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TomSchmit

No more L-head engines

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TomSchmit
As you have probably seen, overhead valve engines have completely replaced the L-head design over the past few years, mainly due to the need to meet emissions regulations. Now days, you can't find a new (or NOS) L-head engine at any of the catalog or internet sellers of aftermarket engines or even the places that sell surplus and "take-offs". The last ones I saw were some 10 hp vertical shaft Techumseh engines, not too long after they ceased production of that brand completely. Now I cant find a singe one, horizontal or vertical, any horsepower. They are completely gone. So I am going to grab up a few good used L-head engines to work with in the future. The overhead valve engines are larger (longer) and do not fit well in our old tractors. The world keeps changing on us, but we can save some of the past! Tom

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SmilinSam
As far as I'm concerned the L heads are more efficient than the overheads. I have found that the overheads use more fuel to do the same work at the same horsepower than the old L heads. More fuel means more emissions doesnt it? I wonder if they are really that much cleaner when the added fuel consumption is all taken into account?

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powerking_one
Sam, I'd have to disagree with you on your statement that L-head/Flat head engines are "more efficient" than OHV or OHC designs. If this were true, then our current cars' engines would all be flat heads like the automotive 1920's-1940's motors. It is the basic laws of thermodynamics in combustion chamber design that more optimal transfer of the cumbustion/flame propogation directly to the piston using OHV/OHC designs is factual. Pratt & Whitney, Rolls Royce, Curtiss and other 4-cycle aircraft engine manufacturers realized this design's power increase, fuel efficiencies and lower operating temp advantages way back in the 1920's. Those early OHV designs were consistantly pushing 1-2 HP per cubic inch of displacement and it took Detroit another 20 years to finally adopt this type of engine design for automotive use. Then again, it took the small L&G engine industry another 40 years to finally adopt it (thank Honda for being the first ~~ 20 years ago) with the assistance of CARB and the E.P.A. Don't get me wrong, I still like these old L-head (or even T-head) engines. Tom (PK)

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maxtorman1234
Hey Sam, I'm not sure which engines you have, but I would agree with them seeming to use more fuel. I replaced my 16hp K341 with a CH18, and it definitely uses way more than that and even my M20's and M18's. It's nice and quiet though,

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dentwizz
Operationally I would side with the OHV every time, but I would take a flat head for working on any day. In my opinion the simplistic nature is part of why they have survived this long. The inconsistent head temperatures and lower compression ratings are two things that distinctly affect the efficiency and percent of combustion. Notice how the newer OHV designs are higher HP per CI? I still like the vintage feel for personal play, but in business it is a no brainer.

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SmilinSam
quote:
Originally posted by powerking_one
Sam, I'd have to disagree with you on your statement that L-head/Flat head engines are "more efficient" than OHV or OHC designs. If this were true, then our current cars' engines would all be flat heads like the automotive 1920's-1940's motors. It is the basic laws of thermodynamics in combustion chamber design that more optimal transfer of the cumbustion/flame propogation directly to the piston using OHV/OHC designs is factual. Pratt & Whitney, Rolls Royce, Curtiss and other 4-cycle aircraft engine manufacturers realized this design's power increase, fuel efficiencies and lower operating temp advantages way back in the 1920's. Those early OHV designs were consistantly pushing 1-2 HP per cubic inch of displacement and it took Detroit another 20 years to finally adopt this type of engine design for automotive use. Then again, it took the small L&G engine industry another 40 years to finally adopt it (thank Honda for being the first ~~ 20 years ago) with the assistance of CARB and the E.P.A. Don't get me wrong, I still like these old L-head (or even T-head) engines. Tom (PK)
I wouldnt disagree wityh your commentary Tom, but my definitionof "efficient" is soley in regards to these lawn & garden applications as pertaining to cost of operation and also I suppose cost of repair and maintinance. Its just something I have noticed over the years of operating both types of engines.

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MrSteele
A few years back, a dealer that I will never grace the doors of again, explained that if he had parts for the 10 HP I was looking for parts to fit, he would not sell them to me. In the ensuing conversation, he tried to sell me a new engine to replace the old one. How large? His first attempt was a 20 HP to do almost..almost the same work as my 10, and he had a "good deal" on a 20. More efficient? If the new engines are more efficient, why would I need a 20 to replace a 10? If the newer are so efficient, would I not be looking at an 8 HP instead of a 20 HP?

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acfarmer
You're exactly right the newer enignes have to be run over 2/3rds throttle to even come close to the rated HP,so the operator ends up running the tractor at 3/4 throttle and the hydro at less than half speed with a newer engine while doing the same job the operator could run an older single cylinder Kohler at 1/3rd throttle and the hydro at 3/4 speed.Now which is the 'most efficient'? I have several newer style engines here both Kohler and Briggs Vanguard with less than 500hrs that have 'given up the ghost' BTW

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MrSteele
Someone is going to jump in with the "Older engines have more torque, and the newer engines run at a higher RPM than the old, with less torque, so, the newer short stroke engines have to run faster to get the same work as the old. Thus, you need more horsepower due to the reduced amount of torque at slow speeds" And that statement is true. I have a 15 HP Fairbanks, circa around 1889, that weighs in at around 2 tons, with a top speed of 350 RPM. If I could figger out a way to mount it....

