Rebirth of the Gasoline Engine


Manufacturers respond to the market with more reliability, better fuel efficiency and cleaner power

Many of us make that early morning stop at the Quick Mart for some of that fresh and precious fluid that keeps us going through our workdays. It energizes us. It gets us going so that we can get meaningful work done. It allows us to do make a living and on a grander scale to make the world a better place.

I’m speaking of gasoline, of course.

Gasoline is that dear and wonderful fluid that has allowed the development of small spark-ignited (SSI) engines and all the many different machines that we now use and depend on in the turf industry. Consider the many variations of the primary machines used to cut the turf. Or the many variations of the support machines used to clean, prune, edge, cut, carry or move things, including us.

But what of the claims as to how horrible these engines are and what horrific damage they do in terms of pollution? Haven’t there been changes made because of the EPA and CARB and all the new requirements? Have they been effective? Have they been worth the effort and cost?

Well, in fact, the changes have been substantial and have now been accomplished. As the engineers and regulatory folks look back on what has been achieved and breathe a sigh of relief; we all breathe a bit easier as well.

Understanding the Emissions Warranty

In order to ensure emissions compliant operation throughout the life of an engine, EPA requires that the engine manufacturer warranty any parts whose failure would directly affect the emissions output and potentially cause them to increase.

The list of these parts is typically quite complete as can be seen on the separate Emissions Control Warranty Statement provided with the engine and equipment by the particular manufacturer.

Interestingly, some of the parts listed (spark plug, air filter) would in a prior era have been considered nothing more than just standard maintenance items.

The engine manufacturer is required to provide service and replacement on all of these parts through authorized dealers.

The user of the engine is required to perform any maintenance or replacement of these parts, as might be noted by the manufacturer, in order for the warranty to remain in full effect.

Leading to Phase One

The birth of current SSI engines came about some decades ago with the ability to cast the blocks from aluminum and produce engines at a low cost and in high volume. Initially just single-cylinder and air-cooled, there are now, of course, twin-cylinder and even liquid-cooled versions available.

And for many years SSI engines were in fact quite simple and of modest technology. Such things as side valve design (easy for high volume production) and an overly rich fuel supply (effective for cooling the engine during the era of low fuel costs) were common.

However as the world progressed and expanded (more suburbs, more lawns, more parks, etc.) and we became aware of air pollution and the damage it did – and the sources of such pollution were identified and quantified – it became apparent that SSI engines were in fact a major contributor. This was true, to some extent on a per engine basis, but to a greater extent due to the considerable number of them in use.

Kohler Engines unveils vertical shaft, V-twin Confidant engines consisting of four models from 19-25 hp.
Photo courtes y Kohler Engines.

It started with CARB

The first inklings of this were around 20 years ago as California Air Resources Board (CARB) initiated regulations because of the severe air quality issues in the state of California. A handful of contributing factors were to blame: the high population (people and engines), as well as the unfavorable topography that does not allow the air to disperse very well. At times there the climate tends to keep bad stuff close to the ground.

Not to be left behind, the U.S. EPA started establishing regulations as well. Engine manufacturers, for the most part, welcomed the EPA’s decision. They saw the writing on the wall and were not keen on having to manufacture multiple versions of engines. National standards make things easier, whether it’s for automobiles or it’s for small engines.

The initial regulations were straightforward. Generally, the standards could be met by tightening things up a bit. Manufacturers responded by ensuring closer tolerances between internal components, confirming that the engines being produced were not too far out of specification and not running quite so much fuel through the engine.

Hustler mower powered by a Kawasaki FR691V V-twin engine.
Photos by Ron Hall, unless otherwise noted.

The race is on

But the regulatory and developmental procedure was set and in motion and there was more to be gained and the serious work had just begun. The small engine industry realized that a new hierarchy was being established. The sales guys might have cringed and worried that it wouldn’t be quite as easy to sell these great little engines as it had been before because the regulatory attention aimed at these small engines practically guaranteed they would be no longer be viewed as commodities where the low price wins.

Consequently, the engineers in the back rooms reacted as they typically might in looking forward for the most part to the technical challenges that awaited them. They knew their work was just starting and, whether they realized it at the time, the new regulations added to their job security. The newly anointed “emissions” guys took on a new status because they would be driving a lot of the development work in the coming years. The company would be basing resource allocation and investments on the advice of these individuals. Their role became crucial.

