I am in the process of designing my next engine. It will be 540 - 572 EFI motor. I was wondering if anyone has some insight into the HP limitations of the 502 EFI Intake. I plan on running larger injectors and remapping the ECU.

I am hoping to get 650 - 700 HP naturally aspirated, fuel injected. Is this possible with the 502 Intake. If not what is recommended and proven?

Thank you

If I remember correctly the 502 mag efi intake is limited to about 640HP on a 540 motor by Lingerfelter. I have a 4 barrel (single plane dart looking) efi intake and throttle body available if you are interested in converting over to it.

I was told by Mark at Precision EFI, that the Merc MPI intake was only good for about 5400rpm on a 502.
It can be ported and the runners shortened for more. How much more???

5400 RPM? Most Mags will go ro 5600 or 5800 without the rev limiter easily.

I don't understand Marks statement.

Give him a call.
He told me, "The Merc intake does not flow enough air much past 5300-5400rpm on a 502."

Tyler Crocket would be another great source.

One thing to ponder; why would Merc change to the AZ Speed intake on the 500s and 525s?

pantera28

agree with the flow #'s above 5400, but I know of (2) 572's and (2) 540's that are built with the 502 mag intakes as long as you cam the motor to run under the volume of air that the intake can deliver your fine,
(you only have to supply the ci of the motor every other rev so a 502 only needs 251 ci of air every rev or 725 cfm @ 5000 rpm,540 is 270 ci ect....)

the 572 guy only turns like 45-4600 sure his hp #'s are lower but he is running around a max torque all the time so he propped the boat there.@#$% that thing runs!!!

just my .02 hope it helps
it is a Lot cheaper than buying the asm intake..

Kirk,It isn't "ideal" but hey,everyone told me I'd never get much past 800 hp with a blower using the 502 mpi intake. Most "experts" say the runners are too restrictive but even in stock form they will flow around 400 cfm which is more than the majority of most heads you'll find. If you do it and you need some help,you know how to reach me,I gained a little experience last winter doing mine,and I am also curious of its full potential. I managed to exceed what the majority feel it can make in a S/C app by 150 hp,I'd like to see someone break ground and make 700 hp N/A with one,Smitty

I turned ALOT of rail stock into scrap too before I got the injectors the way I wanted/needed them

More,the top left pic is my old fuel rail that I had already modified with twin -8 supply lines.

I used AZSM extruned honed.