I have an extra 74mm TB and wanted to machine it out to at least 78mm ? Of course a new butterfly would have to be made, machine gasket to 78mm and port match the S/C inlet too. Just wanted to ask if 78mm is still ok before possibly destroying a new TB.

Any idle issues with this mod? Fly by wire can be tricky

It is not possible. The outer diameter of the TB is 77.5mm

I'm a bit puzzled why the TB would be worth $2k?

If the TB is letting more air into the system.. why not modify the Y pipe to let more air?

LIke open the middle of the y pipe and install a 3rd filter?

Probably because of the nearly 200-degree air it would be ingesting.

>

true if you have a stock HE
not so... if you have an larger H/E.

I ran data logging this past week on a 90 degree humid day in So Cal.

While it may get extra hot air.. if you have a larger HE it will keep things on check.

I have made the extra air hold on my Y pipe with some "home depot" materials and a UNI filter.

I ran the car from 60-110 a few times and we only noticed 5 degree in increased IATs.

from 150-155F @110+mph and after I left off.. I was back to 120's in about 10 seconds.

crusing around town.. no differenct in IAT's.. about 15-20 over ambient.

While I respect people doubting this type of solution. it works for the C32's and is currently working in my car.

But a larger HE is a must for this type of mod.

by they way.. It will produce more PSI.. but our 55k will dump the extra air.

Just like it does with my ASP pulley. However it does help with throttle response.. similar to the sprint booster.



An ECU tune is necessary.

I'm working on that next.....

Someday I am gonna open that Y pipe WIIIIDDDEEE open and plumb her right up through the hood for an ole fashioned cowl. Can use the existing vent area for easy hood access.

Car washes would be rough but be interested what she would do with straight down air injection.

My bad, I was looking at the wrong end of the horse (other side of the tb) and focusing on a pump install when the mail man showed up with it . 76mm, it will be..



Jackpro1, what is the issue with the Y pipe? Duel pipe seems like it will flow far more than the baby 74mm tb. I am still really bothered by the 1 7/8 ID exhaust tubes that go between the cat and the exh. manifold collector. That is a whole new topic though ..

Stock 2003 TB can be opened up to 76 mm. It is worth about 15RWHP.

On 2004 and up cars, Bosch has epoxied the electronics on the TB and it can not be taken apart to be bored out.

80 mm TB is the only way to get more air inside.