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

Snowmann, can you help understand this:

All of the Robins/Subaru documentation say this is a 4000 rpm engine. All of the Ariens documentation says all their engines run at 3600 rpm.

Does Ariens run it at 3600 rpm instead of 4000? If so, how does Ariens compenstate for the 10% power drop? If they run at 4000 rpm, did Ariens change the gearing to keep the wheel and impeller speeds the same as the 3600 rpm models or are they also faster?

Thanks,

David

I don't know who to believe...when I called and talked to an Ariens service tech, he told me that the AutoLok differential drove the outside wheel around a turn. So I guess sometimes you can't believe everything they tell you.  I also don't understand how in some of the Subaru Robin specs for the SX30 engine they show a 8.3 to 1 compression ratio, but in their section on engine features they claim 9:1.  What's the story there?  So you're still thinking about the Deluxe/Subaru eh....if I had need for a 30" unit I would have probably gone that way myself...that motor seems awesome...even better if it runs at 4K rpm & spins the impeller a little faster.  

The Ariens is a snow blower designed and built by people who know the issues and are concerned about performance and reliablity. The Subaru has far better specs than the current generation of snowblower engines which all have many design trade-offs for cost; the reason the snowblower costs haven't gone high as the features increased. The other motors may last longer than the machine, but features like ball bearings reduce friction losses and others such as an OHC improve power by allowing better port design and increasing valve train stability through lower mass and higher stiffness. These and others help insure the engine maintains power throughout its lifetime.

However, the engine was incorporated as a Tecumseh replacement than quickly replaced with the 305cc Briggs, an distinguished motor used for a price point. While I don't know what it sells for or how much it costs to make, it can' be much different in manufacturing costs than the 342cc and is often used on the same chassis (e.g. Ariens Deluxe 30 and Platinum 30). It does provide a marketing feature to distinguish price points. Similar to the relationship between the Chevy Biscayne, Bel Air, then Impala, and later Caprice.

The only component Ariens changed for the Subaru is the sheeve with the output pulleys on the motor; the rest of the unit is as Lane Smith's District Attorney Jim Trotter said in My Cousin Vinny: "Identical!".

So, does the sheeve change the pulley ratios to work at 4000rpm? If the other bearings and components where chosen to work at 3600 rpm and the reductions from the gearing, where they ok with them working 11% faster? Snowmann's posts indicate Ariens is very cautious to insure their products achieve the intended performance, reliablity, and life expectancy. Marketing and spec sheets from Ariens show the engine running at 3600rpm. Calls to Ariens says it is running at 3600rpm.

If it is running at 3600rpm, it is very unlikely Subaru made or was able to make changes to achieve the same power levels it achieves at 4000rpm. The Subaru site has performance curves that indicate power would be off 10-15%. It is a good engine, and Ariens may have found its performance at 3600rpm more than adequate to replace the Tecumseh 10hp. However, that isn't the same as that engine running 4000rpm with the impeller running 11% faster; stuff all us snowblower junkies drool over. We need a different hobby!

The only ones available are mail order. No local dealer has one nor do I know someone who has one. To the best of my knowledge, there isn't even a picture of one on the Internet. If I had access to one, I'd take out my camera and take some 480frame/sec or 1000 frame/sec videos and measure the speeds. Call to Ariens say 3600rpm. Lacking different information from someone who measured it or really knows, that is what I would go on.

For me, it is the difference between buying the Deluxe 30 or the Platinum 30.