Author	[Modern View]
equeen 11-11-2012 10:07:45 209.102.248.236 Report to Moderator	Okay, JMOR, here's another one for you. Back in my younger days we had a horse named Maude. That ole gal could pull logs all day long. She could pull a turning plow and do all sorts of heavy work. No telling what 20 ole Maudes harnessed together could pull/do. For sure ole Maude, all by herself, could drag my 20 HORSEPOWER riding lawnmower all over the place. And my 20 or so HP 8N could probably drag 100 or more of my little dinky 20 HP lawnmowers from here to kingdom come. So, why is my dinky little lawnmower rated as a 20 HORSEPOWER lawn mower? It's a lie, isn't it? Just wondering. [Reply]   [No Email]
W_B 11-14-2012 12:36:04 155.188.183.24 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to JMOR, 11-11-2012 10:07:45   Quoting Removed, click Modern View to see Same here, for one, the older one, but the newer one gave me all kinds of grief until I figured out (with the help of a small engine forum!) what the problems were... misaligned starter that was breaking the (plastic) gear and a valve guide that was slipping out of place and causing a bent push rod. The $44 (or so) was scant compensation for the problems and costs. It still runs great now. [Reply]  [No Email]
TheOldHokie 11-14-2012 06:29:50 74.110.75.221 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to 36 coupe, 11-11-2012 10:07:45   Indiana Ken said: (quoted from post at 21:40:44 11/13/12) A 20 HP lawn mower engine in a 8N will pull a 2 bottow plow if the gearing is revised to allow the engine to operate within its RPM range to develop the 20 HP. That's pretty much what an N-series L-head tractor engine is - 4 five horsepower single cylinder B&S lawnmower engines mounted on a common crankshaft :roll: TOH This post was edited by TheOldHokie at 06:51:01 11/14/12 2 times. [Reply]  [No Email]
Indiana Ken 11-13-2012 17:40:44 66.249.234.243 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to Royse, 11-11-2012 10:07:45   Quoting Removed, click Modern View to see Horsepower is a calculated value: The engine is tested on a dynamometer typically at WOT (Wide Open Throttle) under load. The load is adjusted to hold the engine at various RPM points through out its operating range. The engine torque output is measured at each RPM point. HP is calculated from the following equation: HP = (Torque x RPM) / 5252. Where torque is in ft-lbs, the constant 5252 is used to make the units work out. Note, from the formula, two engines can produce the same HP but have different torque outputs depending on the RPM range they operate within. HP is a measure of the work an engine can do per unit of time. The application is the responsibility of the user! An 8N engine in a lawn mower will not pull a 2 bottom plow since the mower is much to light weight. A 20 HP lawn mower engine in a 8N will pull a 2 bottow plow if the gearing is revised to allow the engine to operate within its RPM range to develop the 20 HP. [Reply]  [No Email]
carlntexas 11-13-2012 09:50:10 69.46.55.46 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to Gaspump, 11-11-2012 10:07:45   I had two of the BS mowers and filed to get my money because I could. I never had a problem with either one and they cut grass just like they're supposed to. [Reply]  [No Email]
W_B 11-13-2012 07:51:38 155.188.183.16 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to 1951 8N, 11-11-2012 10:07:45   Quoting Removed, click Modern View to see Uhhh, yes they did. There was a class action lawsuit filed and settled about misrepresentation of HP ratings on engines. B&S, Kawasaki, Kohler, Toro and Tecumseh. Honda not involved. Payout was about $22 per defendant with a riding mower, I had two that I got a check on. Lesser amount paid for a push mower. Originally they were trying for $75 per, but had so many claims the amount was reduced. Google lawnmower lawsuit class action for info. [Reply]  [No Email]
JMOR 11-13-2012 07:47:41 72.181.173.171 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to Bodo, 11-11-2012 10:07:45   Quoting Removed, click Modern View to see "...but not directly portional ..." So therefore you can't simply stick CR directly into the equation as you did. That's all that is being pointed out. OK? Peace. [Reply]  [No Email]
Jerry/MT 11-13-2012 16:11:53 206.183.116.145 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to JMOR, 11-13-2012 07:47:41   Ya" figures me right, JMOR. [Reply]  [No Email]
JMOR 11-13-2012 07:08:31 72.181.173.171 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to Mr. T. Minnesota, 11-11-2012 10:07:45   Quoting Removed, click Modern View to seeIF all that Jerry was pointing out, and I expect that it was, is that CR does not belong in the equation for HP as in HP=(T x RPM)/5252..then Jerry & I are in agreement. That is HP is not directly proportional to compression ratio, even though it is a factor in same. [Reply]  [No Email]
