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SW 8432R vs 10599R

Good stuff Doug.

I've been searching around for a ballpark measure of pump efficiency (delivered volume/theoretical volume) to include in an equation as you presented. Some leakage from the high side to the low side of the pump is inevitable. What little I've found suggests a curve rather than a single value; apparently efficiency goes down with increased pressure and lower viscosity (hot oil). Out of town today so no progress.

<<Looking through the manuals etc and now understnd that most 4 cyl Lycomings have the 0.75" oil pumps, the 6 cyl engines have the 1".>>

Apparently true for the 4-cyls. However, I think I saw some IO-540 models with the same 18109 series impellers. Of course I could be wrong as a soup sandwich <g>
 
N131RV said:
Not to get too far off topic, but I've pretty much decided to try an 8432 on my 200HP IO360 RV7. I have an 8406 on there now and it's marginal on very hot days (90+).

I've combed this site but can't seen to find a good picture of an 8432 installation. Does anyone have pictures of one? Preferably baffle mounted on an RV7?

Thanks in advance,
Click to expand...

Here are several pics of my installation of the 8432. The idea is borrowed from the RV-10. Air flow from #4 aft baffle is via 4" scat. The 4" flanges are available from Vans. The box is made of scrap aluminum.

The cooler will fit mounted to the baffle but this set up has the advantage of no cooler vibration and no reinforcement of the baffle. The disadvantage is it is a crowded install but it all fits. There is a Vans air shut off sliding louvered device under the cooler. It doesn't work too well, there is much air leaking around it at present. Highest oil temp observed so far - 180 - with the shut off closed.





 
DanH said:
Good stuff Doug.
Apparently true for the 4-cyls. However, I think I saw some IO-540 models with the same 18109 series impellers. Of course I could be wrong as a soup sandwich <g>
Click to expand...

There are two different oil pump setups in the 540. I don't have the parts catalog handy to spit out the numbers. In order to use the larger housing and pump gears off of the angle-valve 540's on a parallel valve 540 you have to modify the drive shaft that goes from the pump gear to the crank gear. The housing is taller so all it takes is some surface grinding to make it work. I caught this mod looking at Mike Mangold's Edge 540 while it was apart for overhaul.
 
Very much agree with David's recomendation of a 4" cooler duct.

The cooler face (8432R or 10599R) is about 6"x4.25", or 25.5 sq in. Assume (rough approximate) half the cooler face is solid (tubes and fins) and the other half is open for air passage. You would have 12.75 sq in. A 4" scat would be pi x D = 12.56 sq in.

The best cooler installations place the return line to the engine on top (or close to it) so the cooler body will self-purge and not trap air entrained in the oil. I suspect a whole lot of marginal installs broke this rule.

It also pays to observe the rules of airflow; low divergent angles, largest possible radius on all turns, avoid sharp edges and corners, smooth transitions from round to square and back. Be creative, lots of ways to do it.



 
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Longer oil pump gears

At one time it became quite fashionable to install the larger Big Block Chevy size oil pump in Small Block Chevy engines, through exactly this sort of family "upgrade" path. Not surprisingly, people found that it took more HP to turn that larger pump, thus reducing engine output, and that 99% of the time, the stock size pump was well up to the task. If you really need the extra flow, ok, but TANSTAAFL.
 
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<<I felt pretty smart there for a second>>

I felt pretty dumb there for a second.
 
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<<It is a SW 8432R.>>

An 8432R is a two pass cooler.....both ports on one tank.



Now look at the install photos. Physical size is a bit large, and note the ribbed tanks....a plate-style cooler, not Stewart Warner.
 
DanH said:
<<It is a SW 8432R.>>

An 8432R is a two pass cooler.....both ports on one tank.



Now look at the install photos. Physical size is a bit large, and note the ribbed tanks....a plate-style cooler, not Stewart Warner.
Click to expand...


Dang, Dan, you are observant. :)

The cooler in the images posted was plan "A". It was a 6"x8" 22 vane NDM left over from the Subby. When the lower cowl was trial fit, the cooler touched the side ever so slightly and there was nothing to do about it. The thing simply did not fit no matter how it was orientated. (It has since been sold it to another Subby guy.)

It was then on to plan "B" - the SW 8432R. The box was rebuilt smaller and the 4" duct flange takes up most of the plan "B" top. It is the same cooler you show above, guaranteed! The install is similar to what I posted and fits nicely. The cooler is orientated flat with the hose attachments aimed inside. Sorry for the confusion.
 
