Carb or Injection for unprogramable systems??

[four05hp]

I have a 93 xj which i believe is obd-1. Im told these are not programable and i need an expensive computer upgrade(stand alone etc.) My machine shop guy suggested using a carburator. Am I going to be leaving alot of power on the table going back to a carb? Does anyone know of a way to use my computer without breaking the bank? The motor I built is somewhere in the neighborhood of 350-400 bhp so i need to be able to feed it the fuel and air to make these numbers. Any help would be fantastic....thanks!

[Plechtan]

no actual experience with ODB1 system, but EFi is better than a carb. I think you can get away with oversize injectors and an adjustable Fuel pressure regulator.

I believe a unichip will work as well, but the cost will be 7-800 dollars by the time you are done.

EDIT:

I didn't read al the way through your post, 400hp? you would have to go to an aftermarket ECU, or buy a Clifford intake for your carb. You can also use the clifford with a TBI setup. Lots of stuff on the internet on GMTBI.

The stock throttle body will not flow enough air, and you also may have to come up with a larger intake.


The Intake costs $359.00 and then you will need a carb. You could probably stick with the EFI and use a Megasquirt like TurboTom. Read his thread under projects.

[TurboTom]

Power wise you can make a carb work. But I would doubt on the stock intake.
Give some engine details, becuase I doubt you will be near 400 HP on a N/A engine.

[1bolt]

Before I go skeptic on your expected horse power can you share some details of your build and why you expect 350 or more horses? 300 would be highly ambitious build around here. Though Pete (plechtan) is working on one that should do well over 450

[four05hp]

Yeah i expected some skeptics, It's a 1993 4.0 block bored 80 over, 258 12cw crank, 4.0 rods, JE custom forged pistons, sbc valves 202/160, custom ground roller cam & rockers solid lifers, head is gasket matched and flowed, Custom intake from socal...not sure the vender my machine shop guy ordered it, holley 2barrel off a circle track car (which was over 400hp). It's right around 12:1 and obviously will run on race fuel. Once I have the completed build sheet i will be happy to post it and share moe details. This is my fisrt build and to be honest with you i don't know alot about it. All I can go by is what my builder tells me. I was just hoping someone had encountered the OBD-1 problem of not being able to tune it for big power and had a solution....thanks for the input.

[gradon]

Comanche91 had a unichip wired in his 91 obd1 comanche with good results, so I'm sure it'll be able to do the job for yours as well.

[gmakra]

Another option is the Weber Redline Fuel Injection. I installed one on my 4.7 in a CJ cause I couldn't get a TBI to work quite right with an emulator and 40 plus chips burned.

The install is very easy and infinitely tunable. The Weber guys have thought the whole process out with little things like pointing the injectors at the back wall of the intake to get better fuel distribution. The software is a breeze and when you order they build a kit for your engine.

I put the kit on a month ago then moved to Chicago from LA pulling a 6x12 U-Haul trailer (long story but it weighed as much as the CJ) but it pulled the trailer through the Vail Pass and the Eisenhower tunnel (elevation 10200 feet above sea level) with out a problem. When I unhooked the trailer I trimmed the fuel and its been running great.

If you have to deal with SMOG visual you could have a problem, but if its a sniff test you will get by with flying colors.

[BADASYJ]

I also have an OBD1 system in my race jeep. I plan on eventually going to a carb just for reliability issues and also its cheaper and easier to get more power.