The time has come for me to decide which to get. I'll be running a 9.2:1 compression 5.7 with Edelbrock E-tec 200
heads, a Comp Cams XR276HR hyrdaulic roller with 1.6 rockers, 3.42 rear gear and T5 trans. The plenum has been
Max-Ported along with the SLP runners by Mikey Graycar and an Edelbrock base. What do you folks think?

 

My opinion is that a 52mm throttle body is fine for a 350. I would use a 58mm for engines 383 or larger, and/or those with forced induction.

 

Could it hurt anything?

 

No, but it could make idle tuning tougher, because you're getting more air than you need.

 

Idle tuning, light throttle conditions as well and alot of playing with IAC constants to make it truly behave like stock again.

The larger TB's like the 58mm also play havoc with the AE settings.

later
Jeremy

 

you could might also think about chipping your car. fixes all those problems. read the tech articles on that. you will be swamped till you read it like 3 times, but its worth learning to do it yourself for later aplications

 

Much appreciated guys....I forgot to mention that I am already 'chipped'.....

 

Run the stock 48mm. Rig a vac gauge up for temporary use(zip ties & wiper arm....etc). Once it's up and running good, find out if you have any vacuum @ WOT/max rpm. If you have vac, then worry about upping the TB size. If not, why go larger? To make tuning more difficult and to loose some throttle response?
Honestly, I doubt that combination is gonna need more than the stock 780 cfm.

 

48mm may be enough for this motor combo.

 

Did the tpi's come with a 52mm stock or a 58mm? If a 52mm stock can I install a 58mm and would i have to bore the plemn out?

 

They came with twin 48mm TBs. For either the 52mm or the 58mm you'll have to port the plenum.

 

I agree with Kevin91Z. Get a 52mm (or stick with stock sized 48mm, in my opinion). No need for anything bigger. Bigger is not always better when it comes to throttle bodies.

I had a hard time finally deciding to buy a 58mm for my engine, and it's a 383 with a 244/254 .608 .608 110 cam, ported heads, and a ported intake, and it will be rev limited at 6800 rpm. AND it's a shorter LT1 intake (it's an LT1 engine), to boot.

 

.. X 2... doesn't sound like you're above what the stock 48mm TB can handle... yet...

 

What do u mean "your already chipped"? Have u already installed and had the car tuned for those Edelbrock heads? cam,etc?

 

Ninetyone thats an old post from 06, anyways the stock 48 is good for up to 450fwp and maybe even more but I can say 450 for sure.

 

.. 'Hunter', what's your current engine combo? Different than your signature, I assume...

 

I have a 5.7l 400hp