This weekend I decided to swap out my stock Throttle Body for a larger 52mm Throttle Body. I bought the new one from a guy on ebay who bores them out larger then resells them, for about $170. Unlike many aftermarket TB's I had zero problems so far with the linkage or settings. It was a straight unbolt and bolt on. I made no adjustments and it idled perfect on the first start up. The biggest problem I had was dealing with the on and off rain all day long. I have not checked the voltage on the TPS yet to see if it is off. I'll try to hook up the laptop and check it tomorrow.

I started by disconnecting all the sensors, hoses, air intake, and unbolting the old TB.


It sure is dirty around there. I doubt this area has been touched since 95. I also bought some new valve cover gaskets that I will try to get to changing next. I figure that may be where all this grease is coming from below and around the intake manifold.


Here is a shot looking into the intake manifold through one of the TB holes. Wow, Should it look that funky in there? I was thinking of going to a smoothed out LT4 intake eventually.??


I had to peel some of the old gasket off of the intake manifold with a razor and some carb cleaner. I'll probably clean off the old TB later just to do it. I was real carefull especially when I saw how easy the metal shaved off. I used a FelPro replacement gasket bought from AutoZone. I swapped the old IAC onto the new TB after cleaning it real well. I set it to 1 1/8th of in inch.


I noticed my MAF screen was really dirty and it was just cleaned about a month ago. I found a crack/leak in the bottom of my air box that will need to be changed. I'm glad I left that screen on. I cleaned it from the opposite side using an extension piece on the end of my air compressor line, carefully avoiding the delicate sensors. Those are the smooth air inlet/power couplers in case you are wondering.


hmm... Should that nozzle be pointing down or toward the TB opening. I'll have to check the manual. I forgot to put the N2O jet back on after re-installing everything. It's a good thing the bottle was empty.


And Finally... Here are a couple of comparison shots of the old with the new. I guess I forgot to take one of the completed job. Oh well, next time. The TB air schmoil is being shipped to the guy I bought the new TB from to be bored to the same size.

 

Quite a mess
I repaired my air box with JB weld. If there is a big crack, maybe a piece of fibreglass clothe and JB weld can fix it. Good thing you left that screen on

 

Thanks for sharing and educating others, man i should have leave screen on my MAF sensor, thats a lot a dirt on MAF screen. I removed both screens after seeing this i should have leave atleast the front one and remove the other.

 

i have had no debris on my screen last year when i cut it out, and that was after 16-17 years. i guess my k&n does a good job.


edit- i just saw u had a crack in the airbox. that might explain it.

 

Heres my K&N. I checked all around the filter itself and it was well sealed. The only thing I noticed was the crack in the base by the screws at the top of the cut lid. It seems like the foam seal should have cought it though. I'm getting a new base and going to a ram air setup. You have to be carefull when tightening those screws not to overtighten.

 

Nice how-to. I've been mildly considering changing out the stock TB in my 95 with a 52mm but have hesitated for a couple of reasons. The first is from my younger days when installing a too-large carburetor in my old RoadRunner actually resulted in the car running much worse and being less responsive. I guess this should not be as much of an issue with modern cars as the computer will (hopefully) compensate. But then again I have read numerous posts attesting to how the 48mm is adequate even for engines with larger displacements than ours.

I would expect that any potential gains by going to a larger TB is with highly modified engines and/or drag strip conditions with WOT. But for typical every day driving, I wonder if this mod will only result in lousier mpg.

Please let us know what your experience is once you have a chance to drive it for a while.

Doug

 

good info.

 

Thanks guys. Here is another post I put up recently with some pics of the N2O setup. I still had the stock TB in those pictures.

http://forums.corvetteforum.com/show....php?t=1463517

 

Industrial strength "Purple Power" degreaser would make short work of the buildup of gunk on and inside that intake. I turned my old intake upside down, filled it full of the stuff and agitated it slightly by rocking the intake back and forth, while it was upside down. Poured the contents into a bucket and it was almost a sludge coming out of the holes.

Looked like brand new on the inside though!

 

I'd be interested to see a new dyno chart and a/f ratio. A retune may help more now as well. I love my 52mm tb. That and headers really made a big difference on my car.

 

What does a bigger throttle body do? Pros and cons??

Thanks

 

It's been debated before. I'd like to see a dyno sheet. Most will tell you that you will see no horse power gain with a larger 52mm TB up to about 400 or 450hp, than the extra airflow can help. The Intake manifold opening is 52mm, so it matches up nicely now. I installed it because I believe I was having problems with the old one. In my case most of my hp comes from the N2O which adds plenty of oxygen anyway. So I don't know how much, if any, it will help exactly, but at least I know it is functioning correctly now. I have recently read that some people see evidence in sensor readings from diagnostic scans that this mod can be benifical even at lower hp. Either way, I know I didn't loose any hp, and all the dirt is gone.

 

That gunk inside is a great example of one of the major reasons why I pulled my EGR system.

Others may have a different opinion.

 

good pic's