Bypass at high revs?

[Fbear]

If you have a car that revs to say 8,000 rpm can or will the oil filter go into bypass at high RPM from the flow rate being so high to protect the engine?

 

[tomcat27]

engineers try to avoid that from happening. it could, with cold oil and a restrictive filter. some oil filters are more restrictive to oil flow than others. from some BITOG testing, I believe that the Fram Tough Guard was the worst yet the Fram Extended Guard was the best. you will also find that racing oil filters are less restrictive but also dont filter as well - yet they dont need to since in a true racing application the oil will be changed aafter the race - or in pro racing, the motor may be rebuilt anyway.

 

[bepperb]

What is the engine?

Anyway, probably not at operting temp. The times you're likely to go would be when it's cold and you're at a higher rpm, or if the media becomes clogged for whatever reason.

 

[ZZman]

Depends on many factors:

1. Filter media type and Flow rate of media
2. Bypass setting high or low
3. Filter clogged or not
4. Viscosity of oil (Very thick, cold)

 

[Gary Allan]

If the oil volume is high enough, yes. Otherwise, it's not a common occurrence. You'll encounter far more bypass events, if any, during/around cold start.

 

[widman]

Most engines have a bypass at the pump to divert oil directly back to the oil pan to avoid excessive pressure and assure oil availability without foam at the pickup screen. This is frequently around 3000 rpm.

 

[SuperBusa]

If the filter and its bypass valve is designed correctly, it really shouldn't go into bypass mode unless the filter media starts loading up significantly and causes too much PSID across the media.

Engines that have a high pump pressure relief settings and flow a significant amount of oil volume are the cases where the filter could go into bypass much easier; especially if the filter's bypass valve setting is relatively low for the vehicle application.

Quote:
Most engines have a bypass at the pump to divert oil directly back to the oil pan to avoid excessive pressure ...


Ideally, if the pump's pressure relief system works well enough to keep the maximum oil supply pressure to the filter/engine circuit constant at all times, then the PSID ratio across the filter and engine should be relatively constant (ie, say filter PSID is 10% and engine PSID is 90%). This means if the filter doesn't go into bypass at pressure relief with hot oil, then it also should not go into bypass at pressure relief with cold oil. That's because with cold oil the flow volume will be much less, thereby keeping the same relative PSID ratio across the filter and engine. It's the combination of the flow volume and viscosity that determines the PSIDs in the system.