Redline / 3.73's / 140MPH / 5th (A long read)

[gtncpa]

As some of you know I upgraded my car over the winter. Here are some of the mods

1. 3.73's From 3.55's
2. Eaton TruTrack From Ford LSD

To start with, the 3.73's and Eaton were spot on when I was at Watkins Glen. Top speed at the Glen approach 140 but only approached it for a short period of time before getting on the brakes. My last track day at Pocono was very different. The set up was perfect when I was going thru the infield. The problem I had was on the super speedway. We were using 2.0 miles of the 2.5 mile tri-oval. I don't believe there were any "stock" cars in my run group. Even a Z4 who I thought I would eat got by me on the straights. I later learned why, like a lot of guys on track had a blower.

So here is how it was on the straights for me. I would get into 4th and my car would pull very strong to 130. 140 would come at about 6,200 RPM. I have my shift light set at 6,100. I just did not feel comfortable keeping my car near the 6,500 redline for so long, so I stayed clear of the rev limiter. On a side note a Z06 (dedicated track car) with a supercharge went by me at the end of the day. He grenaded his engine. I know I am NA but that is exactly what I was worried about.

I know a certain Trak Pak owner that has 3.90's. With 3.90's what would be the top speed? That lead me to think about 5th again. I spoke to the guy that rents out '08 Mustang GTs at the track events I go to. He is one of the head instructors of NASA. He gets the rental Stangs up to 142 with few mods and running 3.55's. I asked him how. His answer was very interesting. He short shifts his car and gets into 5th and lets the car pull in 5th. I did not try it. I did however try dropping my car into 5th at 130. I blipped the throttle, but even with that it felt like some one pulled the ebrake. I am never doing that again. As a side note the rental Stangs did poorly IMO thru thru the twisties.

So hindsite being 20/20 would I go from 3.55's to 3.73's again. Absolutely! The car feels so much better in the turns and under acceleration I am, however, very glad I did not go with 4.10's.

I think I will stay off super-speedways with my car in advanced run groups. The cars in the advanced groups have to much top end for me. To try to make a good showing I would stay on the accelerated and brake very late going into the hair pin. This suprised when M3 that tried to brake as late as me. Good thing there was plenty of run off. I still have not used my 6 pistons to their full potential. Speaking of the StopTechs, I noticed that some of the Z06 guys take off their 6 piston Vette brakes and run the 6 piston StopTechs. I asked one good why. His answer was the StopTechs are just better. I think the pad size is actually the same.

I will be at NJMP on the lighting track on August 3rd. This thread is a moot point. My car is set up perfectly for NJ.

So the bottom line on this thread, what experience do you guys have with different rears running on tracks.

[WVTrakPak]

Other tracks, i did not realize ther were other tracks!

Your 3:73's are perfect for VIR.

[Ryan.]

Playing with a calculator here: http://www.apexgarage.com/tech/gear_ratios.shtml
Top speed should be 145 in 4th gear with 3.55 and figuring 6500 redline
With 3.90 it says 132
At VIR on the long back stretch I was just getting ready to touch 140 (per the speedo) at my braking point which I need to move up.

[gtncpa]

Great info. So now I need help figuring out how to use the program. If I have 3.73's and 275 40 18's. How would I figure out my to speed in 4th?

[gtncpa]

Is it possible just to change the 5th gear?

[skwerl]

Is it possible just to change the 5th gear?

No.





This forum requires 10 letters or more in a reply so ignore this sentence.

[gtncpa]

Ha ha ha ! Thx Brian.

[skwerl]

You're welcome, Greg.

[SteveL]

Long straights on a road course is a horsepower war. [More accurately it's a power-to-weight ratio war.] Who's got the highest redline and how fast can you get there. I have not run on a 'rovel' course but I'll still take speed in the corners over the drag race.

Unless you have a useable 5th gear (a 0.8x ratio), I would not recommend using it. Going from 4th to 5th is one thing. Going from 5th back to 4th without first getting the rpms down far enough can overspin the motor.

[Ryan.]

