If the opening in my intake measure 52.5 mm, why would I need a throttle body bigger than that or do I?

 

Not much info here to work with....What engine do you have? How did you measure the opening? Look at VWandDodge's avitar. If the tb you have looks like that - you probably have a Fastman or similar tb already.....for a 5.9, he bores the tb to 52mm, for a 5.2 he bores them to 50mm. I don't know what the intake opening is - but as long as it is not smaller than the tb it is cool...
Take a pic and post it - then we can tell you for sure

 

Yep. Mine is a nicely tapers 50mm for the 5.2L engine.

 

I measured the openings in the TB compared to the openings in the Intake itself, then double ck'd my own measurements against my mopar performance library that I have been collecting. I have a 1997 Dodge ram with a 5.9 360 motor that I getting ready to turn into a torque monster 408. I sent an e-mail to the fastman about a TB and he said to use a 55mm, but If the openings in the intake are only 52.5mm why go with anything bigger. I'm definatly not disagreeing with the fastman, I am simply curious and would like to know. I just don't want to bother him with another e-mail. Oh yea...its a stock intake and I don't plan on using anything esle either. It's a stock TB too.

 

If you use the bigger TB, I think you would need to bore the intake to match, to make it effective.

 

Have any of you put a TB on that was bigger than 52mm? I'm really not too excited about cutting into my intake.

 

If you are going to make 408 then you are going to have to let the engine breathe. Outher wise you will never get all the power the engine can produce. Will be like running a restrictior plate. More air =more hp to a point. You can go too big. However if Dan recommends to go bigger You cn pretty much take it to the bank. My .02

 

Check my #2 Engine thread. Cut the intake runners. It is worth it.

 

Machining the intake out to 55mm or so would not hurt anything as long as you have a machine shop or the proper tools at home to do it right. Even if you didn't end up going with a 55mm tb it still wouldn't hurt it. A 55mm tb with a 52mm hole would not be good though....

 

If you do go bigger on the TB Then you will probly have to open the manifold or again you have a restricter plate. Opening up the manifold shouldn't hurt, just look the way Holly an Elbrock make some of their's. again my .02