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52mm TB

Edmond

Well-known member
Joined
Aug 1, 2001
Messages
5,218
Location
Louisiana
Corvette
2003 Z06
I've been seriously considering getting the 52mm throttle body so I can increase the input of the engine. If I do go with the 52mm TB, will I notice a difference in mileage?

I saw that they were selling on eBay for about $225 or so. Is that a fair price to pay? I haven't called around to any Corvette salvage yards yet, but I'm going to this week.

I've mainly been thinking about doing the following mods:

Borla mufflers
Open air filter lid
Hypertech chip

And this has crossed my mind:

High flow catalytic convertor

Any thoughts or comments?
 
S

swedvette

Guest
some info

Larger TBs reduce the inlet friction, resulting in higher density air at the combustion chamber. The stock throttle body is 48MM (435 CFM). There are two options available here, 52MM (750 CFM) and 58MM (1000 CFM). However, don't be fooled. Your 350 engine will probably never flow 750 CFM and wont even get close to 1000 CFM unless you're planning on turning 12,145 RPMs, 9,109 RPMs to flow 750 CFM. It's simply a matter of engine displacement x RPM. You have to knock off 23% from the number due to the expansion of air in the intake (vacuum). With larger TBs you will lose throttle resolution of the inlet airflow. On a 58MM 100% of the air will flow by 3/4 throttle. Remember it's a throttle, and you want it to throttle accurately with good resolution. If your not going to modify the intake manifold then I recommend a 52MM throttle body. The stock intake manifold has 52MM ports in it that mate up to the throttle body.
 

Edmond

Well-known member
Joined
Aug 1, 2001
Messages
5,218
Location
Louisiana
Corvette
2003 Z06
For me the 58 is out of the question because I'm not going to go to that extreme! I was just thinking about some light tinkering.

How would the 52 vs. 48 affect exhaust tone? Since more air is coming in, more would go out right?
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
I have the 52 reman unit from TPiS on my car now. Considering the fact that I did an entire engine change and intake change at the same time, I can't tell you what difference the TB made on its own.

I can tell you that I am not aware of any problems or loss of power. The car is stronger everywhere. It was easy to install. I got mine with exchange around $250 from TPiS.

They even told me that with only .030 over bore, and stock displacement that the 58 is serious overkill.

I don't think you will regret the purchase. If you get it from TPiS it comes with a neat top plate that says TPiS. They build the 52 out of stock units, so you will have to turn yours in as a core. The core charge is almost as much as the new reman unit!
 

Edmond

Well-known member
Joined
Aug 1, 2001
Messages
5,218
Location
Louisiana
Corvette
2003 Z06
69,

What I was thinking about doing with some parts:

I was thinking that I would buy the 52mm and sell the 48 on eBay, but I don't know how much I could get for it. I figure that if the 52mm can be had for about $225 on eBay; and that I could get maybe $100 or so for the 48 (is that hopefull?) I could come out decent.

I was thinking the same thing with the catalytic convertor.

But I haven't contacted any salvage yards yet, which I will do this week. There is a place called Dino's Corvette Salvage, I've bought from him before and seems reasonable.
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Buy NEW

For the most part, wrecking yard parts are high milage cars that no one wants to repair.

IF you personally do not remove the part, you have NO IDEA what kinda car it came out of.

Now for that being said.. there are exceptions!

A cherry car being T boned etc etc.. but those are few and far between.

The bushings might be funky....you will probably have to replace the TPS, clean the IAC etc etc.

The time spent refurbishing the old one almost makes it a push.

Now if this was an A/C bracket or a manifold it would be a different story.

For this part I suggest NEW.
I agree, anything OVER 52 is a waste for a STOCK engine.

Mike
 
B

Bill C

Guest
I had to replace my EGR valve and had my injectors rebuilt. While I had the top end apart down to the manifold I had a chance to do a little bit of carving on the STOCK parts. I did some MAJOR porting on the upper plenum removing a ton of obstructions. I port matched the plenum to the runners AND I ported the openings on the throttle body. I didn't touch the blades and bore where the blades control air flow but, on either side I smoothed and blended the areas in the air stream and port matched the TB to the plenum. I also blended in the air foil that was on it to be smooth and fit properly to my porting attempt. I also trimmed down the diameter of the shafts and cut the excess screw length off of the screws that hold the blades to the shafts. Yes I did restake the screws.

It made a big difference in seat of the pants feel so.. I guess I gained something and I lost NO throttle response! Smothing out the air flow does help.

If you don,t want to spend the bucks on a 52mm give that a try! :)
 
V

vetsvette

Guest
I'm using a BBK/Edelbrock 52mm and I am very happy with the performance. Had to modify the slot in the TPS to get the reading right but other than that it was pretty straight forward. A little pricey at around $300 but there are some that cost even more.
 

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