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

hawgman

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.

BLOWN05GT

There is already a special tune on the car that came with the Vortech Supercharger Kit. I wonder if I should stray away from this tune and how it might effect the performance of the S/C not to mention the warranty on it.

hawgman

Ok darnit...not going to keep replying to your duplicate thread in two different forums

Yes, I know you got a tune with the supercharger. TRUST ME, go to a dyno shop and have them tune the car. I will just bet it makes a world of difference. You are taking for granted horsepower numbers that were provided to you by the vendor. That in no way means that is the horsepower you are actually getting. Just ask lostsouls about that. Without a custom tune he was getting around 350hp with his procharger.

BLOWN05GT

I will try not to sound too much like a novice, but what you are saying is the place in town that does dyno testing can program a custom tune that takes the S/C and new gear ratios into consideration. Any idea on how much this sort of thing might cost? (I posted my original question in three different sections on the forum in hopes to get more people to see it and respond ... sorry.)

discofan

Dear Blown05GT,

I have to strongly agree with "Hawgman" about the gear selection...

My SVT Ford Dealer, who will install my Saleen S/C told me that with the automatic, a 3.73 is as much gear as you would need...

Not the 4.11 but the 3.73...

With the power generated by the S/C and having an automatic, your selection is simple...


Best of Luck and get better tires, Dave