2002z28ssconv

My buddy and I spent an entire autocross season tweaking on the Holley 650 carb we got from Racing Beat. We were told that it would be hard to tune it for cornering but we didn't think it would be impossible. Eventually all the starving and flooding got the best of the engine and we lost compression on one rotor. We never tore it down but figure the apex seals are dead. The internals were stock @ over 100,000 miles.

The straight line power from the Holley was outstanding but unfortunately we spend more time with the wheels turned than we do with them straight so in the end that was just not satisfactory.

I'd like to go to a TBI setup on top of the RB intake. That should eliminate all of the fuel starvation and flooding issues that we have been so frustrated by for over a year now.

I have read and read and read some more. It sounds like the Holley Commander isn't as adjustable as we would need it to be. MegaSquirt sounds better and cheaper too. So what all would be needed to get a 13B NA engine up and running with TBI? There is no chance of forced induction so I don't need to plan for that.

Can I just ****** a 4 bbl TBI system off of an '89ish Chevy pickup, bolt it to the RB intake, attach the FI portion of the Chevy engine harness and plug it into a stand alone MegaSquirt ECU?

budrud

I'm in the process of building an engine with that very setup right now only I put a turbo on it. The 5.0 chevy tbi is very close cfm wise and the injectors should be good according to the megasquirt website info. You need water temp, air temp, o2 sensor, and a megasquirt minimum for fuel only. The pressure regulator, throttle position sensor, and enricher generally come still bolted on the chevy tbi. I'm using all gm sensors cause they're cheep and easy to come by. Will it work- I have no idea. I'll keep you posted

PercentSevenC

I'm interested in the results of this thread. I'd just as soon dump my Edelbrock in favor of EFI.

rxtasy3

iTrader: (2)

i currently have a setup that one day soon i'll get installed. it consists of holley 4di control unit and 700cfm 4bbl tbi. it being a dd makes it hard to work on it and drive it too.

PercentSevenC

Which Chevy trucks came with a 4bbl TBI? The ones I've been able to find are all 2bbl. Which would work fine for me, since my supercharger acts like an open plenum. Seems like the 454 TBI with the 90 pph injectors would be perfect.

2002z28ssconv

They may very well all be 2 bbl TBI's. I haven't gone that far yet. More in the stages of wondering if the theory is sound. One things for sure, I'm not racing it with the Holley carb ever again. So once we get another 13B dropped in we'll either be looking for webers, or a TBI to go on top of the RB 4 bbl intake. I'd rather have the sucky restrictive stock fuel injection than the Holley carb at this point.

So it sounds like the theory is sound. Maybe I'll hit the junk yard this weekend to look for a TBI and grab its IAT, coolant temp and O2 sensors too.

Where's the best place to get the MegaSquirt?

budrud

Yeah sorry I'm using a stock 2 barrel gm tbi. I got the megasquirt on ebay but you can buy kits at Glenn's for one. I'm using a megasquirt I since I'm running fuel only, it may be a mistake we'll see. I've been collecting parts for awhile and I'm ready to get it going over the next couple months as long as I still have a job that is. The wiring diagram is on the megasquirt site so you can see whats needed.

PercentSevenC

I think DIYAutotune still has the best prices on MegaSquirt stuff.

RXDad

iTrader: (2)

http://www.auto-nomics.com/cgi-bin/s...part=12168-001

RXDad

2002z28ssconv

One thing that concerns me is the 2bbl thing. The Racing Beat intake has 4 seperate openings (it's not ported) that align with each of the 4 venturis.



By going to 2 venturis, I would be reducing the flow rate through the intake.

I found a 4 bbl Holley Pro-Jection system for a reasonable price.

Does anyone around here have any knowledge of those?

budrud

I see what you mean about the 4 bbl thing. I'm using a manifold with just one big square bore going into a draw-thru turbo setup. I found a tbi to square bore adapter plate on ebay. There is some good info on setting up progressive injector setups with the megasquirt in the megasquirt section of this forum but I didn't want to mess with it if possible. I'm trying to keep my setup as simple as possible at first to see how it works out. I'm using a street port 12a and a locked dizzy.

Rx-7Doctor

iTrader: (13)

Why not go back to the stock SE injection set up?

buldozr

iTrader: (1)

most of the gm tbi use a three bolt 2 barrel design on the v8/v6 88-96 trucks, you could possibly use a 4500 to 2300 (4barrel to 2barrel) carb adapter. I am not certain if the bolt holes are going to line up or even if it will be the same diameter bores doing this though. You may run into hood clearance with a spacer/adapter on it. I know if you do go forward with it, I would undoubtedly get the GM fuel injectors flow balanced/rebuilt for safety. Some people are able to modify the holley's for roadracing but It is not a walk in the park. Some of the Puerto Ricans use a 4bbl throttle body(which uses the 4500 series standard 4bbl flange and bolt holes) and also has bosses for 8 total injectors but that doesnt mean you have to run 8, you can still run four and pull injectors off of a s4/s5 6p n/a and get the wirring and ecu to work or go with the megasquirt like you were originally planning. GL with your build and I will see if I can find a link to that TB.

buldozr

iTrader: (1)

^ EDIT: 4500 is the dominator flange, which is not what your looking for, its the 4150 standard 4bbl flange on a regular 4bbl carburetor. 4500 is the big dominator carburetor flange used for 500ci+ big blocks.

Here is a link to what I was talking about, 4bbl throttle body for standard 4150 flange with the 8 injector bosses and fuel rails, this is not the only company but this gets the idea across.

http://estore.websitepros.com/1636426/Detail.bok?no=1

rxtasy3

iTrader: (2)

u can get an adapter plate that will allow the use of the 2bbl tbi. some of the setups on ebay include this plate. did a quick search:
http://cgi.ebay.com/ebaymotors/Holle...Q5fAccessories

just the plate:
http://cgi.ebay.com/ebaymotors/Holle...Q5fAccessories

2002z28ssconv

Ummm.... The stock FI setup got donated elsewhere. Plus it was restrictive as hell. There's so much more power now that the engine can get the air to flow. The stock setup would just be a disappointment.

Imagine having Meg Ryan as a girlfriend. At first you're happy and could be so for a very long time. But then you have an affair with Jennifer Aniston! Even though you break things off because you find out that Jennifer is kinda nuts, you'll never be happy with Meg again.

I was thinking of using a 2==>4 adaptor but that would still leave very little air flow to two of the intake runners. Plus there is absolutely no hood clearance already. So anything that raises the carb/tbi would be a bad idea.

Thinking VERY seriously about the 4bbl pro-jection.