Author Topic: Hydraulic Cam Chain Tensioner  (Read 1829 times)

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  • Grogu
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Re: Hydraulic Cam Chain Tensioner
« Reply #15 on: March 21, 2022, 02:03:51 PM »
The Colloidal Graphite "Filtrate" type products were from a completely different lubrication strategy, likely originating in pre detergent oil type and genuinely assisted oils available to help avoid metal pickup etc.
Pre-detergent types relied upon the oil not holding contaminants in suspension and letting them drop out of circulation into sump etc to be removed and cleaned out to pre determined schedule,  often without any real filtration. 
Detergent type try to keep any contamination in suspension to be filtered through whatever filtration was present to be removed in that way.
My father used filtrate additive in racing a bike, was supported by the factory agreement for which I still have the paperwork,  along with telegram of congratulations for a specific race result. 
He observed though that the factory NSU race team was very significantly different to most in that era for lubrication on their bikes. They prepped them and heated the engine with a blown heat scource,  also heating the oil in a pan on a primus stove prior to filling the engine and starting it, then to be sent straight out to race.
The significant point of this is that the Honda blue print is more or less exactly that NSU  arrangement, of very tight engineering tolerances and favouring absolute optimum heat range and targeted oil viscosity as pre requisite to engine design.

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It's this type of engine Honda appears to have copied.

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Re: Hydraulic Cam Chain Tensioner
« Reply #16 on: March 21, 2022, 02:25:32 PM »
From Honda's own data, all of these engines are designed with a hot oil viscosity of 30 which dictates their tolerance and metallurgical philosophy. All other viscosity brings compromise.
Simply because they have no thermostat as a water cooled engine has, then with ambient temperature below 60 it moves to viscosity of 20 not because of tolerances but that the cooling effect in that environment (effectively wind chill given the fins are the same) but because 30 viscosity stays too cold to flow at the correct rate. Viscosity 20 will then have the same targeted flow as 30. This builds a picture of what their engineers where doing in making their decisions, also showing that viscosity is simply system resistance in combination with the oil system's flow design and not conforming to generally projected view that "the thicker the oil the better the protection" sentiment. 
It particularly targets oil replenishment over everything else in characteristics. 
The stated viscosity on oil products doesn't give anything like the full picture in selecting an oil to use, but then there's so many myths about oil it's usually a complete smokescreen anyway.
A triumph of marketing, take the contemporary view of Filtrate being good,  so it must help these odd little Japanese engines, being so far away from understanding what really happened inside them.
Later on my dad supported his friend in racing race kitted Honda benly motorcycles and so got to appreciate those too.

 

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