dyno stuff

[Eric Bryant]

> Here's one--I had a SB Dodge car at 6200 RPM, peak torque was 
> 1774 with a
> manual trans. I had the
> torque calculated at 389 ft/lbs at the flywheel--then doing 
> the math it was
> 459 HP--yet the actual dyno HP was substantially less. That's 
> why I'm still
> questioning this thing...SnapOn's formula is really 
> strange--as soon as I
> can find it again, I'll post it.

If you're getting HP numbers that are way off, it could just be
characteristic of the dyno. 

On the car side of the issue, I've noted that people obtain much different
numbers on Dynojet dynos than they do on Mustang dynos.  I'm not familar
with the Mustang dyno at all, so I really can't comment on the issue.

With motorcycle dynos, there's two big names - Dynojet and Factory.  The DJ
motorcycle dyno is just like a downsized DJ car dyno - it uses the inertia
of the roller to provide resistance.  The Factory dyno is an eddy current
dyno.  The Factory dyno will read 15% lower than the DJ dyno, and so no one
likes to use the Factory equipment - it doesn't make for impressive numbers.

What's my point?  I don't really know.  Different dynos will produce some
strange numbers.  I'd just like to know why it's so difficult to get a
"real" reading - I understand minor differences between dynos of different
brands, but it's almost like some manufacturers are using some very
"special" math.

Eric Bryant
mailto:bryante at ghsp.com
http://www.novagate.com/~bryante 
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