58mm BBK TB. Can I throw it on a stock engine? Negatives of doing so? Will it work?
I called BBK and they said. Yeh.. no problem. Just throw it on.. then the emails stopped. I guess I asked to many question. I purchased the 58mm . That's going back..

 

IMO you wont gain any power on a stock motor with a 58mm TB. Also the BBK aren't the best quality and you may have idle issues right off the bat, plus it would need to be tuned because it would be running lean. Plus the intake openings would need to be ported to 58mm since they are only 52mm stock.
When your motor starts making over 400-500hp you start to see some gains in hp with a bigger TB.
I would recommend these brands of TB's for best quality.......TPIS, AS&M, and Lingenfelter if you can find one. IMO TPIS makes the best quality TB for the LT1.

 

Not only will a 58 not work on a stock LT1 unless you have the port openings machined to 58 the stock motor does not need it. The PCM needs to be tuned for it or tranny failure will soon follow

IMHO the "best" larger TB is a stock one bored to 52mm...if you can find a source to do it these days. The PCM still needs to be tuned for it though but it will bolt directly on and require no machining of the intake

 

58mm TPIS here ON A 6 SPEED CAR. Very nice throttle body, I've had it for a very very long time. I installed it when I did my first cam only build up so I can't say anything about it on a stock engine but I will say that all of the above mentioned on an Automatic car is true as far as drivability issues are concerned. I can say anything about power honestly. With a good tune it might be worth a couple of numbers but with stock fuel and timing maps in it, it's going to be lean plus mess with shift points etc. You'll have a slower car without a good tune.

 

I really like my 52mm TPIS TB. Billet bottom piece to replace the ugly piece thats on the stock unit, the throttle blade shaft rides on roller bearings, and its got a built in airfoil. Nicest TB i have ever seen. TPIS units are known to not have idle problems.
But on a budget the stock 48mm bored to 52mm is an excellent choice also.
I plan on using my 52mm TB all the way to 600hp on a s/c 355.

 

I threw on a BBK 58mm last year just because I got it so cheap. I never really noticed any difference power wise at my current level. I did open up my intake ports myself, cleaning out the intake of metal shavings is the fun part haha!

 

I also have 58mm BBK. Cannot say I noticed any power difference.

A million years ago someone made a monoblade throttlebody that was a beastly work of art.

 

Arizona Speed & Marine IIRC

 

TPIS still does iirc.