THE ULTIMATE NSX Oil Filter Page and Analysis

I took apart the new OEM Honda "short" filter and was surprised at the findings.


The NSX's oil filter stats are pretty weak when compared to the OEM filter of:

1991-2005 NSX - 3.0/3.2L - 6qt - OEM filter: 129.5sq/in
1991-2005 NSX - 3.0/3.2L - 6qt - Purolator L24484:________sq/in

1995-1999 E36 BMW M3 - 3.0/3.2L - 6qt - OEM filter: ~330sq/in

1990-2004 Mazda Miata - 1.6/1.8L - 4qt - OEM filter: 102.5sq/in

CDX_NSX said:

The Purolator L24484 filter is essentially the fitment/size equivalent of Honda's larger 15400-PL2-004 filter. It fits the C27a, C30a, C32a and C32b (all year Legends and NSXs).

Click to expand...

I am going to buy and cut open a L24484 and post the results of the design and surface area, but either way the OEM Honda 'short' filter is not much better than a Miata and IMO does not cut it especially for track use.


As a background, these websites are good reads on the different designs, components, and materials of oil filters:

http://minimopar.knizefamily.net/oilfilters/reference.html

http://shoclub.com/news.php?extend.6

From the above sites, metal end caps and rubber/silicon anti-drain back valves are characteristics of higher quality oil filters. The above sites also show an average filter surface area of 300sq/in and 200sq/in respectively for the given application.


Here's what I saw when I cut it open:

OEM Honda "Short" Filter housing:



Visually on par high quality rubber/silicon anti-drain back valve:


Filter elements cut out and cartridge leaf spring below. I used a razor blade and carefully cut as close to the end caps as I could and stretched the whole thing out and measured:


Total Surface Area = 129.5sq/in!!



By comparison, here's the 1.6L OEM Miata filter:




Similar high quality anti-drain back valve and cartridge leaf spring below:


Total Surface Area of 102.5sq/in:



Please post your findings of different filters and corresponding surface area.


Billy

i can't wait......

nice thread billy... this is good data for sure...

see... you win ohio... all types of good idea's pop up

I'm not sure why so many owners flock to using the short OEM filter when the Purolator L22484 long filter is readily available at a lower price. I agree with stuntman, that when it comes to filters of any kind, bigger is better - assuming the same quality filter media.

A bit of history: Purolator started in NJ and was one of the original oil filters. Oil filters were an add-on in early cars (before my time). Purolator advertised that you add their filter to your engine to get Pure Oil Lator.

I have been using their filters in all my cars for nearly 50 years. I usually replace my cars at about 150,000+ miles & never have had a problem with the filter or engine wear. That includes an Integra (sold at 160 k mi) and the last 12 years in my NSX (only 64 k mi so far).

So I also eagerly await the measurements on the L22484.

I am using the Bosch because it was the best I could find but it may not be any better than the OEM. I will keep it on the next change and measure and report. This is a great idea. Might as well keep things and cut'em open!

I found this chart to be helpful. The element surface area is revealing.

Are there any correlations to be made between filter surface area and a drop in oil pressure?

On that same note, what about the density of the filter element...will that affect oil pressure?

I assume both will to an extent but not sure if it's enough to worry about.

Since we're on the subject does anyone have the ability to measure the density of each of the filter elements used?

ftuhy said:

I'm not sure why so many owners flock to using the short OEM filter when the Purolator L22484 long filter is readily available at a lower price. I agree with stuntman, that when it comes to filters of any kind, bigger is better - assuming the same quality filter media.

A bit of history: Purolator started in NJ and was one of the original oil filters. Oil filters were an add-on in early cars (before my time). Purolator advertised that you add their filter to your engine to get Pure Oil Lator.

I have been using their filters in all my cars for nearly 50 years. I usually replace my cars at about 150,000+ miles & never have had a problem with the filter or engine wear. That includes an Integra (sold at 160 k mi) and the last 12 years in my NSX (only 64 k mi so far).

So I also eagerly await the measurements on the L22484.

Click to expand...

There are many people (mostly the import guys that I've seem to notice) that subscribe to Keep It Stock Stupid (KISS) religion, hence for the Honda OEM filter craze. Of course when asked about surface area and/or MPE and SPE ratings there really is nothing that I've seen that gives me the confidence that an OEM filter is equal if not better than the high end aftermarket oil filters.

TURBO2GO said:

I am using the Bosch because it was the best I could find but it may not be any better than the OEM. I will keep it on the next change and measure and report. This is a great idea. Might as well keep things and cut'em open!

Click to expand...

