Hey guys, I recently decided that i’m going to replace my tb since it’s on its last legs and I’ve done all I can to make it last. The only problem is that when I look online for a replacement, I can’t seem to find a stock 48mm tb new. I do notice that there are lots of 52mm tb’s, specifically BBK. I was wondering If it would be possible to just get the 52mm while having a stock engine. Would it make it run too lean? Or would the car be able to adjust to it? Id appreciated your input since I’m trying to get this done ASAP

 

It won’t make any difference. I put a 52 mm Holley on my 89. But the volume of air is still be limited by the MAF sensor.
I did get better throttle response, but my old TB was really sloppy.

 

Interesting. I’ve also seen a lot of praise for the holley tb and I’m leaning towards getting it, but I can’t seem to find it online anywhere! Do you happen to have the link to it? No worries if you don’t!

 

Sorry, I don’t have any info.
I purchased it from another forum member.

 

It won’t make any difference using at 52mm to the computer but you may feel a little better throttle response

 

Mine I think is shot at this point. I have a bolt missing from the tps sensor. I think my only option is to go to a 52mm TB but I'm not worried about getting any power from it I just want better throttle response. I'm only getting 9mpg and can't find any 48mm TB's in good enough shape. What do you think?

 

The better initial response is probably a little deceiving since all you're doing is getting more air in proportion to throttle opening vs the 48. But after a certain point probably no difference.

 

The MAF has no effect on the amount of air flowing through the intake. It only measures it. Then the computer needs to send the appropriate pulse to the injectors in order to achieve the best fuel/air ratio. Step by step, here's what I would do. Starting at the front, remove air cleaner and toss it to the side. Order a plastic replacement that has the hole on the lid opened up. After all, you're trying to get more air. Add a K&N washable performance filter. While that is off, clean or replace your MAF and set the snorkel to the side. Make sure your snorkel is smooth, not ribbed. If it has the air foil/diffuser on the throttle body remove and set aside. For 1988 and above, remove the frisbee from the water pump and toss it. It's about 20lbs of useless weight and you will instead send that HP to the rear wheels. Remove the smog pump with a delete kit and pulley that uses the stock serpentine belt. Again, it's not needed and sends about 12 hp to the rear wheels. Remove throttle body and remove and clean TPS and Idle control sensors. Clean well, including electrical connectors. Inspect your connectors, you might need to replace if they don't sit snuggly in their sensor plug. (Drink a beer) Install everything back together and adjust sensors to proper voltage. Lift the car and cut off your exhaust and replace it with almost anything that isn't stock. More air in means more exhaust needs to get out. Now disconnect your battery and remove all the fuses from your fuse block. Get a can of electrical contact cleaner and spray the heck out of the fuse block. Inspect each fuse and sand connectors as needed. Make sure they fit snuggly. Some of the cheaper fuses have blades so thin that they barely make contact. (go inside and drink a beer while you polish the bejeezus out of the air foil) Replace the air foil in the throttle body. Tighten everything and see where you're at but you probably still have a little work to do if you REALLY want to have a 52mm TB. Change the sock on your fuel pump and install a fresh, hi-po fuel filter. Now pull the air intake, fuel rails and injectors. Have the injectors professionally cleaned OR, get delphi 24# injectors and an adjustable fuel pressure regulator. You need to give your computer something to work with. You added a lot more air, now the computer needs operational flexibility with the fuel ratio. If you do all that, you will get 12ish rwhp from the 52mm TB. Plus 50-70HP from the other stuff. And please, please use good spark plugs, wires and upgrade distributor cap, coil and ignition control module. Hope that helps

 

There wasn't a 1989 Corvette made that has a MAF sensor (Mass Air Flow). They came with a MAP sensor (Manifold Absolute Pressure). These sensors monitor TOTALLY different parameters and neither one EVER had any influence on air flow. Absolute pressure is compared to pressure inside a vacuum. Mass air flow measures the volume of air flowing across a sensor (ish). Then it sends a signal to the ECU which sends a pulse (right or wrong) to your injectors.

The 52 mm has been the standard replacement for the 48 mm for about 15 years. Before I go any further, I spent 21 years as an Environmental Scientist III for the State of Tennessee, Environment and Conservation. Specifically, Air Pollution Control....and we science the hell out of combustion processes. If you install a 52mm you will see increased throttle response, and if you run it over 5000 rpm you will see 7-12 hp gain. But if you really want to get your $ worth, you need to address all the components of combustion. If you really want to get it done, let me know and I'll take you through it step by step

 

People have rebushed it and repaired them to like knew.
only issue most aftermarket T Bodies had were idle circuitry on LT1/4 Cars. The manifild and IAC circuitry is pipied through the manifold in a unique way.
L98, not sure.
But, I would try to find an OEM that is new, or remanufactured, Or an OEM that has been bored to 52mm if you desire a bigger one.
make sure throttle camshaft is the same as many F Bodies sold online may be a bit different in attachment of throttle cable.
i stayed at airbnbs i. ITALY, and saw the Monza F1 ra e in Monza, so I have that knowledge too. Lol

 

Funny ... My '89 has a MAF

 

A 52mm , albiet not.much bigger, will not make throttle respinse quicker.
Tje throttle camshaft will it it different. Look at a same year Camaro Vs Corvette.throttle body cam. Corvette is more aggressive to make blades open quicker. On C4s and similiar year Camaros.
Of course, returning it to extra every extra cfm of air coming in helps too.
So many tricks.
But just bolting on little parts dont make much differense.
Air Foil, Coolant bypass come to mind.

 

Can you post a picture of it? I'd love to have a look.

 

Funny thing, I saw a 40th ruby in Ecklers one year that had a MAF as well. It was a very late build model.. I was thinking that was normal for GM to do stuff like that with over runs etc.