How can my TB be this size???
 

So I've decided I better get a 65mm TB to go along with the goodies I'm adding (see below). After searching the many posts on TB issues I thought I had it figured out. (Thanks also to Jimberg for your help.) As I talk to my Motorsport guy to order one he wasn't quite sure how to handle my questions on whether or not I need the 65mm EGR plate. So I tell him I'll measure my stock plate with dial calipers and see how it compares.

Here's what I get. And I just multiplied the inside dia's by 25.4 to get mm's.

Upstream side of TB: 2.420" = 61.47mm
Downstream side of TB and also EGR plate: 2.440" = 61.98mm
TFS intake: 2.950" = 74.93mm

I thought stock TB's were like 58 mm. If so I'm like halfway to 65mm already.
Am I measuring this right?
Is it a no-brainer to match the EGR plate size or do you blend a little to match the dia's?

BTW: Summit has a 1" TB spacer that claims 20 hp.....whats up with that?? Why wouldn't everybody immediately do that if it's so great. Would one of these help me with my combo?


Any help is appreciated.

Dan

Your measuring is a bit off, the TFS Street intake opening is 70mm.

if i remember correctly the tfs intake has a 72.5mm throttle opening. it was supposed to be 75.

I had the trick flow street, and they had a chart and it said the intake opening was 70mm. It wasn't supposed to be 75mm.

O.K., I went back out and measured again - same numbers, and I haven't drank anything - yet.

The 75mm TFS measurement seemed to make sense to me since then you could use anything up to 75mm, which seems to be the biggest "commonly available" size.

Is it possible that the TB measurement is taken farther in where I cant get to with my calipers?

What do you think about matching the EGR plate size....and what about that 1" spacer?

Dan

Measure the TB right at the throttle blade location (tough to do without disassembling it). I'd bet that it measures 58mm at that point. The FRPP 65mm will have a noticable step at the throttle blade where it measures 65mm then steps on both sides to slightly more than 65mm. Probably to account for casting and machining tolerances. In class competition, they measure it at the TB with a 'go - no go' gauge.