have a MAC cai, and planning to get plenum (not sure which brand), but also want t/b to complete the intake setup.

heard that 75mm is too big for a natural aspirated engine and since i don't plan on adding any forced induction any time soon (slight possibility of adding a 30-70 hit of nos eventually)...think i'll go for the 70mm.

in reading forums i'm getting mixed ideas about whether to go with 75mm or 70mm... some say only go 75mm if your using forced induction, and that anything bigger can actually be harmful. others say go for 75mm (seems kinda like the ongoing 3.73/4.10 gears debate). is it just preference, or is there a distinct advantage of one over the other?

 

The way I see it; What is a engine but a pump right?.. You can only put in what you can take out. With out making the engine itself flow better you will only get minimum gains either way. For the price IMO, its not worth it. Save for something better.

 

yeah I remember seein that also. I think that 70mm is what is recommended if you have a N/A car. And if your running forced induction then you need the 75mm. That was the conclusion I have come up with just by reading.

 

Ive read that a 75mm on a NA bolt on comes with a slight lost of low end torque.

 

yah, that's what i heard. just wanted to make sure i didn't completely waste my money on something that's going to actually take away from performance! i'm planning on a 70mm t/b and plenum (not sure which manufacturers yet). figure those will be good additions to the MAC cai....

aw yes...the mod craze has begun (and i'm not complaining)! :-)

 

i also read in some reviews on stangnet.com that the professional products throttle body has a tendency to either stick open or closed (either way is bad news). sound possible, have any experience?

 

Pro Prod stuff just isn't super well made. It's fine but not Accufab by any stretch. I have their plenum and 75mm TB on my engine. They took some massaging to get either fit and the out of the box fit and finish was kinda rough but they've been reliable and durable if nothing else and I normally have to mod every part so it wasn't a big deal for me.

70mm for NA 4.6 street cars. Track cars, all bets are off... use whatever works best for you.
.

 

think i'll compromise on this...

go better then pro products but not as extravagant as accufab.

C&L plenum and BBK 70mm T/B?! sound like a good middle of the road setup?