Engines in Snowblowers - Advice


Dec 5, 2003 (Updated Nov 21, 2004)


The Bottom Line The engine in a snow blower makes a difference, here's why.

Snowblower Engines

While the other reviews in Epinions advice cover snow blower features nicely, little is said about the small engines used in snow blowers. I'll discuss snowblower features in relationship to engines.

There is a vast difference in the quality of a snow blower engine and reliability based on certain features. Most small engine manufacturers make a variety of snow blower engines. Snow is often very heavy when packed, and a powerful engine can help cut through the plowed-in snow at the end of a driveway.

Types of Snowblowers

A single stage snowblower uses the augur to pull itself through the snow, so less torque and power is needed for these. The single stage's augur will last about 10 years with significant use, so expect it to wear as it scrapes the concrete. Single stages clean very well.

A single stage snow blower (augur) generally has a 3.5 to 6.0 horse power (HP) engine, while two stage blowers generally have a 5 horse power to 13 horse engine, and may be self-propelled. Power steering in the larger self-propelled versions requires more power, also. Many owners like the tracked rather than wheeled two stage snowblowers. Expect these features at the 13 HP super snowblower models, and consider them essential if you have a big curved, steep driveway. A larger propelled blower without steering (power or not) is hard to corner easily.

A smaller person (100-120 lb) with a larger self propelled, power steering, and tracked snowblower is better off than with a smaller wheeled, self-propelled, and non-steerable snowblower that must be forced about or pushed on a big steep driveway.

I am told that "electric motor" small single stage snowblowers are fine for small areas, and are generally better liked than their gas counterparts. An electric motor is a reliable powerplant, especially in very cold weather. Some call these electrics - power shovels.

An underpowered 2 stage snowblower is usually poorly rated by it's owners. A 5 HP two stage may be insufficient for significant snow. Mine is a 7.75 OHV powered 2 stage snowblower (self-propelled), and I would not want less.

Types of Engines in Snowblowers

Today's small engines have electronic ignition, rather than points and condensers. It's on almost every engine, and isn't a special option of an engine anymore, like it used to be. You may look for an electric starter as a standard item, it does not cost that much if it's already installed. It's a nice feature at 30 below. Engines in snowblowers are winterized for cold weather use.

Most small engines have an aluminum block, but if the engine has an aluminum block, it should have a cylinder sleeve (usually cast iron). Don't assume that a engine does have this sleeve, many smaller engines do not. The sleeve protects the cylinder from wear, which is pretty quick with an aluminum cylinder.

There are a few major engine designs used today in gasoline-powered blowers, which are side valve (2 and 4 cycle) and overhead valve. Side valve engines (all 2 cycle engines are side valves) that can produce up to 13 HP; will run harder, hotter, dirtier (EPA rates them up 30 times more pollution) and a lot louder. They are named side valve engines because the fuel mixture and exhaust enter and leave the cylinder from the side.

The 2 cycle side valve engines produce power on every other cycle, and so have a smaller cylinder than a 4 cycle engine. They generally don't last as long and are often hard starters, but have few moving parts and are cheap to fix. The 4 cycle side valve engines are common in larger HP and higher torque applications. The smallest augur driven snowblowers have 3.5 HP 2 cycle engines. A two cycle engine will require you to mix your gas with oil. (Note: As an exception, Tecumseh makes a 7 horsepower 2 cycle engine with a cast iron sleeve.)

The cycles of an engine in an 2 cycle (or 2 stroke) engine have a power/exhaust stroke and the compression/intake stroke. The 4 cycle engine has separate strokes for the power, exhaust, compression and intake strokes. 4 cycle side valve engines are common in lower cost, higher horsepower snowblowers. You may hear that a 2 cycle engine has more power for a given displacement than a 4 cycle cycle engine, which is true, but this fact is essentially useless to you. A 2 cycle engine is lighter and smaller by nature, and is primarily used as a trimmer or chainsaw engine. It is built small to carry. Single stage snowblowers use these engines in the lowest cost versions. A 2 cycle can be a hard starter and is especially susceptible to fuel quality.

Pollution in some states is pushing the banning of side valve engines, which generally waste 20-30% of fuel as unburned exhaust.

