I am looking at getting a new throttle body. what size should I get.
I have a 96 ws6 LT-1, with 3.73 gears, TSP rumbler exhaust, k&n filter and a few free mods. I will probably be pulling or gutting my cats soon. Mostlikely long tubes this summer sometime.

Now for my set up should I get the bbk 52mm or the 58mm? I plan to match up the intake manifold to it to complete the installation.

Would the 58mm be more for cars with high flow fuel injectors?

I plan to put nitrous on soon. I was planning on the 58mm. But like I said I am not sure.

Let me know what you guys think

 

Really... stock's good enough for bolt ons... if it were me, I'd hold off on the TB until after you go into the engine. If you really want a TB now, 52mm would be ok. If you're going to wait, the 58mm would be nice on a heads cam car.

 

None of the above! Ur nowhere near exceeding the flow range of the stock TB yet. Maybe u should look elsewhere for power. Cold air kit or something. You may see gains now with goin for a bigger TB but they will be minimal at most for ur current application, even if u are spraying the car

 

A 52 mm is fine for a bolton car. A 58 mm is definately too big for what you have now.

 

With your bolt-on setup the stock TB is fine. Later if you do heads/cam or a power adder a 52mm will be sufficient. I also have a 96 WS6 and with 400rwhp, the 52mm is good. A 58mm did not make any more power when tested on tyhe dyno.

S

 

go with the 58mm , I mean come one its a 350!!!!!!!!!!!!

 

Everyone else says to got with the stock throttle body. Why should I go with a 58 mm?


Now for everyone else that reads this


If I do the 58mm even if that has no benifit now. will it hurt anything.

I plan to do an lt4 conversion kit in about a year.

Thanks

 

if I get the 58mm will that hinder my gains at all or just be the same as the gains obtained with the 52mm?

Thanks

 

You will run into 3 problems if you get the 58 mm TB for your setup:

1. The opening on your intake manifold will only accomodate a 54 mm TB without having to port the intake.

2. The 52 mm TB will flow roughly 748 CFM and the 58 mm flows in the range of 1000 CFM. For a NA 350 CI displacement engine you will have to turn 10,000 RPMS to require 1000 CFM. You would need to be turning around 7400 RPMS

3. A large TB can cause some throttle response issues due to decreased port velocity down low.

 

Save the $350 and buy something worthwhile. A 48 mm is more than enough to sufficiently you up to 500hp. Get an airfoil to help the airflow a little, but a 52mm will be a waste of money for what you have right now. I got one just cause I got a awesome deal. Like I said, put the $$ to something else.

 

Yeah 48mm is good for most everything, FWIW the Ram Jet 502 crate engine makes 502 HP with the same 48mm TB

 

I plan to port it to 58mm.

Now as far as throttle response. This may accually make it less responsive?

would it be worth more for me to get an aftermarket MAF sensor. Or will that do the same give me to much air flow?



Thanks

Ed

 

Stock MAF is good. Aftermarket MAF's can cause some issues too. 58mm is too much airflow for a bolt on car... Put the money towards the headers, or something.

 

I made 365 NA with the stock tb and 364 with a bbk 52mm

 

It has a 48mm TB because GM makes 48mm TBs. It was an off-the-shelf part

I would be willing to bet that 502 would make considerably more hp w/ a larger TB.

Matt

 

I would stay with 52 mm. They are expensive and if your not gaining anything. Its not worth it

 

Hey edlt1 whereabouts are you from in MI.

There was an article long ago, that was a great write up on intake pulse tuning. it says that as long as the velocity of the air through the throttle body is less than 180fps, then the pulses from the intake ports can get out through the TB, in effect creating a much larger intake plenum. This makes for more torque until the critical velocity is reached.

If you calculate the intake velocity through the stock throttle body using David Vizard's (the guy that wrote the article) equations, it reaches critical velocity at 4800rpm, which is perfect for a stock LT1 engine. The 58mm TB maxes out at around 6500 rpm on a 350, which, again, is just about right for a built engine. 52mm TB would be good IMO

 

So if I do change it out I should use the 52mm.


Now what about when I use nitrous will the 52 or the 58 be better?


Thanks

Ed