Which Bosch part number are u using? They have different levels/models.

RYU said:

Are there any correlations to be made between filter surface area and a drop in oil pressure?

On that same note, what about the density of the filter element...will that affect oil pressure?

I assume both will to an extent but not sure if it's enough to worry about.....

Click to expand...

Both would be my conjecture based on Vulcan logic.

RYU said:

Are there any correlations to be made between filter surface area and a drop in oil pressure?

On that same note, what about the density of the filter element...will that affect oil pressure?

I assume both will to an extent but not sure if it's enough to worry about.

Since we're on the subject does anyone have the ability to measure the density of each of the filter elements used?

Click to expand...

You hit the nail on the head, while this is very interesting data about filter construction ,the one spec is the pressure differential that will cause the by pass to engage. Have any of you ever performed or seen this test done ,I have, some times the more restrictive filters will by pass early ,this is not good . Unfiltered oilis sent directly to critical components, look all these filters are quality units but sometimes bigger &tighter are not always best--just my 2 cts

Using BATMANs Vulcan logic, the restriction should be a factor of how fine the microscopic holes in the filtering material are, how many of those holes there are per square inch, how many square inches of filtering material are in the housing, and how stopped up the filter is with crud. If two filters have the same filtering material and the only difference is the square inches of it in the housing, then the filter with the larger surface area should pose less restriction and take longer to get stopped up with crud. The smaller filter will pose more of a restriction and should be replaced more frequently.

I have no idea at what point the old OEM long filter and the new OEM short filter start posing so much restriction that the bypass valves open up. If both have the same filtering material and can filter the oil at 8000 rpm when new without opening up the bypass but you should cut the change intervals in half because the new one gets stopped up more quickly, that’s fine with me.

If Honda increased the size of the holes in the filtering material so that the new short filter lasts as long as the old filter but doesn’t filter as well anymore, that would suck. If the new short filter has the same material but more pleats than the old tall filter, it might have the same surface area and really be quite interchangeable. If there are more advanced filtering materials available now than 20 years ago and Honda upgraded the material when they reduced the size, all bets are off.

Do we have any data regarding pressure drops, how many microns the various filters filter, how long it takes until the restriction has increased by a certain amount, and at what psi the bypass valves open? What puts me at ease is simply carrying out frequent oil and filter changes.

most filters by pass in the 10 -20 psi range . The by-pass valves comes into play when the oil is cold or if the filter is dirty causing restriction above psi setting .

greenberet said:

If two filters have the same filtering material

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A critical factor to know when doing such a comparison.

For example:
My spray booth has 4 different kinds of filters.Two of them look the same but work differently.
There are many vendors that offer replacement filters that look exactly the same as what is required but are not the same at all. The correct ones when they capture the dirt have a structure that allows the dirt molecules to be caught and be arranged in such a way as to not influence the airflow in the same manner. They give a significantly longer service interval before flow begins to decrease. To the eye they look the same to the as the ones offered by other vendors. They even have the same filter rating but are not the same once in service past a certain number of hours.
I have meters that regulate and display changes in airflow to two decimal places so I could verify and observe the airflow and found that this was indeed true.

My point is how the filter media works on a mechanical and molecular level makes a tremendous difference and the naked eye may not be of much use in determining if two filter medias are the same.

I also would think the weight of the specified oil again would make a big difference.
5w-20 oil system vs a 5w-30 system would be capturing different size of molecules so just comparing the square inches of their respective filter media may not be a relevant at all.

There may be more needed for a credible comparison than a hacksaw and a measuring tape. I don't know.

Here's a good video on How to Evaluate Oil Filters:

http://www.youtube.com/watch?v=aiLhfAFhkvs&feature=related


Here's an explanation on how the oil bypass valve works:

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=309756



Billy

Excellent video! It would be great to get all the specifications mentioned for the various filter options we have. One thing I'd really like to see is how the original long OEM filter compares to the new short OEM filter.

pbassjo said:

There may be more needed for a credible comparison than a hacksaw and a measuring tape.

Click to expand...

And the answer is:biggrin::

stuntman said:

Here's a good video on How to Evaluate Oil Filters:

http://www.youtube.com/watch?v=aiLhfAFhkvs&feature=related

Click to expand...

Really informative. Thanks Billy.

Now how do you apply that to your study?
Do we have access to the information, that is, the specifications of the different filter offerings as outlined in the video or is it proprietary?

stuntman said:

Here's a good video on How to Evaluate Oil Filters:

http://www.youtube.com/watch?v=aiLhfAFhkvs&feature=related


Here's an explanation on how the oil bypass valve works:

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=309756



Billy

Click to expand...

