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

Recently I installed a tach/hour meter on my Toro 828 LXE and found theat the maximum operating governed engine speed was 3,300 RPM spiking to 3,330 RPM's.  I actually felt it was running a bit slowly but decided to use it, as is,  immediately after it stopped snowing on Sunday.  Well, we had about a foot of snow on the driveway with some 18" drifts, and the EOD was about 21", thanks to the snow plows.  The machine handled it perfectly until I got to the  EOD.  While blowing through it, the Tecumseh engine wanted to stall.  Nobody can tell me this is normal on a high end snowblower like this.  It was 15 degrees and it was freshly plowed loose snow.  If it had been wet, I would have been able to look past it.

With all the research I've done in the last 24 hours, I am nearly convinced that the governed RPM set by the manufacurer may have much to do with the horse power rating they give them.  The Tecumseh 9hp-11hp Snowking engines all vary greatly in governed RPM, as low as 3,350 up to 3,700 on the 11hp OHV version.  When I see that the Tecumseh 9hp is 318cc's and the 11hp is also 318cc's, where are they getting these horse power ratings from. Making an engine OHV gives you that much more power?

Well, I wasn't able to find the governed operating RPM for my Tec 8hp L-head engine, and given the wide margin of RPM's on their engines, I decided to raise the operating speed of mine to what I felt it should be.  Initially I raised it to 3,600 as it was suggested to me to do, but I felt this was too fast by the way it sounded.  So I then reduced it to 3,400 spiking to 3,430.  Roughly 80-100 RPM's higher than what it was. 

The result of this, I took it out into the street to the 28" high, five foot across snow drifts left on the side of the street from the snowplows.  These drifts are 8" higher than my auger housing.  The sun was out and the snow was nice and moist, perfect for making snowballs.  I raised the throttle to operating RPM, put it in 1st gear and off I sent it into the drift.  The chute started to toss the snow some 40 feet across the road and you could now hear the engine under a load.  The difference this time is that the engine was maintained speed and not a hint of it wanting to stall.  In fact, the tires actually broke loose and I started pushing it into the drift to the point it began tunneling.  The entire time the engine didn't faulter for a second and I actually felt I had a 10 hp engine on this great machine.

What a difference a very small increase in governed engine RPM makes.  At one point on Sunday I was upset with myself for not shelling out the extra money for Toro's top of the line 11 hp OHV version for over $1,600.00.  Well, after how this experiment worked out, now I feel I just saved myself over $400.00 because this snowblower can go through anything now.

Hey Emmo,

Toro has several model numbers for my engine.  The LH31SA or HMSK80.  Going by the models you shown on that link you posted, it appears I adjusted my governor inbetween the lowest and the highest RPM of those 3 motors.  Not bad, thank you. 

By Emmo's link, it appears it depends on the model you have.

I'm not an expert on these engines but I do believe it possible to get an extra horsepower from OHV's and jetting.

Glad to hear you got it working better. 

Hi there Marshall,

I do believe OHV engines are more efficient, therefore afford you a better more powerful engine, especially in the area of low end torque.  But how much extra do they afford an engine?  From what I've seen, there appears to be a lot of playing with RPM from model to model.  What are the manufacturers doing to these engines to increase their advertised horse power?  If they are generally leaving the cubic centermeters the same, typically 318cc's, is simply increasing the operating RPM where a good portion of this horse power comes from?  I know on 2-stroke engines I used to race, changing exhaust mufflers has a drastic impact on engine performance, from a snail to a jack-rabbit just by switching a "can" type muffler to a high performance tuned exhaust. 

JoGo, right now that seems to be the $64,000 question.  I'd like to think it is that simple, but I'm not done investigating this to make a stand.  I'm trying to get my hands on the exploded view manuals for some of these engines.  I want to look at the carbs for starters, I'm curious if the jetting is the same, and I want to see if the heads are the same part numbers.   

Richie wrote: Hi Richie,

In Emmo's link it show's three different 9HP models of the same engine, running at three different RPM's. Although RPM's can effect how much HP an engine puts out, if it has the extra HP available, I don't think RPM's are what make or account for the extra horsepower on an engine rated at higher HP. So, I believe they are gaining extra HP through other means, be it OHV's, jetting, heads, breathing, pistons, exhuast, etc.

Just my .02 cents.       

Certainly part of the difference is pure displacement. 

The 11hp L-head has a 3.312X2.532 Bore & stroke  (358 cc)

The 11hp OHV has a  3.125X2.532 B & S  (318 cc)



YET both of the 9 hp motors have the same 318 cc displacement.

I'm sure it's a combo of displacement, heads, rpms and probably carbs.

Maybe lint or Marty or whoever has seen the guts of a bunch of these could enlighten us.

Hi again Marshall,

I'm sure you are correct but Tecumseh engines models are confusing me.  For example, Nibbler asked for a part number or serial number.  I just came from the garage and found the model number stamped on my engine.  It is, LH318SA.  There is also a
"Spec" number, 156563G.  Here's the confusing part, the link Emmo was kind enough to dig out for me shows ALL 9hp models, yet Toro says this is a 8hp engine.  So I have a DE-rated 9hp??  Is Toro calling a 9hp an 8hp for EPA reasons???  Also, speaking about Emmo's link, you'll also notice that the two engines with charging systems have a much higher governed operating RPM than one without lighting or an alternator.  If I go by those, now that I confirmed my engine model number, I set my governed engine speed lower than what it should be.  In fact, that link may actually prove it certainly was way too low.  What do you think? Thank you all for the assistance you are giving me.

Time for someone to get inside information from the manufacturer...

An inside informant !  


Dave...

How about it T-Man? Inquiring minds want to know!

Marc

Just reviewed Emmos' chart and found three different crankshaft service #'s. I assume this could account for differences in HP for engines of the same displacement. . This could mean the weight of the rotating mass in the engines are different and could also effect HP.

Marc

Richie wrote:
Yes Ritchie, You are right. No messing with stuff we shouldn't.

But where exactly is that screw? I don't need to adjust it much. Just until it throws further than Ross's machine. You know the guy across the street with the Porcshe.


Do you think a Tec L head can hold 15 pounds of boost?

Or how about just a little taste of nitrous when it's nice and sunny on the weekend and everyone is outside brushing off the cars?

Hey Rob,

Now you're talking I have no problem helping you break a rich guys chops  Remember, I felt my Toro was running slower than it should and I also have the tach/hour meter installed as a guide.  But, if you must experiment; just inside where the red throttle lever is, about a 1/4"-1/2" inside that slot the lever rides in, you'll see a very little silver allen head screw.  I turned it about one turn clockwise or less.  One important thing, you have to have a very good flashlight pointed in there when doing this.  Even with the light, its actually hard to tell it is even turning.  Keep your eyes sharp while doing it.  I'd hate to have you come back on the board and tell us you made the adjustment and the engine turned at 4,000 RPM's   I also did this while it was running at max RPM so I could hear what was going on in addition to cheching the RPM meter.