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Excessive oil temps - suspect piston squirters?

airguy

Unrepentant fanboy
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First off, I'll say that I bought my engine from a Reno racer at 105 TTSN 0 SMOH - and the engine log doesn't give me any indication if it has piston squirters or not (IO360, parallel valve). I have right at 8 hours on the engine now so I should be at the point where the rings are seated (or at least seating) and break-in heat loads should be reduced. I'm easily able to keep CHT's below 400, but my oil temp consistently runs in the low-to-mid 240's at 24" and 2400 rpm, using a Niagara 7-row oil cooler on a firewall mount with 4" SCAT tubing off a James plenum, and my Vernatherm is confirmed good. From what I know (and admittedly I have holes in my knowledge) about the oil heat load, the only way this makes sense right now is with piston squirters in the engine to supply that extra oil heat load. I'm unable to contact the engine builder now, apparently his phone number has changed, so without a teardown myself I'm unable to confirm the existence of the piston squirters. Local temps at my testing altitude have been 60's and 70's Fahrenheit.

I guess I'm just asking for the tribal knowledge of the gray-hair wrench turners here, does this sound about right? I ordered a 10-row AeroClassics oil cooler today to try to make a dent in the oil temps, that should be here in a few days.
 
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First off, I'll say that I bought my engine from a Reno racer at 105 TTSN 0 SMOH - and the engine log doesn't give me any indication if it has piston squirters or not (IO360, parallel valve). I have right at 8 hours on the engine now so I should be at the point where the rings are seated (or at least seating) and break-in heat loads should be reduced. I'm easily able to keep CHT's below 400, but my oil temp consistently runs in the low-to-mid 240's at 24" and 2400 rpm, using a Niagara 7-row oil cooler on a firewall mount with 4" SCAT tubing off a James plenum, and my Vernatherm is confirmed good. From what I know (and admittedly I have holes in my knowledge) about the oil heat load, the only way this makes sense right now is with piston squirters in the engine to supply that extra oil heat load. I'm unable to contact the engine builder now, apparently his phone number has changed, so without a teardown myself I'm unable to confirm the existence of the piston squirters.

I guess I'm just asking for the tribal knowledge of the gray-hair wrench turners here, does this sound about right? I ordered a 10-row AeroClassics oil cooler today to try to make a dent in the oil temps, that should be here in a few days.

I have no experience with piston squirters or how much cooling load they move to the oil system. However, I have not seen any discussion of oil temps that high with them. While blow-by during break-in can raise oil temps, I don't believe it is anywhere near that level. I had a lot of blow-by from a glazed cylinder and never got over 200 in 100* ambient temps. At 8 hours, your rings should have seated well enough that they wouldn't be adding that much additional friction heat.

I think you need to look more closely at your oil cooling system. I would confirm that you don't have any blockages and I would re-confirm the Vernatherm, as that is the most likely culprit for those temps. I would also do some more research on the air ducting for your setup. Seems several folks struggle with higher than normal temps from firewall mounted coolers.

Larry
 
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Any time someone has cooling issues, the first thing I ask is "what have you changed from the stock design?" That doesn't mean I am anti-modifications, it is simply a statement of fact that if you build per plans, you get factory results, and anytime you start takign the design "off point", you are going to poke out a parameter somewhere else.

Piston squirrels can make a difference, but 60 degrees of oil temp? That seems unlikely to me. More likely, as Larry says, you have a fundamental issue in getting cooling air past your oil. There are losses invovled with the ducting to a firewall mounted cooler, so there's a change. Sam James Plenum? There's a change. How about airspeed? Are you flying with or without having pants and fairings? In order to get good cooling, you need good airflow. To get good airflow, you need speed - flying without all the fairings makes a hug difference in top end speed, and cooling air available goes up with dynamic pressure, which goes up with the square of airspeed. And, of cours,e the -9 is not designed to go quite as fast as a -7, so there's a couple of knots as well.

So look at your changes - they are the most likely source of issues.
 
A few things...

First, do confirm the temp probe is reading correctly. place it in boiling water and check the readout, correcting for altitude if you are at a high elevation airport.

Second, oil cooling is about 2 things---- oil flow through the cooler and air flow across the cooler. Make sure you have the right size hoses going to/from the cooler. They should be dash 8's minimum. I have seen 6's inadvertently installed. You would be surprised at the flow specs on the oil pump.

