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

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.

Yes, it would be considered voiding the warranty, but I only turned the governor one complete turn.  I know exactly where to put it back if an issue comes up.  Truthfully, 80-100 RPM's was so little, you almost couldn't hear a difference in the engine.  It's such a slight amount, even with a sharp ear, I had to check the RPM meter to know exactly how much it actually went up. 

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. 

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.   

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.

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

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.

I just realized that exact thing just before going to bed, exactly what you posted.  What made me realize this was because we were trying to find engine specifications for a Tecumseh 8hp l-head engine, but couldn't.   Why can't any of us find it, because it doesn't exist.  A Toro 828 LXE is actually a 9hp L-head, the model engine number proved it.  So anyone that has purchase this snowblower, you can feel a bit happier you have a larger engine that you didn't even know you received, but due to an industry wide marketing ploy, you paid for it somewhere along the line.  As you pointed out, Marshall, this is obviously an industry wide thing and certainly some type of marketing ploy is at the bottom of it.  I hope I'm not jumping the gun here, but it seems that because I felt my engine was running a bit slower at operating RPM, this ordeal seems to have uncovered one of this industries dirty little secrets, I think.  I also fully agree with you, as long as the machine does what is expected, I have no problem with it.  Lets see what tomorrow brings.  Thanks again, Marshall.   

        Do you have have to change the Jet or do you change the carb assmbly??

If, the jet, I assume it has to be the high speed one. Am I correct ?

                                                                                             Fred  

As the tech explained to me, jetting does it all.  He didn't say the carb assembly has to be replaced, strictly jetting.  In fact, I did specifically ask about the 10hp engines having the same 318cc's and what makes it a 10hp as opposed to an 8 or 9.  Is it a different crank or muffler and such that Tecumseh uses; he was very insistant about it being jetting.  As for exactly what type of jet or the jet size, one must look in a service manual or find the exploded views of a specific engine.  That will tell you the jetting you need.  Re-jetting actually is pretty easy.  I used to do it on my twin cylinder, twin carb Skidoo 500cc snowmobile.  Jetting was crucial on those recreational machines because you really wanted to match the carb jetting to the altitude were going to be playing in.  Hope this helps a bit.  Maybe someone can locate the service manuals for us so we can order some jetting, assuming some want to play

Terrapin, try not to chop the throttle down so quickly.  Easing the engine down from operating RPM will stop it from backfiring.  If you do make a jetting change, please let use know.  Thanks.

John

Ust to re-jet the Mikuni carbs on by bikes and my Merc outboards to gain HP, worked best with air intake and exhuast flow increased to match.

    Based on your info, Toro is charging $100. 00 more for the 1028LXE over the 828LXE, just for a JET difference!!

Sounds like Toro is ripping off the public!!

Greater HP out of the same displacement, means shorter engine life!

                                                                   Fred      

I'm not thrilled either about this, but I believe it is just as Marshall pointed out yesterday.  This is an industry wide thing that goes on and I have no doubt Briggs & Stratton ranks their engines in the same manner.  As for Toro, they don't make the engines, they purchase them from Tecumseh.  In fact, any snowblower manufacturer that uses Tecumseh engines are doing this, Ariens and the others as well.  As I said before, maybe this is one of those dirty little industry secrets we've discovered.  I'll get my hands on the real service manual and look at the parts myself before I make a final judgment.  Of course, paying very close attention to carburetion components between engines

            I know Tec makes the engine. But is Toro paying $100.00 more for the engine?

No way!  Maybe $5.00 more. Still a RIP OFF by Toro and the Rest!!

                                                                            Fred   

the tecumseh ohv engines arent really that new.

they just have new style carbs on them.built this way to pass emmissions regulations.

as far as the engine producing more power with a larger jet thats simple enough.the jet they are refering to is what is actually called the main nozzle .its a pink colored tube held in place with 2 o rings right up the middle of the carb.cost is very resonable ,couple bucks at most.

the tricky part is going to be getting one.

you will have to wander around a bit and copy the model and serial numbers of a new machine.then see your friendly parts guy and tell him that you left gas in your machine ant it turned the carb gummy.

of course the only piece thet really gets rotten is the main nozzle.

they may just sell you one that way

if you promise to behave i will get part numbers for the nozzle and even check  some other stuff in the carb and engine

the bowl nut on these newer engines can also affect performance if gummy but i think they are the same on the 9 10 and 11,but ill check part #

later snowshoveler

Where the heck have you been? Glad you haven't missed all the fun and it looks like you stopped by just in time.  That sounds great about the part numbers.  It would save me a lot of work getting manuals.  I'm curious, what if the consumer simply wanted a carb rebuild kit and you had the model number of the snowblower? Don't you get all new jets or the main nozzle with it, or do they expect you to just clean and reinstall them and simply supply all the gaskets?  BTW...I'll be real good At least I'll try.

and we all know that gas will rot in one of those real fast.

seems that the more different metals you put in a carb the faster it goes sour ,then things get messy.

im still unsure of the horsepower difference,i think its more than just the carb.

im betting there is a bore and stroke change.

ill know tomorrow,soon as i get to the microfiche cards.

hmmm i feel like a secret agent...

later chris 

the 8,8.5,9, 10, 10.5,11L heads all have the same piston... part # 35776a

the 10,11,12,12.5,13 ohv all have the same piston...part #40011

only differences i could find (and i might add i was on my lunch break) was in the carb.

the bowl nut (aka high speed)  part #s 640005 ,640024 ,640012 ,640137. sells for6.56 to 11.46

and main nozzle (aka plastic tube) part # 640005 ,640013.sells for 1.73 to 3.53

all prices are canadian and subject to change without notice bla bla bla ha ha

so it would seem that there is little difference between the engines.

next i went to the service manual and found that the l head engines all have the same bore and stroke but there are 2 different

cubic inch displacements .

didnt get to look for the dislacement info on the ohv engines.

so far its kinda interesting

later chris.

ps i dont know which carb takes which nozzle or bowl nut...i will need engine spec numbers for that.

