Has anyone ever built a sheet metal upper plentumn for a Speed Density 5.0? Like, build a box that will bolt on to the stock lower intake, and adapt the throttle body to a homemade plentumn. Would it run ok? Looking to eliminatethat huge EFI plentumn so the stock shock tower braces will still be used.
There is a lot of engineering to making that piece. It is made the way it is to get all you can out of the engine. Anyone can build an adapter but it will never perform properly unless it is engineered to match the rest of the engine system.
Only problem I can for see is manifold vacuum pressure being dropped to low, by the design being to large to operate a stock engine. If the vacuum is too low its possible to throw off the MAP sensor input and throw off the computer. Spacer plates for the stock plentum helps, but will rub the tower braces, and make it too tall and barely miss the hood for clearence in a Maverick. Thats really the bad part about the EFI swaps, is that you may have to,, well,, certainly modify the support braces, and to me, Trying to keep the car body as stock as I can, in appearence for a cleaner looking swap. Hence, the custom upper plentumn made for the maverick. Its never going to be turbocharged, etc etc, just a daily driver. If I can keep the "box" small enough to not throw off the vacuum signals, from what stock would be, Id give it a try for sure! Another point is the thottle body location on the stock plentumn,,, almost impossible to make any kind of Ford linkages to work for the kick down to a C-4 transmission, without buying a cable or conversion kit. I was thinking of having the throttle body either sit on the box, at the rear of the "box" facing the firewall of the car so the linkage sits in more of a close to stock location, possibly still use a lever type kickdown, and use a 6 cyl throttle cable. Second thought would be to find 2 smaller throttle bodies,, up to 65mm total for both,, and make like a twin throttle body,,,, like the tunnel ram look, but with two of em with small air cleaners,,,
the runner lenght and plunum (sp) volume have direct effect on the rpm power band. If you make a box intake the shortens the runners drasticly you will find that the low end torque will be gone. and if you dont have enough motor ie compression, and cam, the top end will be doged also. i had a 87 5.0 mustang and got a hold of a box uper intake from a friend. the motor was internaly stock. the car lost .5 sec in the 1/4 with that intake. The box intakes work alot beter with a boosted application than naturaly asperated.
