[Mr.MustangGT]

I was wondering about what the differences are in the sizes. i was looking a few bbk throttle bodies, the one that seemed best was a 78mm but out of any throttle bodies i've seen i've only seen the one 78mm, alot of 70's and 75's and i'm wondering what the big difference is

[sterlingboy]

just the size of the tb of course... the bigger it is the more air that can flow through it at one time, but you are not going to want to have a bigger throttle body then the stock one unless you have some pretty decent aftermarket mods to your motor because it will be totally worthless if you dont and you could even ending up losing 1 or 2 horsepower.

[badsupra101]

Bigger is better

[sj408]

Originally Posted by sterlingboy just the size of the tb of course... the bigger it is the more air that can flow through it at one time, but you are not going to want to have a bigger throttle body then the stock one unless you have some pretty decent aftermarket mods to your motor because it will be totally worthless if you dont and you could even ending up losing 1 or 2 horsepower.

lol you wont lose any hp.... maybe tq but your only trading it for hp in the upper rpms.

OP the real difference between 70 and 75 isnt all that noticeable. i bought the 78mm due to the fact it was one piece with the plenum and t/b. also 78 costs a good deal less than doing a plenum + 75/70mm.

also dont go looking for any noticeable gains in hp with a tb/plenum, the part youll really notice is increased throttle response.

my .02

[RDY4WAR]

Originally Posted by badsupra101 Bigger is better

Not always true. You can actually lose a slight amount of power if your TB is too big. For example, what's the point of a 78mm throttle body if you have a 70mm MAF housing? All that will be getting to the throttle body in the first place is 70mm worth of air flow so any TB over 70mm is actually useless.

[invsn]

Im currently using a 75mm BBK tb and i havnt had any problems yet

[95mustangGT/SVT]

I just bought a 75mm tb and plenum. I think that should be good