My custom BP plenum project

[Rocketman]

Howdy guys-

Wanted to show some progress pics of my custom BP plenum project. These pictures are of the pattern I've made, I will be casting this when the pattern is completed.

The basis of this project is the stock lower manifold from an N/A USDM BP. The nice bit about it, is that it's modular - the stock plenum can be unbolted & replaced with something different. I want something that is capable of big power, can use a larger throttlebody, and isn't a BP26 or GTR manifold.

I had originally designed something like this:




But I deemed that a little too large, volume-wise & wanted something a little nicer.

So I went to a full-round plenum. 4" ID. Here's a basic mockup:



Which I've refined the design a bit more. My prototype will be cast as two pieces, an upper & lower that will have a joining flange and a handful of bolts to hold it together.





I've tried to make a nice smooth inlet to each runner here, it's not exactly possible to run velocity stacks given the cyl #1&2 runner spacing, as well as port shape.

As for the throttlebody, I'm setting it up to use a Ford Mustang 65mm TB which is one of my favorite TB's for aftermarket stuff, it's a bare-bones setup so no extra valves or vacuum/coolant passages. The TB flange & port can be adjusted though, to suit most any TB.

Update:More pics.

Throttlebody flange attached, flange added on both halves





I'm thinking I should taper the upper half of the plenum down toward the back. Thoughts on this? Thinking the upper will be ~1.25" to 1" tall at the back instead of 2.25"



-Rocket

PS. We don't have a custom fab section here?

[XelderX]

I would be very interested in trying one of these out. Some of the big hitter Miatas that run the same rule set as me use stock JDM Miata manifolds ported out by Rebello Racing. I've been looking for a slightly cheaper way of getting a little more volume and better flow without having to go to ITBs. I recently dynoed a stock throttle body and a bigger throttle body on my lightly ported stock manifold back to back and saw no gains from just the throttle body. This is on an N/A motor of course. I'm sure a boosted motor would benefit hugely.

[Mazda_Powered]

that's coming along nicely! My friend just had his front facing intake made up for his mk3 supra and my idea for a BP intake was spot on your design lol

[bomdoutscort]

Howdy guys-

Wanted to show some progress pics of my custom BP plenum project. These pictures are of the pattern I've made, I will be casting this when the pattern is completed.

The basis of this project is the stock lower manifold from an N/A USDM BP. The nice bit about it, is that it's modular - the stock plenum can be unbolted & replaced with something different. I want something that is capable of big power, can use a larger throttlebody, and isn't a BP26 or GTR manifold.

I had originally designed something like this:




But I deemed that a little too large, volume-wise & wanted something a little nicer.

So I went to a full-round plenum. 4" ID. Here's a basic mockup:



Which I've refined the design a bit more. My prototype will be cast as two pieces, an upper & lower that will have a joining flange and a handful of bolts to hold it together.





I've tried to make a nice smooth inlet to each runner here, it's not exactly possible to run velocity stacks given the cyl #1&2 runner spacing, as well as port shape.

As for the throttlebody, I'm setting it up to use a Ford Mustang 65mm TB which is one of my favorite TB's for aftermarket stuff, it's a bare-bones setup so no extra valves or vacuum/coolant passages. The TB flange & port can be adjusted though, to suit most any TB.

Update:More pics.

Throttlebody flange attached, flange added on both halves





I'm thinking I should taper the upper half of the plenum down toward the back. Thoughts on this? Thinking the upper will be ~1.25" to 1" tall at the back instead of 2.25"



-Rocket

PS. We don't have a custom fab section here?

The fab section is at the top of the photo section. Nice work on this manifold and everything you're having done for the bp.

[FE3-323]

with all respect. mazda had designed the NA intake manifold with a good amount of time & trouble invested. the VICS system is very helpful.
I would put some more time & effort into researching runner length & where you want your TQ band to be. dual runner system is very nice. perhaps you could recast the lower half of the intake manifold retaining the VICS but create a larger plenum that way with more equal clyinder filling.
As a tip in terms of the NA intake manifold---- peek at the 2nd gen BP design.

[Rocketman]

with all respect. mazda had designed the NA intake manifold with a good amount of time & trouble invested. the VICS system is very helpful.
I would put some more time & effort into researching runner length & where you want your TQ band to be. dual runner system is very nice. perhaps you could recast the lower half of the intake manifold retaining the VICS but create a larger plenum that way with more equal clyinder filling.
As a tip in terms of the NA intake manifold---- peek at the 2nd gen BP design.

This is intented for forced induction use, not N/A. I'm not really sure if I could do much at all to make an effective N/A manifold short of ITB's. (which I will be doing, soon)

I'm trying to avoid casting lowers, or anything with long runners - too complex / hard a part to make reliably with my current foundry setup

[DeeAOne]

Nice work man. Looks like it will flow nicely.

[bp_turbo'd]

what throttle body u gonna use?

[MD323]

looking interesting thats for sure

[Rocketman]

what throttle body u gonna use?

As for the throttlebody, I'm setting it up to use a Ford Mustang 65mm TB which is one of my favorite TB's for aftermarket stuff, it's a bare-bones setup so no extra valves or vacuum/coolant passages. The TB flange & port can be adjusted though, to suit most any TB.

[bp_turbo'd]

is it intake manifold or just a mock up?

[MD323]

is it intake manifold or just a mock up?

Which I've refined the design a bit more. My prototype will be cast as two pieces, an upper & lower that will have a joining flange and a handful of bolts to hold it together.

[Rocketman]

^^ Thank you. What you see in the pictures is what's called a "pattern" It's the exact shape of the final part, but made from wood / plastic / whatever. I'll mold it in foundry sand, remove it leaving an impression/cavity, and pour metal in place. The final part will be cast aluminum

[bogaut]

will you be making more than just one of these?

[FE3-323]

^ he has the ability to!