Check that you have good flow out the exit of the aircraft. The Sam James cowls I have had expereince with all seem to adversely affect cooling. That doesn't mean they ALL do. If you have room, try 2 things--- a 13 row cooler from Air Performance coolers or Pacific oil coolers. They seem to have the better heat rejection. The Stewart Warner bar and plate coolers are the best, but they cost more, too.

Another option that does help drop temps is to install an Airwolf remote oil cooler mount. It's usually good for 10-15 degrees of cooling, and makes changing the oil eaiser as well.

Vic
 
I did some measurements on the area of the niagara cooler. IIRC, the area needs a 4" tube to cool it. Others have used two tubes coming together at the cooler inlet. Looking at your build pictures, that airflow transition to the scat and on top of the cooler will restrict the flow considerably (40% or more). You have the fiberglass skills to make a better diffuser for the inlet of the cooler. Paul, and others, have much experience in the numbers. I think you need more data than just the oil temp at the engine to cost effectively solve this. You can likely overcome poor air flow with a huge cooler.

Air temps into and exiting the cooler along with same for oil temps will tell you what you need to know for a solution. You can even tape/wrap a thermo couple on the fittings with some rescue tape and some insulation on the outside to get within a couple of degrees. thermocouples and a meter probably $150, unless you can borrow from someone nearby. :D

Good luck! Keep us informed.

Edit: I see you did use 4", but the inlet losses and expansion to the cooler are still quite important. I think the SJ has less total air flow than Vans, so leaks are very important to fix. You could also experiment with blocking all losses - like heater (reduce to 1" dia), alternator, and other blow tubes, if you have them. The lower baffles at the cylinder bases have a 1/4" X 1" gap. HUGE. James recommends 1" gap at the cylinder exit and 2 1/4" at the heads, Are yours larger? Still recommend you get instrumentation for data as you progress, so you can more precisely measure improvements.
 
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My -8 has 200 HP and piston squirters and cools just fine with the std vans supplied oil cooler mounted on the baffles. Even in the heat of summer it rarely touches 200 on climb out. Normal cruise is 185.

As others have said, Id start looking for a fundamental issue. Your setup should cool fine.
 
In my experience, helping build my friend's RV-8 with ECI Titan IO-360 engine w/piston oil squirters, and debugging high oil temps, it seems that the oil squirters contribute to somewhere between 20-30 degrees higher oil temps on a hot Texas summer day if your oil cooler is too small They also take off nearly that much CHT too. We ultimately ended up installing a SW10599 oil cooler. The original 7 row Niagara cooler was way inadequate for that engine.
 
The original 7 row Niagara cooler was way inadequate for that engine.

For the same airflow, about 20% less heat rejection than an SW8406, and 50% less than an SW8432.

Don't know about the 10 row Aero Classics, but when you get a larger cooler, ditch the top hat entry plenum for a better shape, and seal the edge.

 
oil coolers....

Greg, I'm not a real injunear, but some things I've picked up here 'n there....( like from Dan!)

your fw mounted cooler may not be seeing a good pressure delta.....possibly reducing the flow. ....great ram pressure, then it just 'dumps' into the cowl?
.... the exit of any radiator type unit is as important than the inlet. Note the pains taken to flow downstream of a P-51 belly rad for instance.....if the cooler just 'ends'.....the turbulence and backpressure cuts the airflow in half.
My eyeball says it needs at least a 4" skirt/ramp, flaring gradually to slow to the airflow speed exiting the cowl. I realize this is a problem inside a tight space.

(just my silly opinion of course.)
 
Here are my knowns...

The oil hoses are -8, I will pull them and check them for any blockage.
The vernatherm was confirmed working when installed, and now the inlet and outlet hoses to the cooler are both hot to the touch upon decowling so I made the ASSUMPTION that it was still working properly - but to be fair all I really know here is that SOME oil is flowing through the cooler.
The air flow inlet to the cooler is definitely somewhat less than desirable - I'll make a fiberglass transition when I install the 10-row cooler to improve this.
The oil temp sender indicates the correct pre-startup ambient temperature, but I don't know for a fact that the high temp is correct, I'll check it with boiling water.
When I graph the temperature in Excel under consistent full power operation after takeoff, the temperature rises rapidly and then smoothly levels off in the 240-245 area, it's definitely stable there, but I need it lower.
I'm using the default inlet rings (4.625" ID) for the Sam James cowl, there is a larger one available but I suspect I need to pay more attention to my cowl exit than my inlet.

