Ported/Aftermarket TB discussion

[Halon]

I also don't understand the appeal of such a large TB. A 64mm I can understand, a 75 seems a bit overkill for the amount of power 99% of us ever plan to make.

But again, I don't know much about Evo X's. It was mentioned larger TB's are good because idle control is done by opening the butterfly. Why does that make idle control easier? In my hollow mind, I'd think a larger butterfly would make idle more trickyas you're "gain" has essentially gone up. With a much larger opening, with every little change in butterfly angle, the percentage of difference in quantity of air making it past would be increased quite a bit. So your resolution wouldn't be as good anymore. Changing the butterfly by 1* on a 58mm vs. a 75mm is quite a difference in air quantity.

Again, just how my thinking works in my mind. Not that I'm right or wrong, i just find it interesting that a much larger TB would really offer better idle control simply because it's larger.

[DSM_421]

I'm assuming the ECU just computes the airflow off the percentage that the butterfly is open? But then again you would need to compensate for the larger surface area, so I'm wondering how that works on Xs as well.

[Murlo26]

I think Scheides was saying that a 75mm TB on the X has better idle control than on an 8/9 or DSM because it uses the butterfly valve. Not that going to a giant TB makes it have a better idle.

[Halon]

And if that's the case, then I still don't understand why anyone on here would really want a 75mm TB. I'd think a stock 58mm would be plenty for most, and a 64mm upgrade may be a little bit reasonable, but 75mm seems like a waste of a mod.

Again, just my opinion :)

[Murlo26]

I am not arguing with that at all. I already said the 64mm one seems plenty for anyone.

[Halon]

High 5.

[scheides]

I think Scheides was saying that a 75mm TB on the X has better idle control than on an 8/9 or DSM because it uses the butterfly valve. Not that going to a giant TB makes it have a better idle.

This. All I was saying was that the idle control on the X is a lot better than the dsm & evo8/9 so running a bigger TB (or bigger cams) is less of a problem for driveability.

At what point the 75mm is actually going to be 'needed' or outperform a 64mm (and with what intake manifold behind it) is what I'd really like to know.

[Goat Blower]

Besides, you would probably want 3" piping to go with a 75mm TB, which once again is overkill for most everyone. It looked cooler though.

[DSM_421]

Besides, you would probably want 3" piping to go with a 75mm TB, which once again is overkill for most everyone. It looked cooler though.

Lol I bet, I've always had 2.5" piping but I bet 3" would look bad-ass as hell under the hood.

[311evo]

I think I saw a test on evolutionm where they gained around 15whp switching from a oem TB to a Boomba. (was on a Magnus intake mani for both tests)

And IIRC, they did a full 3" IC pipe conversion after that and actually ended up losing power or staying the same. not sure exactly.