K&N oil filter observation

Status
Not open for further replies.

Patman

Staff member
Joined
May 27, 2002
Messages
22,185
Location
Guelph, Ontario
Since I started using the K&N oil filter on my Firebird on the last oil change, I haven't really driven the car hard very often since the roads have been wet most of the time but today I had the chance to open her up and watch the oil pressure gauge.

Here is what I observed. At 70mph in overdrive with my oil fully warmed up (after driving over a half hour mostly highway) the oil pressure was just over 40psi. I put the pedal to the floor and watched the oil pressure gauge as the rpms climbed to the redline, and the oil pressure did not change. This gauge is not an idiot light like Ford oil pressure gauges, it does move according to actual pressure (it shows 18psi at idle on warmed up oil for instance).

So my theory is this, and someone correct me if I'm wrong. I figure that since the oil pressure does not rise, then that means this filter must be handling the flow of oil very well and is not causing my bypass to kick in (in this LT1 350 engine the bypass is in the block, not in the oil filter) So that is telling me that this filter is indeed flowing perfectly for my needs. IIRC, with the other filters I have used in the past the oil pressure would move up from 40 to about 50-55psi at full throttle (I used Purolator Premium Plus and AC Delco in the past)

Comments anyone?
 
You think the filter is regulating the oil pressure? I would prefer the higher oil pressure the other filters appear to have allowed. One could argue the filter is impeding the flow and thus the lower oil pressure? I don't know but that crossed my mind. Have you used different type or brand of oil in the comparison?

So, if the filter is responsible for the lower oil pressure you have to decide, is better filtration worth the slight drop in oil pressure? Not saying either is bad, just thinking out loud (so to speak).


I am trying to recall what the oil pressure is in my LS1. I am sure my it is at least 60 psi or better at normal 55 mph and I am using the 2002 brochure showing the gauges to base this on. I am using synthetic 10W-30 but car is in storage for winter.

The minimum hot PSI for the 2002 LS1 is;

@ 1000 rpm - 6 psig
@ 2000 rpm - 18 psig
@ 4000 rpm - 24 psig

I am not sure you can assume the gauges are completely accurate.

[ January 19, 2003, 09:47 AM: Message edited by: Mike ]
 
Patman

Somehow the scenario does not make sense to me. Pre K&N your pressure exceeded 40psi at full throttle. Now with the K&N 40 psi is the max. pressure. All with a positive displacement pump and no other changes.

Is the engine pressure regulating valve up or down stream from the filter? And what are its settings? Like cracking pressure and full open pressure.

Where is the pressure guage up or down stream from the filter?

Could the difference you see be a by-pass in the K&N. If nothing else has changed then the change has to be the filter itself.
 
Patman,

I wouldn't run that filter anymore on your LT1 as 45psi is barely enough when spinning to close to 6k like your LT1 does. Whether or not its in the by-pass mode, I would much rather run other filters where you'll the higher pressure. Considering the price of this filter, I am not impressed with it, especially when the Bosch Premium does at leastjust about as well (actually better for me as pressure dropped all around when switching to the K@N) for half the price.

Jason
 
Well I guess that's a sign that you should move to Indiana or the U.S.
smile.gif
. Seriously though I would think you could order the Bosch Premiums somewhere online.

Jason
 
The pressure relief valve in a stock SBC oil pump opens at 40-45 psi. This is true of all OEM SBC pumps, except those used in the old 302 Z/28.

High pressure SBC pumps (as used in the 302) have 60-70 psi relief settings (this is just a function of the relief valve spring).

If you were seeing higher pressures before, it is probably more a function of higher viscosity oil, and not any thing filter related.

Just my opinion.
smile.gif
 
More than ever I'm eager to get to the end of this interval to try out the AC Delco filter and see if pressure shows the same. Perhaps it was and my memory is wrong.

My gut feeling says that these K&N filters have to be better than most filters out there in terms of flow, since they make such a big deal on their website about how well they flow. What other oil filters out there actually boast about flowing so well? Everyone else is boasting about filtering out smaller particles.
 
Scroll down this page, Wix says their filter drops less than 2 psi yada yada. http://www.wixfilters.com/productinformation/gff_oilfilters.html
Wix seems to claim a good balance of flow & filtering(25 microns, IIRC).
Speaking of oil flow, I'm wondering if I'll see more wear in the 9,000 mile interval I'm on(a little over 7,000 miles on it now) due to the Pure One filter.
confused.gif
Analysis should tell!

[ January 19, 2003, 11:30 PM: Message edited by: Stuart Hughes ]
 
quote:

Originally posted by Neil:
Patman

Somehow the scenario does not make sense to me. Pre K&N your pressure exceeded 40psi at full throttle. Now with the K&N 40 psi is the max. pressure. All with a positive displacement pump and no other changes.

Is the engine pressure regulating valve up or down stream from the filter? And what are its settings? Like cracking pressure and full open pressure.

Where is the pressure guage up or down stream from the filter?