Marc 

                                                                                                      18 Degrees

Degrees, I'd second that carb. 

I too searched & found out that there WERE different head/piston/connecting rod/carb combinations. That line the Tecumseh rep gave about jetting is HOGWASH. You guys are too quick to "jump on the bandwagon". Chris (Snowshoveller) is the only one besides me that realizes this. On a single cylinder, small cubic inch (15 ci?) OPE engine, you just aren't going to pick up TWO or THREE HORSEPOWER by a jetting change. NO WAY. I've changed jetting on automotive engines & dynoed them - I have found that I never gained more than 10-15hp on a properly carburated engine. These engines were all in excess of 400 cubic inches, mostly Pontiacs (400, 406, 428, 434, 440, 455, 462, 473, 480, 496ci) powerplants. Those "odd numbered" ci displacements are different rod/stroke/piston height/crankshafts to obtain some LARGE displacements, and better rod/stroke ratios for high RPM drag engines (6500 RPM+). These Tecumseh's have about 15 cubic inches, so I want someone to provide me with PROOF that a jetting change can yield 2 or 3 more HP on such a small engine. Its done by changing a COMBINATION of other engine components that will change: compression ratio, head flow, higher CFM carb (CFM=cubic feet per minute, a measurement of airflow). These items will provide a small, believable hp increase. Carb jetting alone on a one-lunged engine will not.

Mods - if you can go back (if possible) to WTB & obtain the thread where I posted my findings, it may shed some light here. I spent quite a bit of time researching this & wish not to "reinvent the wheel".

Nuff said...

Marty

Even if its THIRTY cubic inches, a jetting change will NOT yield 2 or 3 hp...

Marty

Even if its THIRTY cubic inches, a jetting change will NOT yield 2 or 3 hp...

Nobody has said it would.  To keep confusion, if any, to a minimum, I was correcting the 15 cu. in. in your post to exactly what engine sizes are in question. 

Let me know and I will go get it and copy it here....

C

This is a quote from a friend who deals with Tecumseh engines.  He too has been trying to get a few questions answered for me and spoke with a Tecumseh rep yeserday.  Below is what he was told by a different tech than I spoke with.  

Richie this is straight from Tecumseh engineers. There is no difference between a 8 thru 11 hp Tecumseh snowblower carb . The difference is in the intakes and valves. But there is no difference in the carbs. Don.

Everything is the same on an 8-10, including carburetor, jetting, head, crank, exhaust valve, intake valve, cam shaft.  The difference is that the piston and connecting rod are different.  I was also told from a mechanic that works on these engines that the Tecumseh 11 hp OHV engine uses a new cheaper type of carburetor.  So, is it really worth the extra money for a 10 hp L-head, that is up to the buyer.  Is it worth the extra money for the 11 hp OHV engine, I'd always prefer an OHV over an L-head.  Just depends on how deep your pockets are.

Hi there Marshall,

       thanks for all your long work in research.                                             18 degrees

The obvious-Every engine has a spec#.Regardless of the stickers if the spec #'s are the same the engine is the same.

Not sure about Tecumseh but if you remember the Briggs -Simplicity situation last spring we confirmed that the 9 through12 HP Briggs were the exact same engine. We also found that several of the engines in that run did not appear in the Briggs catalog of engines. The phantom models were produced for Simplicity by Briggs on special order and were simply re:stickered. If anyone missed that discussion search for the thread "Converation with Simplicity".

Marc  

I'm told that the difference between a Mercury 50 hp 4-stroke Outboard and a Mercury 60hp 4-stroke Outboard is a carburator restricter plate (reducing the air/gas mixture and thus making a potential 60 hp motor into a 50 hp motor).  I personally haven't verified this.... but I know an authorized Mercury outboard mechanic who told me this in confidence.

*(:>)*

Hi Nate,

What  may be taught to a companies sales force or technicians and what the public (consumer) is sold are two different things.  Last year Marc discovered just how deep all this goes from his quote below.  

mml4 wrote:

Glad to see this post is still being tossed around.  Hopefully in the last year it has helped save the consumer a lot of money by not purchasing the higher horse power engines.

Richie

I bought a 9HP OHV, 27 in cut snowblower.

The HP rating was on the blower body, not the engine!!

When I checked  my engine spec with Tecumseh, I was told that I have an 11 HP OHV Engine!!!!

Also going to their web site, my Spec numbers on my series engine is an 11 HP engine.

So I paid for 9 HP and got 11 HP!!!

Not Bad.

                                                                      Fred 

Hi Fred,

That is really great!  Which blower was that, the Husquvarna? 

Yes it was!!

                                  Fred

 Also, what is the estimated gas consumption measured in gallons-per-hour while running the engine on high speed as recommended by the company?  The gas tank holds one gallon.