Now for some unknowns...
The exit ramp on my James cowl may need some work - though my CHT's are controllable right now, that may be primarily because I'm still running very rich for break-in. Maybe I need to be moving more air out of the lower cowl for better pressure delta. I have zero information right now about my pressure deltas.
The 4" SCAT to the current oil cooler location is a hair longer than it needs to be and "S-bends" a bit, that is detrimental to good flow, but I don't know how bad that is.
The vernatherm and temp indicator will get checked for proper operation.

Now here is a question for the group - the exit air from the oil cooler - do I need some kind of separate ducting to the cowl exit for that? Or just dump it into the lower cowl? The standard baffle-mount coolers don't use any kind of exit air guidance, do they?
 
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...ditch the top hat entry plenum for a better shape, and seal the edge.


So, if this is your cooler setup, then yes - big issues there. My baffle mounted cooler on the -8 has a plenum incorporated, and it is sealed tight.

Listen to Dan.

My solution is here. It is baffle mounted, but might give you some ideas.
 
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but to be fair all I really know here is that SOME oil is flowing through the cooler.

Not to push the Vernatherm issue, as it seems less likely then poor air flow in your case, you should know that when the the Vernatherm is open (i.e. not directing oil to the cooler) oil still flows through the cooler circuit. It does not flow a great volume, but it does flow. This is why people up need to cover them in the winter.

Larry
 
Here are my knowns...

The oil hoses are -8, I will pull them and check them for any blockage.
The vernatherm was confirmed working when installed, and now the inlet and outlet hoses to the cooler are both hot to the touch upon decowling so I made the ASSUMPTION that it was still working properly - but to be fair all I really know here is that SOME oil is flowing through the cooler.
The air flow inlet to the cooler is definitely somewhat less than desirable - I'll make a fiberglass transition when I install the 10-row cooler to improve this.
The oil temp sender indicates the correct pre-startup ambient temperature, but I don't know for a fact that the high temp is correct, I'll check it with boiling water.
When I graph the temperature in Excel under consistent full power operation after takeoff, the temperature rises rapidly and then smoothly levels off in the 240-245 area, it's definitely stable there, but I need it lower.
I'm using the default inlet rings (4.625" ID) for the Sam James cowl, there is a larger one available but I suspect I need to pay more attention to my cowl exit than my inlet.

Now for some unknowns...
The exit ramp on my James cowl may need some work - though my CHT's are controllable right now, that may be primarily because I'm still running very rich for break-in. Maybe I need to be moving more air out of the lower cowl for better pressure delta. I have zero information right now about my pressure deltas.
The 4" SCAT to the current oil cooler location is a hair longer than it needs to be and "S-bends" a bit, that is detrimental to good flow, but I don't know how bad that is.
The vernatherm and temp indicator will get checked for proper operation.

Now here is a question for the group - the exit air from the oil cooler - do I need some kind of separate ducting to the cowl exit for that? Or just dump it into the lower cowl? The standard baffle-mount coolers don't use any kind of exit air guidance, do they?

Do a perfect job of sealing, remove the screen in the oil cooler airflow path, get some data. The S bend is insignificant to others, exit may help, but other things will have a larger effect now, there is no reason you shouldn't have enough airflow with those inlets.

It seems you wanted a 360 and 9 for an efficient airplane, don't give up now.
 
When I graph the temperature in Excel under consistent full power operation after takeoff, the temperature rises rapidly and then smoothly levels off in the 240-245 area...

The rise rate (rise vs time) should flatten at about 185F (ballpark) when the vernatherm fully seats. A straight line rise to 240 says you have a vernatherm problem. When you swapped from the original screen housing to the ECI spin-on filter adapter, are you sure you got the correct gasket, and are you sure the vernatherm tip is seating squarely into the accessory case hole?

Maybe I need to be moving more air out of the lower cowl for better pressure delta. I have zero information right now about my pressure deltas.

