rustylugnuts

My garage test results for factory C-1 oil filter canister bypass.

Test (1): bypass came off its seat .095 at 35*F using 10w-30 grade oil @ 13.6 psi.
Test (2): increasing oil temp to 55*F using same oil, bypass opened @ 18.2 psi.
Test (3): increasing oil temp to 75*F bypass opened @ 21.7 psi.
Test (4): increased oil temp to 95*F bypass opened @ 23.5 psi.
Test (5): increased oil temp to 115*F bypass opened @ 24.4 psi.
Test (6): increasing oil temp to 135*F bypass opened @ 24.8 psi.
Test (8): increasing oil temp to 155*F bypass opened @ 25.2 psi.
Test (9): increasing oil temp to 195*F bypass opened @ 25.7 psi.


My next test I added a digital flow meter (only to the bypass) measuring the volume. Also I’m staying with the same temps that are indicated in each test above. I increased the pressure to move bypass off its seat .218 or 7/32” increasing flow to (1) qt. and measured the approx fill time.


Test (1): volume oil flow through bypass (only) at 35*F @ 16.8 lbs. (1) qt. approx every 10.1 sec.

Test (2): at 55*F @ 21.3 psi. (1) qt. approx every 13.2 sec.
Test (3): at 75*F @ 24.8 psi. (1) qt. approx every 14.0 sec.
Test (4): at 95*F @ 25.4 psi. (1) qt. approx every 15.9 sec.
Test (5): at 115*F @ 26.1 psi. (1) qt. approx every 17.4 sec.
Test (6 – 9) are less then a quart, or bypass closed.

All measurements are within +/- 1%
The conclusion stock oil filter bypasses are open most of the time during cold starts and cruising speeds. That indicates your oil is 100% filtered only when oil is warm at idle, or under 24 psi of oil pressure.

rustylugnuts

Matt Gruber

interesting tests!
on the advice on some hot rod books, and being in Fla i put a pipe plug in both my 350's.
So 100% gets filtered.
10 yrs ago my 72 wiped a cam lobe,
so no shavings into bearings,
so new cam went in without having to clean out oil passages and rebuild engine.
I'd up the spring pressure if i still lived up north. very cold starts needs a bypass

rustylugnuts

I agree with you Matt, and I also live in Florida. Yes, the weather down here is great 97% of the time, and plugging the oil filter bypass will serve well under mild weather conditions. However "if" you drive your Corvette only when weather is perfect, 60*F to 95*F then plugging bypass applies anywhere! I don't see the majority of enthusiasts driving their C1's below 50*F anyhow! but then, there are always a few exceptions...

rustylugnuts

toms silver 60

Any guestimate on how much of the oil is filtered when the bypass is open? One would think that ??% would still be going through the filter at any particular set of conditions.
Also, excessive oil pressure can cause other problems as well, right?

rustylugnuts

I didn't have an additional flow meter, I thought about getting one though. In general from my test observation it varies between 50% when cold to 75% filtered 24 psi of oil pressure at operating temp. Taking from my scribbled hard to read notes. Hope that helps!

rustylugnuts

rustylugnuts

Sorry, forgot this: Bypass is closed and filtering of oil is at 100% @ approx 23 psi. It is directly proportional to pressure or reference to throttle response. The more throttle the more pressure, the more pressure the more oil filter bypass opens diverting from filtration.

Living down south and driving only at temperatures 55*F to 95*F I recently blocked off oil filter bypass, resulting in 100% filtration all the time.
(I wouldn't advise blocking bypass), if you drive under 50*F, just to be on the safe side.

Blockman blocks all his oil filter bypass, and suggests using NAPA Gold #1143 cannister type filter, made by WIX. He is a professional performance engine builder and racer with 40 years experience. He has stated using this filter in race applications without any failures using a high pressure oil pump.
For details and related information leading up to testing, please view:
"Oil Bypass?" thread

rustylugnuts

larrywalk

Can you illustrate how you did these tests by posting a diagram or picture of your configuration (plumbing) and gauge location?

