Hey guys, I was wondering if anyone has ever done a DIY EFI on a carbed sbc. Like using a TPI setup on a dual plane manifold with welded in injectors, with the carb switched to just a throttle body. Right now im running a 2000 vortec motor out of a cadillac escalade. I switched everything to a carb setup 5 years ago when I was running it in my mudbog truck. Recently i put the motor in my IROC, but the carb is old and running like crap and I have been thinking about switching to some sort of EFI. I was figuring if i could weld in a set of injectors on the edelbrock performer intake I have, use the carb as just a throttle body, with a TPS hooked up to it, then run a TPI setup to squirt the injectors. Am I crazy? Is this something that could ever be done? I would love to be able to say I created something myself that also worked well. Ive never done anything like this before, but I have a pretty good understanding of EFI systems. PLEASE any help, info or suggestions would be appreciated. Oh and im not scared to try something new, basically everything I have learned has been by diving in head first.

 

Your idea isn't crazy. Homespun EFI is nothing new. Instead of fabricating your own throttle body, it might be easier to start with a TBI unit (or two) since it already hoses a TPS and the IAC that will probably be necessary to control idle RPM. There are aftermarket TBs, but there are also complete aftermarket EFI systems designed to bolt in place of a carb.

 

vader, I could prob. use the throttle body off my stock vortec intake manifold. Make it fit the edelbrock some how, I have a complete intake setup for a stock vortec 5.7, but i converted it to carb a while ago. I don't have the harness or computer, and it appears a TPI setup would be cheaper than a truck setup with CFI. Though i did read an article on swtiching to an LS setup with a fake distributor that acts as a cam sensor. I was just trying to get some peoples points of view that have done it. but looks like im on my own. I would like multipoint, i don't see a point in a TBI setup for the money. Thanks for the input! always appreciated

 

I was suggesting using the TB from a TBI as a "dry" TB only, then installing the port injectors as you were considering. The TPS and IAC are easily solved that way. If you could slave a second TB to the primary unit in a psuedo "dual carb" type setup, airflow would also be solved. The MAP sensor can tap the intake for its vacuum signal almost anywhere it is convenient. The rest can be a factory or aftermarket (Painless or similar) wire harness and ECM.

Another rather unusual possibility might be two TPI or LT1 type TBs siamesed (side-by-side or back-to-back) on a custom upper plenum designed to bolt in place of a carb. Again, the TPS, IAC, and air flow would be solved, and the MAP and rest of the system could be similar to stock.

 

Thanks for the input man, I knew you meant a dry TBI, i was just stating for the money to run EFI i don't see a point in a TBI setup. right now the motor is basically stock with a intake, so it doesn't need much more that a stock TB. I just wish the stock CFI didn't require a whole new set of injectors to be any good. Just ran into a money problem yesterday, so the car is on hold for now untill it starts flowing again.