Briggs’ new commercial Vanguard 810cc already showing up on popular brands.

The need to reduce emissions levels advanced as Phase Two followed Phase One. It hardly surprised the engine companies that had become somewhat comfortable working with CARB and EPA. They had been in discussions about the feasibility emissions reductions with regulators and establishing reasonable targets and deadlines. They met individually and, on association, as a group.

Gasoline Engine Technology Races On

By Ron Hall

Kawasaki and other small engine manufacturers had a strong presence at the GIE+EXPO.

This past September, Briggs & Stratton hosted me and other industry journalists to Auburn, Ala., where we spent several hours assembling Vanguard 810cc engines. With the components neatly arranged on tables in front of us, we put them together. For the record, we appreciated the helpful guidance provided by Briggs experts.

Next we toured the Auburn plant where a select group of three Master Service Technicians (MSTs) were assembling and rigorously testing the new 810cc engines. The new line, which is rapidly growing, is dedicated solely to the 810cc engine (24 hp and 26 hp models). While 85 percent of all Briggs’ engines are built in the United States, this will be its first U.S.-built commercial offering.

As Briggs managers promised at Auburn, the new 810cc engines turned up on several of the industry’s most popular mower brands at the 2013 GIE+EXPO. It was also featured on the sleek new mower from industry newcomer Altoz.

Factories today are all about lean, precision manufacturing and assembly, layers of product testing, quality control and, ultimately, customer feedback and satisfaction.

I was greatly impressed with the cleanliness, order and processes within the Auburn plant (especially on new state-of-the-art 810cc line). Judging from the quality of the spectrum of small engines that power the commercial landscape market, it’s obvious (to me, at least) that competing manufacturers are hardly asleep at the wheel.

This was evident to me as I visited the booths of engine manufacturers on the floor of the mammoth GIE+EXPO show. The array of shiny new engines, from the smallest consumer models to the big commercial units, such as Suburu’s new 999cc, 35 hp EH90, was enough to warm the heart of any motorhead.

The Kohler booth featured one of the more fascinating exhibits, an actual Kohler Command Pro EFI sliced in such a way that you could examine its interior components. While today’s carbureted engines are vastly more efficient than they were even a decade ago (and they still predominate in the market), a growing trend in commercial mowing is electronic fuel-injected engines. Kohler touts its closed-loop system.

Tom Cromwell, left, President of Kohler Engines, and Kohler Company President David Kohler.

The message I heard from each and every engine manufacturer at the GIE+EXPO, was the same: mowing professionals insist upon engines that are reliable, durable and fuel-efficient. Sometimes the order is different, depending upon end users, but today’s small gasoline engines must deliver on all three promises.

As for trends in small engines, here are several that led to the development of the Vanguard 810cc engine, says Briggs:

  • Engine displacement is trending up to greater cc. The world of commercial mowing is increasingly “bigger, faster, more production.”
  • Engine compartment footprints are not changing.
  • New safety standards are impacting the design (ANSI B71.4 safety regulations)
  • Engines are increasingly built for durability and reliability, paired with attractive warranties.

Yes, diesel-fueled equipment has its place in commercial landscaping. And propane and, perhaps even compressed natural and batteries, will become more commonplace in powering our production units.

But don’t write off gasoline-powered equipment as the industry’s main muscle. It’s taken us this far and is not about to be replaced anytime in the foreseeable future.

Ron Hall is editor-in-chief of Turf magazine. Reach him at

Meeting the challenge

Changes had already started with the basic design of engines. The longtime side-valve engine just does not allow for an effective combustion process. Its days were limited. The better approach was to center the combustion process directly over the piston in the middle of the combustion chamber, which allows for a more complete burning of the fuel.

Also, fueling took on an even greater importance. No longer was a generous supply of fuel permissible with the excess “harmlessly” making its way out the exhaust as this generated high hydrocarbon (HC) levels, one of the bigger concerns for SSI engines.

Manufacturers began producing carburetors with greater precision and placed limits on the adjustable range of the jets with no chance for too much adjustment. The fuel delivery setting was carefully matched to the needs of the particular engine.

The new commercial Vanguard 810cc from Briggs produced in Auburn, Ala.

