Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I have a 15 year old Ariens . ST 924. It came with a 8 hp Techumseh. I'm planning to retiring the engine .  Which is better  a Subaru Robin sx30  with 9.5 hp 4000 rpm max , a Honda GX 390. or a 305 Briggs?  The Subaru does not give me as much  HP as the Honda, but I get more rpm. If i put Clarences kit on my unit then is will be even better. The Briggs is the cheapest , but I do not really know its power output They only tell me 305 cc and 13.5 lbs of torque. My Techunseh is a 318 cc so I guess the 305 Briggs is close to 8 HP. I prefer 12 volt electric start. The biggest Briggs is there 342 16.5 I was considering that one too.

Honda, Honda, Honda! Yes hp does matter! IMO go as big as possible but in all reality the 305cc on a 24" unit will kick ass! Nevermind the honda or subaru, you cannot lose either way.

My only concern is where did you get that you tecumseh is 318cc? I dont think so! 8hp is give or take 250cc, the 305 briggs is 10hp......342cc briggs is 11hp, etc.

stresst wrote:
My 318  Techumseh.  came with my blower 15 years ago. Remember now mine is a flat head. Newer engines today are OHV or OHC. They make more power with less cc

My two cents would be. Honda, no question.  You simply can't be their ease of starting in any conditions.  And the way they run.

"Does HP Matter?" no. No. NO. NO.
Ignore HP, it is nothing but a number made up by a salesman to compare steam engines to horses. Torque is what you want. Torque does the work. Snowblowers only perform under load and how much load the engine can handle is determined by torque, not by horsepower.
If you're trying to decide which engine will give your blower the most power, compare them by looking at the torque curves. The highest number between approx 3200 RPM and 3600 RPM wins. Your engine will run at close to 3600 RPM most of the time, but as soon as it hits some heavy/deep stuff and starts to bog down, that when you need torque. Don't be surprised if the engine that has the most torque in that band is not the engine with the highest HP rating. It can happen.
Too many manufacturers played the numbers game to get the highest HP rating possible, they got caught, now they can't do it anymore. Ft-lbs @ RPM is all that matters.

Bill_H 
+1

Without horsepower, torque will just sit around unmotivated and does nothing.  :)

You need both to do the work.  The Indians aren't going to do anything without a chief. 

Bill_H wrote:

I hear you about the hp numbers! Technically you are 100% correct but for a newbie its gets too complicated imo. Much easier to say yes you need HP!

You could just paraphrase Carrol Shelby and say " HP sells snowblowers, Torque throws snow."

stresst wrote:
As Steve pointed out (great post, BTW ), HP is (was) a sales gimmick. And newbies better learn fast because since they lost that court case the manufacturers aren't spouting horsepower numbers anymore. Now it seems like they are advertising displacement, as if more displacement means you'll get more power - you might, but it's not directly related.

IMO.... if money wasnt a consideration id go with the Honda 100%...if u wanna save some coin go with B/S the 305 is a good engine but id go with the 342 if possible...either way u cant go wrong..if it was me l would get the briggs 342

Just to pile it on...that's one reason why Diesels are popular to do serious work.  High torque compared to the HP figures.

I believe that the Briggs engines are an excellent choice.  The 305 with 14.5 torque  for blowers up to 27 inches.

and the 342 with 16.5 torque  for blowers over 27 inches.     I am referring to the engines built in the USA  and they are stamped  as built in the USA.

But it seems that the 305 and  342  engines (and other sizes) labelled "Polar Force engines By Briggs "  are  manufactured in China.

If anyone has other information on these Polar Force  engines., please reply.   Thankyou

Well, there's the formula most of us know about:

Horsepower = torque (in ft-lbs.) x rpm (typically 3600)
                                                5252

Thus, if you have a 305cc engine with a 14.50 torque figure, it comes out:         HP = 14.5 x 3600   =   9.94
                                                                                                                                             5252

The 5252 is a real figure, not just something made up to make us happy:       http://www.epi-eng.com/piston_engine_technology/power_and_torque.htm

See the end section of the article entitled "Derivation of the Power Equation (for anyone interested)".  It explains how the number 5252 is arrived at.  Very interesting.


