onefastmx5

Years are passing and I'm still working on my 385 build. I assembly the engine about 5 years ago and have had it covered in the garage. I'm starting the process of swapping my new motor for the old stock engine and came across a problem. When I built the engine, I guess i wasn't paying attention when I purchased a port/polished intake manifold on ebay many years ago. I went to install the fuel rail and noticed it was not recessed for the front crossover pipe, so it must be a 92-93 manifold. So i have to make a decision, either build/fab a new fuel rail or purchase a different manifold. Here's a little on the build to see if that will shift me one direction or another:
385 stroker, forged bottom end, 9.0:1 compression, LE heads/cam, Vortech SC pushing 12psi, 58mm TB, P&P intake, plans to put 150 wet shot on top after its broke in.

-If the stock fuel rail can sustain my target 600HP, then i think it might be best to have my old intake manifold ported, polished and powdercoated.

-I noticed the 93 fuel rail might work, but not sure if it will support my goal HP. I like that it has a dual feed/return for better distribution. The tube size is the same for input/return I'm assuming, so i can retain my Speedinc stainless lines.

-I saw an Edelbrock Intake as an aftermarket option, but it was pricey. Haven't heard any feedback on these.

Thoughts?

Thanks,
James

Injuneer

The 93 fuel rail is designed for batch fire injection, not full sequential like 94 and up. The 93 fuel hard line incorporates a pulsation damper to try to control pressure fluctuation. With higher than stock fuel flow, the pressure may not be as uniform as you need. Not sure what you mean by dual feed/return. One line in, one line out through the fuel pressure regulator. Yes, two crossover pipes. But not clear to me how they function. If there are no internal return passages, what you have is two dead-ended rails.

600 HP at the flywheel, or at the rear wheels? I run the stock rails at 800 flywheel HP. To minimize pressure variation from the inlet on one end of the right rail, to the return at the end of the left rail, my rails are converted to run in parallel, rather than in series. The -6AN supply line splits through a Y fitting, with a -6AN line into the back end of each rail (-6AN fitting welded on). The -6AN return line connects to a fitting welded to the diagonal crossover pipe. The return line runs to a Weldon fuel pressure regulator mounted under the cowl.

Buddy of mine made 1,125 HP at the flywheel with the stock rails, piped in parallel like mine. He did have a return fitting on the front end of each rail, rather than a single return on the crossover pipe.

How extensively was the 92/93 LT1 intake modified? Port matched to heads? Obviously the 58mm bores for the throttle body. A used 94-97 manifold should be dirt cheap. My original LT1 manifold is collecting dust in my garage. Current intake and heads are LT4.

The Edelbrock manifold is not very good. Adding the "air gap" feature cut down on the plenum volume. In normally aspirated testing, the plenum volume was judged to be inadequate for big HP.

onefastmx5

Thanks Fred, the intake wasn't specifically ported to the heads but it looks pretty lol. I remember the ports being enlarged, the interior cleaned up and the 58mm opening. Other than being installed on the motor already I don't have an attachment to keeping it.

I guess I'll just clean up the 94 intake and have it powdercoated black. Any reason to port it out, or not worth the effort? Reusing the gaskets should be fine?

Chimera96

I am not a Thermal Engineer...but I would suspect powder coating the intake would cause it to retain heat vs dissipate it more quickly

onefastmx5

Ok, engine paint it is

bw_hunter

The LT4 manifold was powder coated red from the factory and they did fine, except for application method, powder coating is just a tough heavy paint. Don't be afraid of it....

Injuneer

Depends.... the exterior/top side of the manifold is exposed to high temperatures from the under hood heat. You want to keep that away from the aluminum surfaces, so the powder coating would reduce heat gain from under hood. But then there's the heat that comes from the heads (insulated by the gaskets), the block (insulated by the bead of RTV) and from the hot oil splashing on the bottom of the manifold (deflected by the sheet metal pan on the bottom of the manifold. Would be nice if that heat couldget out through the powder coating.

Sort of a standoff....

I never was concerned about it: