1972: SAE Gross --> SAE Net HP figures - how did the 'configuration' change?

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pgtr - 01 Oct 2004 06:37 GMT

It seems that the Gov mandated all advertised HP figures be stated as
SAE Net as of '72 (and still holds today AFAIK). Figures dropped
across the board by roughly ~25% or so give or take that year.

How was the engine basically configuration for each type of test?

Were all accessories installed for SAE Net like alternator, waterpump
etc... vs an un-encumbered SAE Gross rating?

What about 'options' like PS or A/C?

Exhaust manifold?

Air Cleaner?

'Blue-printed' engine assembly vs typical factory tolerance engine?

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Anthony - 01 Oct 2004 10:32 GMT

> It seems that the Gov mandated all advertised HP figures be stated as
> SAE Net as of '72 (and still holds today AFAIK). Figures dropped
[quoted text clipped - 12 lines]
>
> 'Blue-printed' engine assembly vs typical factory tolerance engine?

http://neptune.spacebears.com/opine/horsepwr.html

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Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

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Dave Baker - 01 Oct 2004 11:38 GMT

>Subject: Re: 1972: SAE Gross --> SAE Net HP figures - how did the
>'configuration' change?
[quoted text clipped - 20 lines]
>
>http://neptune.spacebears.com/opine/horsepwr.html

An excellent precis and nice to see someone else quoting realistic drive train
losses too. For more detailed info see the power and torque articles on my
website.

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Dave Baker - Puma Race Engines (www.pumaracing.co.uk)

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pgtr - 01 Oct 2004 18:16 GMT

Thanks - very interesting.

Does anyone know if what kind of load has to be put on the alternator
in SAE J1349 NET?

Also what about OPTIONS like say power steering or air conditioning.
Are they on or off for SAE J1349 NET?

>http://neptune.spacebears.com/opine/horsepwr.html

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Kathy and Erich Coiner - 02 Oct 2004 03:46 GMT

The standards says that items like P/S or A/C would be connected and driven
by the belt, but they don't have to be doing any "work".
That means the P/S pump is spinning but steering wheel is not being moved.
On A/C it means the clutch is NOT engaged. So You are measuring the losses
in the belt and idler under essentially no load.

If those items are truly optional equipment, I suspect the auto maker will
test the car without those items.

The alternator would be sourcing power for the ignition but nothing else. No
headlights or battery charging.

Erich

> Thanks - very interesting.
>
[quoted text clipped - 5 lines]
>
> >http://neptune.spacebears.com/opine/horsepwr.html

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pgtr - 02 Oct 2004 23:03 GMT

>The standards says that items like P/S or A/C would be connected and driven
>by the belt, but they don't have to be doing any "work".

When the standard says this does it make any distinction between the
item being STANDARD or OPTIONAL. On some cars they can be purchased w/
or w/o optioanl AC or PS etc. Others it's standard and there is no
option.

The PS would be doing some work a small bit of work just by pumping
the fluid thru while driving in a theoretic straight line. But EVEN if
it's an engine OPTION and the car could be purchased w/o they have to
have it installed and operating for the SAE NET test?

AC is turned off and we are just spinning the clutch on it's bearings
right? Regardless of whether the car/engine could be ordered new w/ NO
AC even installed?

What about load on teh alternator - is there a minimal or nominal amp
draw that is mandated - that could certainly affect the results I
would think.

>That means the P/S pump is spinning but steering wheel is not being moved.
>On A/C it means the clutch is NOT engaged. So You are measuring the losses
>in the belt and idler under essentially no load.
>
>If those items are truly optional equipment, I suspect the auto maker will
>test the car without those items.

Yes, I'm talking about OPTIONAL A/C and OPTIONAL PS. This would be
more true of older vehicles and/or more base models/engines.

When they first switched to teh SAE Net standard probably less than
half the cars produced were getting optional factory AC.

>The alternator would be sourcing power for the ignition but nothing else. No
>headlights or battery charging.
>
>Erich

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