Well, it is not because of the bigger throttle body, but the car runs killer now. The install was straight forward. I cut off the coolant ports and capped the vac port (more on this later). I also got the proper size silicone coupling. Previously I was running a 3" which we all know is too big (with KAE TB, I now use a 2 3/4" coupling). All you have to do is swap over the throttle position sensor and you are golden. Make sure that you use the KA24E gasket, and port to match. FYI, even the gasket is about 1mm oversize, so I just ported then smoothed out the edges to meet the size of the gasket. When looking at the 2 TBs side by side, the size difference is very noticable.

The things that really fixed my car up nice were the fact that there is a vac port under the CA (and KAE) throttle body that I have no clue why, but we left open when we did my swap. The port leads to a tiny hole just before the throttle plates, so leaving it open was a def. vac leak! Also, using the proper size coupling meant 0 leak at the coupling. Finished off with a proper throttle position sensor adjustment, and the car is like new! There is still cold start woes, but beyond that, driviblity has increased exponentionally. My idle is rock solid again, and even my BOV seems a little chirpier. The TB cost me a whopping $30 shipped, and the gasket was $11 shipped from Courtesy Nissan in Dallas. The total job took 3 hours and that is mainly due to the fact that I had to modify my cold pipe and the grinding pads I had for my new Dremel MultiPro that I bought for the project were all wood working ones, so I had to change them out every 5 minutes. On a perfect day, this is a 1-2 hour job. Nothing that any of us couldn't figure out. Next on the menu? A boost controller and chip, followed by a Z32 MAF and new injectors. Then 14psi until I kill the T25G.

pictures?

it's gonna look like stock. just a wider inner part. The exterior dimensions are the same.

btw, sounds like a good mod rico! I'm gonna consider doing this as one of my next mods I'd really like to fab up an intake manifold though... I'm building the intake and exhaust manifolds for our formula SAE car, and depending on how much work it takes to do that, I'm going to try and make one for my s13.

Sean

I could have fully matched the inlet on the intake mani to the throttle body, but there is a lot of material there (the mani is like 1.5" thick at the TB), so I just did a bevel to smooth flow into the mani. Not the most effective way to do it, but it works. The butterfly difference is only a few millimeters, so this is not the killer mod that it may sound like, but every increase in flow potential helps!

This thread gave me an idea! Ill share...

Is there anyone who has thought of modifying the stock Secondary TB's somehow to act as ITB's? I wonder if there would be any gain form the main TB being eliminated...

There's not enough butteryfly's. You only have plates on every other intake valve. You would have a build a custom intake manifold and butteryflys. Big ol pain the the butt, and for nothing really....

ITBs on a turbo car are a flow hinderance, not a benefit. Why do you think that everyone from Nismo to JUN make "surge tanks" for the RB and other ITB motors that replace them all with one, large throttle body?

is there any fuel runnin' through the throttle body? ever?

is it just air flow control?

No, no fuel through the throttle body. The fuel is injected at the fuel injectors, just before the intake valves.

Barring REALLY new, heavily computer controlled, direct injected stuff, all spark ignition vehicles have the power output controlled via an air throttle on the intake side. There's a lot of different ways to do it, but the most common is the butterfly style valve.