Why 75mm TB/ Not 70mm?
 

I was wondering why most people upgrade to a 75mm TB instead of a 70mm TB. Can a stock 4.6 with the usual bolt ons like exaust and intake make good use of the CFM a 75mm TB can provide? I know the stock TB flows about 428-450 CFM. And the 70mm TB flows somewhere around 628-640 CFM. Wouldn't that work well?

Someone please educate me, thanks, Mark M :foot:

im not positive about this but i think i heard sumwhere u get betta gains wit the 70mm unless u have a blower or another power adder

I have the 70mm and love it!!

i was told by jason steen that the modulars dont lose anything by going bigger like the 5.0's...

Depends on the plenum you're using. If you're using a C&L plenum then youll want the Accufab 75mm t/b for max results. If you're using the Accufab plenum then youll want the Accufab 70mm t/b. http://www.modulardepot.com/?show=articlesdet&aid=38

yeah.. paid half price for my 75mm. Didnt want to argue with the guy.

Plus i got cams so it probably helps.

For me the issue was throttle response when I did my 70mm. I had heard from several people that their throttle response dropped off a bit when going to a 75 without enough mods to need it. I never drove a car with one so I don't know firsthand how much it dropped. I know I was ecstatic with my 70mm.

No Way!! I just put my 75mm TB/Plenum on and it works GREAT!! I love the new Throttle Response!!

I have a C&L plenum and Accufab 75mm TB and it works great. Everywhere that i looked they always recommened Plenum with 75mm TB.

If your plenum is big enough to fit the 75 without a step then by all means go wtih the 75. Some will tell you you'll lose tq but I can't see that being caused by a 75 since the tq is really affected most further in the intake like by runner length and cam choice.

The stock upper plenum has a 70mm opening and the stock TB is 65mm so a 70 TB is really the minimum as far as I'm concerned. Heavily porting your upper plenum (including some epoxy work) will help a little but 75's are best left to the aftermarket plenums.

I have a 70mm accufab and a 75mm accufab. I'm now using the 70 on my 4.6 and the 75 is going on the 5.4

Go with a 75mm if you think your going to be getting a power adder. You might as well buy it right the first time.
:beerchug: