Just did GT40P heads and intake, and a B cam. Will a bigger TB and shorties help?

tykempster · Feb 25, 2014

Hey everyone. New to this forum, slightly new to Mustangs and cars in general. I completed a GT40P swap a week ago, runs awesome, a lot more power. I am getting BBK shorties to help the plugs clear a bit better, and was wondering if a 70 or 75mm TB put on at the same time would help the car breath much better and what I could expect from the two?

Here's my current engine mods:

CAI
GT40P upper/lower
GT40P heads
B cam
Underdrive pulleys
SCT tuner
New distributor, plugs, wires

Thanks!

white95 · Feb 25, 2014

Throttle body

Go with the 70mm over the 75mm. You potentially would have enlarge the opening in the adaptor elbow [supposing you haven't done a fox throttle body swap yet] for the throttle blade to open without interferance. You most likely will see a slight increase in power, less than 5 or so. You may also run the risk of a surging idle and other driveability issues without a tune. Some cars are excellent patients and you can get away without a tune but most, like mine, get all :handz: and won't run right.

Headers

Anything is better than the dinky, restrictive stocker headers and you should feel a bit of difference depending on your other exhaust mods. Don't be surprised if you lose a little torque down low to gain 5-10 hp [generous estimate] in the 3000-5000 rpm range. Best way to fix this? GEARS!!!!

GT Rob · Feb 25, 2014

tykempster · Feb 25, 2014

I have 3.90 gears, so that's not a problem. First gear is burnout gear now! I also have a full exhaust. H pipe and SLP LM1s.

CC'S95GT · Feb 25, 2014

Welcome to the madness
you will still have a problem with 1 plug with the BBK headers. but it's not anything that can't be overcome.
FRPP and MAC both make P specific headers.

tykempster · Feb 25, 2014

CC'S95GT said:
Welcome to the madness you will still have a problem with 1 plug with the BBK headers. but it's not anything that can't be overcome. FRPP and MAC both make P specific headers.

I got a really good deal on these I couldn't pass up, I read they have more clearance than the stock headers so at least I won't have to worry about burning plugs I think?