Well put Alan. One small addition: According to G-Tech, the measurement
that their "box" takes is closer to the Rear-wheel than Flywheel. Since
most of us want to know that we're "putting out on pavement", you'd be
better off with the actual Chassis Dyno (or G-Tech if there is no Dyno shop
close by).
I personally have (and occasionally use) two Dyno programs for my PC:
Dyno2000 - Motion Simulation - http://www.motionsoftware.com - $60.00
Engine & Performance Analyzer Pro - Performance Trends (Used to use this in
the old shop. Really good but expensive.) -
http://www.performancetrends.com - $500.00
Both work great for engine horsepower, torque, VE%, ME%, Valve Train
Efficiency, etc...but they really don't take into consideration the actual
driveline HP loss. You can add this in as a variable but Automatics,
Sticks, Tires, Gears, all this needs to be taken into consideration before
you can come up with an accurate number. 20-30% is the average...40% is a
little high, but it may happen due to a bad design.
Later,
Bernd
A engine dyno measures HP at the "crank" because that is where it
attaches. Pure engine to dyno data.
A rear wheel dyno measures HP at the drive wheels, because you don't
want to remove the engine.
A G-tech is an accelerometer that essentially measures the "thrust" of
your vehicle over a specified duration and uses mathmatical equations to
convert the data to HP.
3 totally different ways to measure "work" done.
Each way is not relative to the next, and should only be used as a
comparison to data which is collected in the same manner.
Comparing a G-tech result with any kind of dyno has no value, and vice
versa.
Alan S.
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:14:29 EDT