Then do nothing to the cowl until you do.

Now here is a question for the group - the exit air from the oil cooler - do I need some kind of separate ducting to the cowl exit for that? Or just dump it into the lower cowl?

There are two reasons to duct the oil cooler exit. One is to accelerate the flow with a converging duct, trading pressure for velocity. This doesn't apply to your application unless you manage to build a duct of the correct shape, and direct the exit rearward. As a practical matter, it easier to simply dump the cooler outflow into the lower cowl volume, and then worry about creating a high velocity exit for the entire cooling flow.

The other reason is to place the duct exit in a region of pressure less than the lower cowl pressure, thus increasing pressure delta across the cooler, thus increasing flow through the cooler without increasing flow through the cylinder baffles.

remove the screen in the oil cooler airflow path

Good catch Bill. Yep, screens are a surprising reduction in flow area.
 
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Do a perfect job of sealing, remove the screen in the oil cooler airflow path, get some data. The S bend is insignificant to others, exit may help, but other things will have a larger effect now, there is no reason you shouldn't have enough airflow with those inlets.

It seems you wanted a 360 and 9 for an efficient airplane, don't give up now.

The screen on the 4" scat tubing that you see in my plenum build photos was removed after the first flight when I saw the high oil temps the first time, it's no longer a factor and the temps remain high.

I went into this game knowing that a tightly cowled IO360 might be a cooling challenge, and it appears I was right - now I have to get to work and figure out how to address it.
 
I agree with Dan on this one.

A friend and I molded the cooler transition piece from clay and foam and it solved his cooling issue.


(Click to enlarge)
 
I agree with Dan on this one.

A friend and I molded the cooler transition piece from clay and foam and it solved his cooling issue.


(Click to enlarge)

This is obviously the first and easiest thing to try, looks like I'm off to the arts and craft junk store to find some foam to make a plug.
 
For the same airflow, about 20% less heat rejection than an SW8406, and 50% less than an SW8432.

The SW10599 is somewhat less efficient than the SW8432 and they are pretty much the same external physical dimensions. If I would've done a little more research, I would've got the 8432 instead for my friend's RV8. I ordered the 10599 at the Pacific Oil Coolers booth at Oshkosh based on the recommendation of PAC's sales rep, and it does pretty well, with oil temps hitting 210 or a little higher on a hot Texas summer day in the climb, but the extra bit more efficiency of the 8432 sure would've been well worth the incremental added cost
 
The SW10599 is somewhat less efficient than the SW8432 and they are pretty much the same external physical dimensions. If I would've done a little more research, I would've got the 8432 instead for my friend's RV8. I ordered the 10599 at the Pacific Oil Coolers booth at Oshkosh based on the recommendation of PAC's sales rep, and it does pretty well, with oil temps hitting 210 or a little higher on a hot Texas summer day in the climb, but the extra bit more efficiency of the 8432 sure would've been well worth the incremental added cost

Not me. At Lycoming flow rates an 8432 is hard against its limits. The result has to be a pressure increase at the vernatherm tip, and increased power requirement to turn the pump.

Yes, I know, lots of successful users...
 
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Greg...I have the ten row aero classics cooler mounted behind the #4 cylinder per the plans. It has been more than adequate for my angle valve IO 360.
 
Greg...I have the ten row aero classics cooler mounted behind the #4 cylinder per the plans. It has been more than adequate for my angle valve IO 360.

Then I should be in good shape using that - once I get my airflow issues figured out. The more I roll the problem over in my head, the more I'm convinced I have an airflow issue somewhere.
 
Not me. At Lycoming flow rates an 8432 is hard against its limits. The result has to be a pressure increase at the vernatherm tip, and increased power requirement to turn the pump.

Yes, I know, lots of successful users...

So, the SW10599 was a good choice then? At least the inlet and outlet fittings lined up the same as with the 7 row Niagara and allowed us to use the same hoses. With the 8432, we might have had to change out one or both hoses with longer ones.
 
