T/B question
 

I was wondering if I would benefit if I put a 70mm T/B on my stock '88 GT or would I need bigger injectors then? ALso I heard I would need to change over to MAF for any major changes such as cams or heads. Is that true?
I am looking for low-mid 13's. Do you think I can do it just with the common mods such as gears,exhaust and pullies or will I need to change T/B and injector sizes?
I am new to this stuff. I never modified one of these fuelie mustangs before.


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'82 GT 351W,BBK shorties,
Comp Cam,edelbrock intake
625 cfm carter carb. c-4 tranny w/ pro stick shifter. 4 core radiator
Mallory distributor. 3:27
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Your stock 19lb injectors will do up to 300(? someone help me, I know thats not right) horsepower. I know that you wont need to change the stockers if you're just doing the throttle body, and they should be good even if you put in a new intake, headers, etc.

When I started modding my 86GT I was told not to go too big on the TB since it would hurt low end torque. If you look at my sig, I'm only runnig a 65 mm TB, and I just dynoed 277 RWHP, which works out to somewhere around 325 HP or so at the flywheel. If my convertible wasn't such a pig I bet I'd be looking at low 13's. Take a look at the Analyzer here - you can probably keep the stock injectors and just add a fuel pressure regulator and be OK on fuel.

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86 GT, GT40P heads, Crane 2031, 1.7 RR's, Cobra intake, 65mm TB, 73mm Vortech, 24# injectors, MAC GT40P headers, 2-1/2" BBK H-pipe (w/cats), Flowmasters, 3.55s, Groundpounder subs and lower control arms, 277 RWHP.

Would I notice much of a difference if I only changed to a 65mm T/B
Is changing the T/B as easy as changing a carb.?


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'82 GT 351W,BBK shorties,
Comp Cam,edelbrock intake
625 cfm carter carb. c-4 tranny w/ pro stick shifter. 4 core radiator
Mallory distributor. 3:27
.........................

I'll qualify this by saying there's a lot of people on this site that have a ton more knowledge than I do, but from what I do know, the throttle body is only going to make a difference if you can suck enough air through your engine for that to be the restriction in your airflow. If I was doing the mods, I would do the mods you suggested in your first post: exhaust, gears, pullies and also 65mm TB and a fuel pressure regulator. You were talking about MAF conversion - some say not necessary, I did and I love it. TB swap is way easier than a carb.

Definitely go 65mm. I've been told that the 19# injectors are fine up to 300 hp UNLESS you go with a NOS shot or jump to a blower. I can't find the articles but I've seen several that have a formula for figuring out what size injector you need. A fuel pressure regulator can also help improve the output of your 19# injectors though I wouldn't push it too far. I'm not going to change my injectors until I get my heads and intake. Just my $.02

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91 LX 5.0
Z t-5, 3:73 gear, Vortech 73mm Mass Air, Accufab 65mm TB, BBK underdrives, Crane HI-6S Ignition, BBK unequal length headers, Bassani x pipe, 2.5" Dynomax Super Turbo cat back, Kenny Brown Super Subs, Factory Five Control Arms, Mac cold air kit and more to come!