4.6L (1996-2004 Modular) Mustang Technical discussions on 1996-2004 4.6 Liter Modular Motors (2V and 4V) within.

70 or 75 mm Throttle Body/Plenum

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Old Nov 15, 2006 | 01:47 AM
  #1  
GThopeful's Avatar
GThopeful
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Default 70 or 75 mm Throttle Body/Plenum

So right now all I have done to my car is an X-pipe and catback. After Christmas I plan on adding a JLT RAI and a throttle body/plenum combo of some kind. I also have BBK shorty headers sitting in my room that I have yet to decide wheter I am putting on or not. Anyways, let's say that I get the RAI put on; with just those 3 mods is it a good idea to go with the 70 or 75 mm throttle body/plenum? I'm more than likely going to go with Accufab, but if anyone has any other suggestions, please let me know and I'll check them out.

Also, when a site says "equal length" headers, what exactly are those? Are they shorties? I'm def. not doing longtubes right now just because of installation prices. They are going to have to wait at least a year - year and a half until I graduate college.

Thanks everyone.
Old Nov 15, 2006 | 03:03 AM
  #2  
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Default RE: 70 or 75 mm Throttle Body/Plenum

equal length means all 4 tubes off the valve are the same length, i assume , could be worng. There is also Full length...
Old Nov 15, 2006 | 03:45 AM
  #3  
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Default RE: 70 or 75 mm Throttle Body/Plenum

75[sm=signs007.gif]
Old Nov 15, 2006 | 04:48 AM
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Default RE: 70 or 75 mm Throttle Body/Plenum

equal length are not necessarily what you want - if your going to buy long tubes you want "tuned length" - they have a better configuration to reduce turbulance and increase flow than equals or shorties... the tuning keeps the exhaust puleses in the proper phase to promote HP gain... so basically equal is bad and tuned is good - unless they are tuned equal length - which is another story entirely- lol
Old Nov 15, 2006 | 04:53 AM
  #5  
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Default RE: 70 or 75 mm Throttle Body/Plenum

The size of the t/b really isn't going to be a huge deal. Even comparing to stock you will not be able to tell the difference on your butt dyno. I have seen dynos going from the stocker to a 75 making only 1-2 WHP, so the 70 vs 75 will be virtually identical.
Old Nov 15, 2006 | 04:58 AM
  #6  
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Default RE: 70 or 75 mm Throttle Body/Plenum

you guys know that if you have access to a lift you can do headers yourself .. they aren't that hard.. and mechanics should only charge at most 3 hours a labor .. all you have to do is drop the front suspension .. much easier than trying to squeeze them on .. or lifting the motor off the mounts ...
Old Nov 15, 2006 | 07:47 AM
  #7  
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Default RE: 70 or 75 mm Throttle Body/Plenum

70 for n/a and bolt ons

75 for any kinda forced induction.
Old Nov 15, 2006 | 09:45 AM
  #8  
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Default RE: 70 or 75 mm Throttle Body/Plenum

if your looking to open up your intake with a TB then why wouldnt you want to open it all the way to a 75mm. Sure you might not take full advantage with out forced induction but it isnt like you are going to lose HP and the price is pretty much the same. I say go with the 75mm. All I have is a Steeda CAI and im getting a 75mm TB/plenum combo. then ill be working my way all the way back with some shotries O/R/ Mac prochamber and then LM1's. Afte that some 4.10 gears, new springs..........ect......ect.......will it ever end.
Old Nov 15, 2006 | 09:53 AM
  #9  
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Default RE: 70 or 75 mm Throttle Body/Plenum


ORIGINAL: leglocking101

if your looking to open up your intake with a TB then why wouldnt you want to open it all the way to a 75mm. Sure you might not take full advantage with out forced induction but it isnt like you are going to lose HP and the price is pretty much the same. I say go with the 75mm. All I have is a Steeda CAI and im getting a 75mm TB/plenum combo. then ill be working my way all the way back with some shotries O/R/ Mac prochamber and then LM1's. Afte that some 4.10 gears, new springs..........ect......ect.......will it ever end.

Yea why not..... plan ahead.
Old Nov 15, 2006 | 10:08 AM
  #10  
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leglocking101
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Default RE: 70 or 75 mm Throttle Body/Plenum

only thing holding me back is $$$$. But since that is an issue im deffinatly planning ahead.
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