<<you are observant>>

Actually I didn't notice until this AM. I got around to posting some duct pictures and realized your 4" hole was a small percentage of the supposed 6x4 cooler face. Bet I stared at it for 10 minutes. Figured one of us had gone round the bend, and clearly I wasn't having my sharpest morning. <g>

Was the big Niagara used for oil cooling with the Sube?
 
Different versions of the same bsic part?

DanH said:
<<It is a SW 8432R.>>

An 8432R is a two pass cooler.....both ports on one tank.



Now look at the install photos. Physical size is a bit large, and note the ribbed tanks....a plate-style cooler, not Stewart Warner.
Click to expand...


Sometimes. Here's a ribbed 8432R. At least, that's how it's marked...
dsc08384q.jpg
 
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Neal,
Got any idea of its age?

Whatever it is, turn it around and put the ports on top.
 
DanH said:
Air flow in series (stacked coolers): compared to a single cooler, less total cooling mass through the system for the same baffle drop. I doubt the reduction would be significant. The second cooler would again be operating with less deltaT; it not only receives partially cooled oil, but also receives heated air.
Click to expand...

Just a thought...

Most (all?) of the industrial process equipment I've seen uses reverse flow. In the case of series stacked oil coolers, you would bring the hot oil to the downstream cooler, then flow out of that into the upstream cooler. The oil would be somewhat cooler at this point, and so would the air.
 
DanH said:
Neal,
Got any idea of its age?
Click to expand...

No. I bought it second-hand and sent it to Pacific for overhaul. I was told it came out of a C-182.

Whatever it is, turn it around and put the ports on top.

That's not the final position, just the best photo I could find quickly.
 
Butterfly Air Controller for Oil Cooler

Guys I make a butterfly style air controller that seems to work better than the shutter style. I have it in the 4" and the 3" version. Check it out on the website. You can get a lot more air flow in hot temps and then completely close it off when starting up until the you get to operating temperatures.

http://www.nonstopaviation.com/rv10-controller-cooler-p-14566.html

Also Avery Tool is now carrying the air controllers.

http://www.averytools.com/p-1070-rv-10-4-air-controller-for-oil-cooler.aspx
 
Well, the thread kinda ran out so maybe it's time for a wrap. Ya'll see if this is a reasonable summary.

The 8432R dual pass cooler (or S, same unit, different port locations) is superior in terms of heat rejection, as compared to the same physical size 10559R single pass cooler.

The system is driven by a positive displacement pump, and thus the same quantity of oil (more or less) is pushed through the cooler regardless of effective cooler orifice size. The dual pass 8432 has half the tubes and thus roughly twice the velocity within the tubes. The increased velocity results in higher turbulence and reduced stagnant boundary layer, thus heat transfer is increased.

No free lunch of course. The flow restriction results in higher line pressure between the pump and the 8432 cooler, at least 10 psi @ 7 GPM per the Stewart Warner charts.

Additional horsepower is required to drive the pump. It's been hard to find book equations addressing this point, but what I have found suggests around 0.8 HP is spent on the additional 10 PSI.

An 8432 may not be a good choice for a system with 1" wide pump gears, as oil flow will be closer to 9 GPM and pressure rise due to flow resistance will be off the SW chart.

There are no side seals in a Lycoming pump. Higher pressure will increase internal pump leakage (high to low side), so an 8432 installation will be more sensitive to pump cavity wear.

Higher pressure differential across the vernatherm makes vernatherm port leakage more critical. Some attention should be paid to vernatherm tip wear.

On the good side, oil flow with the vernatherm retracted (oil cool) is governed by pressure differential between the cooler circuit and the bypass circuit. The 8432's pressure drop should force more oil through the bypass, reducing warm up time and increasing oil temperatures during cold weather operations when cooler flow isn't desired.

Good thread, I learned a lot.
 
hey Guys

Sorry to reopen this debate, but I'm also finding myself having to decide between the 8432 and the 10599.

I've already sifted through this tread and gotten an idea of why the 8432 is in fact a better heat transfer system. What I'm wondering, is if anyone actually has any experience flying a Lyc IO-390 with the 8432?

This guy here only reached low enough oil temperatures after installing the 10599

http://www.io-390.com/IO-390.com/Flights_-_2.html

He says that every IO-390 owner should try to install the biggest oil cooler possible, which makes me wonder if a 8432 on a IO-390 is the right choice.

