bored tb...how big to go

[mario]

I had a 66mm tb that I bored out on my car but I traded that one for two stock tb's and a intake manifold. I noticed a little difference with the stock one I have on there now and want to bore the other one but I'm not sure how big to make this one. What's the best for a car with just about every bolt-on including NOS?

[crazyprobe]

i think 66.5mm is as big as you need to go.

[Paluce3]

65 unless you go turbo... over this you loose too much intake air velocity...

Daniele DeFranceschi
95 PGT Turbo

[ASword]

The bigger you go, the worse the drivability will be. A larger tube means more air when you first crack the throttle, which means less fine control. I found this quite noticable just going to 65mm -- not enough to make me want to undo it, but I certainly wouldn't recommend going farther.

[Neiding]

What size gain could a person expect to get by adding a TB. I am assuming that the gain would increase provided that complimentary performance parts like a CAI, knife edged manifold, headers, cat, catback, ect. With all of this what do you think the gain would be?

[Rick_96PGT]

Try keeping the same size bore at the butterfly but tappering the front of the TB to 68mm+....

[mario]

Rick, did you try that? If so did you just mount it on a lathe? I made a fixture and a mill on the one I bored to 66mm. hmmm I think I'm gona try that first, If I don't like it I can always bore it all the way.

[Rick_96PGT]

Lathe?...That would be to easy....:grin:

I used a Router and a tapered bit....Its only aluminum....

You can take the leading edge to a knife edge when you do this, then i radiused the edge to about .010r to keep from cutting my self and the TB elbow I use...

[Triped]

Rick, how could you post on April 0(1) at 8:57 PM, when it's only April 1, 11:06 AM(central)? :grin:

Mike, Thanks for the TB, Next weekend should be fine for the STS.

What are your plans for the intake?

I just board my tb and now it idle's just over 1000rpm anyone know how to fix this?