I wish I knew the answers to these questions but I don't. And I'm not 100% sure on the oil pressure readings with the previous filters, but relatively sure I guess. I'm running the same oil this interval as I did in the last (Schaeffer 10w30) with the only change being the K&N oil filter this time instead of a Purolator.


At the end of this interval I will be doing an Auto-rx treatment so I will use an AC Delco filter again and see how the pressure reads.


I have always felt confident that the K&N oil filter offered much better oil flow than 95% of the filters on the market, I wish there was a way I could confirm it. I hate to continue paying $14 for one when the AC Delco is only $4 and might flow the same.
 
That is strange, indeed. Even with no filter, the pressure has to increase, with a standard positive displacement pump, and climbing rpm. Until the relief valve in the pump (or whereever it is in a GM) opens. I think most relief valves have an upper limit somewhere around 60 psi. Maybe you have a different weight oil than before?
Mike

Oops, I see you snuck in a reply before mine, indicating the oil was the same. Well, its my story and I'm sticking with it
grin.gif
that the pressure has to increase with increasing rpm, regardless of filter.

[ January 19, 2003, 12:34 PM: Message edited by: Mike Thompson ]
 
novadude,

Do you know the pressure relief psi of a stock Mopar small block such as the 318 in my Grand Cherokee? At 127k miles, I still get around 60psi cruising warm and just over 60 at WOT. Cold idle is 70 and warm idle is 30psi. I use 10w40 GTX high mileage oil.

Jason
 
bandit, 318 magnum relief valve spec was ~75psi. (same for 242 and 360) That'll be lower by the time you hit 100K+ miles due to relief valve spring fatigue. Your 70psi cold pressure is likely hitting this limit.

Other specs:
Idle pressure 6psi min
3000rpm 30-80psi (30+ okay)
Filter bypass 9-15psid

These pressures are fairly generic. They at least hold true across the 318/360 magnums.

David
 
Thanks OneQuartLow

This might sound kind of stupid but what are the pros and cons of having a pressure relief valve that opens earlier around 45psi like the sbc's. I like the fact the Dodge has a higher pressure spring as it seems to me the bearings and such are getting more oil that isn't circulating back to the pan with a lower pressure spring. Is this true or am I way out in left field about this?

Jason
 
Jason, the magnum spec is very forgiving once you get past minimums. I'd say you have lots of safety margin. As for different "normal" values, one engine design might need additional pressure to keep distant bearings safe. The maker may have learned that some point fails prematurely, so they bump the pump output and/or relief valve rating.

There is such a thing as too high. Within the spec higher is better, but higher also means more HP loss & wear at the oil pump. A frozen relief valve can allow pressures that collapse filter cores, burst the case, or cause problems for other weak areas of the oiling system.

You get the idea.

I'm not an engine designer so take this for what it's worth.
 
Does anyone know the actual gallons per minute an oil pump puts out in normal service?

Most oil filters are rated with their normal 2 or 2.5 psid pressure drop at something like 3 gpm. Is this normal oil flow?


Ken
 
I'd say that's a normal maximum for sub-2Krpm service, but I've seen just enough to know it's all over the place. Different engines & operating rpm ranges make it a tough one to generalize.

Have to assume the common filter ratings are due to broad applications for each oil filter, and ease of testing/comparison. May have something to do with SAE test benches or their included test suites. i.e. SAE HS-806 states to stabiize temps and test pressure drop at 20% intervals of rated flow. Might be nice, but I know from garage experiments that flow affects temperature affects flow affects getting home for dinner.
 
quote:

Originally posted by mebanditws6:
Well I guess that's a sign that you should move to Indiana or the U.S.
smile.gif
. Seriously though I would think you could order the Bosch Premiums somewhere online.

Jason


Even if I could order them online, shipping them up here to Canada would end up costing me more $$$ than simply buying the K&Ns like I do now.

I'm gonna stick with these filters, I honestly don't think that there is another choice that I have up here which will outflow this filter.

The experiment with the AC Delco filter during my Auto-rx treatment coming up will be interesting. Then I can confirm for sure if I do see higher oil pressure with that filter.
 
quote:

Originally posted by Stuart Hughes:
... I'm wondering if I'll see more wear in the 9,000 mile interval I'm on(a little over 7,000 miles on it now) due to the Pure One filter.
confused.gif
Analysis should tell!


Stuart,
Do you plan to open up this filter? And have you opened any others for comparison to this one?
 
I don't see how a filter could effect the oil pressure at all. Let's take it to the extremes. If you are running no filter, you will get max flow and therefore max pressure. If you have a clogged filter, the bypass valve will open allowing full flow to the bearings. This is especially true since your pressure is remaining the same as the pump is spinning faster. This tells me that your pump is bypassing oil back into the pan via the pressure relief spring.

What I think you need to do is pull the pan (or is it easier to pull the engine on those LT1 F-body's) and put a sensor on the bypass valve to a light on your dash. That way, you could see when it is in bypass mode and we wouldn't have to speculate about anything. Then we could each send you a filter brand of our choice and a qt of your favorite oil and let the testing begin
cheers.gif
. So, are you up for it?
 
Status
Not open for further replies.
Back
Top