What do you guys think?

grubac
 
DanH said:
An 8432 may not be a good choice for a system with 1" wide pump gears, as oil flow will be closer to 9 GPM and pressure rise due to flow resistance will be off the SW chart...Good thread, I learned a lot.
Click to expand...

Me too, Dan, and thanks to all for participating. Dan, are you saying that the narrower pump gears (.75" in my case) would result in lower flow and thus be on the chart (and likely in the "acceptable" range)? Sorry if I missed it, where did you find oil flow versus pump gear width vs. rpm?
 
Grubac; the 10599 and the 8432 are the same physical size and have the same air flow. However, in theory the 8432 should out-perform a 10599 for the reasons covered previously. I have no idea why Marc found the 10599 superior. Perhaps it was a simple matter of reduced oil temperature following break-in.

<<Dan, are you saying that the narrower pump gears (.75" in my case) would result in lower flow and thus be on the chart (and likely in the "acceptable" range)? Sorry if I missed it, where did you find oil flow versus pump gear width vs. rpm?>>

The Stewart Warner oil volume vs pressure drop chart is available at the Pacific Oil Cooler website. 7 GPM (about 50 lbs) is at the far right chart limits for a 8432. Oil volume vs pump gear width is per a private note from a Lycoming rep, ie 7GPM for the 3/4" pumps and 9GPM for the 1" pumps. Doug ran some calcs in post #48. Precise volume per minute for each pump width? Frankly, I doubt anyone has actually measured it since the 1950's.
 
Thanks for responding Dan

The thing with Marc is that he originally had a 8406R mounted. This resulted in high oil temperatures. The questions is why he didn't try thte 8432R before mounting the 10599R. Whatever, not important.

So Dan, are you holding good oil temps with the 8432R in your IO-390?

grubac
 
<<The thing with Marc is that he originally had a 8406R mounted.>>

Ahhh, my mistake, assumed 8432. I'm using a ducted 10599, not yet flying.
 
This was a great topic and thread. I learned a lot from it. It caused me to take a closer look at my oil cooler, hoses and installation and make some positive changes. Next step will be a change in coolers away from the Harrison 8529245 but I want to tighten up baffling and improve oil line routing first. I'll probably install an 8432R but am concerned with the port locations making hose lengths and routings problematic. The line to the outboard port will need to make a 135 or 180 degreen turn ASAP.

My thanks to everyone who participated and added info. I especially liked the scientific and thorough analysis given this by DanH. Between this thread and the urethane thread and the small fiberglass part thread I have learned a lot this summer from DanH.
 
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Just installed an 8432R

I just (today) replaced my SW 8406 with an 8432R. I had expected it to be major surgery but all in all was a pretty minor amount of work. The 8432 is almost exactly one inch wider than the 8406 and the fittings are arranged differently.

It fits on the left rear baffle of my RV7 (IO360A1B6) in essentially the same place as the 8406. It's tight, but there is adequate clearance.

I used the two existing inboard bolt holes and nut plates. I expanded the cutout in the baffle and put two new holes in the outboard flange. I was able to reuse one of the existing hoses (input) and had to make a new hose for the return line (about 16 inches longer).

To maintain clearance between the outer elbow and the cowl, I tilted the cooler approximately 5 degrees to gain an extra quarter inch of clearance. Total clearance between the outer fitting and the cowl is about half an inch (plenty).

I have pictures if anyone is interested.

On to performance.

With the 8406, long climbs in these dog days of summer result in oil temperatures of 220-225 degrees (I try to never let it get above that).

Level flight cruise would drop down between 207 and 214 degrees. In the green, but too high for my preference.

With the 8432, I did a sustained climb from 600msl to 10500 and oil temps reached a peak of 212 while I was doing a "hard climb". Cruise climb was more like 207-209.

After leveling at 10500, the temps dropped down to around 198 in level flight.

Outside air temp was 101 on the ground and still in the 70s at 10500. Bumpy too. :)

It's not a dramatic improvement, but it's about what the charts indicated it would do, 10 to 15 degrees difference.

YMMV.

P.S. I have a good used SW 8406 for sale. :)
 
Gentlemen,

Once again, I'm sorry to reopen this debate, but something about the thermostatic bypass and pressure relief valve is not clear to me.

Point #22 in the Lycoming Specification 2665 for the IO-390-A1A6 states that "the pressure relief valve limits pressure drop through the cooler connection to 35 psi".

I'm guessing this means that the pressure at the cooler intake is always 35 psi, controlled by the valve.

It then goes on to state "if pressure drop across the cooler exceeds 75 + 15 psi the pressure relief valve opens bypasing the cooler".