Thanks!

rongold

I think you are mistaken---I don't think that the bypass opens based on engine oil pressure, but based on the pressure necessary to push the oil through the filter media.

Powershift

The oil filter bypass valve opens based on pressure differential across the filter media.

Larry

rustylugnuts

If I find the time between the holidays, I'll try to post test flow diagram.

As for the next question, this is true up to a point depending on filter mesh the filter gives resistance to the oil pressure, the oil wants to flow quicker but the filters resistance do to oil viscosity, mesh, and oil temperature increasing pressure restricting flow through the filter.
Resulting in the bypass to open equalizing the differential pressure. This is why your bypass opens fully on cold starts 0 to 40F. If a finer meshed or double pleated filter is used expect increased pressure. Now your not going to see this increased oil pressure on you oil gauge, because the filters pressure is diverted through the bypass keeping it equal, and unfiltered, see first thread up top.

So the more the oil pressure increases the greater the bypass will open. The same as if the filter gets completely clogged, the filter bypass will then fully open.

I haven't tested but logically thinking when bypasses are blocked some oil filters will rupture do to the increased oil pressure being forced through the filter without relief (or bypass open).

Thats the reason Blockman suggests the NAPA gold filter, it takes the increased volume & pressures.

Hope this answers your questions.

rustylugnuts

BLOCKMAN

Its not so much prssure but the volume if its a cheap filter the bypass will be open most of the time.

We have had customers put on a cheap Fram filter and oil pressure would not go over 35 pounds with bypass plugged and a standard volume pump. Changed back to the NAPA gold 1061 and plenty of oil pressure.

So with the cheap filter and a bypass the most of the oil is being bypassed!!!!!!!!!!!!!

BLOCKMAN

Jackfits engine the bypass has been plugged as it came in that way and its been in the single numbers and he is driving his car with no problems so far with 15/40 oil.

I also have some street rods that have been plugged for years now with no problems.

Using a good filter is key!!!!!!!!!!!!!

toms silver 60

Good exchange of information and perspectives. One thing I found out in minerals processing, be careful what you wish for in screening/filtering, you may just get what you wanted. In our case, it could be zero flow unless you had a bypass. The bypass could be by design or it could be self generated. This would hold true for 10 ml/min or 100k gpm.

weather sux today, had frost on windshield.

R1234

So, what I'm gathering from this exchange of information is that plugging the oil by-pass, especially on a rebuilt motor and using a NAPA Gold 1061 filter is a good preventive measure to keep any hidden debris from getting into your motor bearings during break-in.

Is that correct?

MikeM

Detroit probably spent $.10-$.15 a car to put that little by-pass gadget on every car out the door and besides, they had to warranty those engines. That's tens of millions of dollars squandered now isn't it?

R1234

OK, that's one for not plugging the by-pass. Thanks!

BLOCKMAN

I plug all mine and alot of shops I deal with doso as well, But like I have said a cheap filter and having the bypass its wide open most of the time, GM is really clean when their blocs are assembled.

If you loose a cam and lifter your bearings will be toast as I have seen this to many times or even a dist.

One ther reason GM put a bypass in the adaptor is if water ever gets in the fitler it will pug up and probably blow off.

So far we will continue to plug them till we see a problem but in 35 plus years no issues yet unless they try touse the orange filters then th4ey do need a bypass,

Filtered oil is the best oil, Most guys that run bypasses like unfiltered oil going to the bearings.

R1234

Knowing my local machine shop probably doesn't have the same quality control for cleanliness that GM does, I'm gonna go ahead with the plugging of the by-pass to give me assurance that the filter catches any left over debris during start-up and break-in of my newly rebuilt motor.

rustylugnuts

A good point! Yes, a little frost, nothing to worry about, just look what up north is encountering.... we have it made here in Florida! But it would be nice to be back home having a white Christmas.... I miss that!

rustylugnuts

larrywalk

Hey Rusty, when are you going to show a diagram of how you did your tests?