am new member. and have not driven it on the xway. was wondering what the r.p.m. should be at about 60mph to 70mph with the stock 4.12 gear and 195/65 series tire, thanks bill.
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am new member. and have not driven it on the xway. was wondering what the r.p.m. should be at about 60mph to 70mph with the stock 4.12 gear and 195/65 series tire, thanks bill.
Somewhere around 3,500 rpm, give or take a little.
It's OK to run these little engines at 3,500 - 4,200 rpm for a long period, provided that the oil temp stays below 230F. Best way to confirm oil temp is with a dipstick thermometer - looks like a candy thermometer for cooking, but goes down the dipstick hole. www.mainelycustombydesign.com
It's OK to run these little engines at 3,500 - 4,200 rpm for a long period, provided that the oil temp stays below 230F. Best way to confirm oil temp is with a dipstick thermometer - looks like a candy thermometer for cooking, but goes down the dipstick hole. www.mainelycustombydesign.com
With the tire combination, final drive and assuming you have a .89 4th gear.
You speed in 4th gear will be roughly double the tach number + a "0" showing on your tachometer
So, lets say 3 is showing on your tach (3,000 RPM's)
you exact speed will be 60 mph.
If you're showing 35 (3,500 RPM's) then your speed will be 70 mph.
etc etc
You speed in 4th gear will be roughly double the tach number + a "0" showing on your tachometer
So, lets say 3 is showing on your tach (3,000 RPM's)
you exact speed will be 60 mph.
If you're showing 35 (3,500 RPM's) then your speed will be 70 mph.
etc etc
That's a handy piece of information, Larry.
GPS says you're right on the money -- no surprise there. Just curious, how come that formula works?
GPS says you're right on the money -- no surprise there. Just curious, how come that formula works?
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sorry for the bad formatting. how do you maintain leading spaces on this board?
What size is the wheel? This affects the formula.
................(RPM*PI*DIA_Tire(in)*60)
Speed(MPH)= -------------------------------
................(GEAR_RATIO*12*5280)
For a 195/65 - 14 the diameter is ~24 in so:
................(3000*3.14*24*60)
Speed(MPH) = ------------------------- = 58.4 MPH
................(4.12*.89*12*5280)
So, there is the formula, Cory.
Tomm
................(RPM*PI*DIA_Tire(in)*60)
Speed(MPH)= -------------------------------
................(GEAR_RATIO*12*5280)
For a 195/65 - 14 the diameter is ~24 in so:
................(3000*3.14*24*60)
Speed(MPH) = ------------------------- = 58.4 MPH
................(4.12*.89*12*5280)
So, there is the formula, Cory.
Tomm
Tomm, It's a hit and miss proposition. Often times, when I format a response, I have to go back and edit until the formatting is correct
Formula's are great when all you have is a piece of paper and a pencil however, when you're near the internet a "pre-made calculator" is much easier to use.
Here is the one I use http://www.scirocco.org/gears/
Regarding William Demeter's car (he asked the initial question) all that was necessary was to fill in the blanks starting with tire size, in this case, 195, next box 65, next box 15, next box 4.12, next box .89 and the next box, your desired RPM or if you wish, drop down and insert speed
Then simply press the "calculate" button
(on a daily basis, I thank Al Gore for inventing the internet)
Here is the one I use http://www.scirocco.org/gears/
Regarding William Demeter's car (he asked the initial question) all that was necessary was to fill in the blanks starting with tire size, in this case, 195, next box 65, next box 15, next box 4.12, next box .89 and the next box, your desired RPM or if you wish, drop down and insert speed
Then simply press the "calculate" button
(on a daily basis, I thank Al Gore for inventing the internet)
Cory, Forgot to answer you: You stated "Just curious, how come that formula works?"
I'm assuming you're asking why it's right on the money at 3,000 = 60 MPH etc.
Only because as stated above, the math works out because of the tire size, 4th gear ratio and final drive ratio.
Mess around with the calculator above and you'll discover that if he had a 3.88 final drive, his tach would read 3,000 RPM's and his speed would be 64 MPH.
It's just "math"
I'm assuming you're asking why it's right on the money at 3,000 = 60 MPH etc.
Only because as stated above, the math works out because of the tire size, 4th gear ratio and final drive ratio.
Mess around with the calculator above and you'll discover that if he had a 3.88 final drive, his tach would read 3,000 RPM's and his speed would be 64 MPH.
It's just "math"
Stuff like the "universal proportion" and the like have always fascinated me. Thanks for the calculator. I'll be playing with that for DAYS.
cool formula, ran my numbers and it was right on to what i had figured out how fast i was going because of kilo speedo vs. tach speed
This gear calculater is what I use: http://www.locost7.info/gearcalc.php
If anyone has ExCell software, I can offer them a one page spreadsheet with the all formulas. You input tire sizes, gear ratios, RPM, final drive, etc, and it compares overall gearing, or vice versa.
Got another one for comparing engines builds. Input bore, stroke, deck height, number of cylinders, head cc. It calculates compression ratio (for flat top pistons), or vice versa. Send me request on Email if interested. Math for gearheads is fun.
Got another one for comparing engines builds. Input bore, stroke, deck height, number of cylinders, head cc. It calculates compression ratio (for flat top pistons), or vice versa. Send me request on Email if interested. Math for gearheads is fun.