[Spridgets] Bentley-RR Trivia: was calculating speed

[Jim Johnson]

Billy alludes to the point here without quite hitting it on the head. Fact
is, BHP or HP by any measure really has nothing to do with speed. Only in
elapsed time to reach a given speed. I have seen a 20 HP motorcycle reach
110 mph because of its wheel diameter and gearing. Likewise, I have seen 200
HP V-8s that couldn't hit 90 MPH.

Cheers!!
Jim

On Tue, Oct 21, 2008 at 11:57 AM, Kitterer Bob <bkitterer at mac.com> wrote:

> The placards on the Bentley and RR at the Gilmore Car Museum have
> bothered me for some time and having opened my mouth here it forced
> me to do some research which I should have done long ago.  I should
> mention that the Gilmore is a great museum located in SW Michigan.
>
> The HP question:  From physics a HP is a HP is a HP - - - well not
> quite.  In Britain the RAC (Royal Automobile Club) computed
> automotive HP by an equation of their own.  This apparently work for
> early cars and indeed it was used for tax purposes hence taxable
> HP.    It continued in use into the 1960's but the RAC had made three
> assumptions which did not hold up over time.  There is an
> explanation, with the equations, at  http://www.designchambers.com/
> wolfhound/wolfhoundRACHP.htm  It would be fun to plug in some numbers
> from current cars just to see how HP comes out in RAC HP but I do not
> have time for that now.
>
> The following information came from various sites which do not all
> agree with each other but these were not "production line" cars so
> some variance is expected.
>
> Bentley Speed Six (supercharged perhaps)  4850 lbs, 180 to 200 hp,
> top speed 84 to 125 mph.
>
> RR Phantom II Sports Coupe, 5485 lbs, 43.3 RAC HP, 120 BHP, top speed
> 92 mph.
>
> Almost all Phantom II's were custom bodied but seem consistent
> mechanically with exception of wheel base.  The Bentley seems only
> slightly more consistent.
>
> Bob Kitterer
>
> 1960 Austin Healey Sprite (Mk IV in disguise)
> 1966 Austin Healey Sprite Mk III (Trevor) - still in boxes
> 2000 Miata Special Edition
>
>
>
>
> On Oct 20, 2008, at 6:36 PM, Billy Zoom wrote:
>
> > I doubt that the Bentley weighed anywhere near as much as the
> > Rolls, but you
> > can't judge anything by the top speed.   I'm sure the Rolls was
> > geared a lot
> > taller, and I'll bet that was taxable horsepower, which is
> > calculated  by
> > the area of the tops of the pistons and has nothing to do with power.
> > Bentley's were race cars. I'll bet it got to 95 a lot quicker than an
> > overweight cruiser like a Rolls.
> > James Bonds Bentley was always credited with doing over 100 when he
> > wanted
> > it to.
> > BZ
> _______________________________________________
> Support Team.Net  http://www.team.net/donate.html
>
> You are subscribed as bmwwxman at gmail.com
>
> http://www.team.net/archive
>
> http://autox.team.net/mailman/listinfo/spridgets
>



-- 
Cheers!!
Jim