Snow blower power ratings

Page 1 of 4  

I am looking for a new snow blower and have discovered that the power rating of the engines are no longer in "Horse Power" but in "Foot Pounds" if given at all. Sometimes all that is given is the CC's of the engine.
Even the people selling these machines don't know what the "Horse Power" ratings are so that old geezers like myself can understand what is going on. Does anyone have any general rules regarding the conversion of Foot Pounds or CC's to Horse Power?
--
Ron P

Quick questions rarely have quick answers
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 10 Oct 2009 09:35:04 -0400, "Worn Out Retread"

Your best bet is to find old literature for small engines and make a chart of displacement=hp. Then use that chart to determine approximate HP of newer equipment where you know the displacement but not the HP. It will be a fairly accurate guide.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Horsepower to CC is highly variable and not a good measure of power. My cars have different engines. The 3800 cc is 190 HP but my 3300 cc is 234 HP. I suspect smaller engines are similar.
Foot Pounds is actually more useful as it is the torque to the shaft that is doing the work. That said, none are truly meaningful in the whole scheme of things. What good is high horsepower ratings with a poorly designed snow throwing system?
Check out some models here http://www.dontshovel.com/snow_blower_comparisons.html http://www.consumerdemocracy.com/phelp/cd4/listPosRevs2B.aspx?catId 96
If I was buying a new machine, I'd base my decision on features, size, drive type, and what is important for my situation. The manufacturer will couple the right sized engine to perform with the design of his machine. A half HP difference is going to be not noticed, but a clogged chute will piss you off every time.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

For the types of engines generally found on lawn equipment, comparison of new engines and old engines of same brand and displacement is a valid comparison. These are utility engines designed to run at optimum RPM's while in use. A car engines is vastly different in it's requirements.
If an old snowthrower with a 13 hp Briggs engine is 350cc, then a new 350cc Briggs powered snow blower will be about the same HP.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

B & S is using the foot pounds from what I've seen. an 8.5 ft lb is 6.5 hp 11.5 = 7.5 hp 15.5 = 11 hp
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote in message

This is the most useful of the information supplied so far. I am going to make note of the ft lbs/hp ratios as the foot pound rating is the most popular of the ratings around here. The displacement ratings are almost useless in my opinion.
Thank you.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 10 Oct 2009 11:19:38 -0400, snipped-for-privacy@dog.com wrote:

Unless the old 350cc 13hp Briggs is a "side valve" engine with 5.6:1 compression ratio, and the new 350cc engine is an overhead valve engine with 11.5:1 compression ratio - which MIGHT be a 18HP engine.
Numbers just picked out of thin air, but the principal is there.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 10 Oct 2009 19:36:45 -0400, snipped-for-privacy@snyder.on.ca wrote:

The principle is pretty gaseous as well. In the real world, the old and new 350 cc engines will have about the same HP. Seen any snow blowers with Briggs or Tecumseh engines that call for premium gas lately? Ever?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 10 Oct 2009 22:28:39 -0400, snipped-for-privacy@dog.com wrote:

You are blowing smoke. Because you don't know anything about engines. My numbers were a bit high. A 20HP Intek is 8.8:1. A 25 HP Kohler Command is 9:1, and the Briggs Animal runs 9.5, 9.7, or 10.0 :1 depending on class.
From Popular Hot Rod's tech pages:
Basics Increasing the CR produces an increase in output throughout the rpm range. It is also worth an increase in fuel economy. If a longer duration cam is installed, raising the CR at the same time can be worth even greater dividends than these two moves considered separately. When the CR is raised, peak combustion pressures are increased. As a rough rule of thumb, cylinder pressures are about 100 times what the CR is so, from a 10:1 engine, we would expect to see about 1,000 psi of peak combustion pressure.
Cylinder pressures and output will increase as the CR is raised, but what is less obvious is that the increase in compression also increases the engines thermal efficiency. Thermal efficiency is a measure of how effectively the engine converts heat into mechanical power. To appreciate this it is better to consider the engines expansion ratio (ER). This is the opposite side of the coin to the CR and describes what is occurring as the piston moves down on the power stroke rather than what happens as it moves up on the compression stroke.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

