Port injected low deck project.

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mischiefdart

mischiefdart

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I want to build a ram jet style port injection system for a 400 B motor. It is going in a stick shift 70 Dart Swinger. The trans is a 1970 heavy duty A833 with the bigger 308 bearings and the rear is a 3.73 Dana 60 with power lock. The motor is .020 over with zero decked kb pistons, forged 383 crank and closed chamber stock heads. If it were a raised deck I would have simply bought the edelbrock manifold but they don't make it for low deck motors last time I checked. I just found a low deck Weiand tunnel ram base on Craigslist and I already had the offenhauser single quad top that has been cut open. They are not a perfect match but I can deal. Plan is to weld a flange around the opening and have a removable top and a front facing throttle body. Going to remove the nitrous nozzles and add injector bungs. For you guys running fuel injection, what system is suitable for this combo? I have seen a lot of people are running the holley system. What injectors are most people running? Any ideas on optimum plenum volume? I plan on using the aeromotive in tank pump set up. This is my first attempt at converting an old motor to fuel injection so any useful feedback will be appreciated

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Generally plenum volume matches total cylinder volume in high horsepower applications. When we build a plenum for say a 2.0 liter engine we match the intake plenum to 2.0 liters. This way the plenum can hold enough air all at once to fill every cylinder completely. Shape is important too. If the plenum was just a big rectangle when the air passed over the throttle body it would be launched to the top of the plenum, hit the plenum roof, and be forced towards the rearward most runners, not completely distributing the air. Tapering the plenum towards the rear and playing with different shapes at the rear should slow down incoming air velocity so it moves into the fronts as well.

Im a big fan of the Megasquirt system and use it on 90% of the installs we do. For stand alone engine manangement it feels like a science project at first, but its possibilities are almost unlimited.

Bosch, Denso, JECS, Siemens are all good injectors.
 
stroker416 said:
Generally plenum volume matches total cylinder volume in high horsepower applications. When we build a plenum for say a 2.0 liter engine we match the intake plenum to 2.0 liters. This way the plenum can hold enough air all at once to fill every cylinder completely. Shape is important too. If the plenum was just a big rectangle when the air passed over the throttle body it would be launched to the top of the plenum, hit the plenum roof, and be forced towards the rearward most runners, not completely distributing the air. Tapering the plenum towards the rear and playing with different shapes at the rear should slow down incoming air velocity so it moves into the fronts as well.

Im a big fan of the Megasquirt system and use it on 90% of the installs we do. For stand alone engine manangement it feels like a science project at first, but its possibilities are almost unlimited.

Bosch, Denso, JECS, Siemens are all good injectors.
Click to expand...
Should I ditch the divider?
 
mischiefdart said:
Should I ditch the divider?
Click to expand...

Personally I've never dealt with a setup like that. It looks like a good starting point. I don't know if I'd machine down the divider just yet. There's got to be some research out there on it, I'm thinking it will give it some properties similar to that of a single plane manifold. And those runner openings are really close to each other. I'll do some homework on it.

Have you considered a completely fabricated intake and plenum at all?
 
stroker416 said:
Personally I've never dealt with a setup like that. It looks like a good starting point. I don't know if I'd machine down the divider just yet. There's got to be some research out there on it, I'm thinking it will give it some properties similar to that of a single plane manifold. And those runner openings are really close to each other. I'll do some homework on it.

Have you considered a completely fabricated intake and plenum at all?
Click to expand...
The idea behind the divider is for better fuel distribution on the original wet runner set up. It is supposed to keep the previous cylinder on the 2-1 4-3 6-5 pairings from stealing the next cylinders charge. I am not sure it is needed in a dry runner system. Would you recommend a top entry over front? I don't mind a bulge in the hood.
 
I'm by no means an expert, but a top mounted throttle body on an intake elbow somewhere near the middle/front area of the plenum should give you even distribution. Something like this setup. Like I said I'm no expert. I work mainly with turbocharged 4 cylinders, but fluid dynamics is fluid dynamics.

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