BLOWN05GT

I have a 2005 Mustang GT with a non-intercooled Vortech Supercharger KIT on an otherwise stock 4.6L V8 engine.

My Transmission = Automatic = Factory Gear Ratio of 3:31
(Manual Transmission '05 GTs are 3:55)

I am trying to increase acceleration without having to add any additional horsepower so as to better my ET times
in 1/8 mile (and 1/4 mile as well, although I live too far from a 1/4 mile track to enjoy improved 1/4 mile ET times).

I don't have any dyno numbers to show hp at the rear wheels, though Vortech advertises I have 420hp at the flywheel.

Though I was a little disappointed in them, below are the ET times from a pass I made at a local 1/8 mile dragstrip:

2.1635 = 60 FT
5.9558 = 330 FT
8.9422 = 1/8 Mile = 84.07 Mph

I am looking for suggestions on what gears I should put into my GT. An experienced racer at our local drag made
the suggestion for 3:73, while the mechanic that installed my vortech supercharger suggested 4:10. From the little
research I have done online it appears my options are: 3:55, 3:73, 3:90, 4:10, 4:30. The suggestion of 3:73 was
made to me because it would improve ET times without compromising Highway driving too much. I think the
suggestion of 4:10 was made with only improved ET times in mind. Please make suggestions to me and support
them with your reason so as to aid me in making an informed decision.

From the other threads on this Forum the question seems to be if one should go with 3:73 or 4:10 ...
this is really making me think about the 3:90 (kind of like meeting everyone 1/2 way

757GT

That is not your 60 ft. They are x.xx not .xxx. Also I have an auto and I run 8.8 in the 1/8 with what little I have. Post your 60ft. With gears, I am just going 3.73 in mine purely because the shop I work with said that the 4.10s take the '05 GT auto out of powerband too quickly because of how close the gears are.

BLOWN05GT

You are correct, that was my aweful reaction time, I have now edited my post to show the correct 60ft time.

hawgman

Well, since you posted the same thing in the 2005 section that you posted in the GT section, I will just copy and paste my reply from your other post to this one.


I am sure that there will be plenty that argue with me, but if I were going to make a gear suggestion for your setup I would suggest 3:73s. 4:10s are going to wind way too quick with a SC.

BUT....before you spend money on gears, I would suggest spending money on a custom dyno tune. You may just pass on the gears afterward, at least for a little while.

757GT

My 60ft was 2.13 which is not much better than yours. You are running a little bit slower than me in the 1/8. You need a tune that is not right. You are blown and I have 2 bolt ons.

bahbahblacksheep

[sm=exactly.gif] you need a tune

bahbahblacksheep

In addition to what HAWGMAN stated, if you get 4.10's, you better become real good friends with the guy at the local tire shop cause you're gonna need the discounts. You will burn lots a rubber. Probably 3.73's will be better for you

Weedo

Coming from a car with a Paxton and 4.10's, I would say 4.10's without a doubt! They are NOT too high on the freeway either. At 80mph I sit at or just under 3,000rpm. I also have the auto trans. First gear winds up so fast it's amazing, 2nd drops to 5,000rpm then back up to the limiter to 3rd gear. I just don't get the argument of "4.10's get it out of the powerband too quickly". With these gears and my blower, the rpms stay from about 5,000 on up for 2nd gear, then drop to about 4700rpm in 3rd gear. The higher the rpm, the more power my car makes. I wouldn't want the rpms to drop any lower. In reality, there would be no problem with 4.30's in this car with the auto.

If you can, drive one with each gear, I think you'll find what I've found...

jtscuba02

im gonna have to agree with weedo on this one. these cars are so heavy also, you need the lower gears. i have the 5 speed and at 80mph the motor turns 2800 rpm. go with the 4.10s. also what back tires are you using? what rpm are you launching at? is the car spinning the whole time?

Turbo 05

with the extra power you have from the blower you shouldn't need gears all that much, your 1/8 mile times are slighly better then stock if not equil, i would invest in learning how to drive your car and getting it tuned and I am sure you could drop alot of those times. I wouldn't go any more then 3.73 if you do the gears, with the increase in HP you dont want to use up your top speed to much with gears.