aponyfan

Forgive me if this is a stupid question, but I don't have that much experience with engine/transmission performance calculations.

Assuming shifting each car at 2200 RPMs for each gear (relatively conservative driving), does anyone know what the speeds would be for both an 05 V6 and an 05 GT at each gear shift?

I'd like to be able to compare a table like this:

V6 GT

1st -> 2nd wmph amph
2nd -> 3rd xmph bmph
3rd -> 4th ymph cmph
4th -> 5th zmph dmph


to see, purely from an efficiency standpoint (not looks, sound, etc.), which one makes more sense for a daily, short, mostly city, mostly in traffic commute.

I've seen all the statistics on 0-60mph and 1/4 mile times, but those focus more on performance driving rather than just getting to work in the morning.

Thanks for your input!

RRRoamer

The math is pretty simple. You need to find a table that has the gear ratios for each gear for the V6 and the GT for the trannys you are interested in as well as the final gear ratios for both cars and the tire sizes.

So, 2200 engine rpm/(transmission gear ratio * axle gear ratio) = wheel rpm.
(eg: 2200 rpm / (3.6 * 3.55) = 172.144 wheel rpm (first gear ratio of 3.6 just pulled out of thin air!)

(wheel width (in mm) / 25.4 mm/in) * 2 * aspect ratio + rim diameter = wheel diameter
(eg: (255/25.4) * 2 * .5 + 17 = 27.039"

wheel diamter * PI = wheel circumference .
(eg: 27.039" * 3.14159 = 84.945" per revolution)

So, wheel rpm * wheel circumference = distance traveled in inches per minute
(eg: 84.945 inches / revolution * 172.144 revolutions / minute = 14622.85 inches / minute)

That is how fast the car is in first gear (with a ratio of 3.6:1) at 2200 rpm with an axle ratio of 3.55:1 and using 255/50-17 tires.

So you want that in mph instead of ipm?
inches/minute * 60 minutes/hour = inches/hour
inches/hour * 1 foot / 12 inches = foot /hour
foot / hour * 1 mile / 5280 feet = miles / hour

(eg: 14622.85 inches / minute * 60 * 1/12 * 1/5280 = 13.85 mph

simple, no?

RRRoamer

But, if you are JUST interested in a commuter car, the V6 with the automatic will be VERY hard to beat. Unless you want that extra mpg, then get the stick.

Badandy

The problem is, if you are very disciplined the stick makes sense. But just having a stick forces me not to shift that low and thus decreasing my mileage. If I shifted that low, yes you get better mileage than autos.

aponyfan

Thanks, RRRoamer. I do follow the math. It is pretty straightforward.

Do you by any chance know where I could find the right data tables which would let me complete the calculations for both the 05 V6 and GT?

I think you're also right about commuter-ability. (Is that a word?) That's why I'm leaning more toward the V6 for daily driving. (Since my last car had about 124hp, the V6 seems like a big improvement.)

I just haven't decided on automatic vs. stick. I haven't driven a stick in a lot of years, so I don't remember how much of a pain it is in stop-and-go traffic.

No to mention, as Badandy pointed out, you have to be disciplined enough to shift low enough to get the benefits of better gas mileage.

RRRoamer

I couldn't find a web link, but I DO still have a copy of the Mustang manufacturers spec sheet, so I pulled this from that document:

V6 - Manual
Axle gear ratio: 3.31:1
1st - 3.75:1
2nd - 2.19:1
3rd - 1.41:1
4th - 1.00:1
5th - 0.72:1
Reverse - 3.53:1

V6 - Automatic
Axle gear ratio: 3.31:1
1st - 3.22:1
2nd - 2.29:1
3rd - 1.54:1
4th - 1.00:1
5th - 0.71:1
Reverse - 3.07:1

GT - Manual
Axle gear ratio: 3.55:1
1st - 3.38:1
2nd - 2.00:1
3rd - 1.32:1
4th - 1.00:1
5th - 0.675:1
Reverse - 3.38:1

GT - Automatic
Axle gear ratio: 3.31:1
1st - 3.22:1
2nd - 2.29:1
3rd - 1.54:1
4th - 1.00:1
5th - 0.71:1
Reverse - 3.07:1

Both the 6 and 8 have the exact same automatic tranny (and gear ratios). The V8 has a higher gear ratio in the axle, but the transmission gear ratios are lower. You could do the math, but it looks like they all come out pretty close to each other gear for gear.

bison

Here you go: http://www.velocityjrnl.com/jrnl/2005/vmd2941sp.html

bison

Dang, you cut and paste faster than I do.

Here's another link: http://www.shadetreemechanic.com/for...2005_specs.htm

bison

One more: http://www.allfordmustangs.com/artman/publ...ticle_417.shtml

This one list ratios that are more in line with those posted by RRRoamer. I wonder which ones are right?

Stubbies

Wow, I don't believe I get to pull this one on someone else

:geek:

aponyfan

RRRoamer,

In case you (or anyone else is interested), I'm attaching a shot of a spreadsheet which I put together to complete all of the calculations with the data (and links) provided.

You're right. They do come out very close. Generally between 1-2 mph difference. (Assuming I've done the calculations correctly and put the right data in the right places.)

You've got to start shifting over about 3500-4000 before you start to see any more of a difference, and then only really around 5th gear and only about 4-5 mph.

So, for day-to-day city driving, there really isn't a significant difference.

bison

Wow! That's impressive!

Now do it again with 215/65-16 and 235/55-17 tires.

aponyfan

[/b][/quote]
Bison,

What are those numbers for? A different model year?

Mongoose

WOW !!!!!!!!!!! Thanks

mrtedrich

What if he backs up. We forgot the stats for reverse.

holderca1

The owners manual has recommended shift points to maximize fuel economy, hold on let me find the page number.

Edit: Found it at the bottom of page 156.

holderca1

How many reverse gears do you have???

bison

Bison,

What are those numbers for? A different model year? [/b][/quote]
No, those are the '05 tire sizes. The V6 works out to about 27.0" tire diameter, and the GT slightly larger, so the results won't change much.

holderca1

Bison,

What are those numbers for? A different model year? [/b][/quote]
No, those are the '05 tire sizes. The V6 works out to about 27.0" tire diameter, and the GT slightly larger, so the results won't change much. [/b][/quote]
Those aren't the correct tire sizes, the V6 runs on 215, the GT on 235, the wheel diameter comes out the same on both.

Edit: Nevermind what I said, I thought you were talking about the 255's the calculation was based on.

aponyfan

Thanks for clarifying, guys.

I've changed the 255 to 215 and 235, respectively for the V6 and GT, and added reverse since that was requested, as well.

There's now a bit more of a difference in speeds between the two - especially in 5th gear.

(For those that are interested, there's very little difference in reverse.)

Thanks, again, to all of those who helped maked these calculations possible. They've helped as I continue my personal V6 vs. GT decision.

Let me know if anyone is interested in an update based on the recommended shift points holderca1 posted.