What is the difference of the injection system from a 454/502 EFI/MPI magnum 385/415hp and the EFI system that comes with the HP500/HP525?
How much HP can be made with the 454/502 EFIection if the injectors, map and fuel pressure is changed?

Anybody tried to run a rectangle intake on large oval heads with good result and how much power will I loose ofhe mismach ? the reson I ask is that I want to use my EFI/MPI injection from a 454magnum 385HP on a modified 454 with Brodix RR large oval alum heads.

Come on, there must be some EFI guys who can help me with ansvers

dont really understand your question but I think you mean whats the diff between efi and mpi? MPI is multi port injected....meaning usually one injector per cylinder. EFI electronic fuel injected can be either multi injectors or a single throttle body injected. Al least thats what I think but I'm a auto tech mainly.... Boat tech on the side. I'm sure some one else will chime in..........

the intake is the limiting factor in the 415 HP 502.

to make much over mid 500's without forced induction will be hard.

If I'm understanding the first part of your question properly
EFI (electronic fuel injection) generally refers to an induction system which introduces the fuel prior to entering the intake manifold similar to a throttle body type system
MPI ( multi port injection) utilizes a seperate injector in each intake runner typically aimed at the intake valve
Hope this helps

no,,, the first 502's has efi on the manifold,,,, then switched the sticker to MPI,,,,, same thing.

Its all semantics,,,,, all MPI's are efi,,,,but like said above,,,, efi can also be throttle body

MPI = multi port injection

EFI= electronic fuel injection

You can use the efi system just fine on your heads. Merc did it on several oval port engines. You'll need to get it tuned properly for your current engine. I believe the injectors are large enough. I'm sure you'll give up a little HP but it should work OK. I've done several 502's that made over 500 with that intake.

Thanks, I will try to use the 415 EFI/MPI in combination with my oval heads. I still wonder what the difference is between the 415efi/MPI and the 500/525HP EFI/MPI system. The 415 has throttle body to starbord and the 500/525 has straight throttle body but I guess thats not the only difference?

cam,heads and programming of ecu are difference.

I am using the Big Brodies on my 502 MPI system. They are the BBIIX's. It makes 942hp.

But I also has to stroke it to 540, do the injectors, cam, cut down and bore out the runners, better exhaust, have some serious programming and use 9 lbs of boost along with a whole bunch of other goodies.

For N/A purposes you can do the heads, cam exhaust, injectors, intake work and a few other goodies to get some pretty good power.

Young Performance did my work.