Ken(Ark) 11-12-2012 18:08:56 71.30.143.11 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to GB in MT., 11-11-2012 10:07:45   Quoting Removed, click Modern View to see I remember somebody ??? got into legal trouble because of their false claim of the horsepower of their motor . It was a class action suit for people that had purchased the unit thinking it had the higher advertised hp than it actually did . The company ??? paid out partial refunds is what I believe I heard on the radio . [Reply]  [No Email]
1951 8N 11-11-2012 19:04:30 139.55.253.58 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to equeen, 11-11-2012 10:07:45   equeen said: Someone "got into trouble" for those nonsense ratings on B&S and other small engines. I believe that all are now rated in cc or some such. Makes far more sense. HP for those little things never did make any sense - especially if one had ever worked a horse. Smile. I don't know what you're talking about. Most small engines are still rated by horsepower. Nobody got into trouble for anything and the ratings are not nonsense. This post was edited by 1951 8N at 19:06:02 11/11/12. [Reply]  [No Email]
George Marsh 11-11-2012 14:18:20 50.104.246.0 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to equeen, 11-11-2012 10:07:45   James Watt invented the term horsepower. He measured the work a horse would do in a 10 hour day, took the average. Keep in mind in James Watt's improved the steam engine and wanted an idea how many horses his engine could replace. Horses were used to lift coal out of a mine. So James Watt came up with the term 550 ft-lb of work in a second. This unit can also be converted in to circular units too. Let's say you have a pulley with a rope lifting a 55 lb weight. If the outer speed of the pulley is 10 ft/s, then you are using one horsepower, 55 lb x 10 ft/sec = 550 ft-lb/sec. Things can get a little more complicated if you want to talk about torque. Let's say you have 550 lb-ft of torque turning at 1 rev per second, you will have 550 x 1 x 2 pi = 3454 ft-lb/sec = 6.28 hp Keep in mind I put my Physic book away a long time ago. Sure someone may think this isn't right. When computing hp and using circular unit, revolutions must be converted to radians per second. 1 revolution is 2 pi radians. Google James Watt and see what the experts have to say about horsepower and torque. As for a horse, yes it can pull a 20 hp lawn mower backwards. Bet a horse can't pull a 20 hp IH C backwards. Difference, old tractors measured true horsepower at the wheels, PTO, or belt. Didn't briggs get in trouble for over inflating the hp ratings? George [Reply]  [No Email]
Bulldozer 11-11-2012 18:42:40 24.165.92.6 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to George Marsh, 11-11-2012 14:18:20   According to Wikipedia, the European Union (EU) dropped the use of horsepower Jan 1 , 2010. Probably because it is misleading. However, Honda is real good about showing specification on its engines, since it is basically an engine company first and foremost. Honda still quotes horsepower and torque ratings on their engines. Bare in mind that the quoted rated horsepower is usually the peak on the HP vs rmp curve and maximum HP is usually at red line rpm. Believe torque rating is a better indicator of engine umph and peaks out at rpm less than red line. [Reply]  [No Email]
equeen 11-11-2012 14:50:38 209.102.248.236 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to George Marsh, 11-11-2012 14:18:20   Someone "got into trouble" for those nonsense ratings on B&S and other small engines. I believe that all are now rated in cc or some such. Makes far more sense. HP for those little things never did make any sense - especially if one had ever worked a horse. Smile. [Reply]  [No Email]
JMOR 11-11-2012 13:47:35 72.181.173.171 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to JMOR, 11-11-2012 10:07:45   Quoting Removed, click Modern View to seeAll nine pages for the 9N test are on the NTC site. [Reply]  [No Email]
Jerry/MT 11-11-2012 13:30:04 206.183.116.145 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to equeen, 11-11-2012 10:07:45   HP = Constant X Torque X RPM. If you gear the lawnmower engine down so the rear axles are running at the same rpm as your 20 hp 8N, the torque at the rear axle would be the same ASSUMING the driveline losses were the same [Reply]  [No Email]
Bulldozer 11-11-2012 18:54:10 24.165.92.6 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to Jerry/MT, 11-11-2012 13:30:04   Bear in mind that the 20 HP lawn tractor engine is rated at a higher rpm than the 8N at 2000 rpm, probably close to 3600 to 4000 rpm. The 8N develops more torque than the lawn tractor because the engine displacement is 50 ci for the lawn tractor and 120 ci for the 8N. 20 HP = T(8N) x 2000 rpm x 2pi = T (lawn tractor) x 4000 rpm x 2pi [Reply]  [No Email]