I'm not understanding this parameter 75 + 15 psi. Can anyone explain this to me???

cheers

grubac
 
Almost free lunch

DanH said:
No free lunch of course. The flow restriction results in higher line pressure between the pump and the 8432 cooler, at least 10 psi @ 7 GPM per the Stewart Warner charts.

Additional horsepower is required to drive the pump. It's been hard to find book equations addressing this point, but what I have found suggests around 0.8 HP is spent on the additional 10 PSI.
Click to expand...
Power = flowrate * pressure. When using SI units (m3/s and pascal) this can be calculated directly and the result is in W.

However, there is lots of usefull formulaes here: http://www.precisionfluidpower.com/fluid_power_formulas.htm
Power (HP) = (flowrate(GPM) * Pressur(PSI))/1714 = 0.04 HP. When taking into account the pump efficiency, certainly no more than 75%, the total extra HP at 7 GPM and 10 PSI should be very close to 0.04/0.75 = 0.05 HP.

(I guess you calculated the total HP from the pump?)

Seems to me the 8432R dual pass cooler simply is a much better design all over, both in cold and hot climates. Something to remember when the time comes, thanks Dan.
 
<<the total extra HP at 7 GPM and 10 PSI should be very close to 0.04/0.75 = 0.05 HP.>>

Good catch Dr. S!

<<(I guess you calculated the total HP from the pump?)>>

Incorrectly applied terms in equations from the Bosch Automotive Handbook, which is not as clear as the excellent reference page you linked. I've printed that page and tucked it into my library....thanks.
 
Gentlemen,

If you get the chance, check out this link. It's an article about choosing oil coolers. The author somehow determined that his Lycoming IO-360 would need 2 SW oil coolers. I find this hard to believe, it being that many people are already successfully holding good oil temps with only one cooler installed. I can't, however, find the mistake in his calculations.

http://www.kitplanes.com/magazine/engines/8876-1.phtml

Does anyone know where he screwed up in his calculation? See section "let's do the math". BTW - view in PDF format - it'll be easier

Cheers

Grubac
 
2 OIL COOLERS ARE NOT NEEDED.....

grubac said:
Gentlemen,

If you get the chance, check out this link. It's an article about choosing oil coolers. The author somehow determined that his Lycoming IO-360 would need 2 SW oil coolers. I find this hard to believe, it being that many people are already successfully holding good oil temps with only one cooler installed. I can't, however, find the mistake in his calculations.

http://www.kitplanes.com/magazine/engines/8876-1.phtml

Does anyone know where he screwed up in his calculation? See section "let's do the math". BTW - view in PDF format - it'll be easier

Cheers

Grubac
Click to expand...

I've been thinking about commenting on oil cooling and this article is more reason to do so.

The math does add up but the conclusion would indicate something is remiss. The physical factors behind the numbers are not proven or demonstrated in an airplane. The numbers are a compilation of values garnered from various sources, not necessarily an indication of what is really going on after installation.

The conclusion that 2 oil coolers are needed for an I0360 is proof of what I say - they are not needed and I can prove it, not mathematically but with a simple oil temp gauge.

In fact, one cooler properly installed can provide TOO much cooling.

My concern since first flight with this new IO360 from Barrett has been low oil temperature. In August, a WOT climb to 10,000' resulted in a max oil temp of 180. Lately, it would just reach 160 on a local flight and I began to doubt the accuracy of the oil temp indication system.

This past week end, while changing to 10W50 from mineral oil, the temp probe sensor was removed and dropped into a coffee can of very hot water. A digital thermometer read 192 at the can, the EIS indication at the panel was 191. The indicating system is OK. (The temp probe is installed on the engine at the oil filter housing as per Lycoming drawings.)

I believe the key to good cooling is a proven cooler, in this case the SW8432R; adequate air flow through it, in this case a 4" source from the #4 baffle, and regulation of that air flow. Perhaps the most important element is air flow across the cooler. I opted for a remote cooler mount as per the RV10

Yesterday, on a climb to 6500', oil temp was 185 at level off. What made the difference was a well sealed off air flow shutter at the cooler exit with shutter closed after take off. There had been a 1/8-1/4" opening between it and the cooler exit and it was sealed off with rubber baffle material. Now if the cooler shutter is opened after level off, oil temp drops from 185 to 159 in about 10 minutes. Before the cooler and shutter were sealed the shutter seemed to be of little consequence - oil temp rarely reached 180 even on a hot summer day.