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First off, I'll say that I bought my engine from a Reno racer at 105 TTSN 0 SMOH - and the engine log doesn't give me any indication if it has piston squirters or not (IO360, parallel valve). I have right at 8 hours on the engine now so I should be at the point where the rings are seated (or at least seating) and break-in heat loads should be reduced. I'm easily able to keep CHT's below 400, but my oil temp consistently runs in the low-to-mid 240's at 24" and 2400 rpm, using a Niagara 7-row oil cooler on a firewall mount with 4" SCAT tubing off a James plenum, and my Vernatherm is confirmed good. From what I know (and admittedly I have holes in my knowledge) about the oil heat load, the only way this makes sense right now is with piston squirters in the engine to supply that extra oil heat load. I'm unable to contact the engine builder now, apparently his phone number has changed, so without a teardown myself I'm unable to confirm the existence of the piston squirters. Local temps at my testing altitude have been 60's and 70's Fahrenheit.

I guess I'm just asking for the tribal knowledge of the gray-hair wrench turners here, does this sound about right? I ordered a 10-row AeroClassics oil cooler today to try to make a dent in the oil temps, that should be here in a few days.

The oil temp for this engine is not normal even with 7 row niagara.
I'd focus on air flow across the cooler. What is the pressure ratio from in-air to out-air? You may have to open the exit area to lower pressure and get more air across the cooler. Where is the 4" scat tube dumping it's air, what is the pressure there relative to the plenum pressure? If it is near the same no cooler will work.
 
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We have piston squirters in our engine and the normal oil temp is 180 in cruise. We can see as much as 200 in a long climb on a 90 degree plus day but never hot enough to be a issue. I like getting some heat out of the Pistons. I doubt overall it makes more then a 10 degree difference.
George
 
So, the SW10599 was a good choice then? At least the inlet and outlet fittings lined up the same as with the 7 row Niagara and allowed us to use the same hoses. With the 8432, we might have had to change out one or both hoses with longer ones.

Always compromises to consider, like most choices.

A good RV installation is unlikely to have much more than 5" H2O air pressure delta across the cooler at 100 knots (some have reported as little as 3"). The SW charts for the 8432 and 10599 say air mass flow would thus be about 27 lbs/min. At 27 air and 55 lbs/min oil flow (about 7 gallons, the circulation rate for our Lycomings), the heat rejection charts say the difference between the coolers is about 10%. Consider only that point, and the 8432 will be judged as better.

So what is the trade? Take a look at the oil side pressure drop charts. Inlet-outlet delta for the 10599 is listed at about 4 psi, while the 8324 is over 15 psi. Note that these values are taken at 235F, so the rules of viscosity will make the 8432 pressure delta really high at 180F, the point where we might like to see our vernatherm closing off the bypass passage and forcing all flow through the cooler. The vernatherm must close against that pressure (the spec sheet says it is to be fully seated at 183F~187F), and recall that it has a spring behind its tip. Bottom line? I'm pretty sure an 8432 doesn't allow the bypass to get fully closed until some point further up the temperature scale. So, around the desired operating point, the oil returning from the 8432 might be a little cooler, but it would get mixed with hot oil at the bypass, and the resulting temperature at the filter would little different from the 10599.

The higher pressure drop would also tend to magnify vernatherm seating or wax capsule issues, and there is some pumping loss. On the flip side, given a good vernatherm, an 8432 should outperform a 10599 at high temperatures where the vernatherm is fully seated with high spring pressure and viscosity is lower.

So, compromises...pick what you like. Personally, I like the lower pressures, and don't consider the performance edge of the 8432 at very high oil temps to be of great value to me. I don't ever want to see them that high.

Opinion; the collective tends to use coolers that are too small. After all, they cost less, and it's what everybody else is using. I tinkered with various details of a 10599/8432 sized installation on the 390, gathered some data, and ultimately went to a 10611...3 psi pressure drop, about 30% more heat rejection.
 
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Then I should be in good shape using that - once I get my airflow issues figured out. The more I roll the problem over in my head, the more I'm convinced I have an airflow issue somewhere.

Greg,
I looked at your web sight and I would agree with opening up the exit.
There is a lot of obstacles in the exit.
I had the same setup with a 4 pipe exhaust.
Opened the exit 2 inches and had great results.
Slit the exhaust ramp,open 2",glass, go fly. If it doesn't work. Cut and put back!!
It is posted on this sight.

Hope this helps.