Bulldozer 11-12-2012 08:15:51 24.165.92.6 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to Bulldozer, 11-11-2012 18:54:10   something to add. The newer lawn tractor will have compression ratio around 8.5:1 compared to the 8N of 6.7:1 Using proportioning and the 8N as a base case and the ratio of engine displacements, rated rpm & compression ratios HP(lawn tractor) = 20 HP (8N) x (49.8/119.7)x (3800 rpm/2000 rpm) x (8.5/6.7) = 20 HP(lawn tractor) where 49.9 = lawn tractor engine displacement 119.7 = 8N engine displacement 3800 rpm = rated lawn tractor engine speed 2000 rpm = rated 8N engine speed 8.5 = compression ratio of lawn tractor 6.7 = compression ratio of 8N tractor Therefore, the lawn tractor measures up to its specs at 20 HP based on the 8N as a base . If the lawn tractor and 8N are fully loaded that is putting out every thing its has, both machines will do the same amount of work in one hour, assuming the power train efficiency in each machine are equal. However, in a tractor pull the 8N will pull the lawn tractor all around the barn yard! [Reply]  [No Email]
Jerry/MT 11-12-2012 17:37:08 206.183.116.145 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to Bulldozer, 11-12-2012 08:15:51   Why does compression ratio come into it? HP=C x torque x rpm. That"s independent of compression ratio. [Reply]  [No Email]
Bulldozer 11-13-2012 06:52:28 24.165.92.6 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to Jerry/MT, 11-12-2012 17:37:08   The torque an engine develops is a fuction of many variables but compression ratio of the engine is a major contributor. Consider two engines with equal displacement, one has a compression ratio of 6.7:1 and another engine has a compression ratio of 11:1. Which engine will develop the most torque? [Reply]  [No Email]
Jerry/MT 11-13-2012 09:08:30 206.183.116.145 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to Bulldozer, 11-13-2012 06:52:28   If two engines are rated at 20 hp and at the same rpm, it will produce the same torue at that rpm independent of the displacement or the compression ratio. Horsepower is horsepower. An engine with a higher compression ratio will produce a given horsepower with less displacement than one with lower compression ratio. A large displacement low compression ratio engine can produce the same horsepower as small displacemnt high compression ratio engine. How ever if they are rated at the same horsepower and they have the same OUTPUT SHAFT RPM, THEY WILL PRODUCE THE SAME TORQUE. Torque = HP/C X RPM! These are facts. You can believe what you want. [Reply]  [No Email]
Bulldozer 11-13-2012 07:42:05 24.165.92.6 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to Bulldozer, 11-13-2012 06:52:28   Torque ~ engine displacement, compression ratio For example what engine develops the most torque having equal displacement, the aircooled gasoline engine with CR = 6.7:1 or the diesel engine with CR = 22:1 ? The engine output shaft torque is proportional to the engine compression ratio but not directly portional but enters the equation as a major contributor. [Reply]  [No Email]
Bulldozer 11-11-2012 12:22:22 24.165.92.6 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to equeen, 11-11-2012 10:07:45   placed the same question another forum about 3 months ago and it was removed because the administrator thought it was a stupid question. So I have two tractors rated at 20 HP An Allis Chambers 620 with hyraulic drive and a 20 HP 8N. AC 620 50 cid 3600 rated rpm 8N 120 cid 2000 rated rpm In a tractor pull which one wins? In 1 hour which tractor can plow the most dirt? Have seen videos on You-Tube of the AC620 pulling at single bottom plow at a high rate of speed. Can find no Nebraska tractor pull data on either tractor. [Reply]  [No Email]
Bulldozer 11-11-2012 11:38:38 24.165.92.6 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to equeen, 11-11-2012 10:07:45   The horsepower unit was first used as a comparison of power output from a steam engine to the power output of a single draft horse. So, if a modern horse can pull a plow with soil resistance of 400 lb a distance of 82 ft in one minute ,the horseis keeping up with his great grandfather. That is about 33,000 lb-ft /min = 1 hp [Reply]  [No Email]
Jock(OR) 11-11-2012 11:05:29 71.216.23.229 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to 59junior, 11-11-2012 10:07:45   Quoting Removed, click Modern View to see Yes, but Maude had higher emissions. [Reply]  [No Email]
JMOR 11-11-2012 10:14:20 72.181.173.171 Report to Moderator	Re: JMOR - Explain Horses and Horsepower in reply to 59junior, 11-11-2012 10:07:45   Quoting Removed, click Modern View to seeMaude had better traction......didn't ever see her spin out, did you? [Reply]  [No Email]