The prime indication here is the cooler is working very well. I do not agree two coolers are necessary. The math is faulty from the beginning.
 
David is right

I agree with David. A second oil cooler is a waste of time, weight and money. I've mentioned this numerous times but it apparently is lost somewhere. I fly in the hottest conditions in RV land, the Phoenix area heat. Because I fly to work, I often leave in the peak temperature times. On at least 10 occasions this past summer, I took off in 110 + degree temps.

I have one 8432R, baffle mounted. On those hot summer days, I will reach 210 on oil temps, reaching 220 when taxiing in from the flight. I only climb to 2900 ft on my trips to work.

If you do a good job of sealing things up, temps should not be a problem. I'm in the mindset, if it works here, it will work anywhere.
 
Thanks for the replies guys. I knew this article was a little fishy. Nice to hear you've got a 8432R! I was thinking about installing this, but then changed my mind. My IO-390-A1B6 is going to probably need a bigger cooler. I'm looking at the SW10559R.

grubac
 
One of the things that has confused me has been why worry about pressure drop across the oil cooler branch of the oil flow if the pump is a positive displacement pump. At a given engine speed the pump will put out a constant volume of oil...somewhere.

I read the article and gained a little more understanding. Let's see if I have this figured out now.

It's the "somewhere" in teh above statement that I think holds the key. If pressure drop gets too high the relief valve opens allowing some of the oil from the pump to go back to the sump, which reduces the amount of oil going through the cooler and therefore reduces the amount of heat removed from the oil and therefore the engine.

Reducing engine rpm would reduce the heat load from the engine to the oil but would also reduce the pump flowrate and the pressure drop. Maybe it drops enough to close the relief valve and return all flow to the cooler.

If small lines are used with several 90 degree fittings perhaps the pressure drop even with hot oil would be enough to do this. Therefore larger lines (-8) and -45 fittings where possible instead of -90 degree fittings should help. Minimal hose run too.

Do I have the fundamentals right? I like to understand the mechanisms at work.
 
Bubblehead said:
One of the things that has confused me has been why worry about pressure drop across the oil cooler branch of the oil flow if the pump is a positive displacement pump. At a given engine speed the pump will put out a constant volume of oil...somewhere.

I read the article and gained a little more understanding. Let's see if I have this figured out now.

It's the "somewhere" in teh above statement that I think holds the key. If pressure drop gets too high the relief valve opens allowing some of the oil from the pump to go back to the sump, which reduces the amount of oil going through the cooler and therefore reduces the amount of heat removed from the oil and therefore the engine.

Reducing engine rpm would reduce the heat load from the engine to the oil but would also reduce the pump flowrate and the pressure drop. Maybe it drops enough to close the relief valve and return all flow to the cooler.

If small lines are used with several 90 degree fittings perhaps the pressure drop even with hot oil would be enough to do this. Therefore larger lines (-8) and -45 fittings where possible instead of -90 degree fittings should help. Minimal hose run too.

Do I have the fundamentals right? I like to understand the mechanisms at work.
Click to expand...

John,

The mechanism at work is not all that complicated. Pressure is regulated by a ball held in a seat with a spring, cooling is regulated somewhat by the vernatherm.

Oil through the cooler gets cooled, otherwise not. How it gets there varies from engine to engine because of the factors you site but the bottom line is oil flows to the cooler or back into the engine depending on whether the vernatherm has closed the Y port back to the engine. When oil temps are low, like less than 180 or so, both ports are open and oil can flow to the cooler or back to the engine. When oil temps are hot, the vernatherm closes the port to the engine and oil is forced through the cooler. The port to the cooler is NEVER closed which is why an oil cooler air flow shut off plate is installed in winter months with certified airplanes like the Cherokee.

I don't see what pressure has to do with it except it may take more pressure to force oil through the cooler than back to the engine, but not always. With most engines, oil is flowing through the cooler all the time. Obviously, some oil is by-passed from cooling path with the ball and seat regulation of pressure but it is a given with every engine. There is no other way to regulate pressure whether it be oil or fuel injection pressure.

The vernatherm is not a thermostat. It's only functiion is to force oil through the cooler when oil gets hot (190+). The port to the cooler is always open, the port to the engine is open sometimes. It is an ingenious design with a built in fail safe function that has worked for many years. The only down side is there is no absolute control of oil flow through the cooler when oil temps are low.

I suppose 90 vrs 45 degree fittings and hose size could make a difference. It seems the only hose size used for years has been #8 so why even consider 6. Oil cooling is not all that complicated. Go with what works.
 
