Does anyone know if GM made a 52mm throttle body for the LT1 (1994)? Stock was 48mm right? If they did, does anyone have a part number? I ordered a BBK from Summitt a while back, but I have reason to believe it is not the right one - even though model #s etc seem to match.

 

The stock GM units are all 48mm. BBK/Edelbrock makes them in 52 and 58mm sizes. The 52mm is recommended for stock displacement motors.

 

There is no GM 52mm TB. If there is, it is the most well guarded secret in the industry!
Nitrojunky,
What kind of times are you running with your setup? What cam do you have?
Thanks,

 

Stock TB is 48mm.

I run a Holley 58mm tb. I wouldn't recommend a 58mm for anything less than a heads and cam car, but I was pleased with the quality of the Holley product and they make a 52mm version.

Why is your BBK the incorrect TB? Any fitment or idle problems?

 

Darn, didn't delete my ignorant reply in time (52mm tb)... I could have sworn they had one and then I realized I had posted under someone who said there isn't one and owns an LT-4...sorry gentlemen, I'm new here so I'll keep my posts to myself unless from now on unless I have some research or experience to back them up.

Re: the original post: I believe the pn for the Holley unit is 112-508, but Holley seems to draw a distinction between Corvette & Camaro. I think they cross over, but I'd call Holley's tech line to be sure.

Don't have any times yet, but I did beat a Z-06 (rolling start and in a straight line, of course) the first day the car was out; I think I pulled at least a car, and he was drafting me. There was a lot of traffic out, so I can't say exactly how close it was. I just got this configuration running a week ago and it still doesn't have >500 miles on it.

I'm expecting high 11's on slicks, low 12's on street tires. Since I haven't coughed up the ~$2300 for a strange yet, my times will be on street tires for a while. There's quite a few f-bodies with similar setups (GTP II heads, 235/242 cam, longtubes, lifters, rockers, tb, cai, exhaust, etc.) and that's most of them end up with. Most of us dyno about 420-440 rwhp na. Right now, the PCM is just tune-by-mail, and I plan to get it on a dyno with a wideband within the month. Not bad for my investment, though I definitely can't tangle with your 550+ hp setup. Nice.

 

I actually have a BBK one now, but I have reason to believe it may actually be the wrong model.

 

I know who is in the process of making 52 and 58 Billet Aluminum throttle bodies. The shaft even rotates on bearings instead of bushings. They should be about the same price as BBK's. If you are interested than e-mail me and I will keep you posted on the progress. They should be ready to sell in 30-60 days.