3:90 Gear


BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
Ricardo's theoretical top speed calculations for each gear were:

1st: 53 MPH
2nd: 81 MPH
3rd: 112 MPH
4th: 146 MPH
5th: 180 MPH
6th: 220 MPH

However, I have confirmation from one of our customer's that they have seen speeds in excess of 200 MPH in 5th gear.

Note these number are with the stock redline of 6500. At 7000 the speeds would be

1st: 57 MPH
2nd: 87 MPH
3rd: 121 MPH
4th: 157 MPH
5th: 194 MPH
6th: 237 MPH

However at 7000 you are probably past peak HP, 6800 maybe closer to the HP peak. Number for a 6800 redline.

1st: 55 MPH
2nd: 85 MPH
3rd: 117 MPH
4th: 152 MPH
5th: 188 MPH
6th: 230 MPH
 

THughes

GT Owner
Feb 20, 2006
35
Shadowman is in the process of installing the 3:90 in my gal as we speak, I hope that BlackICE has the right numbers in his post, I would like to see 194 in the mile with my car. As I posted earlier, with the stock gear I ran 185.87 and never shifted out of 4th gear. My car had a whipple and the redline was raised to 7000. I hope that with the 3:90 and a shadowman tune, I can achieve top of fifth gear at the end of the mile.

Ted
 

MR2Race

FGT The Velvet Hammer
Apr 6, 2006
304
Northville Mi.
What kind of power and torque do you think will be required to carry 237 MPH?
 

soroush

Ford Gt Owner
Mark II Lifetime
Aug 8, 2007
5,256
Shadowman is in the process of installing the 3:90 in my gal as we speak, I hope that BlackICE has the right numbers in his post, I would like to see 194 in the mile with my car. As I posted earlier, with the stock gear I ran 185.87 and never shifted out of 4th gear. My car had a whipple and the redline was raised to 7000. I hope that with the 3:90 and a shadowman tune, I can achieve top of fifth gear at the end of the mile.

Ted

a whipple car with meth injection ran the mile here in texas at 202mph stock gears
 

kumar

GT Owner
Jan 31, 2007
1,011
Dallas
a whipple car with meth injection ran the mile here in texas at 202mph stock gears

that car was running 23psi and hoosiers right?
 

mardyn

GT Owner
Dec 20, 2005
490
Beautiful East Texas
Man, I want a 3.90 set up for my car.

Back in the olden days, I went from 3.23s to 3.91s in my '71 Dodge Challenger (340/727TF) and it was night and day difference.... I suspect the GT would love 'em just as much.

mardyn
 

dbk

The Favor Factory™
Staff member
Le Mans 2010 Supporter
Jul 30, 2005
15,187
Metro Detroit
The GT definitely is a much different car with the 3.90s. I drove a stock car with the 3.90s and it was more what you'd expect from the factory. With the TT and the 3.90s, it was insane.
 

kumar

GT Owner
Jan 31, 2007
1,011
Dallas
3.90s would definitely be a huge improvement performance wise but I kinda like the loooooooooooong gears in the GT for highway cruising.
 

BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
3.90s would definitely be a huge improvement performance wise but I kinda like the loooooooooooong gears in the GT for highway cruising.

I guess you like the gas mileage with the loooo....og gears. :lol
 

kumar

GT Owner
Jan 31, 2007
1,011
Dallas
nah I just like how I only have to shift twice from 50-180 when it feels like the car next to me is shifting 5 times. lol
 

kmillen

Well-known member
Jan 29, 2007
504
Hey Guys,

I have had about 5 people in the Texas area that appear to be interested in getting the 3.9 ring and pinion installed. A couple of people have mentioned that they would like for us to travel out there. Unfortunately, that just isn't possible. Because of the specialized tools, assembly procedures, and shim grinding process as well as all of the parts required to do the work, it just wouldn't be an effective way to do the work. In order to diassemble and rebuild these transmissions we have 7 custom fabricated tools, the shims need to be electromagnetically ground (this is the most difficult part of the job.) We also have a 55 gallon drum of gear oil here, and all of the spare parts and pieces that we need.