Boomer
 
Greg,
I looked at your web sight and I would agree with opening up the exit.
There is a lot of obstacles in the exit.
I had the same setup with a 4 pipe exhaust.
Opened the exit 2 inches and had great results.
Slit the exhaust ramp,open 2",glass, go fly. If it doesn't work. Cut and put back!!
It is posted on this sight.

Hope this helps.

Boomer

Bruce - are you saying to simply remove 2" of the exit area on the cowling bottom, moving the aft edge 2" forward for the exit area, or extend it downward 2"? I tried to find a reference for it on your build site but was unsuccessful.
 
Does it seem counterproductive to use a "low drag" James cowl, then open up the exit, increasing cooling drag?
 
Oil Cooling

Hi Greg,

I have a 9a with an IO360, James cowl and plenum, and a firewall mounted cooler. Started out with a 3" scat from the back of the #4 to the SW 8406 and was not satisfied with the oil temp (210-215) in S. Texas cruise. Went to a 4" Sceet tube, smooth fg pickup point (raised as high as possible on the back of the left side baffle) and diffuser, and a decreasing diameter exit (fiberglass) down to the cowl exit---also went to the SW10599. All this was done back in 2009----I actually have excess oil cooling---although this is much easier to control than not enough oil cooling. I will see if I can find some pics!

Cheers,

db
 
Does it seem counterproductive to use a "low drag" James cowl, then open up the exit, increasing cooling drag?

Yes, it most definitely does. I'm interested first and foremost in controlling the temperatures, secondarily I want to control them as efficiently as possible. Right now I don't know how bad my problem is, or how drastic the solution will be, I'm just evaluating all possible aspects of it until I can get some instrumentation FWF and test it to better define the challenge.



Hi Greg,

I have a 9a with an IO360, James cowl and plenum, and a firewall mounted cooler. Started out with a 3" scat from the back of the #4 to the SW 8406 and was not satisfied with the oil temp (210-215) in S. Texas cruise. Went to a 4" Sceet tube, smooth fg pickup point (raised as high as possible on the back of the left side baffle) and diffuser, and a decreasing diameter exit (fiberglass) down to the cowl exit---also went to the SW10599. All this was done back in 2009----I actually have excess oil cooling---although this is much easier to control than not enough oil cooling. I will see if I can find some pics!

Cheers,

db

Yes - please! I'd love to see the fiberglass transitions you made. I picked up some foamboard a few days ago and I'll probably start making an oil cooler inlet plug this weekend. I have a fulltime day job plus 40-minute commute each way, and a 2-year old at home, so weekends are my only time to play with my toys.
 
Went to a 4" Sceet tube, smooth fg pickup point (raised as high as possible on the back of the left side baffle) and diffuser, and a decreasing diameter exit (fiberglass) down to the cowl exit---also went to the SW10599.

That's doing all the right things.
 
Oil Cooler Ducting

Hi Greg,

I will be at the airport tomorrow. I will pull the top cowl and take some pics for you!

Full time job, 40 minute commute, AND a two yr old at home--l would say you have your hands full!!

Cheers,

db
 
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Bruce - are you saying to simply remove 2" of the exit area on the cowling bottom, moving the aft edge 2" forward for the exit area, or extend it downward 2"? I tried to find a reference for it on your build site but was unsuccessful.

Extend downward. If that fixes the problem, then you can throttle the exit.
Dan has fix for that.
 
That's doing all the right things.

Makes me feel better about the 10599 we put on my friend's RV8 too. I didn't know about the high "back pressure" issue of the 8432. I'm sure we could do some things to help improve the airflow differential across the cooler since it's simply mounted on the rear baffle of the engine but for now it seems to perform mostly good enough except maybe on the hottest summer days in extended climbs.
 
Went to a 4" Sceet tube, smooth fg pickup point (raised as high as possible on the back of the left side baffle) and diffuser, and a decreasing diameter exit (fiberglass) down to the cowl exit---also went to the SW10599.
db

What is a "smooth fg pickup point"???
 
What is a "smooth fg pickup point"???

I think he is talking about a radiused inlet off the baffle to avoid a vena-contracta. Like a velocity stack inlet - - that reduces the inlet transition losses that could cut flow by 20%. It does not have to be large, a 3/4" radius out in the plenum should do it.
 
