Why do people put 70mm TB's on 96-98 GT's

[Dark_5.0]

I have read in many members sig's where they have installed a 70mm TB on a pretty much stock 96-98 GT. I have also seen people reccomend putting a 70mm TB on 96-98GT's

Yet On a 5.0 a 65mm TB will suppoort 400HP.

Any reasoning behind this?

[91LX2Bfast]

I have one on my car because I picked it up used for fairly cheap, and I knew I would be adding bigger power sometime in the future (as in I just purchased a nitrous kit.) So far I am happy with the combo, as my car runs just as hard a 96-98 GT auto's with bolt on's and yet my car is 400+lbs heavier. So I figure why try to mess with a good thing if my car is running well.
I guess I could go to the track and make some runs with the 70mm, and then make some runs with the 65mm, and see if there is any difference, I figure and difference will be impossible to tell w/o a chassis dyno. So for now, it stays on. Plus you get better throttle response from the stiffer return spring. I wouldn't recogmend to put one on a bolt on engine, there are far to many better mods to do first, but if you can get one on the cheap like I did, then why not.

[Mustang92]

I did a back to back test at the track (same day) in my 2000 and it lost consistent ET and MPH. Now add restrictive heads and you be the judge. Also there is at least one guy on the corral that has dyno results that shows a 1HP gain and peak and as much as a 10RWHP loss below the curve.

Bill

[91LX2Bfast]

Now thats very interesting. I guess I may have to go to the track then and put the stock back on and see if I can go 14.7's. I had heard of some people losing hp, others gaining hp, so I figured what the hell. I'll take Bill's info to heart and I'll give it a try at the track.

[tireburner163]

Same reason they throw on a Lighting 80 or 90mm Mass-air on with that TB. Lack of knowlege

[StoplightWarrior]

I had a MAC 70mm on my GT for about 2 weeks. I think I lost about 10rwhp...took that POS off and sold it. What a waste.

[91LX2Bfast]

Tireburner - explain to me how I am retarded and show me my Lack of Knowledge for running a 80mm MAF.
Again, my combo is working fairly well, and its gonna take alot to make me change my mind when I see auto 96-98GT's w/ more mods/different combo's running slower times.
I know N/A cars that are picking up power from going from a 80mm MAF to 90mm MAF. Its all in the tune buddy.

Quote from someone who does modular cars for a living...
"The T Bird 4.6 does real well on the lighting 80MM and 90 depending on your Mods, Now there is a new Maf out that is 80MM on the new 02 Mustangs YC2F-12B579-BA and for N/A cars it works better, let me explain. The lightning MAF (XL3F-12B579-AA) has a Max range at 5 volts of about 56 #/min of air. The Max amount varies depending on how you mount the MAF and the bends before and after it. This is critical if you have sharp bends in front of the Maf it will throw off the air meter transfer function.
The MAF in the 02 GT Mustang's is the exact same housing as a lightning MAF it has the same pressure drop as the lightning MAF, but revised electronics. At Max voltage that MAF has only 46 #/min of air flow.

Now, when you look at an N/A car like most of yours, you'll only use about 35#/min of air peak. So, if you put a lightning Maf in you'd only be using 35/56 or 63% of the MAF. So With GT MAF you'd be using about 35/46 or about 76% of that MAF. On a car like a non PI head 4.6L, you will see a peak air flow of less than 30#/min.

Why is this important? It has to do with fuel control. The air meter transfer function has 30 points to it. It's a function with 30 points from 0 to 5 volts. If this range of 0-5 volts is 0-56#/min and you are only using 0-30#/min of it, you won't have good enough fuel control since you are only using about 1/2 the air meter range. I will be stocking these as I do with the regular Lighting 80/90. I also have the wiring adapter and K&N adapter to. The sad part is Ford will no longer allow me to just send any core back as they have in the past, so there is always going to be a 75.00 core charge." ...... "The general consensus seems to be that the '02 gt maf is superior for n/a applications, and the lmaf for p/a apps"

When I get my nitrous kit in the car and spray, I will be right in the said range for the Lightning MAF.
Remember, I got this MAF chip combo 2 years ago before the '02GT MAF came out with revised electronics. At the time, the 80mm LMAF was the best option available, and it still works great.
I dropped .57 seconds of ET and gained 2mph with my "generic" chip and lack of knowledge MAF. I haven't seen too many results like that on Mustangs.

"80 or 90mm Mass-air meter....BWHAHAHHAHAHAHHA......are you retarded???"
You need to get a clue.
Ask Bill why he has an 80mm MAF and running 12.6 in a N/A, simple bolt on GT?

BTW, lets see your sig so we at least know you have experience with a modified modular car.

[gilmoujr]

I went to Cincy Speed a few weekends ago and got on the Dyno. About four other GT's got on too (with different configs), so I speak the truth. H-Pipes are good for about 6-8 RWHP. My 85mm MAF + weld in Magnaflows got me 230 RWHP (~280bhp). Everyone with minor bolt-ons was pushing between 230 (me) and 233 rwhp (the highest guy). That is not a big enough difference in my eyes to make up for poor driving at the track. BTW, I ran a 13.760 on my last run - all on 230rwhp. I still need improvement.

[Dark_5.0]

All I wanted to know is are people running 70mm TB's on there modular engine cause a modular engine responds different than a 5.0 to more air flow.

I was wondering if I was missing something or what.

Later,

[tireburner163]

Okay, so you state right in your defense that the Lightning MAF flows 56#, but a stock 4.6 uses less than 30#. You also state because of that, you'll be using just a small portion of the MAF's range and you won't have good enough fuel control. Sounds like you're agreeing with me already. To go on, you state you picked up .57sec and 2mph. Well, since 2mph will generally get you more like 2-3 tenths in the 1/4, that would mean you must have had a better run. Not to mention you added a chip at the same time, which are well known for increasing performance on the AOD-E 4.6's. It's kinda like saying you picked up 2 seconds with a new MAF... and a supercharger. Not too hard to figure out which part was really helping. Finally, you say you'll be right in the range of the Lightning MAF with your N20. I hate to break this to you, but the N20 will have no effect on your MAF whatsoever. The N20 adds oxygen to the system AFTER the MAF reads incoming air, and it uses a seperate system to compensate for the extra oxygen. Not the factory computer, which would be able to do so if you injected the N20 in front of the MAF.Your displacement won't be increased, nor will your rpms, or flow numbers, therefore your N20 isn't going to help your over-sized MAF problem.Most MAF's increase power on stock vehicles because aftermarket manufacturer units are more accurate than OEM parts. If you run into modified cars, you need more flow than the stock unit can provide. Ever notice the 5.0's can put down 250hp with the stock 55mm MAF