Rx-8 throttle body

[Hound]

SO since we are speaking on throttle bodies and I am interested in this too, everyone seems to always want to go bigger.... as do I; However in terms of velocity if one were to reduce the size of the TB and have a boosted engine or any engine for that matter do you think you could see a bit of an increase? Especially in the case of moving to multiple TB's at a much lower diameter?

Also I hear people keep mentioning CorkSport, I have checked them and seen some great stuff there but as of recently it seems all the Protg stuff is disappearing.....anyone know whats up with that or are they just working on their site??

 

[magnumP5]

SO since we are speaking on throttle bodies and I am interested in this too, everyone seems to always want to go bigger.... as do I; However in terms of velocity if one were to reduce the size of the TB and have a boosted engine or any engine for that matter do you think you could see a bit of an increase? Especially in the case of moving to multiple TB's at a much lower diameter?

Bigger/smaller doesn't necessarily always mean less/more velocity. Incompressible (i.e. low speed) flow assumes velocity is inversely proportional to area. Since air IS compressible it's not a 1:1 correlation. In the simplest sense, in general you want a small inlet area when flow is low and a larger area when flow is high to maximize intake velocity and therefore power. Since most economy cars don't have complex intake systems with variable-area inlets it's a compromise between low-speed and high-speed power. The same concepts apply with pressurized intakes on turbocharged vehicles with the inlet area being higher due to higher flow rates. Too big and you lose low-end power and too small you lose high-end power.

Also I hear people keep mentioning CorkSport, I have checked them and seen some great stuff there but as of recently it seems all the Protg stuff is disappearing.....anyone know whats up with that or are they just working on their site??

The last production Proteges in the U.S. were assembled 11 years ago. Compared to other "tuner cars" (e.g. Civics) Proteges are low-production, niche cars. Even Corksport's RX-7 parts lists is dwindling and it's a much more iconic, "classic tuner car." There isn't (much) money to be made by continuing to build, stock, and support parts for them. It's just a sad fact of business.

 

[AN7]

OK Well about 2 weeks before this thread was started I ordered a NC Miata throttle body. It isn't as large as the RX-8, but it is still a lot larger than the M2. To get the numbers, the M2 one is about 1.8" in diameter. The NC Miata is 2.4". The opening in the intake manifold is 2.1" so there really isn't any reason to go any larger than the NC since the intake manifold is your limit. Anyway so I did the things needed to get the NC throttle to fit. I did a number of back to back pulls on the dyno and they were all within 1hp throughout the the entire curve so as we thought there is no gain from the throttle body.

What do you need to fit the nc throttle?
Is an adapter between the mani and the throttle needed?

 

[zps2004]

You need an adapter, but the spacing needs to be right to make everything clear the rest of the intake because of the larger size so it isn't as simple as it sounds. There are some wiring differences as well.