new small engines
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Posting Guru
Joined: Feb 2004
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From: Saratoga, NY
new small engines
ok so the last few years I have noticed that lawn mowers, and other small engine powered equipment has dropped a HP rating and either have a torque rating or a cc number. Now how am I suppose to know what I'm getting based off of that? What was wrong with HP numbers? Why can't things like this be left alone, If I was buying a motorbike then I would give a S*#T what the cc displacement was
Logistics Pro
Joined: Nov 2004
Posts: 3,550
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From: Lancaster County PA
Well, Briggs starting using torque as their descriptor because they claim it more accurately reflects the work cpability of the engine.
Torque is the twisting force measured at the crankshaft.
However, it is only useful when comparing Briggs to Briggs unless and until the other mfrs start listing gross torque on their labels as well.
Torque is the twisting force measured at the crankshaft.
However, it is only useful when comparing Briggs to Briggs unless and until the other mfrs start listing gross torque on their labels as well.
Thread Starter
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Posting Guru
Joined: Feb 2004
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From: Saratoga, NY
Well, Briggs starting using torque as their descriptor because they claim it more accurately reflects the work cpability of the engine.
Torque is the twisting force measured at the crankshaft.
However, it is only useful when comparing Briggs to Briggs unless and until the other mfrs start listing gross torque on their labels as well.
Torque is the twisting force measured at the crankshaft.
However, it is only useful when comparing Briggs to Briggs unless and until the other mfrs start listing gross torque on their labels as well.
Cargo Master
Joined: Apr 2003
Posts: 3,476
Likes: 224
From: Frequently frozen MN
I got caught in this one, although it really didn't matter. I bought a cheap lawn mower, and I was surprised that it said '4.5'. When I finally got around to RTFM, I think that it was 4.5 in oz 
-- well maybe it was ft -lb. (There was no indication on the unit what the 4.5 meant)
Lawnmower does what I needed it to do -- but not what a 4.5 HP would do.
However, I agree with the OP. There is a lot of general experience with engines rated in HP. I'm sure that it's not extremely accurate, but I have a general feel for what various HP engines will do.
Might not be as true with newer engines. Older engines seemed to have pretty similar power profiles from all that I could tell. Maybe newer ones don't.
Does Briggs publish any kind of explanation of their new rating?
-- well maybe it was ft -lb. (There was no indication on the unit what the 4.5 meant)Lawnmower does what I needed it to do -- but not what a 4.5 HP would do.
However, I agree with the OP. There is a lot of general experience with engines rated in HP. I'm sure that it's not extremely accurate, but I have a general feel for what various HP engines will do.
Might not be as true with newer engines. Older engines seemed to have pretty similar power profiles from all that I could tell. Maybe newer ones don't.
Does Briggs publish any kind of explanation of their new rating?
Thread Starter
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Posting Guru
Joined: Feb 2004
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From: Saratoga, NY
Oh Yeah, how about a link?
Elder User
Joined: Jul 2003
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From: North Richland Hills, TX
Click on articles/specs at top of this page and click on automotive calculators, then brake hp.
Last edited by BillC; Sep 25, 2009 at 01:47 PM. Reason: more info
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Logistics Pro
Joined: Sep 2007
Posts: 3,737
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From: Western Mass
It probably is something similar to what happened to compressors a few years back (at least the sears ones). Where they had to start putting the running HP rating, instead of the starting HP rating which they had been using.
Torque might be a better way to rate lawnmowers, hell if I know...
Torque might be a better way to rate lawnmowers, hell if I know...
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Cargo Master
Joined: Dec 2004
Posts: 2,232
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From: NE Texas
Torque X RPM / 5252
5 ft. lbs. at 3,600 / 5252 = 3.42 HP @ 3,600 RPM
This formula, if you know the torque at a specific RPM, gives the horsepower developed at THAT RPM. To get the true picture, you need the torque curve and then calculate HP at various RPM to determine where the horsepower peak is located in the band.
I'm not sure that it is safe to assume that the specified torque is always at 3,600 RPM, but Briggs may be putting it out that way.
I agree with the remarks about the marketers. They are nothing but politicians trying to spin the facts to suit themselves.
5 ft. lbs. at 3,600 / 5252 = 3.42 HP @ 3,600 RPM
This formula, if you know the torque at a specific RPM, gives the horsepower developed at THAT RPM. To get the true picture, you need the torque curve and then calculate HP at various RPM to determine where the horsepower peak is located in the band.
I'm not sure that it is safe to assume that the specified torque is always at 3,600 RPM, but Briggs may be putting it out that way.
I agree with the remarks about the marketers. They are nothing but politicians trying to spin the facts to suit themselves.