Maybe I am mistaken, but I thought that only some filters are built with an internal, spring-loaded valve that will allow unfiltered oil to flow back to the engine if the filter media become so clogged that it can no longer allow oil to pass through. Without a bypass valve, in such a situation your engine would be oil-starved and bad things would happen really quick.
The housing that the filter screws on to has the spring loaded bypass valve. It is a good habit to check the valve when replacing the filter.
Yes, BUT, the by-pass valve is for what is stated, BUT ALSO when you put your foot into it most filters DO NOT have the capacity to flow the amount of oil nec. to lubricate the engine. SO in that case when your foot is at WOT the oil by-passes & NO filtered oil is getting to your engine. The reason for HP filters. They have the capacity to flow the nec. amount of oil to the engine, BUT with ONLY larger filter media to be able to pass the nec. oil needed for lubrication. The down side is the HP filters will NOT catch the smaller particles that a more dense media does. BUT when your racing your changing your oil more often anyways so it's not as important.
Interesting! Always wondered if the "HP" filter stuff was just hype. They usually say "flows better" They don't say the whys and hows, you just did, thank you
You are welcome Mark. I ran into this MANY years ago & wondered why also until I called & spoke with an engineer, as a matter of fact 3 diff. ones.
I was starting to wonder if my memory was faulty--getting old and breathing big-block exhaust for years is taking a toll on my brain. I started to wonder if that check ball was the anti-drain valve instead of a bypass. Anyway, if you wanted to, apparently you can make your Sys 1 a non-bypass type by buying this ball-less plate: https://www.jegs.com/i/System-1/888/214-0440/10002/-1
