355D 18 vs 20HP - Page 2
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Thread: 355D 18 vs 20HP

  1. Top | #11

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    Yanmar isnít Briggs.

    Besides that if you have the buying power of Deere and want 10,000 widgets the manufacturer will make them custom to your spec.

    Another thing is having identical castings with different machining specs is common and has been since the 60ís. A k181 and k241 share bock, head and shroud dimensions, same with som k301, k321 and k341. The power outputs are not the same because almost every single part you donít see is different.
    BigJim55 likes this.

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  3. Top | #12

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    Quote Originally Posted by jgayman View Post
    I think you are right. Did you ever take note of the low-end gear driven riding mowers? They are made by MTD and sold under a dozen different brands and usually differ only in color. They all typically have oil filter-less B&S engines that look identical with stickers that read 14.5, 15.5, 17.5 and 19HP. I find it hard to believe that B&S actually produced that many different identical engines which were 1HP apart. :-)
    To some extent you have hit the nail on the head. Not in all cases but in a lot of them.

    The rating of engines is not just a simple HP and torque number. The oft forgotten and very important duty cycle rating has a huge impact on the durability of the engine. Electric motor have an equivalent rating which is called service factor (SF).

    The duty rating of an engine speaks to how long any particular engine can run at a given output before failure is expected. So the same exact engine could be rated for multiple different HP outputs at different duty ratings. Sometimes the same exact engine can have it's duty rating increased by added extra cooling. The addition of an external oil filter can add significant cooling to an air cooled engine.

    As people have known for a while now HP ratings of an engine can be vastly misleading. Buyer beware and take the whole package into account before passing judgement based on HP claims.
    X738, 54HC deck w/ auto connect, 3PH
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  4. Top | #13

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    Reasons for Deere to derate the engine to 18 hp and a lower RPM would be noise level and thrown objects certification. Most small engines are designed for and rated at 3600 RPM.

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  6. Top | #14

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    Quote Originally Posted by ExperimentalMechanic View Post
    Reasons for Deere to de-rate the engine to 18 hp and a lower RPM would be noise level and thrown objects certification. Most small engines are designed for and rated at 3600 RPM.
    My research is pointing me in this direction as well. I have found guys going to 4K on this engine. The 355D used all the same attachments as the gas counterparts so I suspect they just set it up to work at 3000 RPM. Bumping it to 3600 will increase blade tip speed (noise) and increase engine noise as well. I'm going to give it a go, I just need to figure out how to at this point. Not sure if its an adjustment or an actual shim in the fuel pump....if its the latter I will likely leave well enough alone.

    I saw a comment earlier abut the snow blower....this machine uses a single stage snow thrower....RPM is king with these.

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