What revs will a four speed manual do @ 100 with 3.23 diff

[fordmuscle83]

The gearbox is 6 cyl single rail with a forth of 1:1.

Diff is lsd 3.23.

14'' wheels with 225/50 tires.


Thanks
Pete

 

[80broncoman]

I have had this formula in head since I worked at crane:
MPH x GEAR Ratio x 336 dividied by overall tire hieght (inches) = RPM

100 x 3.23 x 336 dividied by oal in inches 26? = 4174

Remember autos without a lockup converter the rpm will be slightly higher.
manuals are very close

 

[xctasy]

Thats a good formula because its simple, and it works.


Only one thing for nerds like me. There is 2.2% tyre crush on most radials when the car is loaded.

I have a more complicated one which works better but is a PITA to remember.

225/50X 14 is 2*(225*0.50)+(14*25.4) = 580.6 mm (static, unloaded)

Then divide by 5.42, and again by 3.23:1, which gives km/h per 1000 rpm of the loaded wheel on the road. Tyre squash is about 2.2% on a car like yours.

Thats 33.15 km/h at 1000 rpm

Then take 100 km/h, and divide by 33.15, and presto, 3016 rpm.

At 100 mph, or 160.934 km/h, it will do 4854 rpm.

Every one loves to get Falcons nice and low, and 225/5014's do that. Only problem is the tyre is supposed to be 642 mm tall unloaded, so its doing lots more revs each mile.

With a set of 26" (unloaded) tyres at 100 mph, I get 4268 rpm, and 4174 rpm like 80broncoman if there was no tyre crush due to the weight of the vehicle.

 

[Anonymous]

and remeber thats MPH skippy not KPH

 

[fordmuscle83]

4174rpm @ 100MPH which is 160kph

So 4174 minus 40% less (1669) is 2505rpm...............hmm that cant be right becuase thats lower than with the 2.77 gears now!


Isnt the actually tire size in my car 22.86 inches?

112.50mm from > 225*50mm
to inches 112.50/25.40= 4.430 inches

14ich rim 4.430 * 2 (top and bottom?)

=22.86 inches (havent included tire crush)


EDIT*LOOKS like it will be about 2860rpm@100kph*

 

[Anonymous]

check out
http://racingdownloads.com/racing_software-22.html

tells you all speeds in gears and all coolstuff in both mph and kmph

according to the software at 100kmph you will be doing 2951rpm

cheers
pcman

 

[xctasy]

Great site!

There is no such thing as KPH. Km/h is correct term, not that I give a hoot.

 

[ZC-Cruiser]

There is no such thing as KPH. Km/h is correct term, not that I give a hoot.

Well I give a hoot and K is the abbreviation for Kelvin, as in degrees Kelvin.

The abbreviation for Kilo is "k"

So, there is no such thing as KPH and Km/h (Kelvin meters per hour) doesn't make sense.

Kilometers per hour is abbreviated to km/h

</rant>

 

[xctasy]

I am prepared to say you are right. I am wrong.

(That is only because it is rude to start the first letter of a scentance(sp?) with a little letter.

hello.my name is dean.km/h are something i hate. )

 

[TeddyXY71]

Just as a small side note:
100 mph is about 160 km/h, not the 140 km/h mentioned above.

Cheers,

Teddy

 

[fordmuscle83]

pcman, that download is awesome