Rearranging the formula gives us :

Torque = Horsepower x 5252
                rpm (typically 3600)

So, if you have an engine like the 10HP Tecumseh 358cc on my El Toro! 1028LXE, it looks like this:     Torque = 10.0 x 5252   =   14.58
                                                                                                                                                                                          3600

Do these figures seem good, realistic?  I think so.   The only thing I'm not sure about is that I've read that torque is supposedly measured at 3060rpm instead of 3600rpm.  Assuming that's the case, then how could we plug in a torque figure based on 3060rpm into a formula assuming 3600rpm, and expect a decent result?  That would change the above horsepower formula to a higher final result, assuming the torque keeps climbing all the way to 3600rpm.  Doesn't it peak out before that on these engines?   The torque formula is based on 3600 since we didn't start with a torque figure to begin with, so my result of 14.58 ft-lbs for my Tecumseh engine is based on the horsepower figure and 3600rpm.  And we assume horsepower is calculated on 3600rpm, anyway, so that 14.58 torque number seems to be right.  Also, assuming that a 358cc L-Head is equal in torque/horsepower to a 305cc OHV, that 14.58 is mighty close to the 14.50 figure we get from today's Briggs 305cc engines.  After all, the Briggs 305cc replaced the Tecumseh 358cc on the Toro 1028 (LXE going to OXE).  I hope I'm not losing anyone on this.  I find it interesting.

Here is an 11 HP Honda GX 340
Peak HP at 3600 RPM, Peak Torque at ~2400 RPM.
Most engines have similar torque curves.

coasteray wrote:
Careful.  HP is a function of RPM and torque at that RPM.  And peak torque and peak HP rarely, if ever occur at the same RPM.  Many times the peak torque occurs well below 3600 RPM.  See the example chart above.  I don't know what constraints manufacturers are under when reporting torque.  Probably, they can report peak torque at whatever RPM it occurs.

So, as you essentially state, it is key that you know at what RPM your torque value occurs.  Then you can calculate the HP at that RPM, but not necessarily peak HP.  If you know that your 14.5 torque is at 3060, then your HP is 8.44 at 3060.  Peak HP may be higher at 3600 RPM.  You appear to come to the same conclusion.

Honda Engines come with sediment cupsfuel shutoff, a throttle (most new machines no longer have a throttle the way your 15 year old machine did, and the B&S engine is probably made in China by coolies.

manjestic wrote:
That just does not seem right. torque with out HP behind it is useless . My 1" 1800 ft lb impact wrench has more torque than my wifes 2.3 engine in her car. If torque was the only factor then i could power my wifes car with my torque wrench. I DON'T THINK SO

bus708 wrote:
Measure your impact wrench's RPM under load.  Then we'll talk. 

I get 20 rpm full load   1800 x 20/ 5252= 6.8 hp    at 1 rpm stall speed i get  .34  hp which is nothing

bus708 wrote: You say your wrench is rated at 1800 ft. lbs. -- but at what RPM? You have to know the rated torque at RPM to determine HP. I suspect that 1800 is stall speed torque.
HP doesn't drive torque, it's the other way around.

BTW, 1/3 HP isn't nothing, look at the rating of the motor in your drill press. Nothing compared to an auto engine, yes.

http://en.wikipedia.org/wiki/Horsepower#Relationship_with_torque

  Referring to cars, Dan Gurney  said :  "   If 200 horsepower was good and 300 horsepower was too much, then 400 horsepower would be about right. "

My   Chrysler  300c  SRT8 is rated at 425  horsepower and it is about right.

The Tecumseh 9 HP was not as powerful as a Honda GX 270 which comes in about 8.5 HP.  IF the friction wheel and drive plate can be made to transfer the power and not slip from 15 years of wear, this would be a wise choice.  The problem is the 15 years will have taken their toll on the friction wheel, and the drive plate making that unlikely at best.   The power is useless if it doesn't transfer to the wheels, that is what you need to concentrate on after 15 years.

New_Yorker wrote:
90% of the horsepower is used to move the snow and only about10% or less to move the machine.  If a human could push the machine into the snow that would be one person power.  The only time the drive system will see a lot of stress is if the operator tries to go to fast into too much snow.  If the operator uses the machine properly and matches the ground speed to the blowers ability to move the amount of snow in front of the blower the friction drive will see very little stress. 

If the operator goes too fast into more snow then the blower section can handle then the blower becomes a snow plow and not a snow blower. 

I put a GX340 on an old 80's Cub Cadet 8/26 that originally came with an 8hp tec flat head and it still has the original friction disk.  If you try to hold it back on dry pavement it will pull you down the driveway or if you can get a good enough grip on it it will spin the tires on dry concrete but the friction disk does not slip.

I would not have any concerns putting a gx270 in place of an 9hp tech flat head.

Carl