Hi guys, I figured this would be a good spot to post this. It's not necessarily dealing with a Corvette in my application, but would be useful information for anybody with a carbureted engine.

I've narrowed down my Fuel Injection choices to Atomic EFI or EZ-EFI for my Cobra. The websites can be found here........

http://www.atomicefi.com/home.aspx

http://www.fuelairspark.com/fas/efi-...tion/kits.html

Does anybody have any experience with these kits on their engines?

 

We recently installed the Holley Avenger TBI system on a 72 with a zz4 crate engine. The install and tune was quick and easy, although we did drop the tank to modify it for an in tank pump. The FAST EZ-efi is also very nice, we used it on a BBC in an old Impala. No experience with the MSD system.

Rob

 

go with the EZ EFI it is a SPI system and will get you the most for your money. both of those systems are pretty good for tuning and customer support. the atomic is a TBI system and I personaly would chose a carburator over those.

there are three types of EFI

TBI throttle body injection which introduces fuel at the top of the intake just like a carburetor

TPI tuned port injection which sprays fuel at the end for the runners above the valves. this one sprays fuel one bank at a time. it sprays fuel for all the cylinders at the same time on one side or the other.

SPI sequential port injection which sprays fuel at the end of the runners above the valves but can fire each injector independently for each cylinder.

avoid the TBI systems they will give you the least bang for your buck and really most gains you would see would be negligible if you have your carburetor tuned correctly.

TPI and SPI are definitely where you should invest your money both atomize fuel better. both system will get you the best mpg. TPI are cheaper only if you pull your components out the the junk yard but ultimately your looking at about 3 grand no matter which direction you go if you buy new. if your carburetor is tuned to your engine you may at best see a 10 percent increase in fuel economy and if you are looking for horses then you need look into cams and better heads.

 

10% not worth it at all.
A well tuned or custom made carb is so much cheaper
This is about EFI though so Ill shut my big fat mouth.

Agree on sequential thats the way to go
Other two cant be more efficient than a carb.

 

That was extremely helpful and informative, thank you very much.

 

TPI was a GM style of batch-fire MPFI (Multi-Port Fuel Injection). It's obsolete, rpm-limited and I wouldn't recommend it for anything.

There are aftermarket MPFI systems and they are often a good choice. Compared to SFI (Sequential FI), they are easier to install as they don't require a cam sync. Many newer systems can be run in either batch or sequential.

 

I ended up installing Holley's HP multi-port injection kit. It has a throttle body that looks similar to a carb without the fuel bowls and the injectors are right above each valve in the intake. So far it has been a great upgrade and I'm glad I did it. But, we really need to know your reasons or goals for switching to EFI. There are a lot of great guys and great advice here but you might also try the Chevelle Forum. They have an EFI section and the main guys at Holley and FAST post there all the time.
Good luck in your decision and I hope your happy with what you get.

 

Legacy pretty much covered it.
I will add that the pretty spectacular milage and performance of todays motors (LS series) is due to a combination sequential injection, engine/head design, cam design, spark control, and OD trans.
This allows very low rpm cruise and great milage with heads that flow as well as high dollar aftermarket Gen I heads.

 

If you are interested at all in TPI (I like it, it is cheap, reliable, easy to setup, you can buy parts anywhere, and it has great drive ability.) Check out these guys Larry's Electric Good prices and great support. I bought a used setup off E-Bay, then the harness and computer from Larry's and it all came to well under a $1000.00!