----------
From: HERBEAM(at)aol.com
>Has anybody information about the amount of horsepower and or torque
required
>to maintain different speeds on a flat highway with no headwind? I'm
talking
>about higher speeds as I'm wondering how much power is required to
maintain
>120 MPH in a tiger or Alpine?
I have a software package that I developed that allows you to input
a torque curve, gear ratios, final drive, drag coef, tire size ECT into
a table, then run the numbers to find the derived 0-60 time, 1/4mile
time
top speed ECT.
I didnt run the data for 120MPH but rather what MPH you get with
various torque curves and gearing changes.
On a 1900lb Alpine running 3.89 gears and about 160BHP
(113lbft of torque) at 7400RPM, the claculated top speed was 129MPH.
At this speed the aerodynamic drag and drivetrain losses equaled the
produced power of 160BHP.
This was running the car well beyond its torque peak, but while the
HP curve was still rizing, or at least flat.
Running with a slightly lower final drive ratio (3.70) would raise the
top
speed a tad more, but the increase in engine torque is mostly offset
by the the loss in rear wheel torque due to the lower numerical ratio.
Most would find the 3.70 ratio unacceptable, and would even go to
a higher numerical ratio in favour of acceleration over top speed.
Top potential speed is normally attained with a given gearing where
the engines developed power (HP) crossed the drag losses (HP)
line on the drag/speed curve.
Jarrid Gross
This archive was generated by hypermail 2b30 : Tue Sep 05 2000 - 10:07:20 CDT