[Shotimes] Dyno charts

[Ron Porter]

Ah, you have hit upon the fallacy of HP numbers. Yes, it is well worth it to
run that motor at 4,500 rpm if the torque only dropped 1 lb/ft from 200 to
199 between 1,500 and 4,500, but in reality the torque drops a lot more than
that as rpm increases.

Ransom's example was the best.....a lawn mower could put out 220 HP like a
SHO if you could wind it to 150,000 rpm, but all this proves is that the
whole mathematical concept of "horsepower" is really pretty meaningless.

In a CVT, it may make some sense to run to engine above a peak torque
number, but it may not make sense to run it at the HP peak, but rather at
another point between peak torque and peak HP that gives a better efficiency
ratio.

Theoretically (and practically, from what I've seen), an engine gets it's
best fuel economy at peak torque. This would seem to be what future engine
designers would strive for. It is also a big advantage of electric motors
that have peak torque at "1" rpm.

Ron Porter

-----Original Message-----
From: Ron Childs [mailto:rchildssho@hotmail.com]
Sent: Friday, January 17, 2003 1:54 PM
To: ronporter@prodigy.net; shotimes@autox.team.net
Subject: RE: [Shotimes] Dyno charts


Imagine an engine with a broad torque curve e.g. 200 lb.-ft. from 1500 rpm
to 5000 rpm. The engine would produce triple the horsepower at 4500 than it
would at 1500 rpm, even though the torque is the same. This imaginary engine
would only have 57 hp at 1500 rpm (which may be the torque peak) but 170 hp
at 4500 if torque dropped to say 199. 57 hp is 57 hp, no matter what your
torque is.

-Ron Childs



>From: "Ron Porter" <ronporter@prodigy.net>
>To: <shotimes@autox.team.net>
>Subject: RE: [Shotimes] Dyno charts
>Date: Fri, 17 Jan 2003 12:56:06 -0500
>
>In the situation of a CVT, running the engine at peak torque would be the
>best solution, I believe. Peak torque is where the engine is running most
>efficiently. Gearing can handle where the speeds should fall. Much like a
>diesel, they're geared for the lower operating rpm.
>
>Ron Porter
>
>-----Original Message-----
>From: shotimes-admin@autox.team.net
>[mailto:shotimes-admin@autox.team.net]On Behalf Of Ron Childs
>Sent: Thursday, January 16, 2003 11:16 AM
>To: shotimes@autox.team.net
>Subject: RE: [Shotimes] Dyno charts
>
>
>Several cars now, and more to come have CVTs, Continuously Variable
>Transmissions. Although their behaviour depends on programming, the ideal
>for performance is to let the engine rev to peak hp and the tranny will
>adjust and accelerate the car. Wide torque band no longer needed.
>
>-Ron Childs  '91
>
>
> >From: "Ron Porter" <ronporter@prodigy.net>
> >
> >I agree with your final conclusion, but I don't agree that the amount of
> >horsepower is "most important"
> >
> >In reality, horsepower doesn't exist. It is a math formula to show how
>much
> >work is done over time. Torque is a real force, and the horsepower
> >calculation shows how much work that torque can do.
> >
> >Let's look at Ransom's example: a lawnmower producing 220 HP at 150K rpm,
> >or
> >a SHO motor producing 220 HP at 6K rpm. They technically producing the
>same
> >amount of work at their peaks, but engines don't only run at their power
> >peaks.
>
>
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