25ss

01-24-2005, 03:43 AM

Just got a 100 mph keller speedo.

Thought i saw a thead some time ago on a way to convert air pressure to speed?

Dale!

Thought i saw a thead some time ago on a way to convert air pressure to speed?

Dale!

View Full Version : Speedo

25ss

01-24-2005, 03:43 AM

Just got a 100 mph keller speedo.

Thought i saw a thead some time ago on a way to convert air pressure to speed?

Dale!

Thought i saw a thead some time ago on a way to convert air pressure to speed?

Dale!

Mark75H

01-24-2005, 08:44 AM

mph= the square root of (pressure divided by .0145)

or

pressure = (speed divided by 8.417) squared

in physics it is expressed as "Dynamic Pressure":

Q= .5 X P X Vē , where P (rho) = 1.9376 and V is feet per second;

using this I calculated 60 mph (88fps) to be 52.1 psi

exact:

69 psi = 69 mph (kinda easy to remember for a couple reasons, huh?)

approximate:

20 psi = 40 mph

40 psi = 52 mph

70 psi = 70 mph

100 psi = 85 mph

130 psi = 95 mph

147 psi = 100 mph

or

pressure = (speed divided by 8.417) squared

in physics it is expressed as "Dynamic Pressure":

Q= .5 X P X Vē , where P (rho) = 1.9376 and V is feet per second;

using this I calculated 60 mph (88fps) to be 52.1 psi

exact:

69 psi = 69 mph (kinda easy to remember for a couple reasons, huh?)

approximate:

20 psi = 40 mph

40 psi = 52 mph

70 psi = 70 mph

100 psi = 85 mph

130 psi = 95 mph

147 psi = 100 mph

LakeRacer99

01-24-2005, 02:53 PM

If you haven't checked out Teleflex's Instrument Technical Reference, I recommend it. Even if you don't use their gauges.

http://www.teleflexmarine.com/Pdf/Instruments/TechCat3_1-Instruments-TECH%20REF.pdf

http://www.teleflexmarine.com/Pdf/Instruments/TechCat3_1-Instruments-TECH%20REF.pdf

25ss

01-26-2005, 12:03 AM

Thanks thats what i needed.

Dale!

Dale!