Series 1 Vs series 2 silvertop throttles

[Sam-Q]

motor - 20v silvertop

I have been making up a batch of trumpets using an mock up engine I have handy. Fitted awesome and all but I was surprised when the opening was smaller on the throttles for my own car. Thinking I had made a whole batch of trumpets up using modified throttles as a reference I freaked out. Luckily I held back on going ape shit and setting my car on fire to see that the first throttles where indeed original and that it appeared they where larger due to being the series 1 throttles.

Moving on from my un-necessary story does anyone know or can anyone confirm the opening of their throttles?

Here is what I suspect:

series 1 (dual linkage)- 48mm I.D
series 2 (single linkage)- 46 to 47mm I.D

I am guessing no-one cares about the size difference when buying trumpets?

[Jacobxxx]

Blacktop ones...

[Sam-Q]

blacktop are 50mm I.D so no

[assassin10000]

I've never heard of different series/sized silvertop throttles, always thought they were 48mm.

Andrew

[Sam-Q]

I remeasured them, ignoring the outside of the small bevel on the end the larger of the two and the same as what a friend has is 47.5mm, the ones on my car 46.5mm

[Celica RA45]

the blacktops are 49mm and sam they might have changed the casting a little bit as i have 3 different silver top inlets with different openings etc

[Sam-Q]

you could be right there, I just re-measured my other silvertop throttles and they also are 47.5mm, I get 49.5mm on the blacks

[FoldKing86]

It is my understanding that there are 2 series of silvertops.

Early ones have a round shape inlet and the 2nd one having the tri shaped inlet.

Truth to it i dont know, but source is reliable.

[LittleRedSpirit]

To turn this into a more useful resource, can I suggest a table of the following info. May as well do the same for BT throttles as well, and any others people use and can give info for eg gsxr throttles.

Everyone measures them different and everyone measures a different part. Some the butterfly, others the inlet. Some more accurately than others.

Looking from my current perspective, when fitting them in different applications there are a few things you need.

Diameter at the butterfly.
So you can have a comparison of size and flow to select the right throttle to begin with. This is a constant whether you are talking about cylindrical throttle bodies or tapered (when you start talking about after market eg jenvey this is a concern, but I guess for silvertop comparisons its irrelevant as we all realise they are tapered and a fixed length).


Diameter at the inlet and trumpet/airbox pattern.
So you know how big the trumpets will have to be and the holes in the airbox you make.


Diameter at the outlet.
So you can factor the pipe size you use to construct your itb manifold vs your port size vs your throttle outlet.


Length of the throttle body.
So you can work out the angle on the taper and the space they take up.

Im pretty sure there are 2 different st linkage designs aswell.

[FoldKing86]

FWIW

silvertop part numbers so far!!
22210‑16620 (06/1991 - 06/1991)
22210‑16621 (07/1991 - 12/1992)
22210‑16571 (01/1993 - 11/1994)
22210‑16572 (12/1994 - 04/1995)


blacktop

22210‑16760 (05/1995 - 11/1995)
22210‑16761 (12/1995 - 03/1997)
22210‑16763 (10/1998 - 07/2000)

Same numbers for automatics or manual that i can see. Im sure the more i dig the more ill find.

[SHEPPO3930]

Have a look at the 3rd post by oldeskweltoy - shows the different throttles as 1st & 2nd gen ST, and BT.

http://forums.club4ag.com/zerothread?id=87535 (http://forums.club4ag.com/zerothread?id=87535)

[LittleRedSpirit]

21218
Shamelessly borrowed from oldeskewltoy on twincam forum.

[FoldKing86]

What areas to attack when porting??

[Sam-Q]

any overlapping areas from the manifold, so bolt to the manifold to the head without the factory spacer, scribe, take off, port, put back in with spacer, port the spacer and your done.

I did it and I must of done something right, my torque "curve" is seriously flat