Just to let all of you know that I took delivery of my new throttle bodies for my (under construction) 1/3 Bridge 6 Port. They have 46mm chokes (50 mm bores) and are complete with 90 degree TPS, individual throat idle setting capability and siamesed vacuum fittings.

Don't really know how they will work, however all of the theory says that they should work extremely well. Now I can finish off the manifold and get rolling on installing the Megasquirt and Spark, etc....

Really looking forward to getting it all together and trying it out next spring in the Touring GT Series.

 

very sharp... I was thinking about dual BBK 80mm monsters and whether they would work.

 

Those are very nice. Where abouts did you get them?

The manifold I just built for my car uses a single 75MM Mustang throttle body...

 

I got them from a Motorcycle wrecking yard. Cost $300 bucks and really ease the construction of a manifold. Only concern is determining intake length. Right now I am at approx 10" from mounting flange to motor interface to throttle shaft. Problem is trying to fit it all in on the pass side of the motor. I don't want the standard horseshoe over top of the motor.

Another issue I am trying to work out is the taper of the intake from the 50 mm mounting flange to approx 40 mm. Need to work out length of taper and effect on pulse resonances (sp?). Still trying to eke out some cylinder pulse charging.

 

the sizing seems good, definetly enough...actually if you have 2x46mm going to primary you might even have some low throttle issues depending on the intake manifold setup (so i have heard anyways for two 48mm IDA TBs).
i'm definetly interested in seeing what kind of intake manifold you can come up with.
i guess it really depends on how high you want to rev.
the downdraft style manifold you want usually works out to be a pretty good high end design...the advantage of the sidedraft style is that you get more length so your powerband will be shifted down. you could always try out a few different combos and see what works best? in terms of weight of course the straight down design will save you a few pounds.

you mention pulse charging (pressure wave resonance)? this implies that you want to have shared runners between each pair of ports? what i mean in this, is having your two PRIMARIES share runners, and then your four SECONDARY/AUX share another set of runners...the point in this is allowing your front rotor to have a path to your rear rotor, and vice versa...you of course can't have any charging effects if the runners are completely seperate.

keep us updated on that manifold