However, if there is enough interest I can arrange for a carrier to meet in one central location and pick up all of the vehicles. I have been in touch with Plycar transportation and they tell me they can fit 7 GT's in one trailer. If we can get 7 cars together it will cost around six thousand dollars for the entire trailer each way. That's around $875.00 each way. Once the car's arrive to our facility it will take about 3-4 days per car to complete all of the work. The cars will be stored under cover in our brand new manufacturing facility. Fortunately we just recently finished the building so we haven't moved in any of the machinery or anything yet.

If you are located in the Texas area (or neighboring states) and you're interested in the 3.9 ring and pinion please let me know. 888-222-2702 ext. 173 or email me at kmillen@stillen.com
 

BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
Shadowman is in the process of installing the 3:90 in my gal as we speak, I hope that BlackICE has the right numbers in his post, I would like to see 194 in the mile with my car. As I posted earlier, with the stock gear I ran 185.87 and never shifted out of 4th gear. My car had a whipple and the redline was raised to 7000. I hope that with the 3:90 and a shadowman tune, I can achieve top of fifth gear at the end of the mile.

Ted

The tire diameter also factors into the speeds. You should look at your torque curve to decide where the best shift points are. You should shift when the RWTQ number would be greater in the higher gear. At 190 you might be better off in 6th with the gears, pulling to 7000 may not be the fastest. On my dyno chart the torque is falling off quickly after 6k and the RWHP are flat. Of course your numbers will differ.
 

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GTED

GT Owner
Apr 4, 2006
783
Ice,

Did i read the chart incorrectly? While the hp reads ~730, but the top corner says "flywheel HP". Whippled GTs put out ~700+ rwhp, right?

GTED
 

BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
Measured at the wheels.
 

HeritageBruce

GT Owner
Mark II Lifetime
Mar 13, 2006
748
Southern CA
Shadowman is in the process of installing the 3:90 in my gal as we speak, I hope that BlackICE has the right numbers in his post, I would like to see 194 in the mile with my car. As I posted earlier, with the stock gear I ran 185.87 and never shifted out of 4th gear. My car had a whipple and the redline was raised to 7000. I hope that with the 3:90 and a shadowman tune, I can achieve top of fifth gear at the end of the mile.

Ted

Ted,
You've got to find a way to reach 200. Which event and elevation will you be running at? There was one episode of Super Car Expose on Speed that had a Tungston that ran 205 at the Texas Mile (saw a Whipple in it) while a Carrer GT ran 187 on the same day. Wonder if that GT belongs to anyone here and how it was tuned? I have the Gen I Whipple w/ a 19# pulley also and once of these days I'll want to do the mile also but I want to shoot for 200.
 

BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
The tungsten that did 205 had a Whipple with methanol injection. I don't know what size pulley it was. I number of people with the 19psi pulley fell slightly short of 200. I think the stars will have to be aligned for a 19 psi whipple and pump gas to do 200, though IMO it is possible. I would think that a 21 PSI pulley with C16 race gas and a good tune will make your chances a lot better. Just C16 and a tune would probably do it with a 19 psi pulley as well.
 

kumar

GT Owner
Jan 31, 2007
1,011
Dallas
The tungsten that did 205 had a Whipple with methanol injection. I don't know what size pulley it was. I number of people with the 19psi pulley fell slightly short of 200. I think the stars will have to be aligned for a 19 psi whipple and pump gas to do 200, though IMO it is possible. I would think that a 21 PSI pulley with C16 race gas and a good tune will make your chances a lot better. Just C16 and a tune would probably do it with a 19 psi pulley as well.
The 205mph Texas Mile car was running a 23psi pulley with 109 octane fuel and methanol.

It was making 850rwhp or about 100rwhp more than most Whippled cars.

http://videos.streetfire.net/video/How-to-ADD-300-HP-to-a-GT_158698.htm

http://autograf.net/fordgt/fordgt.html
 
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THughes

GT Owner
Feb 20, 2006
35
HeritageBruce,
I have a Gen 1 whipple with a 19# pulley. The only mile I have run is the mile associated with the Sandhills open road challenge, it is in August here in Nebraska and the corrected altitude is normally about 5000 feet above sea level so it is harder to get the speed that Texas gets. If I can run +-195 with my combination I will be happy. I am sure that shadowman will do everything in his power to get me there. You never know if everything works out you may see me at the Texas mile this year.

Ted