Rotary Noob

Some stuff on order, like the flange itself (S and S fabrication...50 bucks, plus shipping, 1/2" 6061 T6...couldnt buy the material and get it water jetted for that...)

I have the aluminum tubing laying around at work, and all the welding equipment required to weld this puppy together...like a TIG, a foot pedal, and if I need it, a spool gun. Also have everything else I think I could need, basic metal working tools, grinder, sander, sanding rolls, die grinder, carbides, vise...the list goes on.

Biggest question is, for the throttle body itself, I want to run something I can find easily, and either on a production car, without too much crap on it (return spring+TPS only, if possible), or aftermarket the same way. The 300ZX, and Maxima share a TB, belive its about 55-60mm. I was thinking about two of those...One for the front rotor, one for the rear rotor. Completely seperate the intake air and fuel for each (this will be run on a standalone, thinking of a haltech) and use EGT and AFR to help tune everything on a dyno.

Im planning on running equal length to the TB flange, and tapering the transition from throttle body size to the runner size (grouped together in one), so that flow is smooth and even on both sides. Fuel injector bungs will be welded onto the runners and aimed toward the port openings on the irons to try and keep from puddling in the manifold, and help any other atomization problems.

The reason for the equal length from TB to engine, is to make it easier to tune (at least I think it will be...I havent tested yet, so I have no clue). If I add a stack on to the throttle body, runner length increases, shorter stack shorter runner, changes powerband around. At least thats what Im hoping for.

Suggestions for anything else? throttle body suggestions? Corrections?

Jakor

why not stay with the rx7 throttle body? Do the throttle body mod and remove all the rest of the junk on it. It's big enough and could save you the money of buy a different one.

Rotary Noob

There is that too...but its a tad bulky. And I dont have two... I know that 1 would probably flow enough...but im into symmetry, and indivdual Air fuel induction. That is a possibility though. Just more time spent with the tube bender, and the Tig welder.

bumpstart

being NA, it going to need decent blade surface area
- the problem with big blade single TB's on motors with poor torque
is very poor symmetry in the throttle opening % to total airflow
in effect, a big throttled single plane manifold will be super sensitive to "tip in " throttle movements
- in effect a throttle you have to "feel " and "feed" rather than floor and forget

the staged mazda TB gives you both worlds

- and staged TB's are not all that common !

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i have made my own using a 60 mm diameter GM type single TB
( from a aussie holden commodore 3.8L v6, same as buick )
- a 65mm diameter v8 option will bolt on if required

I found this 60mm TB ( 28.3 cm2 )
still didn't hold the turbo engine back
( had more power over 6500 rpm to stock manifolds and TB )
but was at a point where it was sensitive to tip in throttle movements happening to quickly

so, if large single plane TB can bring issues, and staged TB's with sufficient area rare
then there is one interim solution to mind
- the HC 929 twin TB
its dual blades opens simultaneously together , so in effect, a single TB
but, being smaller, parallel blades
( twin 45mm diameter, 31.8 cm 2 )
a small movement of that dual throttle does not equate to the same non-lineal response of large single blades

- and so may prove a little more drivable and consistent
and , just on quick conversion, its going to breathe air a little better than most 44 choked , and wet with fuel 51 IDA carbs

- so appears ideally sized and configured !!!


the HC TB
( its oval inlet may prove tricky for some to adapt )



VN commie TB ( same as buick V6 ) modified to adapt to a 225 impco mixer




pictured are the modified turbo LIM and manifold suit GM TB ( alum )
this was used successfully with a propane impco 225 mixer

the other manifold was made by someone else, and features a 55mm single bore
GM/ nissan rb30 TB
( used turbo charged to 300 HP )

i would think at only 23.8 cm2 area, its going to be too small NA

Rotary Noob

^^ Good information, thanks.

I suppose I should have clarified what this engine will "live" at.

Anything under 4000rpm, is unimportant. It will live between 4000 and 8500ish rpm. It will only be used on a track, or someplace flat that does not have smog regulations.