Long oil filter vs short

Shaper79

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Mar 25, 2016
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So just checking on this one. I went down to autozone to get some oil and filter. Just told it’s a 94 Chevy 5.7. TBI. The filter they sold me was shorter than the one that was on it i orders last year from Volvo Penta store. It their any significant difference between the short vs long. I know the boat runs at 4000-4200rpms cruise. Would the shorter oil filter not be sufficiently flowing oil at high rpms?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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longer filter has more surface area so the pressure drop is less, therefore more filtration prior to bypassing

Me... I prefer to run the largest diameter filter that I can in the longest length I can with a 30psi bypass valve and an anti-drainback valve
 

aimlow

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Nov 7, 2018
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They used to make a 2 qt. Chevy spin on filter. About a foot long. Current engine conditions..if you NEED a big filter, you've got other problems. Howver, I still prefer a 1 qt filter also. The critical factor..will it physically fit?

Don't buy a cheap filter for marine use..the "can" is usually thinner, and can rust thru sooner.
 

Lou C

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I noticed that both Merc/Quicksliver and Sierra are making smaller filters now for the 4.3. Kinda like a mini filter like the ones I had on my Toyotas back in the ‘80s.
 

Scott Danforth

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you mean they are private labeling smaller filters. Neither Mercruiser or Sierra make filters, they buy em with their label on them.
 

Lou C

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yep. I use em because that is what's easy to find here, but I wonder if a plain old auto application 4.3 filter would be better being a bit larger.
 

harringtondav

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I'm with the 'bigger is better' crowd. More filter media has to be a good thing. Also a touch more oil circulating can't be bad.
 

Shaper79

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Mar 25, 2016
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Yea I’m going to stick with the larger filter from now on. Knowing more about it. And that the boat motor runs st such high RPMs
 

89retta

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Jul 18, 2010
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4000-4200 rpms cruise ? That's pretty close to WOT rpm. Your motor wont last too many years if that your cruising rpm. It should be about 1000 less
 

Redfred1

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Sep 23, 2013
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I had that thought about that right after I bought a CC RZT. The engine is right behind the seat. After an hour of mowing; that aluminum block radiated heat. IR gun showed 220dg. I was thinking a bigger filter (requiring more oil) would make it run cooler. Wrong! Still ran the same temp.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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agreed diameter and length increases capacity and filter media (material and size) determines efficiency.

it also determines the pressure drop across the filter based on the flow output from the pump. generally filters with a higher bypass valve pressure have a better filter media. and generally the larger the filter media size, the lower the pressure drop across the filter.

remember when the bypass opens, there is effectively no filter (all oil systems have a bypass somewhere)

while some filters may be sold as "full-flow" there is still the bypass valve in the block itself
 

Redfred1

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Sep 23, 2013
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That "Running cooler" thing was a Senior thought! All of my stuff has the room for the bigger filter; that's what I use, Takes more oil; but I don't care.Oil and filter change every 4K.
 

aimlow

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Nov 7, 2018
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Bottom line..if you've "plugged" ANY size filter, you've got problems.
 
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