are the ones who do it) and they have had great results.
You could try the S-10 forums as they seem to experiment more with the TBI systems for the older carb'd trucks.

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quote Originally posted by Blacktree: I'm thinking of including an Edelbrock intake in my V6 buildup. Since I'm partial to fuel injection, I'd rather use a TBI unit than a carb. I've seen several 60-degree V6es with Edelbrock intake manifolds and carbs, but none with TBI units. I'm wondering if there's a reason for this (other than the "cool factor" of having a carb). I know that some of the GM cars in the '80s had TBI V6es, so the parts are available. And I'm pretty sure Edelbrock has an adaptor plate for TBI units. So I guess I have 3 main questions here: 1) Why isn't anybody using a TBI with the Edelbrock intake? 2) Is there a TBI unit available that will flow enough air? 3) What mods (if any) have to be made to the Fiero's engine electronics to run the TBI? Thanks in advance.

Do some research over at http://www.diy-efi.org/ as there have been many people who have retrofitted injection systems, which is in essence what you'd be doing here. The hardest part for you won't be finding and attaching the hardware, it will be tuning for your application. You'll need a WB-O2 at a minimum, and likely more than a few hours of dyno time. It can be done, however.

JazzMan

[This message has been edited by JazzMan (edited 11-06-2004).]

Hijack a whole system off an S10 (4.3 would have the largest CFM TBI unit).

You could probably rewire the fiero harness enough to make it run, as they both use similar if not the same sensors, etc. I know the IAC's are the same, the temp sensors are the same (I'm talking connectors - not sure if the voltage vs resistance is the same, but I suspect it is).

You would have to make an adaptor plate to go from the TBI flange to the carb flange - but I don't call that a big deal.

I've got an '86 S10, but I'm using an '89 ECM (since they're re-programmable, the '86 isn't for some reason?!).

One thing to note - the Fiero's were kinda on the rich side stock. The TBI'd cars & trucks were all on the lean side! Jack up the fuel pressure to about 15psi right off the bat, then tune tune tune....

I run the 670 ProJection on my Scout and I'm very happy with it, particularly the crisp throttle response. It took an afternoon to install and a lot of that was because I'm sure Holley never planned on it going on a Scout.

One thing you have to remember is that if you go this way (or with a carb) you're also going to have to go to an older style distributor out of the S10's because the Holley unit will not control your advance timing.

John Stricker

Another solution is to use an intake and throttle body from a 90ish front drive minivan with the 3.1 and TBI. A TBI truck (7747) ecm is nearly a 'plug and play' for the Fiero ecm and there are no sensor incompatability problems. You can re-use the Fiero engine wiring harness by swapping the multi injector leads for TBI leads and re-routing the harness. Here is what it will look like when you are done:

Yes, it is a caddy V8, but the wiring is going to be the same. If you use a TBI from a V8 and the Edlebrock intake, you should have a nice, wide powerband without the Fiero's early horsepower peak. I like the simplicity of the TBI (especially compared to the Caddy engine management) and one of the TBI Fieros with the Caddy just hit 30 MPG on the daily drive to work.

Thanks to everyone for the replies. Cooter, that's exactly what I was looking for. The idea was to transfer an OEM TBI setup onto my engine, so I can ditch the Fiero intake and use the Edelbrock one, while retaining an OEM-style ECM.

I KNEW there were GM cars that used TBI V6es, just wasn't sure which ones. The minivan hint helps.

If I remember correctly, the MPFI system in the Fiero's 2.8 activates all injectors simultaneously, right? That's what a TBI does, only with fewer injectors. This leaves me wondering if the Fiero V6's fuel injection (electrically speaking) is just a hacked TBI setup. If so, then it should be relatively easy to "revert" it back to TBI.

Or maybe I'm just smoking crack.

[This message has been edited by Blacktree (edited 11-06-2004).]

Both systems fire the injectors one side at a time. I can't remember off the top of my head, but one system fires the injectors twice as many times per crankshaft revolution as the other. Using the Fiero ecm you would end up with either a really rich or really lean engine because of the number of pulses per revolution.
Even though the minivan is a good ecm (knock sensor input and control for cooling fan), I don't know if it has not been hacked like the 7747 has been so you run the risk of not being able to massage the PROM for your particular engine.
You can't go wrong with the Holley system because it is totally self contained, complete and ready to run. I just liked the price and availability of parts for the OEM system and installing it was a nice learning experience.

The Fiero set-up fires 3 injectors at a time. Left bank (cylinders 1,3,& 5 ) or right bank (cylinders 2, 4, & 6)

Why not use the S-10 factory TBI manifold?

This would save the price of an adapter plate an give a proven starting point.

Cooter, Oreif: thanks for the input.

Daniel: Would the S-10 manifold yield the same performance increase as the Edelbrock? The reason I'm considering the Edelbrock manifold is because I need to do something to open up the intake.

[This message has been edited by Blacktree (edited 11-06-2004).]

Daniel- I did not even think about the S-10 intake. Here is what the wiring harness would look like before being wrapped. It is not as bad as it looks

(edit because I screwed up the picture)

[This message has been edited by Cooter (edited 11-06-2004).]

You will have to replace the fuel pump with one for a duke. The TBI only needs about 12 psi and the V6 pump is high pressure for port fuel injection. The 1227747 ecm is a really popular choice for a TBI conversion.

The 4.3 and 5.7 TBI units are both the same size (1-11/16 bore) but the 4.3 uses 45lbhr injectors, and the 5.7s use 55lbhr injectors. I'm not sure about the 2.8 TBI injectorsflow rate, but I think the throttle bores are 1-3/8" (a lot smaller).

You will need a custom chip (not a 'performance' chip). Custom means burned specifically for your combination of parts. CFM Technologies can do this as well as others. The wiring mods are minor. Watch your clearance to the rear deck when using an Edelbrock intake with an adaptor plate. I've done TBI conversions, but not on a Fiero. Hope this helps.

[This message has been edited by Jakesdads86gt (edited 11-06-2004).]

quote Originally posted by Blacktree: Would the S-10 manifold yield the same performance increase as the Edelbrock?

Go the edelbrock route - the factory ones bite for flow. I've thought about ripping mine off my S10 about a hundred times!

quote Originally posted by Jakesdads86gt: You will have to replace the fuel pump with one for a duke. The TBI only needs about 12 psi and the V6 pump is high pressure for port fuel injection.

It just so happens that the V6 will be replacing a Duke... which has a relatively new fuel pump.

Once again, thanks for the info.