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3314WV
I can tell from my own "measured" experience the newer engines do not compare in fuel efficiency or bottom end torque. I have an old 23D 16 Briggs in my 3314V that mows circles around my new John Deere 130 with a 23 Magnum Kohler. I switch betweeen the 2 tractors every week so i can compare. The Deere will use twice the fuel and has to be feathered in the taller grass, but not the case with the 3314. According to some class action information i was sent, it would seem that the Deere may not actually even be a 23HP either.....go figure.

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dentwizz
Which is a necessary accompaniment to the longer stroke. The newer engines with higher shaft speeds(nominally) built under safety regulations need smaller flywheels to go with the shorter shut-off rate. If they had an ignition kill switch tied to seat or PTO on an older heavy engine it would barely class as safer since the engines coast so much longer. What is good for the safety is not always as practical for the duty, oh well. sm00

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Chris727
My only experience with the "newer" engines is the 30hp Vanguard "Big Block" in the Ferris. It has plenty of power but seems as if it uses more than twice as much gas as a B-110 or HB-212 to do the same amount of work.

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1969nicholas
I have more then enough parts to keep all my old L-head engines running to last me and my son. I have extra L-head engines built up on the side to last me the rest of my days:D:D:D.The next generations of people have missed all the fun we had with all these old tractors with the L-heads and I wouldn't trade it for anything.sm03sm03sm03

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theoldbadcars
With a mechanical engineer background, and 20 years of repair experience I feel like i have get in on this. OHV will always be more efficient, the design of the head and the valve location will win hands down. Yes you will lose some flywheel weight, but at top RPM they are very efficient, even the new diesels are designed in the same manner. With flywheel weight, torque will always go down. my question is will the attatchments we all love function at the new RPMs to get he work done?

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MrSteele
IS the efficiency like that of the automobile? We have more options such as AC that use gas, electrics that require high output alternators, power steering, air pumps for complete fuel disintegration, and a car that, on average, still gets 20 MPG. (They have since we started driving cars) The car companies tell us about efficiency, just as the lawn and garden manufacturers tell us that we are getting more efficiency out of our engines. All I can see in the new style engines is more parts to wear or break, thereby adding to the efficiency of the engine companies. Perhaps I am wrong, but, the old L-head engines both outlast and outperform anything that is "more efficient" made in the last 10 years or so.

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dentwizz
As a side by side comparison, my dad had a honda 8hp generator and my friend had a Briggs I/C powered generator. Both of the same Kw rating(4). The Honda got 6 hrs per gallon at rated output. The Briggs got 3.5-4 hours. I know there are some variables involved, but the run times were very uniform regardless of time of day and usage. We used to get a lot of hurricanes which would involve anywhere from 1-3 weeks of generator usage until power would restore. Ah the good ol days...not.:p

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RayS
Whats the new RPM`s? My 20 Kohler Command runs at 3600 RPM`s just like my 16hp engines(326437). I have had the Kohler Command for 8 years, have they done something since? My manuals state to mow at WOT in the old and newer machines.

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1969nicholas
I have been thinking about the RPM comment for a couple days now. Like Ray the old 326437 or even the 243431 all will turn 3600 RPM. All your newer Briggs or even Honda's still turn 3600 max RPM against govern under load. I guess I am missing something in that previous comment. I also don,t really care how good the new engine,s of today are I am a firm believer in the Brigg,s and Kohler cast iron engines.I don,t think there will be a engine ever built again to compete with them.

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dentwizz
I think what is refferenced by the RPM is the "torque curve". The longer stroked/heavier flywheeled engines can produce more torque at a lower speed, thus running slower in most applications. Case in point would be running half throttle for the normal mowing operations. New deck designs and engines typically are made to run at WOT to perform as rated.

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memphis
the Lheads are going away because they cannot feasibly get them to meet the new and upcoming emmissions standards for small engines. OHV is a cleaner running engine and thus are pushing the old Lheads out the door.

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RayS
quote:
Originally posted by dentwizz
I think what is refferenced by the RPM is the "torque curve". The longer stroked/heavier flywheeled engines can produce more torque at a lower speed, thus running slower in most applications. Case in point would be running half throttle for the normal mowing operations. New deck designs and engines typically are made to run at WOT to perform as rated.

[img]/club2/attach/RayS/deck.jpg[/img]
This is from an operators manual for a deck for a 3416. It states to run at 3/4 to full throttle. All of them that I have seen state that. The motor actually runs cooler the more volume of air that it pulls through fan or flywheel.

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