Why 75mm TB/ Not 70mm?

markm · 05-02-2006, 05:58 PM

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:

B-rett · 05-02-2006, 06:02 PM

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

*Lances03SVT* · 05-02-2006, 06:06 PM

I have the 70mm and love it!!

StangAddict · 05-02-2006, 06:33 PM

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

*03gtmustang* · 05-02-2006, 07:05 PM

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

Mug11 · 05-02-2006, 07:26 PM

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

Plus i got cams so it probably helps.

RedFirevert04GT · 05-02-2006, 07:35 PM

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.

FullThrottleStang · 05-03-2006, 02:17 AM

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

Saleen S330 · 05-03-2006, 07:18 AM

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.

r3dn3ck · 05-03-2006, 09:19 AM

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

El Diablo · 05-06-2006, 11:09 AM

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.

05-02-2006, 05:58 PM	#1 (permalink)
markm Member Join Date: Mar 2006 Posts: 90	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:

05-02-2006, 06:02 PM	#2 (permalink)
B-rett BMC Member# 03209 Join Date: Jan 2005 Location: north ridgeville, ohio Posts: 1,639	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 __________________ ---35th Anniversary--- 265 rwhp 288 rwtq

05-02-2006, 06:06 PM	#3 (permalink)
Lances03SVT Super Moderator Join Date: May 2005 Location: Carthage, Missouri Posts: 9,247	I have the 70mm and love it!! __________________ _______________________ 2003 Cobra SOLD

05-02-2006, 06:33 PM	#4 (permalink)
StangAddict Saleen Replica(almost) Join Date: Dec 2004 Location: norfolk va Posts: 268	i was told by jason steen that the modulars dont lose anything by going bigger like the 5.0's... __________________ 1999 Mustang GT MODDED 1987 Corvette MOSTLY STOCK

05-02-2006, 07:05 PM	#5 (permalink)
03gtmustang Super Moderator Join Date: Jan 2005 Location: Northern Va Posts: 3,245	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 __________________ D&D Auto Detailing -Dan

05-02-2006, 07:26 PM	#6 (permalink)
Mug11 Senior Member Join Date: Jul 2005 Location: Lubbock/Houston, TX Posts: 909	yeah.. paid half price for my 75mm. Didnt want to argue with the guy. Plus i got cams so it probably helps. __________________

05-02-2006, 07:35 PM	#7 (permalink)
RedFirevert04GT Senior Member Join Date: Jan 2006 Location: Va Beach, Va Posts: 336	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. __________________ '04 Red Fire vert. KB 1.7L intercooled 9lb with all the trimmin's & Big Boost kit w/ Switch Chip. Mac catted h-pipe & Mac catback. 411RWHP / 414 RWTQ.

05-03-2006, 02:17 AM	#8 (permalink)
FullThrottleStang PureAmericanMuscle Join Date: May 2005 Location: Southern California Posts: 147	No Way!! I just put my 75mm TB/Plenum on and it works GREAT!! I love the new Throttle Response!! __________________ :censored: F* Ricers!!!** :censored:

05-03-2006, 07:18 AM	#9 (permalink)
Saleen S330 Banned Join Date: Jan 2006 Location: Sumter, SC Posts: 900	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.

05-03-2006, 09:19 AM	#10 (permalink)
r3dn3ck Wowbagger hates me too! Join Date: Nov 2005 Location: Magrathea/California Posts: 7,014	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

05-06-2006, 11:09 AM	#11 (permalink)
El Diablo Senior Member Join Date: Mar 2006 Posts: 143	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.

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