John, the oil pressure relief ball valve (right main case half, toward the rear, on the right main oil gallery) has nothing to do with how much oil passes through the cooler.
 
As usual I got too wordy and confused the issue. I'll restate my question in it's most basic form.

If the pump is positive displacement, why do we worry about fitting angles and hose size and pressure drop through components? Won't the same amount of oil flow through the oil cooler regardless?
 
Because....Someone correct me if I am wrong, but liquids do not compress and take the path of least resistance. If you have two circuits of liquid flow, more will always flow in the less restrictive loop. The greater the difference in flow pressure drop the greater the difference in flow volume. In the Lycoming case (always two open loops to varied degrees), if you create a large enough flow restriction in the oil cooler lines in proportion to the bypass loop, then little oil will choose that path of flow.
 
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Bubblehead said:
As usual I got too wordy and confused the issue. I'll restate my question in it's most basic form.

If the pump is positive displacement, why do we worry about fitting angles and hose size and pressure drop through components? Won't the same amount of oil flow through the oil cooler regardless?
Click to expand...

I don't think so.

If a quarter inch line were used instead of #8, the flow rate would be less. The rate has to be less because the hole is smaller.

Don't ask me to prove it, but it is true. Its a conclusion based on common sense.

Is the pump positive displacement? I think not. It operates at a fixed pressure not fixed displacement, the amount of flow will depend on the restriction in the system. The smaller the hole, the lower the flow rate.
 
David-aviator - I believe the oil pump is a gear type pump which is a positive displacement pump, which means it pumps a fixed volume for every revolution. It will raise the pressure high enough to push out that volume (or die trying!). It only appears to be fixed pressure because there is a relief valve downstream to open if pressure is too high. Besides, if you watch your pressure gage the pressure does vary with engine speed and oil temperature.

Your common sense would be right if this were a different type of pump, like a centrifugal pump.

RV8RIVITER - are there always two open loops? I'm not sure that is true. If the pressure is less than the relief valve setpoint AND the vernatherm is closed all the way then all the flow should go through the cooler. In that case the pump capacity would be the flow rate of oil through the cooler. If you look at teh calculations DanH did and the ones the magazine writer did they assume all the pump volume goes through the cooler.

You are right that when there are two paths the pressure drop across the cooler is very important. Flow will adjust so the pressure drop across two parallel components is equal, just like current adjusts across two resistors in parallel. I'm just not convinced there are always two paths.
 
I still think there are two, but I grant you if the vernatherm is operating properly there should be a small trickle on the bypass side. From the vernatherms I have seen, only 3 though, none appear to be a complete high pressure seal.

Lycoming says a 60-90 psi drop across the oil cooler side, which would be from the vernatherm and back, will cause the vernatherm to open and bypass. Large range there and probably has some error as well over time of use.

Also agree, this is not much of a useful exercise. Oil cooling problems are more related to the overall design and execution of the cooler installation and airflow management.
 
Bubblehead said:
David-aviator - I believe the oil pump is a gear type pump which is a positive displacement pump, which means it pumps a fixed volume for every revolution. It will raise the pressure high enough to push out that volume (or die trying!). It only appears to be fixed pressure because there is a relief valve downstream to open if pressure is too high. Besides, if you watch your pressure gage the pressure does vary with engine speed and oil temperature.

Your common sense would be right if this were a different type of pump, like a centrifugal pump......
Click to expand...

A quarter inch hose to and from the cooler will not work as well as #8.

I will bet you a six pack of beer on that statement. :)
 
Ummmm Beeeeer

It may not work as well, but not because the flowrate is lower through it.

To simplify matters let's just compare two identical system with no relief valve. Just a sump, a positive displacement gear pump, a hose, a cooler and a hose back to the sump.

One system has -6 hoses and fittings and one has -8 hoses and fittings. Which one will move a higher gpm of oil? Neither - the flow rate will be the same in both. The oil will move faster in the -6 line because of the smaller cross sectional area but the pump controls the volumetric flow rate. It will put out a fixed volume of oil per revolution.

Please send Shiner Bock beer to me in Keller TX. If the beer is cold when it gets here I'll even share one of them with you.
 
Hey Guys,

Do any of you have any experience with oil coolers from Airflow Systems? I eyeing the AS-2006X as solution for my IO-390. It's slightly bigger than the 10599, but cheaper.

grubac
 
You might try doing a search on 20006A or Airflow Systems. I was reading a lot of old threads last night and came across some in the RV-10 forums about that cooler.
 
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