Not to nit pick (I guess I am 
) but to clarify, cool 84, the throttle blade of a "Hot Air" TB measures 65.27mm and the back part that you refer to boring out is 57mm stock, same as a IC car's stock TB. I haven't modified but a handful of '84-'85 TBs, but I grind out the IAC flow tubes that protrude into the larger bore, completely remove the "front" half of the throttle shaft, bore out the back to 62mm, "blend" the larger bore to the smaller bore, and machine an aluminum disc to cover the inevitable hole that occurs in one of the "protrusions" on all '84-'85 TBs when machining.
One customer reported about a 10% increase in grams per second from his MAF numbers, with no other changes. Not completely sure if those numbers are THAT consistent, but it was the only feedback from a Hot Air customer I've gotten!
As far as my "theory" on larger TBs, if you look into the bore of your stock TB/upper with the blade at WOT, you'll see the factory's horrendous casting mismatch, and probably parts of the gasket hanging in the airflow path! I consider some of the more important parts of my 62-65mm mods the smoothing and blending of these areas. I feel this is more of an airflow "quality" thing, than all out flow increase. Of course, the tapering of the inlet, the 5 extra mm diameter (57mm stock-- 62mm machined... at the blade), and the removal of the front half of the throttle shaft can't hurt !
One other thing that I have said before is: Why does one buy a 2.5" or 3" exhaust, when for 90% of our cars, a 2" or 2.25" would actually flow enough? I know why... because we want the max flow we can get for our combo and have mods in place that will "grow" for when our "need for speed" increases! Ditto on the TB/upper mods!
I will say that the most consistent feedback I get from customers is increased throttle response and quicker spool up. I have also had probably 30-40 "repeat" customers, which tells me they must have liked the results of the first one!
Man... you had to get me started, didn't you!
) but to clarify, cool 84, the throttle blade of a "Hot Air" TB measures 65.27mm and the back part that you refer to boring out is 57mm stock, same as a IC car's stock TB. I haven't modified but a handful of '84-'85 TBs, but I grind out the IAC flow tubes that protrude into the larger bore, completely remove the "front" half of the throttle shaft, bore out the back to 62mm, "blend" the larger bore to the smaller bore, and machine an aluminum disc to cover the inevitable hole that occurs in one of the "protrusions" on all '84-'85 TBs when machining.One customer reported about a 10% increase in grams per second from his MAF numbers, with no other changes. Not completely sure if those numbers are THAT consistent, but it was the only feedback from a Hot Air customer I've gotten!
As far as my "theory" on larger TBs, if you look into the bore of your stock TB/upper with the blade at WOT, you'll see the factory's horrendous casting mismatch, and probably parts of the gasket hanging in the airflow path! I consider some of the more important parts of my 62-65mm mods the smoothing and blending of these areas. I feel this is more of an airflow "quality" thing, than all out flow increase. Of course, the tapering of the inlet, the 5 extra mm diameter (57mm stock-- 62mm machined... at the blade), and the removal of the front half of the throttle shaft can't hurt
!One other thing that I have said before is: Why does one buy a 2.5" or 3" exhaust, when for 90% of our cars, a 2" or 2.25" would actually flow enough? I know why... because we want the max flow we can get for our combo and have mods in place that will "grow" for when our "need for speed" increases! Ditto on the TB/upper mods!
I will say that the most consistent feedback I get from customers is increased throttle response and quicker spool up. I have also had probably 30-40 "repeat" customers, which tells me they must have liked the results of the first one!
Man... you had to get me started, didn't you!
