It takes some amount of _torque_ to rotate the engine. How much depends on
internal friction as well as the work done compressing the intake charge in each
cylinder and to open and close the valves, and to run the oil pump. Even if this
torque remained constant over all RPM and load conditions, (I would guess that
some friction loads go down, while the torque requirement for the oil pump would
certainly go up 'till you hit the pressure limiter), the power required to
rotate the engine (in HP) is (torque (lb-ft)* RPM) / 5252. So if you measured
the average torque required to rotate the engine through one revolution and
measured 10 lb-ft, that would mean that at 500 RPM engine rotation would suck up
0.95 HP, while at 6000 RPM the same torque load costs you 11.4 HP. SO if a large
part of that is friction maybe you can get a decent benefit from an additive
I hear that Roots-type blowers (on the top fuel cars) typically require 400 or
so horsepower input, at whatever RPM they run the engine at. Those belts gotta
be strong...
Theo Smit
tsmit@novatel.ca
B382002705
> -----Original Message-----
> From: Wright, Larry [SMTP:lrw@aop.com]
> Sent: Thursday, October 01, 1998 1:18 PM
> To: Tigerlist * (E-mail)
> Subject: Think?
>
>
> Doug Mallory wrote:
> *Subject: Think !!!
>
> Well, if you insist; but it _hurts_! :-)
>
> *If you can turn an engine with a 1.5 hp starter how can an oil additive
> *increase hp more the 1.5 hp?
>
> Been mulling this one over all day, it didn't make sense at first.
> Re-reading this for the nth time, I finally come to the conclusion that
> perhaps you're suggesting that if a 1.5hp starter turns the motor over,
> then the engine's internal friction is eats 1.5hp _max_, and the
> additive, even if it reduced the internal friction to zero, cannot help
> by more than that 1.5hp. O.K., plausible statement. Hmmm, one answer
> might be that it _can't_ help more then the 1.5hp, and it's a waste of
> time to use additives. Another might be derivative of whether the
> friction is a constant at all rpm's and temperatures; if the friction
> eats way more grunt at 6000 revs (I don't know), then the additive
> wouldn't have to remove _all_ of the friction to add more than 1.5hp.
> Doug, I think you're trying to get us to dump our preconceived ideas,
> which is always good. But don't go into the business of making
> brain-teaser imprinted cocktail napkins...
>
> Lawrence R. Wright
> Purchasing Analyst
> Andrews Office Products Div. of USOP
> lrw@aop.com
> Ph. 301.386.7923 Fx. 301.386.5333
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