Roger, sorry for the delay---don't get on the site as often as I used to---BillL is correct. If you simply rivet an aluminum 4" flange onto the rear baffle wall you are left with very sharp (90 degree) edges where the transition from plenum chamber to pick up tube occurs. You can make one out of fg and create a nice smooth radius transition with smooth interior tube walls. To make use of the space over the #4 I actually have an oval pick up, with curved edges that transitions to a 4" tube where the SCEET is attached. I also wanted the minimum amount of SCEET required to deal with the engine movement due to the very smooth interior of my glass tube vs the "corrugation" effect of the SCEET interior.

Greg, I have some pics for you----if your email is not in your profile, PM me your email address and I will send direct---still don't have the IMac to VAF picture process down.

Cheers,

db
 
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Greg, I have some pics for you----if your email is not in your profile, PM me your email address and I will send direct---still don't have the IMac to VAF picture process down.
Cheers,
db

Dave, would like pics as well. Please check your private messages.
 
... I picked up some foamboard a few days ago and I'll probably start making an oil cooler inlet plug this weekend. I have a fulltime day job plus 40-minute commute each way, and a 2-year old at home, so weekends are my only time to play with my toys.
Greg, did you see my PM?
 
Results

Hey Greg,

Did you get the diffuser/cooler installed?

What were the results?

Cheers,

db
 
Hey Greg,

Did you get the diffuser/cooler installed?

What were the results?

Cheers,

db

I flew with the diffuser yesterday, it dropped my cruise (24/2400/75%) oil temps to 210-215 stabilized. Quite a bit better, still not where they should be. I know I'm moving a lot more air through the oil cooler now, because I had a 25-degree spread on CHT's previously and now 2 and 4 are quite a bit warmer, total spread is about 60 degrees now. At this point I believe I have sufficient airflow across the oil cooler (and will probably have to adjust that, and the inlet ramps to get a better CHT spread eventually) and I suspect more strongly that I'm not getting proper oil flow through the cooler. The cooler itself is a brand new 10-row, the lines are confirmed open, I'm going to pull the Casper Labs 90-degree oil filter adapter and the vernatherm fitted into it and mic all the parts (hot and cold) to confirm it's right or not. This could be as simple as a vernatherm that moves visibly (confirmed) but not as much as it should (unknown).

My CHT's are easily kept under 400 with mixture during climb and tolerate peak and LOP during cruise (even high power cruise) so I don't believe I have a net airflow problem. I feel that I just have an oil cooling problem. I did two climbs yesterday from 2700' local ground to 17,500 and maintained 500 fpm through 15,000 and then 95 KIAS through 17,500 with 350-400 fpm climb at level-off, hovering on 240 oil temp and CHT's ranging from 360 to 410. The CHT's don't sound wrong to me for that kind of climb, the oil temp does (still). Note that I still am flying without wheel pants and gear fairings so I have more drag than a finished bird, I'm working on those now.

First suspect - vernatherm seat. Second suspect - better diffuser and exit opening on the lower cowl. Third suspect - inlet ramps and rings. I'll pursue them in that order.
 
Improvement!

Hey Greg,

From sustained OT in the 240's and having to run well ROP to control temps to 210-215 and able to run the mixture where you want is quite an improvement--especially given the test conditions involving a very significant climb to 17.5.

It would be interesting to pull a prior test card and run the new configuration under the same conditions as the old----this would give you a better indication of your level of improvement.

The completion and install of your gear leg, wheel pant, and intersection fairings is obviously going to bring your speed up and you will certainly see an incremental improvement in cooling at similar power settings and conditions.

You may have done this but when you remove the 90 degree oil filter adaptor, check to insure you have the right gasket. My Eci 90 degree adaptor originally came with the incorrect gasket which partially blocked an oil port.

Sounds like your CHT's are ok for now and balancing can be addressed after the OT is where you want it----lots of ways to balance the flow to the cylinders--dams, washers, baffle mods, ramp changes, etc.

Insuring the flow from the plenum chamber to the cooler is a gentle curve and the interior of the tubing is as smooth as possible made an incremental difference for me.

I know you have already gone to a new Niagra, but if all else fails (which I doubt) my experience is that the SW brand provides 10-15% better cooling for similar size.

You are making good progress!!

Cheers,

db

Ps: You gonna luv that 9a/180!!!!!
 
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