My personal Rabbit diesel landspeed record

[Dr. Diesel]

that's pretty fast!
my jetta is deep into the tach red red zone @ 150km/h!  (cursed close ratio!!)

[MrDave]

Some quick calculations:

020 tranny
175/70/13 tires, 3.42 FD, .71 5th, 4500 rpm = 200 kph / 124 mph
175/70/13 tires, 3.42 FD, .71 5th, 4700 rpm = 209 kph / 130 mph

tranny swap: 02A tranny
175/70/13 tires, 3.16 FD, .76 5th, 4500 rpm = 203 kph / 126 mph
175/70/13 tires, 3.16 FD, .76 5th, 4700 rpm = 212 kph / 131 mph

tranny swap, 02A, 5th gear swap
175/70/13 tires, 3.16 FD, .72 5th, 4500 rpm = 214 kph / 133 mph
175/70/13 tires, 3.16 FD, .72 5th, 4700 rpm = 223 kph / 139 mph

tranny swap, 02A, 5th gear swap, next size up tire
185/70/13 tires, 3.16 FD, .72 5th, 4500 rpm = 219 kph / 136 mph
185/70/13 tires, 3.16 FD, .72 5th, 4700 rpm = 229 kph / 142 mph

for fun:
185/70/13 tires, 3.16 FD, .72 5th, 5000 rpm = 244 kph / 151 mph


The design of the TDI diesel is such that the power drops off after about 4000 rpm.  The lower I can drop the revs, the more power I'll have, and the faster it'll go.

My dyno

'course, the Rabbits have about the same aerodynamics as a brick, so I'm sure that'll determine the limit of things....

-Dave

[VWRacer]

'course, the Rabbits have about the same aerodynamics as a brick, so I'm sure that'll determine the limit of things....

If you can carefully calculate the frontal area of the rabbit I can calculate the hp required to get to various speeds.

Off to work...back late.

[MrDave]

If you can carefully calculate the frontal area of the rabbit I can calculate the hp required to get to various speeds.

I actually looked at this some time ago, and made a spreadsheet.
Internet research (and some old newsgroup posts from Jake)
yeilded a frontal area of 19.69 sq.ft, and a Cd for a VW rabbit
ranging from 0.41 to 0.46.

A quick calculation reveals that for a speed of 225 kph (140 mph) with Cd=.41
Power(drag) = 107 hp
Power(friction) = 14 hp
total: 121hp

For Cd=.46
Power(drag) = 120 hp
Power(f) = 14
total:  134hp

What other power factors am I missing?

I really should combine the drag spreadsheet with my dyno spreadsheet.
The point where the two curves cross should be the terminal velocity.

-Dave