70 or 75 TB

[bigc2330]

What size throttle body would anybody recommend to run with Trickflow's topend kit (trackheat)?
The manifold has a 75mm opening.
I would not want to hurt low end power.

 

[f8tlfiveo]

If it has 75 go with 75..

 

[84Ttop]

70mm all the way no need for a 75. even with a blower on this combo still no problems. my brothers car with trick flow top end and 70mm t/b with a vortech si and stock pulleys went 10.90 with the ac, p/s and 2 12" subs. on radials

 

[Mustang5L5]

You're gonna get 50 different opinions on this depending on which train of thought people subscribe to.

 

[Kdubslugga]

Im making 510 rwhp with a 70mm, Im thinking about a 75mm Ill let you know if I get any changes in HP.

Also, 84TTop what was your brothers trap speed? Just curious

 

[tannerc91gt]

I have a feeling an extra 5mm isn't going to destroy your low end power...yes there's always velocity, dead air, what the heads flow etc etc etc... Without knowing the whole setup it's hard to say. But I had a 75mm and a track heat on a mostly stock 91 and didnt notice a whole lot of low end power loss.

 

[Rick 91GT]

If you need to buy a tb go 75mm

 

[84Ttop]

Im making 510 rwhp with a 70mm, Im thinking about a 75mm Ill let you know if I get any changes in HP.

Also, 84TTop what was your brothers trap speed? Just curious

his best to date is 10.90 @ 129 with a 1.46 60ft

 

[Kdubslugga]

his best to date is 10.90 @ 129 with a 1.46 60ft

Nice. Doesnt make me feel so bad then. Im running 11.70s at 124 and everyone tells me it should run 10s. Car is not a drag car at all, pure street car, but I always see guys with my trap speed running mid 10s or high 10s and it literally pisses me off! Im shooting for 10.9999999 and Im done with my car. The 11.70s are coming on 1.8 and 1.9 60fts so I know theres much room for improvement!

 

[Gearbanger 101]

Go with the 75mm. Throttle bodies are one of those mods that "more, is better than less"

 

[281pony]

this (imo) is like replacing a fuel pump.

just put a 255 pump in instead of a 155, then realize you should have gotten the 255.

just start with the 75mm and dont worry about going bigger later on.

 

[NIKwoaC]

Get the 75. There is no sound reason for getting a 70 over a 75, especially in a situation like that.

I say it all the time, a throttle body is not a carburetor. All it does it get out of the airflow's way. That's it. It doesn't control fuel flow, it has no air/fuel mixing responsibilities. Air velocity through the TB is a moot point.