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foppert · 05-21-2020, 02:13 PM

Hi guys,

Some background, this is a 1970 Nova that i am building to be a daily driver. The car is currently lowered and has been swapped to a 1998 Tahoe L31 engine hooked to a T5 5 speed manual. The engine is currently being fed by a dual plane intake manifold with an Edelbrock carb. I still have most of the original EFI gear from the Tahoe. (no computer or harness.) The intake has injector type spider replacing the ghastly poppet type injector spider

I am looking to move the car to EFI with economy/drivability as the goal... all on a sub LS swap budget. 270 or so horsepower is plenty for a car with 1970 brakes and handling.

My question is what would be the best route, the TBI carburetor replacement efi conversions like FItech or Holley Sniper? or the stock GM MPFI intake with a flashed 411 pcm?

It feels like a weird step backwards to move to TBI, but everything i have ever read about the Vortec 5.7 intake just calls it awful. Perhaps its only bad for power which is what most folks are aiming for with these v8s. The idea of all those fuel hoses inside the intake plenum doesn't seem like a good plan for anything. Unfortunately the only intakes with conventional fuel rails are so expensive I may as well kick the L31 to the curb and go LS.

I feel like the TBI units might have some edge here with a more modern computer and a wideband. I considered megasquirt on the original intake, but that would require an MS3 with the expansion to get full sequential injection on a v8.

Thoughts?

05-21-2020, 02:13 PM	#1 (permalink)
foppert EcoModding Lurker Join Date: Feb 2014 Location: LA Posts: 6 Thanks: 0 Thanked 0 Times in 0 Posts	OEM MPFI vs modern TBI conversions Hi guys, Some background, this is a 1970 Nova that i am building to be a daily driver. The car is currently lowered and has been swapped to a 1998 Tahoe L31 engine hooked to a T5 5 speed manual. The engine is currently being fed by a dual plane intake manifold with an Edelbrock carb. I still have most of the original EFI gear from the Tahoe. (no computer or harness.) The intake has injector type spider replacing the ghastly poppet type injector spider I am looking to move the car to EFI with economy/drivability as the goal... all on a sub LS swap budget. 270 or so horsepower is plenty for a car with 1970 brakes and handling. My question is what would be the best route, the TBI carburetor replacement efi conversions like FItech or Holley Sniper? or the stock GM MPFI intake with a flashed 411 pcm? It feels like a weird step backwards to move to TBI, but everything i have ever read about the Vortec 5.7 intake just calls it awful. Perhaps its only bad for power which is what most folks are aiming for with these v8s. The idea of all those fuel hoses inside the intake plenum doesn't seem like a good plan for anything. Unfortunately the only intakes with conventional fuel rails are so expensive I may as well kick the L31 to the curb and go LS. I feel like the TBI units might have some edge here with a more modern computer and a wideband. I considered megasquirt on the original intake, but that would require an MS3 with the expansion to get full sequential injection on a v8. Thoughts?