Overhead valve (OHV) engines have valves like a car engine on top of the cylinder. These engines have valves that open and close in the engine in each stroke. They are more expensive engines, but easier to start and quieter. These are generally 4 cycle (4 stroke) engines. Torque is improved, and most owners prefer these engines. A 9 HP side valve engine is generally not as good an engine as an 8 HP OHV, based on the torque and reliability. A two-stage snow blower requires torque to move snow and it's own weight through the snow. Some smaller snow blowers have these in lower HP models down to 5HP. I switched to an OHV engined Sears model 88775 and dropped 20 decibels in sound, yet it feels more powerful than a 9 HP side valve. My older side valve engine hit 105 decibels, while the 7.75 OHV Sears hits about 75-80 decibels. Briggs and Stratton calls side valve engines, "L" head engines. Most OHV engines though not all, will have cast iron cylinder sleeves.

Note: Honda engines have changed in the non-commercial models to nylon bushings in the OHV. A reliable engine design should not be mucked with.

Horsepower is different from the torque of an engine. Horsepower is the force applied at speed, Torque is power under load to "turn" the rotating shaft. A higher torque engine with the same horsepower as a lower torque engine will be less likely to bog down under load, a key feature of a snowblower cutting into plowed snow. OHV engines have higher torque as a result of the design on the engine. The compression cycle is higher for a longer part of the cycle, (improving compression) so more torque (twisting force) is available. The longer power stroke in OHV means more energy is extracted. Torque is important in two stage blowers, which usually have a transmission that pushes the machine (for the self propelled versions).

Fuel injection in OHV engines improves the fuel usage and reduces pollution while giving more power to the engine, look for this in the best small gasoline engines. This is better than have a carburetor, which can flood and uses more gas. (This is often designated as "OHVI".)
Carburetors in winterized engines are often of a different design than a normal engine to protect against icing up.

Diesel small engines are available as a replacement engine, and many owners switch to a pull or electric start diesel for high use machines. A diesel engine is not a poor choice in a snowblower due to the increased torque, which keeps the engine from bogging down.

Generally an OHV engine will last much longer, and be more pleasant to run for a large area, while the cost is rarely more than $200 more in price for equivalent gasoline engines under 10hp.

Engine Manufacturer Designations

The designation of some engine manufacturers to have a brand name like "SnowKing" for Tecumseh has little to do with the features or type of the engine other than it is designed for cold weather. Read the features of the engine, rather than the brand designation. The word "King" is a marketing designation. The premium engine lines may be designated with specific names like the Briggs and Stratton "Vanguard" or Tecumseh "SnowKing Premium Line". On Tecumseh engines installed, the "Premium" designation may not be used, so look at the features of the engines. Almost all Tecumseh OHV engines are their "Premium Line" engines.
Some manufactures put in a oil filter for a pressured lubrication system (have an oil pump), this is only on the best engines. Most small engines are "splash" lubricated, so parts splash into an oil bath. I don't see a problem with a splash lubrication for a homeowner who changes the oil every 50 hours.

Making a choice

Choose the snowblower type with the features you want and then choose one with the engine you can "live with" based on how much usage you expect. Check the other snowblower epinions for info on features like heated handgrips, and construction. You may be able to tolerate a loud snowblower, if it only snows occasionally and you have a small area to clear. A large area in northern states may lend itself to a quieter engine or hearing protection. One other feature you should look for is a good manual with a parts list. Some manufacturers list every part number in the manual and repairing it is easy. (I take a indelible marker and write the air filter, shear bolt, spark plug part #'s on the blower. I mark an arrow at lube points.)

Some Tips

Finally, snowblowers are occasional use items that should have fuel stabilizer added to the gasoline for storage. Change the oil often and check lubrication. Never use any bolt for a shear bolt, except what the manufacturer recommends. Shear bolts are supposed to break off, and the augur won't turn until a broken bolt is replaced. Keep extra bolts on hand. I keep a can of starter fluid on hand for less reliable engines or really cold weather, but never use starter fluid in a 2 cycle engine.

Don't use gasoline additives designed for cars in a small engine, the fuel lines in many smaller engines are rubber, not the reinforced neoprene used in cars. Some fuel dryers and carb cleaners eat up (or melt) the hose walls and gum up the engine. (Check the snowblower manual)

(Hint: I use a boater's "Topsider" to change the oil avoiding the mess. A topsider is an oil pump that siphons the warm oil from a engine through an inserted hose.) After the engine break-in period, first 5 hours or so, replace the oil.

This fixed version replaces the prior opinion, which got deleted.

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