Need some data confirmation

[702GT]

Didn't want to put this in tech or Pitstop, figured here was best.

I've been trying to decide if I want to stick with the 3.73's I already have ready to be installed or sell them and get 4.10's instead.

I don't put my car on the track a lot, maybe 5-6 times a year, and only for fun. I want more rear gear to help make up for bottom end loss and support top end power-band. But I've been working the numbers and if I stay with the 3.73's I will end up shifting to 4th and be out of my power band before the end of the track. (With the 3.55's I have now, I can stay in 3rd and just hit the 1/4 before I run out of gear, but the gears suck monkey sack for my cams.) With 4.10's I will at least hit 4th and pass the 1/4 in good power.

The only thing that's buggin me is how the 4.10's will affect my cruise speeds and economy. I do like to road trip out to CA 2-3 times a year. The last trip out there in december I averaged 24.6mpg at an average speed of 78mph. I thought this was pretty good for my setup. Even had a few 55 to xxx rolls with an STi and a GTO. Mostly cruising between 70-90.

I would prefer my economy and cruise over my drag performance.

Anyway, here's some numbers I figured. With my T-3650, 4.10's, and 275/40/18's:

Gear || Mph per 1000 RPM || Mph @6100 RPM

1 || 5.79 || 35
2 || 9.67 || 59
3 || 14.66 || 89
4 || 19.34 || 118
5 || 28.45 || 174
Rear gear: 4.100


3.55's would be: 70mph @ 2131rpm
3.73's would be: 70mph @ 2239rpm
4.10's would be: 70mph @ 2461rpm


I guess maybe the guys already running 4.10's and 3.73's could give some insight. How do you like your 3.73's and 4.10's. What's your economy like. Pro's and con's you feel about your gears? 3.73's still look ideal, but I'd like to know how well the gear will pull at WOT through the gears, as I'm guessing the 4.10's will blow through the gears extremely fast.

 

[Five Oh Brian]

Your mods are aimed at higher rpm operation, so you should gear up the car to match. 4.10's are just the ticket for your car. 4.10's were the first mod I did to my '07 GT with absolutely no regrets. Like you, I run at the drags several times a year. But, it's a daily driver. Highway mileage barely went down, and in town mileage didn't change at all. Acceleration improved a lot, though. As they say: "don't fear the gear"!

 

[stkjock]

do you run a different tire for the track?

if you do you can always go 3.73s and run a shorter tire to help your gearing, IE a 26" tall tire will give you an effective 3.90 gear ratio.

 

[702GT]

I run 275/40/17 555R's on a seperate rim. So it's pretty close to 26" tall (really 25.7" according to the tire calculator). Never thought about using my drag rims when calculating final gear ratio. Good call stkjock. I think i'll continue with the 3.73's I already have.

On a side note, I watched a S197 pummel the hell out of a 600+whp blown GTO last night. S197 had intake/exhaust CMCV direct port N20 150 shot, 4.10's, and E/T Streets with a 5-speed. Terribly owned 3 digs in a row. S197 almost pulls tire on the street! 4.10's are a mean gear.