Excellent articles ,I believe they validated what I posted. some times bigger and tighter are not always better.

So, is the Purolator L24484 the hot number now (lacking the "tall" OEM filter)?

Hey Pabsso with this heat were having maybe one of those Rossi cappy and Provo wedges are in order or my Fathers favorite ,raw sliced onion smothered in olive oil on crusty Italien bread:biggrin:

MMMMMMMMMMMMMMmmmmmmmmmm.

Interesting thread

People like to discuss oil and filters to great lengths for some reason. What sucks, whats's better, what looks better, whats bigger, whats smaller .....

First of all there is very little for your filter to filter out of your oil so the amount of filter surface area is not a big deal. If there is a wayward piece of debris as long as the media is fine enough to catch it and course enough to let the oil through all is good.

Oil pressure is a function of the clearance of the pressure oiled parts like the crank bearings and cam shaft bearings. There is a bypass built in to the engine that bypasses the filter when the oil is cold and can not pass through the filter, the filter having a bypass is really of no use but what is being called a bypass my actually be a anti-drain back which is good for some mounting positions. The NSX down mounting of the filter keeps it full so its unnecessary.

Of all the oil that goes to the filter not all of it goes through the media. The threaded nipple the filter screws on does not have a seal so it leaks mixing some unfiltered oil with the filtered oil so no mater how good the the media is you are not filtering 100% of the oil anyways.

hey Brian, yes your correct there is a relief valve in the oil cooler center bolt but I can't find the spec at which it relieves . I don't feel it would relieve below the spec of the bypass valve in the filter. Also I agree the drain back valve is non functional in our application. Your absolutely correct this thread iis mental masturbation except about the cappy &provo wedges just ask Pbasso.

Briank said:

Interesting thread

People like to discuss oil and filters to great lengths for some reason. What sucks, whats's better, what looks better, whats bigger, whats smaller .....

First of all there is very little for your filter to filter out of your oil so the amount of filter surface area is not a big deal. If there is a wayward piece of debris as long as the media is fine enough to catch it and course enough to let the oil through all is good.

Oil pressure is a function of the clearance of the pressure oiled parts like the crank bearings and cam shaft bearings. There is a bypass built in to the engine that bypasses the filter when the oil is cold and can not pass through the filter, the filter having a bypass is really of no use but what is being called a bypass my actually be a anti-drain back which is good for some mounting positions. The NSX down mounting of the filter keeps it full so its unnecessary.

Of all the oil that goes to the filter not all of it goes through the media. The threaded nipple the filter screws on does not have a seal so it leaks mixing some unfiltered oil with the filtered oil so no mater how good the the media is you are not filtering 100% of the oil anyways.

Click to expand...

Oul pressure is a function of oil pump displacement and rpm.

Filters are pretty important and i wouldnt necessarily view it as fine to run the short filters just because Honda stopped making the long filter for a shrinking NSX community.

Briank said:

There is a bypass built in to the engine that bypasses the filter when the oil is cold and can not pass through the filter...

Click to expand...

It makes sense for the filter to be bypassed when the engine is cold and the oil can’t flow through the filter element properly. What about at 8000 rpm when the engine is at normal operating temperature? From that Bob Is The Oil Guy link in post #14 above:

“Under ideal conditions, the bypass valve will never open. ... However, in real operation, it opens often... [even] … when the motor is fully warmed. At idle, the oil pressure is about 15 to 20 psi, and the pressure drop across the filter is about 1 or 2 psi. You take off towards the redline, and quickly build oil pressure. During that full-throttle acceleration the pressure drop across the filter will exceed the bypass setting, and send unfiltered oil to the motor…”

So it sounds like the bypass valves in oil filters open up when they see a certain pressure drop across the filter element. Looking at the parts catalog, there’s a bypass valve built into the oil pump as well, as Briank mentioned. I can’t tell whether that bypass valve opens up at a certain absolute pressure or when it sees a certain pressure drop across the oil filter.

If one of the bypasses opens up when the engine is spinning at 8000 rpm at normal operating temperature even with the OEM long oil filter, then the oil isn’t getting filtered at redline anyhow. Different filters will probably just change the rpm at which the filter gets bypassed.

However, if the old OEM long filter filtered the oil up to redline and the new OEM short filter doesn’t, I’d prefer the long filter.

Im due for an oil change... there is alot of info here... almost to much. If you go with a "taller" filter do you have to add extra oil? My head is spinning from reading all this.... maybe I better re-read it again LOL

When i do an online search for Purolator L22484 it comes up with nothing.... is there a new part number?