HI Guys,,Could anyone Please tell me the exact inner diameter opening of the stock plastic Y-pipe trunk going into the Throttle body....I have heard 68 mm all the way to 75 mm???.......Thanks

 

John,

I would have to dig mine out tomorrow and measure it, but I can tell you this...when I first went to a 75mm TB, I used it, but it was very difficult to get it to stretch over the 75mm TB and Y-Pipe ends. I had to use a lubricant and make a shoe horn like tool to get it on. It was a real PITA to do and was less than ideal from a flow standpoint, as it became narrower than the Y-Pipe opening and the TB opening when installed because the ends were stretched so much.

 

HI John,,Thanks,just would like to know now for my info ....
The throttle body's that are sold now,that I am aware of and have,,,is a 74mm by the shaft , in which their is that slight step in the body their [true measurement]......And come with a bigger hose coupling to fit easier now..
The hand ported ones that I have seen have those steps removed and it makes it a 75mm then,,,as also the opening is mouth of the TB thinned out and opened up/tapered.....I guess back in the dayTurbo Mike did them all by hand when he sold them with his plenum....
I sent the IPD plenum I recieved from TimNYC to Calico to get it coated..

 

John,

Here is a picture of mine...ported, etc. - probably done by Mike back in the day...

 

TB in 71,5mm /to intake plenum 80,5mm

 

Thanks for the info!

Where abouts specifically are you measuring for those numbers?

 

exact inner diameter opening of the stock plastic T pipe going to Throttle body 71,5mm / the opening to intake plenum 80,5mm (cross)

(have an old t style plastic)

if you need the oem y pipe diameter, i have to go again in garage smile

 

HI Guys,Thanks for help and info......That is the plastic y-pipe that has the legs that come from the intercooler hoses ,joins and connects to the TB.So then that opening is 71.5 mm ID??.....Sorry,I was not talking about the plastic T-Pipe.Thanks

 

the oem y pipe connection to TB is 68,5mm inside diameter .....that is the reason wy i prefer speed tech 75mm y pipe with a 75mm TB

 

Thanks,,,,that is a good reason....Even though a 74mm TB actually doesnt flow like a straight 74mm pipe due to the shaft and throttle plate restriction plus the turbulence they cause...It would be beneficial to update that Y pipe to a bigger ID....