This resulted in better fuel efficiency, although, perhaps, it wasn’t appreciated as much as it should have been given the relatively low cost of fuel, at least compared to today. The EPA made it quite clear that if any parts of the engine that might affect emissions were in fact “tampered” with the violator would be subject to a considerable fine.

There would be internal changes as well, such things as improved piston profiles and enhanced piston ring positioning and a general use of better materials.

Another major requirement of Phase Two was the need to confirm that the engine was durable enough to meet the lowered emissions level over its expected lifetime of use. This required substantial operation and testing of the engines over what was now known as its useful life.

Phase Three arrives

Now the new epoch begins with the implementation of Phase Three, that features the adoption of such wonderful technologies as overhead valve (OHV), as well as the even more modern overhead cam (OHC).

And the newly required evaporative emissions requirements are fully adopted with such techniques as the use of low permeation fuel lines, treated plastic fuel tanks to minimize fuel permeation and in some cases a return to the noble steel tanks of yore. This might seem to be a minor matter on individual pieces of equipment, but it’s of cumulative significance because so many are in use. The effort and relatively low cost to reduce evaporative emissions is good.

What is a Small SI Engine?

When the EPA initially established regulations for spark-ignition (SI) engines for general off-road applications they separated the category into two groups.

The first would be those based on “automotive” type engines – already emissions regulated for vehicle use and incorporating fairly sophisticated technology, such as electronics, fuel injection, liquid cooling and that all important three-way catalyst that reduces emissions so well. They are expected to operate and be in emissions compliance for many thousands of hours. They require considerable durability testing to confirm this.

The designation for these is large spark-ignition (LSI).

The second group would include the typically smaller engines produced in high volumes for a huge variety of equipment uses and typically of simpler technology, employing mechanical operation, carburetion, air cooling and no specific emissions reduction component – such as a catalyst – in place.

These of course are small spark-ignition (SSI) engines. Designated as being 1,000cc or less in displacement, initially they were classified as generating no more than 19 kW (around 25 hp).

However, things have changed, and a new sort of “LSI” engine has evolved. This would be an engine that is less than 1,000cc in displacement but can now produce up to 30 kW (around 40 hp) under the updated EPA regulations, and that requires the less stringent emissions regulations of the original SSI category. This is a welcome update as these new engines are essential for a wide range of equipment where the added cost and complexity of a “full” LSI engine is just not needed.

We’ve in turn been rewarded with such benefits as a thought-through approach for legally adjusting engines for high altitude operation. And the simple tethering of fuel caps as a requirement that just makes for more convenient daily usage.

Surbaru’s EH99 packs 999cc worth of power.
Photo courtesy Subaru.

The primary benefit of these improvements, of course, is an even lower level and amount of pollutants being generated, of benefit for those in the vicinity of the machine as well as for the atmosphere in general.

So as we let the engine manufacturers worry about the dreaded announcement of an ANPRM (Advance Notice of Proposed Rulemaking) indicating a potential fresh round of emissions regulations, it might be interesting to consider some additional technologies that might be adopted, although not necessarily because of a need to reduce emissions further. For the engines are quite clean these days. That’s a fact that we can all be proud of.

For example, EFI (electronic fuel injection) is an effective means for supplying fuel to an engine under a wide range of operating conditions. As new ways of bringing the base cost of this technology and component to even lower levels we might see it employed on a wider range of engines.

And since engines actually operate most effectively at a single fixed speed for which the parts might be designed and for which the engine is then calibrated, we might see more engines where the engine does operate this way as some of the newest generators using SSI engines do. With the operation and speed of the driven component to be handled electrically or perhaps hydraulically. This is essentially a hybrid system.

Certainly with all this talk of the exhaust gases so far, we might also look at a means of utilizing this energy as well. This, of course, means turbocharging.

But why not if it works, the cost is justified and the performance is enhanced? In fact, turbochargers provide an effective means to compensate for the lower amount of air at higher elevations. This can be done without a need to directly modify the engine. That would just make the daily work that much easier for many.

Let’s return to the present and that early morning stop at the Quick Mart that has now evolved from the early days of just serving gasoline to much broader offerings. That first stop of the day now includes some fresh gasoline for my SSI and some piping hot, fresh coffee for me. Now we’re both fully energized and ready to go to work.

John Fischer more than a decade of experience in the power equipment/engine trade. Contact him at