I was at the junkyard today and was picking parts from a 1987 Iroc z with a 305 TPI Motor.The throttle body had a TPIS Plate on the top where it usually says Tuned Port Injection and it also had an airfoil on it.What I was wondering is How can I tell if this is a real TPIS Throttle Body and not just one with the plate on top?

 

A real TPIS T/B is nothing more than a stock T/B with the air foil on it, honed out to 52mm. It could be that someone simply put an airfoil, and a TPIS plate on a stock 48 mm T/B. If the T/B has the airfoil installed, and there is a "honing" mark, as the airfoil was installed, and then the throttle bores were honed out, would mean a 52mm T/B. These are what TPIS sells. I do not know of them just putting an airfoil on a stock T/B, and selling it as a 48 mm with an airfoil. They sell 52 mms, and a custom casting 58mms both with the airfoil honed to the unit.

 

Here are a few pics of the throttle body

 

And another

 

plate looks alittle new for that TB. And that pic doesnt really help. Show the throttle bores.

 

sorry i replied as you was posting the pics. Look at the airfoil compared to the rest of the bore. I dont think so.

 

I believe that is a stock 48mm T/B with an airfoil and plate installed. In the picture you can see in the left bore, where the airfoil is up against the bore, and not honed smooth where they appear as "one". You can clearly see the difference in the airfoil and bore sizes.

In the left bore between 1 and 3 oclock.

 

Also watch the TPS mounting holes, they are notorious for stripping out.

 

That is a 48MM TB...note the RP logo on the blades...that's for Rochester Products.

 

i was hoping someone would comment on that b/c the many times i have taking my TB off i have never noticed the rp emblem. Im gonna have look for them the next time.

Thanks 406tpi

 

Also, TPiS would have used a matched set of plate screws lol

I had the same thing; TPiS plate and air foil. I don't care what others say, I noticed a difference with that little thing!