Ok here is a companion thread for the carburated single/dual plane debate

What are your experiances with using a efi 1000-2000 cfm four barrel type throttle body and MPI on single / dual plane manifolds. Application would be a large cube 540 or 572. Dyno sheet data if any one has some apreciated.

Can you clearify? are you talking about actual fuel injection from the throttle body on your 4 barrel type?

I do understand MPI as being port.

Roby

These types of systems, http://www.chiefengines.com/efi.htm , either the chief or holley 950 with a 4 barrel throttle body on top of a single or dual plane manifold with one injector over the port per cylinder. Would like to hear from those who have run such a system, thanks.

It's almost impossible to oversize the throttle body on an EFI engine. Since an EFI engine isn't as dependant on a venturi signal to measure fuel, oversizing the TB doesn't really have a negative impact. All it does is allow for a means of regulating airflow into the plenum. Additionally, since it is dry, and doesn't have to worry about atomizing fuel, and sustaining the atomiziation, air velocity isn't a big problem either.

I've run 2000cfm "4 barrel" style EFI throttle bodies with no negative impact on automitive engine's. There may be a very slight negative impact on off-idle throttle response in a car, but it's very slight and hardly noticeable and probably wouldn't be appearant on a boat engine due to the rpm range they operate at.

This is true unless your using the type of fuel injection which the fuel is sprayed from the throttle body itself.

Roby

I ordered the Holley Dominator manifold that I am going to mount the 2000cfm throttle body to. The Holley manifold already has the buds for the injectors in it. Manifold is single plane. I ran the numbers thru desktop dyno & it showed a 61hp inprovement over my now twin 450cfm carbs.

I have now learned that Edelbrock also makes a EFI manifold like the Holleys.

Right, but the question was with regards to MPI, not TBI.

yes I was thinking of the holley manifold http://www.holley.com/HiOctn/ProdLin.../9901-202.html

My thinking is the mpi efi will help the weaker low end torque of the single plane below 3500 rpm and the 2000 cfm will make lots of HP when the revs get to 4500-5200 range

Something like the merlin with brass inserts would be nice to but would require some machineing/welding for the injectors. Would like to hear how you make out.