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

I notice robin subaru portable generators have ohv and ohc on the 2009 models.Is one more reliable or more expensive to produce??Why did they change for the 09 models?I see most generators use ohv engines.

mikiewest wrote:
Not sure about cost to produce but I imagine fuel efficiency might be better with OHC versus OHV.  The Honda EU2000i is OHC and can run up to 15 hours on one gallon of gas while the Yamaha EF2000iS (OHV) runs less at 10.5 hours on one gallon of fuel.  These generators are pretty much identical in specs.

         OHC and OHV engines are both overhead valve engines... The diffrence is the placement of the cam..  The OHC Hondas I have seen run a timing belt to the cam,  this is lighter weight.    It takes fuel to move weight (the weight is always there even under no load,  this weight robs power).  Also the overhead cam system is quieter, less metal to metal contact of gears in lash.  Also there is less vibration in a belt system without pushrods and tappets changing direction every stroke.   All that extra hardware/ weight requires fuel to keep it moving...

 Friiy

Yes OHC is quieter and smoother.

One consideration though, is replacement of the timing belt. My Honda HRX mower manual
makes no mention of the timing belt in the scheduled maintenance chart. The closest they
get is a reference to valve lash adjustment and only to take it to a dealer for that. During valve
adjustment of course, the timing belt will be visible for inspection. 

The mower is warrantied for 36 months, so they expect it to last that long at least.

When I get the Helm maintenance manual I'll see if the HRX has an interference engine
and the timing belt interval.

The Robin Subaru engine that I have is an OHC model and uses a timing chain.  It is without question the quietest, smoothest, and easiest to start engine that I've ever owned. 

I lucked out with a promotion Honda was running in early spring last year. They gave me an extra year of warranty... so 4 total years. I'll take a look in my factory service manual if it mentions anything about the timing belt. samdog wrote:

Push rode OHV engines are also more compact than OHC engines. The additional valve mechanism added to the engine head adds length to the overall dimensions of the cylinder/head component. In certain applications, the compact ohv push rod engines are more desirable. I have a riding mower with a Honda V twin with sohc valve gear driven by belt. Being that the engine has a vertical shaft, the cylinders are horizontal. I cannot speak for other Honda ohc engines, but in the case of the air cooled Honda sohc V twin, the belt(s) runs in oil and is used in conjunction with the pressurized lubrication as another means to get more lubricant to the over head cams. At least that's what written in the material that came with the engine. If the belt(s) do run in oil, wear should not be an issue for a very long time. I'm confident that the belt driven Honda GX series ohc engines will be as robust as their push rod counterparts. Another point of interest that I've read about when comparing large engines such as automobile engines with ohc vs. pushrod ohv is the torque characteristics. Generally speaking, two engines of virtually identical specs other than valve configuration will deliver torque and horsepower differently. By that I mean that usually, a pushrod V-8 will deliver more torque than an ohc engine will at equivalent rpms. However, as the rpms rise, the ohc design will generally provide more horsepower usually due to it's ability to rev higher more efficiently. If you look at modern high performance motorcycle, ATV, snowmobile engines, you'll see that the great preponderance are either sohc or dohc. Being that most ope four stroke engines run at 3600 rpm, pushrods are fine. If I had a choice however, I'd choose ohc. I have no substantial reasons why. I just like the simple sophistication of sohc engines and their ability to achieve higher rpms efficiently.

borat wrote:

According to Honda the GCV190 belt runs in oil as well:

"The GCV190's innovative combination of a compact combustion chamber, overhead cam configuration
and uniblock construction significantly reduces fuel and oil consumption as compared to conventional
side-valve engines. Honda's DuaLube™ System achieves full engine lubrication by combining governor
slinger paddles and an oil bearing timing belt."

 http://www.honda.com/newsandviews/article.aspx?id=4605

I still wonder what they say about change interval though...

"I still wonder what they say about change interval though..." I'd venture to say the belt will likely last the life of the engine. Considering timing belts on automobiles are good for 90,000 plus miles, I'd be willing to bet that a belt designed for similar applications albeit fully enclosed and bathed in oil, on a piece of OPE will last a very, very long time.

The GCV designated Honda engines don't enjoy the heavy duty reputation that the GX designated variants do in my neck of the woods. Most of the  locals view them as light duty and not worth the time or cost to repair. The complaints center around cam belt failure and the expense associated with that component. If going OHC I would prefer a chain driven cam set up. If not available I would opt for an OHV.

Marc  

The OHC Honda engine on my yard tractor is a GX series. I've not heard of any complaints about their durability. If belts are suitable for high mileage automobiles, I have no concerns with their reliability/durability in an OPE application if properly maintained. Time will tell I guess. Regarding your comments about the GC series engines belt failures. Could that be caused by low oil conditions?

borat wrote:

Good question re: low oil. I will ask the next time I see the mechanics at the Local ope shops. There are two local shops and both said they didn't like the belt driven Honda's because of durability and repair cost.

Is it an interference head design? That might account for their comment that they are too costly to repair if the belt breaks.

Marc

By "interference" type I'm assuming you mean if the belt breaks, the valves may make contact with the piston(s). Right? I really don't know if it is or not. I've never had it apart. Don't really plan to either as long as all is well.

borat wrote:

Right, makes a real mess-stems, guides, seals etc.

Marc