On 2005-08-15 snipped-for-privacy@themattfella.zzzz.com said: >Newsgroups: rec.motorcycles.tech,rec.autos.tech >I would like to be able to measure the pressure drop caused by an >air filter. Then I could compare different makes and models of >filters, and compare a new filter to a used one. >My air filter has a peculiar configuration that lets me put the >open end of a clear plastic tube on the inside of the filter while >the engine is running, without modifying the filter. So I can set >up a U-tube of water to measure the pressure difference. >What would be a typical pressure drop (say at idle) for a 1970's >four-stroke engine that uses a paper filter? Or where could I find >specifications or other data so I can know what I should expect? >Any units are fine: mmHg, mmH20, psi, atm, etc. The vehicle of >interest happens to be a '76 Honda 360 motorcycle, but general >information is welcome.
If what you are interested in is what's happening when you're riding, do the test on the road, in realistic conditions. Air flow through a
360cc engine at no load is so low you'll play hell getting any useful numbers. Run your tubes to a handlebar mounted manometer and go down a deserted road (with a friend riding chase).
I'd try to get a differential pressure gage called "Magnahelic" (sp?) for this job - much easier to read its needle.
If it's only data you want, do it on the bench. Suck air through various filters with a vacuum cleaner, powered through a Variac if you want variable speed. Instrument for pressure drop, volume of air flowing through.
If you just want the bike to run better, get a K&N (small version of what Krusty had in his power plant). When I was in the business, they made them to fit your Honda. Far better than the stock paper grit-strainer.
Frankly, I don't understand the fuss about a Honda 360 - it's about the most boring bike I ever rode - not much power, dull handling. Maybe the brakes were pretty good...
Tom Willmon near Mountainair, (mid) New Mexico, USA (In the '70's, owner, Sun Cycle, Rockville, MD)
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