This is perfectly true. Engines of the same displacement can vary greatly in power developed due to the ratio of diameter of piston to the length of stroke, valve configuration, exhaust tuning and other factors.
--
Ron


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 11 Oct 2009 10:26:37 -0400, "Worn Out Retread"

But in THIS category of engines, that isn't generally a factor. Old and new Briggs utility engines of the same displacement will also have similar power characteristics.
You probably won't find a snowblower with a turbo option, and lowered suspension, either.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 11 Oct 2009 17:06:26 -0400, snipped-for-privacy@dog.com wrote:

The difference between a side valve and overhead valve engine of any displacement in any application is generally considerable. It IS a factor, as anyone who is fammiliar with small engines will know.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 11 Oct 2009 22:11:11 -0400, snipped-for-privacy@snyder.on.ca wrote:

Absolutely not a consideration in a snowblower engine, which is run at two speeds. Stopped and Full Throttle.
Don't bother with a reply unless it actually applies to snowblower engines specifically. Hint: Snowblowers are not motorcycles.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 12 Oct 2009 06:24:16 -0400, snipped-for-privacy@dog.com wrote:

See my later post. I have not been talking motorcycles. I've been talking lawn mowers and snow blowers.I have been a small engine mechanic. Worked for an Ariens dealer back before OHV small engines were available. Have also been an auto mechanic for many years. Have owned and worked on flatheads as well as OHV and OHC engines and I know the difference, and the advantages VERY well.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Worn Out Retread wrote:

Unfortunately, not at all precisely, no...thanks to the dam lawyers :(
One can _VERY_CRUDELY_ estimate hp at about 60-70% of torque.
The relationship I recall (I'd have to go off and think again to re-derive the denominator) of hp ~ torque (ft-lb)*rpm/5250 which boils down to the above since most ratings are at 3200-3600 rpm.
Unfortunately, that's about best one can do other than simply try to find similar engine w/ known rating and compare based on displacement. Problem there is that tune and emissions requirements, etc., make that comparison as variable as the above.
Earlier Northern Tool catalog still listed an unofficial "old hp rating" as well but I just looked and the last one doesn't. Now I'm hoping I didn't throw the old one away and lose that cross-reference.
All in all, it sucks to guess how to compare even worse than before when ratings could be tweaked--at least you knew what Sears was doing w/ "peak" or "instantaneous" horsepower; the torque ratings might be absolutely accurate but they're still nearly useless as a comparison to previous ratings and certainly there's not even the same measure used if only provide displacement in one and torque in another.
--


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Multiply the old rating X 5252 and devide by 3600 and you have the torque rating of the old engine to compare. Virtually all of the old engines were rated at 3600 rpm.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

So that works out to be approximately 70% of the rated torque if rated in foot lbs. which would be easily calculated while browsing different models. Someone else gave some equivalents of torque and horse power and the figures pretty well agreed with what you have given.
Thanks
--
Ron


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I had an eight horse power MTD blower and for most most jobs it was perfectly adequate. Now that I want a new blower, I don't want to buy a machine that has less power than the old one but the published specs are just plainly designed to confuse the buyer and there are very few web sites that do much to untangle the mess of misleading information.
If all you are doing is clearing 6 inches of snow off a driveway that is one thing but when the snow plough comes by and dumps a mess 2 feet deep and 6 feet up the drive, that small snow blower is just not going to get the job done without nearly blowing its guts out especially if the material to be cleared has had any great amount of salt added to it making the mess very dense and therefore heavy and difficult to move.
--
Ron


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Worn Out Retread wrote:

They are just trying to pull one over on us by frigging up standard ratings in the US. CC's equate more to Cubic Inches. Foot pounds equate to horsepower. Multiply horsepower by 33,000 to get foot pounds. It's just another crooked business tactic to screw you over.
See the chart: http://www.geocities.com/MotorCity/Show/3753/convert.htm
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Van Chocstraw wrote: ...

cc and ci are both displacements, yes.
torque and horsepower aren't the same units at all---

So a 3hp lawnmower has almost 100,000 ft-lb of torque??? Amazing! Them are some stout crankshafts...
Actually hp*33,000 --> ft-lbs/minute, _not_ ft-lb (as the table shows). The "per minute" part is significant here.
--
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.