GNJ

Question for someone that knows about the 500 EFI MEFI 3 system.
The 500EFI intake is well known to be restrictive when modifying the engine.

With that said, has anybody ever thought of trying Edlebrock's Pro Flo manifold/Throttle body with the MEFI 3 computer system?

Will the TPS and IAC motor on the Edlebrock throttle body and the MAP sensor interact with MEFI 3?

I'm thinking of building larger motors with EFI and looking at possibilities.

HaxbySpeed

You can order the intake on it's own, and use a holley or fast throttle body that you can plug your tps and iac right in to. The edelbrock tbody probably is the same, as it's all generic GM stuff, but I don't know for sure. Your 500 efi distributor will not fit without cutting out a bit of the back of the intake and modifying it, it's not thick enough to grind. Your injectors will work, if they'll support the hp you're after, and there's a provision for the IAT sensor from your old manifold too. There's a spot to mount the 500 efi map sensor on the side of the plenum, or there's multiple npt ports to remote mount it. A pretty straight forward swap. I'm not into tuning the old MEFI's, but Eddie Young and others on here can certainly help you out with that part.

GNJ

Thanks HaxbySpeed for the info. I appreciate it!

offshoredrillin

It depends on where you want to wind up with your setup, you can certainly get to 640ish hp and close to 700 tq with the 500efi setup, where you are limited is by the rpm range as it only flows to about 5300 rpm effectively. Now with that being said, you can change cam, heads, fuel delivery system, injectors and tune and run 640 on 87 octane, i did it for years before i put on my whipples... hope this helps

GNJ

Right now both motors are 9:1 CR, 509's with 741 cam on 114* LSA. Ariz. Speed 1300cfm throttle bodies, Dart 308 iron eagle heads and Mark from precision did the reflash of the computers. Motors pull strong to about 5000 and then fades out to about 5200 tops under load. Less in hotter weather. I'm gonna put a vaccum gauge on it next time I have it out to determine what is going on at WOT inside the manifold.

I'm also wondering if any one has attempted to modify the choke point on the front of the 500EFI manifold where it connects to the TB. I have read where Young performance cut into the top and mounted throttle bodies atop and gained significant increases. Also, Brian @ BD marine did the same, but I would like to see if the front could be modified to overcome this issue and keep the stock look.

Anybody?.

offshoredrillin

Tyler crockett did the throttle body on top, you already have everything to make peak hp and tq, the only way to improve with what you already have is to put a power adder to it to fill the plenum with boost. I have the same engines, cam and afr heads and went to 4.0s.. tuned them to 850 for now, going a little more boost in the spring.

GNJ

What size AFR heads are you running?

offshoredrillin

335

GNJ

What kind of speed did you get before the whipples with you cig?

offshoredrillin

78 all day, fastest was 82, now 88 with no tweaks, am goingbto test props and change lowers in spring, i see another 5-7 with proper set up