I used the following specs...
Transmission Gears - http://en.wikipedia.org/wiki/Tremec_...0_transmission
Tire diameters - http://forums.audiworld.com/showthread.php?t=2704424

Just plug it in and go

[Pentalab]

Gtncpa, you are in a real dilemma. You need help. Your 344 hp - 330 tq just doesn't cut it anymore. For track racing, you don't want to mess with a blower and it's associated heat soak and extra 150+ lbs issues. What you need is a new(er) car. Like a boss 302. Heck, even a 2011-2013 GT with just a CAI + tune and headers is over 400 rwhp. Toss in your favourite gears, cams, bigger manifold, suspension mods, brakes, oil cooler, etc.... and you will have a rocket..and still be NA. Get a coupe this time, then it's way stiffer to begin with. A base model 2011-2013 GT would be ideal...since you are gonna modify it anyway. Toss all 4 seats and replace with 1 race seat. If you really wanted to dump weigh from these cars, it would be an interesting project. The 4 seats weigh a ton, as does the DS and stock K frame and A arms, etc. Heck, the AC unit weighs a ton, toss it. ( like 65 lbs) And ditto with spare tire and anything else in the trunk. Then no more getting sand kicked in your face. What happened to that BMW you just bought.

Jimbo

[gtncpa]

Gtncpa, you are in a real dilemma. You need help. Your 344 hp - 330 tq just doesn't cut it anymore. For track racing, you don't want to mess with a blower and it's associated heat soak and extra 150+ lbs issues. What you need is a new(er) car. Like a boss 302. Heck, even a 2011-2013 GT with just a CAI + tune and headers is over 400 rwhp. Toss in your favourite gears, cams, bigger manifold, suspension mods, brakes, oil cooler, etc.... and you will have a rocket..and still be NA. Get a coupe this time, then it's way stiffer to begin with. A base model 2011-2013 GT would be ideal...since you are gonna modify it anyway. Toss all 4 seats and replace with 1 race seat. If you really wanted to dump weigh from these cars, it would be an interesting project. The 4 seats weigh a ton, as does the DS and stock K frame and A arms, etc. Heck, the AC unit weighs a ton, toss it. ( like 65 lbs) And ditto with spare tire and anything else in the trunk. Then no more getting sand kicked in your face. What happened to that BMW you just bought.

Jimbo

Ouch! That left a mark. Well I have no problem with 5.0's on the track The only place they are better than me is at Pocono on the long straight. On any other track I have them beat with my suspension set up and brakes from the Trak Pak. But you are right. A stripped car is where its at.

Here is my BMW. She has her track shoes on and is almost ready for her maiden voyage around NJMP Lighting on August 3rd. I will have both cars at the track that day. It should be a blast.

[gtncpa]

And here she is in her everyday shoes.

[AutoXRacer]

You're cheating on your Mustang...

[gtncpa]

Cheating would mean I had her on the track, she has not been on the track .... yet ....

[Pentalab]

How come no 3.31 listed. My 2010 auto came with a 3.31 My buddy has a 2008, with the manual tranny, and it too came with a 3.31. Didn't know some came with a 3.23

Jimbo

[Ryan.]

Gtncpa, you are in a real dilemma. You need help. Your 344 hp - 330 tq just doesn't cut it anymore. For track racing, you don't want to mess with a blower and it's associated heat soak and extra 150+ lbs issues. What you need is a new(er) car. Like a boss 302. Heck, even a 2011-2013 GT with just a CAI + tune and headers is over 400 rwhp. Toss in your favourite gears, cams, bigger manifold, suspension mods, brakes, oil cooler, etc.... and you will have a rocket..and still be NA. Get a coupe this time, then it's way stiffer to begin with. A base model 2011-2013 GT would be ideal...since you are gonna modify it anyway. Toss all 4 seats and replace with 1 race seat. If you really wanted to dump weigh from these cars, it would be an interesting project. The 4 seats weigh a ton, as does the DS and stock K frame and A arms, etc. Heck, the AC unit weighs a ton, toss it. ( like 65 lbs) And ditto with spare tire and anything else in the trunk. Then no more getting sand kicked in your face. What happened to that BMW you just bought.

Jimbo

The longer you are in the racing game, the more your car is going to be behind, just a fact of life. Technology gets better, older stuff gets slower...

[twobitcoder]

I want to build my '68 as a stripped down track car from the get-go. Here's a recent photo. Kind of depressing that it's taking so long. Now it's stuck in Phoenix in storage and we moved to Ohio (finally fled the heat!). I was talking with Donald Farr one time about how the Boss 302 R&D car was a 68 coupe with the same stock 302 block and upgraded heads.

[gtncpa]

Wow! That is some project you have going there. I would love to see that bad boy on the track someday!

[camnet]

Playing with a calculator here: http://www.apexgarage.com/tech/gear_ratios.shtml
Top speed should be 145 in 4th gear with 3.55 and figuring 6500 redline
With 3.90 it says 132
At VIR on the long back stretch I was just getting ready to touch 140 (per the speedo) at my braking point which I need to move up.

I would agree with the math. My Trak Pak is doing 130 mph at about 6500 RPM (at the end of the long Thunderhill front straight when i hit it right).