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Posted by: Cracker Aug 29 2016, 04:44 PM

I've been thinking of this lately...

So when selecting an oil filter, there are variables such as flow rate, surface area of the filter itself and line size restrictions. So when using an external oil cooler, which in theory, would work most efficiently "holding" the oil for longer, extracting more energy in its exchange - does it make sense to use the "lowest" flow rated filter that conversely meets the maximum demand of the engine?

This is relative with any engine that uses oil; and that oil gets hot - not an oil cooled/water cooled issue - neither are immune and both could benefit from the most efficient set up.

Many "oil filters" claim hi-volume flow rate (28 gallons per minute!) - whats that good for if my max engine oil flow rate at WOT/Max temp is 6 GPM? The obvious opposing theory is that the longer oil is contained in an engine - the hotter it gets.

So what would be the perfect formula for engine temp and oil quench? What say you?

Tony

Posted by: Chris914n6 Aug 29 2016, 07:16 PM

The largest contributor to less filter flow is how many microns it filters down to. Some brands are better than others but for the most part they all work well enough to keep the bearings happy.

Factory oil coolers are cooled by the radiator, so there is really not that much of a drop below ideal operating temp.

The volume of oil flow is calculated. Reduce it for any reason and you risk spinning bearings.

Posted by: Cracker Aug 29 2016, 07:59 PM

I'm specifically referring to max effort cars/engines. The GT3 RSR Cup uses dedicated water to oil heat exchangers to achieve ideal oil temps - even then, its a challenge. I obviously have the equivalent of nothing compared to Porsche so all my efforts need to achieved through trial and error. A stock scenario is easy peasy - racing, not so much.

Again, just on my mind...probably should have stayed there.

T

Posted by: Chris914n6 Aug 29 2016, 09:36 PM

So you're looking for a formula that will tell you how big of a cooler you need w/wo a fan to keep oil temps within range? You would need to know the amount of heat generated by the engine under those operating conditions that is transferred to the oil. Call GM racing, you might get lucky, or guess by seeing what cars using that engine are using.

My solution because I like easy... temp gauge to see where I'm at and run an oil fan relay off the rad relay since the temps will correlate.

I could calculate BTUs by the before and after cooler temps, but too many factors to pick the right size cooler at first without a ton of research.

Posted by: Cracker Aug 30 2016, 06:03 AM

Chris - My specific situation has proven to be difficult - a tough nut to crack. Thus the reason I've been thinking allot of the subject over the last six-mounts. Mid-engine cars that don't have crazy scoops and such are at a disadvantage when it comes to controlling all things heat. Mine is no exception. Maybe I'll do something "crazy" and my oil temp issue will be bye, bye. Thanks.

BTW: I'm currently running a combined 76 rows of oil cooler on a 11" core - that's a ton of cooler for any car. In my case, I don't have adequate air-flow, with the coolers mounted in the rear of the car.

Tony

Posted by: Racer Chris Aug 30 2016, 06:28 AM

QUOTE(Cracker @ Aug 30 2016, 08:03 AM)

Posted by: Cracker Aug 30 2016, 06:33 AM

Chris - I already have my coolant (hard lines as well) lines running in those recesses. It certainly can be done either way but I don't want any lines in the cabin, at any point. As you know, those pesky wheel wells create a challenge. Besides, anyone can do it correctly and simply put a cooler where it is supposed to be...

Tony

QUOTE(Racer Chris @ Aug 30 2016, 08:28 AM)

QUOTE(Cracker @ Aug 30 2016, 08:03 AM)

I don't have adequate air-flow, with the coolers mounted in the rear of the car.

Moving to a front mounted cooler with exposed hard lines (recessed in the 2 channels below the tunnel) will make a dramatic difference in cooling results.

Posted by: gereed75 Aug 30 2016, 07:02 AM

Sounds like you have a good handle on the issues involved. It would seem to me to do this most efficiently you would run an auxiliary cooling loop off of the sump tank using a separate pump and cooler independent of the pressure / scavenge pump. Has the advantage of sending un-aerated oil to the cooler for better heat xfer

Anyone know if that is standard practice in big boy race cars?? Wonder what the F1 guys do??

Haven,t seen your setup, I assume you are running a big ass fan with your BA cooler

Posted by: Dave_Darling Aug 30 2016, 04:08 PM

If you've already got water cooling, just set up an air-to-water heat exchanger. Keep it "upstream" of the thermostat, so that it gets coolant fed to it even when the engine is cool. That helps put heat into the oil faster, getting it to your operating temp. Then it should keep the oil at or near the temp of the coolant, which is basically where you want it anyway.

--DD

Posted by: Cracker Aug 30 2016, 04:46 PM

The "big boys" generally use Water to air heat exchangers as Dave eluded to below. The long term solution (in part) might be to do just that - the problem is my current cooling system is ideal but has no capacity to bring oil into the system. Therefore, this is not currently an option, yet. The line sizes the race teams use are equally impressive, as in massive, just to move oil through the coolers. I took a break today from this and fabricated new strike plates for the hood - a change of scenery is refreshing sometimes!

Tony

QUOTE(gereed75 @ Aug 30 2016, 09:02 AM)

Posted by: Dave_Darling Aug 30 2016, 10:11 PM

There are exchangers you can get that go on the oil filter, more or less. Hondas used them for years; they went in between the oil filter and the block.

If you have any oil lines, you should be able to fit some kind of heat exchanger in line with them. Plumbing into the cooling system should be relatively straightforward.

--DD

Posted by: Cracker Aug 31 2016, 05:45 AM

Dave - I'm not quite following you...get what exactly you are referring to - what kind of heat exchangers are you suggesting be added?

How do the Big Boys do it? Like this...
Below is an LMP2 from this years Walter Mitty at Road Atlanta. The absolutely massive (everything is huge actually) Oil Filter, plumbed to a water to oil heat exchanger, the coolant/heat exchanger would be the return (cooled) branch, and finally the cooled oil would be returned to a dry sump tank for eventual return to pump/engine.

Its easy...so long as you have a ton of room to work with, and cubic dollars to spend! LOL.

Tony

Posted by: Dave_Darling Aug 31 2016, 01:07 PM

I'm talking water-to-oil heat exchanger. It shouldn't have to be huge, and since you can plumb oil and coolant lines around the car wherever you like, you should have a good amount of flexibility in where to put it.

Like I said, some Hondas had an exchanger that went in between the block and the oil filter. Spaced the filter out a couple of inches, maybe, and helped with oil temps.

--DD