Tempest oil filter

[jrevens]

......
I have never had a filter loosen on my auto or truck in the hundreds of thousands of miles I've driven. Why would the one on the plane loosen if it was installed properly. Again, just because the 1920s design Lyo-Conti-Saurus engines did it doesnt make it gospel.

I agree with that 100%. Aircraft engines may potentially be subjected to more movement & vibration than an auto engine, but when was the last time you could remove a properly installed oil filter from a car or an airplane without a wrench?

A story -
Back in the 90's I designed & built an engine mounted spin-on filter adapter for my Lycoming to replace its filter screen housing, that oriented the filter vertically for clearance and clean filter changes. At that time there was nothing available like it on the market. Started out using Porsche filters because they were cheaper & had greater filter surface area than the Champion aircraft filters at the time. Plus, they had a built-in bypass check valve, which those early aircraft filters did not - it had to be built into the filter adapter. They were designed for very similar flow rates to what the Lycoming requires - many auto filters were not. In choosing a filter, I built a pressure test rig from an old grease gun & tested many brands of oil filters to destruction. Quality of construction, shell wall thickness, filter surface area, etc. varied widely. I clamp the filter to the housing structure with a hose clamp, but it was designed that way to make other people who saw it feel good. I now use K&N filters, and due to that previous experience I developed a real prejudice towards certain brands, and a respect for oil filter design. I would not deviate from Rotax's recommendations carelessly.

Like others have said or implied, I think of oil filters & oil as relatively inexpensive "parts" compared to the precious engine, and I want the best. Rotax genuine filters may indeed be the best, or maybe not. Their previous design was obviously not "the best". I'd like to learn as much as I can about the Tempest filters, but I'll happily use Rotax for now.

[Dick B in KY]

Again, what bad things have been said about the Tempest filters????

Dick B

[Wheels]

I took this off another forum. It came from an IRMT who has more experience than I"ll ever have with Rotax Roger Lee. I don't think I violated any rules here but this should answer the mail.

"You actually have three types of valves so to speak. This is what makes the Rotax filter so unique and different from most auto filters and why you should just use the Rotax filter. One is the white anti drain back valve membrane that covers the small holes around the base. This was changed years ago too to make it more effective. Another is the bypass pressure diiferentail spring type on top of the filter and this is for the clogged filter bypass. Most auto filters bypass between 13-15 psi and I believe the Rotax filter bypasses between 18-22 psi. If this was ever actually activated you're way past a serious problem. Rotax years ago increased this spring bypass pressure because sometimes on a cold start the spring could open and allow so unfiltered oil to pass. If you are using a cheaper oil filter or auto filter you are most likely bypassing unfiltered oil at times during a start. For this bypass to work there must be a differential pressure between the upstream oil flow and the downstream oil flow. The last is the internal check valve that you can see looking into the filer. This helps stop oil filter drain that might cause oil to seep into the cylinders. The oil tank has a specific height relationship to be mounted with the engine. Aircraft like Kitfox mounted the tank too high which would cause oil to weep back towards the cylinders which in the early days could cause hydro lock.


p.s.
Don't use cheaper oil filters trying to save $5. Pay now or pay later and later may be a whole lot more expensive.

[Dave S]

Wheels,

Your mention of the bypass pressure is something that is seldom discussed; however, that is at the heart of the Rotax 912 warm-up procedure - i.e. allowing the oil to warm up to at least a minimum temperature before applying full power. The procedure is required to assure the oil is thin enough to prevent the bypass from opening and allowing unfiltered oil through at full power/max RPM. What I am getting at is the need to know that the bypass pressure of the Tempest (along with other parameters) is indeed equivalent to the Rotax filter. Another fly in the ointment is the filter media density/area has a direct impact on what oil temperature will be necessary to prevent oil bypass at full power - in other words a "looser" filter could get by with a lower oil temp but a "tighter" filter may require a higher temperature. Rotax should have this all thought out when they recommend certain oils with their engines as thinning gradients are not necessarily identical on different oils either.

I think it's great to have new products and experiment with them. In the case of the Tempest filter - it would be great if we could understand each engineering parameter and know it is equivalent. That's going to be hard to get as companies pretty much keep that to themselves.

Many times actual performance experience, good or bad, will not be available until after many people have used a product for a while. I keep recalling that bit of wisdom in investigative science..." The absence of evidence does not constitute the evidence of absence - you just haven't found it yet".