92WhiteRS

Hey all, I was just curious if anyone is running the 4 barrel TBI system? Also, wouldn't it theoretically be possible to run this system with the stock ECU, if you splice the injector wires? I'm just wondering if that would be possible since the 4 barrel TBI by itself isn't too expensive. I'm really interested in this system, because it's able to feed up to 550hp which should be more than I'll ever be making, and is much cheaper than the other aftermarket EFI's. Also, wouldn't 4 90# injectors feed more than 550 hp? Just wondering. Thanks.

ben73

I think you will need extra injector drivers. The load of 4 injectors will hurt your ECM. There is a circuit floating about the net somewhere that will drive the two extra injectors... let me see if i can find it...

1MEAN92RS

Yeah Yellow73bb is making them! External injector drivers are a must. here's the link.

https://www.thirdgen.org/techbb2/sho...hreadid=168041

They've already done one board run, but I think they made a few extras and if not, maybe you can get enought people together for another run.

Later,
Harry

Dan W

Some people have had problems doing it with stock ECMs thats why the add on driver board thing happened.

With that said, I ran a 4bbl setup on my for a while and it worked fine. I wired two sets of injectors in series.

92WhiteRS

Alright...so in all reality it could be run on the stock ECU....hmm, that's interesting. I think I'm gonna go buy that 4 barrel now. Thanks.

JokerRS

Where can you buy the four barrel alone? (with out the rest of the system)

JPrevost

Yeah sure the 4 injectors can be run off the stock set of drivers but how do you expect to get around the half voltage? Seems like a waste of time and money. For the cost, doing it RIGHT seems like the only logical solution.
I've yet to see any good results (proof) of a 4 barrel running well with no extra injector drivers.
I'd also like to know where I can find a new unit by itself. If the price is right I might just buy it instead of welding together 2 stock units.

jlbolin

hey jon i emailed accel about their dfi ecm and its at www.mrgasket.com . the ecm according to them can handle 2 4barrel tbi at once so i would check with them they diddnt say price but i did let them know that some of us were interested in running a 4 injectored tbi or a system with 2 tbi's. as i said their ecm are capable of doing this. but to me it depends on the price. and if im not mistakenthere ecm lets your stock ecm still run emissions and soforth but i could be wrong just check it out for your self. if the web site is wrong ill find it quickly.

JPrevost

I know all about the aftermarket support. They've got a product that will let you run extra injectors but I thought we were talking about keeping the GM ecu? If you're going to spend money on an aftermarket ecm system then you should consider (or reconsider) going to MPI and forget the wetflow. The idea of TBI is to keep in inexpensive. It's just like vortec heads, they've got a potential and then it starts to run out of value. Port injection solves a lot of problems and the 7730 GM ecm is all you need. They cost a LOT less than any aftermarket ecu and comes with a lot of extra code for highway modes and tons of tables. It's really just a choice of time and money. I wish I had both .

Chuck!

There was a 4bbl tbi (almost new with injectors) on ebay for a buy it now of $150 and I didnt have the freakin money. It was gone a few hours later when I looked back. Id say that'd be your best bet to find a tbi only.

Dan W

Right or wrong in your opinon, my setup worked well. Since it worked so well I'd have to say its not wrong and in my case I'd say hacking into a perfectly good computer to add injector drivers to a system that worked would not have been beneficial. In my case the voltage to the injectors was adequate to make them fire normally and I had no problems with low voltage causing injectors not to fire

I was speaking with Howell-EFI and other sources before I set this up. As I understand Howell was very involved in the R&D of the original GM TBI system and trusted their advice. Based on their advice, and lots of learning on my part, I got good results. Maybe there are others who have tried it and have not gotten it to work... maybe they couldnt get it to work because of the injector driver, maybe it was due to other reasons. I don't know what the differences between those other systems and mine were. As far as proof goes, you will just have to take my word for it (or not) either way no skin off my back... I've got nothing to prove here... someone asked a queston and I thought he might like to hear from someone who had experiance with it.

As far as buying a 4bbl TBI unit goes, Holley still sells a version new but they are around $700. A little on the expensive side considering I bought mine for $400 maybe 5 or so years ago. I know some things about their TBI units have changed since then including the injectors and a shiney finish but I'm not sure what else.

92WhiteRS

Well now, I'm confused. Some say it's possible, some say it's not, and I don't know if I'm willing to spend $700 on a chance. My problem is that while I love TBI, I need to upgrade somehow. I don't have the holley 670 yet, but even if I did, I'm about to do heads and cam, and then that would be a restriction. Is my only possibility some aftermarket DFI...because I'm only 18 and can't afford that. Maybe I'll have to go to carb