REFLECTOR: Oil cooler VG photo
Dave Nelson
davenali at charter.net
Mon Jul 17 19:43:13 CDT 2006
Scott - for clarity - Lycoming didn't tell me that there was no
correlation - only that the correlation was very weak, and that I really had
to go after CHT and oil temp issues seperately.
Hope this helps.
Dave
----- Original Message -----
From: "Scott Derrick" <scott at tnstaafl.net>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Sunday, July 16, 2006 9:37 PM
Subject: Re: REFLECTOR: Oil cooler VG photo
> Ron,
>
> Your Cylinder head temps are much more in line to what I have. When I
> had CHT's up in the high 300's I also had high oil temps. It makes
> sense, our engines are not just air cooled, they are oil cooled also. I
> can't believe Lycoming would suggest there is no correlation between
> CHT's and oil temps.. But then they also say that LOP is bad, heads
> firmly inserted mode.
>
> I think if Dave got his CHT's under control its a high probability his
> oil temps come down to a normal range...
>
> Scott
>
> Ron Brown wrote:
>> Dave,
>>
>> Here's another data point for you: I have IO360 Lyc turning a Catto 66 x
>> 70" prop on a 173 Elite RG. I have the top NACA scoops, front edge of
>> prop
>> is 1" from rear of cowl, and I have cylinder wraps that go down below the
>> factory air plenum leaving only about an inch to 1.5" gap for the air to
>> exit the bottom of the cylinders. I also duct taped the engine crank
>> case
>> and laid up 2 bid from the air plenum to the crank case to close up all
>> of
>> those gaps Scott talks about.
>>
>> During our trip to the Symposium, I took a picture of my EIS and other
>> panel
>> data:
>>
>> 174 kt IAS
>> 2640 RPM
>> 22.4 MAP
>> 71 deg F OAT
>> 320 hottest CHT
>> 1362 hottest EGT
>> 203 oil temp
>> 11.8 GPH
>> 29.91 Baro
>> 3600 altitude
>>
>> I also have my oil cooler lines running down separate sides.
>>
>> The only time my oil temperature will go over 220 degrees is during a
>> take
>> off after a quick stop on the ground. Even on 90 degree days. A cruise
>> climb 120 kts and reducing power a bit will lower the temperatures below
>> 220.
>>
>> Ronnie Brown
>>
>>
>> ----- Original Message -----
>> From: "Scott Derrick" <scott at tnstaafl.net>
>> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>> Sent: Sunday, July 16, 2006 4:40 PM
>> Subject: Re: REFLECTOR: Oil cooler VG photo
>>
>>
>>
>>> Dave,
>>>
>>> There has to be things that are different as we are driving the basic
>>> same machine.
>>>
>>> 400 degrees isn't really hot but my CHTs in the summer in cruise were
>>> very close to 330-360 range. So I wonder about your overall engine
>>> cooling. You say your taking some of your armpit cooling air and using
>>> it for induction? I do not. I have a separate ram scoop and use all the
>>> arm pit air for cooling.
>>>
>>> You also didn't mention:
>>>
>>> Are you running LOP or ROP, makes a big difference in your temperatures?
>>>
>>> How unobstructed is your oil cooler duct? If you also use that for
>>> cabin heat how tightly does the diverter flap come up against the side
>>> when cabin heat is turned off? Are their bumps and angles near the
>>> outlet that the air has to negotiate or is it a smooth all the way out?
>>>
>>> Is your baffling really tight, I mean really really tight or do you have
>>> big gaping 1/2 inch or inch wide holes where the baffling meets the
>>> case?
>>>
>>> Each of these things won't make a big difference, but added up together
>>> they can.
>>>
>>> Scott
>>>
>>>
>>> Dave Nelson wrote:
>>>
>>>> Thanks much for the tips, Scott - and for the speedy response. Here's
>>>> more
>>>> background...
>>>>
>>>> I have been going after drag reduction to ensure that I remain faster
>>>> than
>>>> my hangermate (Doug Solinger in his beautiful Cozy Classic). One of
>>>> the
>>>> things I've done is to tighten up air leakage that was occuring between
>>>> the
>>>> old stock armpit scoops and the lower cowl. I did this by engineering
>>>> new
>>>> armpit scoops that are a bit smaller. I also created an airbox to use
>>>> armpit scoop ram air for induction air (and yes, I did size the scoop
>>>> for
>>>> this mod). More recently I designed & had built a new exhaust system
>>>> that
>>>> keeps the entire exhaust internal to the cowl and exits the exhaust
>>>> behind
>>>> the prop (similar to what you see on alot of long-ezs these days). The
>>>> exhaust this new one replaced was purchased from Velocity - the exhaust
>>>> gas
>>>> exited the lower cowl pointing straight down (and created quite a bit
>>>> of
>>>> drag).
>>>>
>>>> I've always been focused on ensuring that every molecule of cooling air
>>>> I
>>>> take in gets used - my plenum is very tight. On a 90 degree day, I
>>>> seldom
>>>> see any cylinder reach 400 deg. F., which I consider acceptable.
>>>>
>>>> I am having a BEAR of a time with oil temps, however. I've been
>>>> working
>>>> on
>>>> this problem for two years now and I'm about at wits end. I've had
>>>> extensive discussions with Lycoming (and others), and I've done all of
>>>> the
>>>> obvious things (detailed measurements of the vernatherm per Lycoming
>>>> specs
>>>> to ensure it's working correctly, flushed the entire oil cooling system
>>>> to
>>>> ensure no "gunk" build up, inverted the oil cooler to put the
>>>> connections
>>>> at
>>>> the top (to eliminate any chance of a bubble), various "scoop"
>>>> modifications
>>>> to the nose NACA for the oil cooler, MANY test flights (standardized so
>>>> I
>>>> could gather data)... I even added a bilge fan under the pilot seat to
>>>> blow
>>>> air into the wiring duct containing the oil lines)... all to no avail.
>>>> Where I'm at right now is, a short flight at 25 squared on a 85 degree
>>>> day
>>>> quickly results in oil temps that have exceeded 225 degrees F.
>>>>
>>>> I'm at the point of giving in. My current theory is that the oil pump
>>>> on
>>>> my
>>>> engine is no longer as capable of pushing the oil through the approx.
>>>> 30
>>>> feet of tubing as it was when I installed it about 750 hours ago.
>>>> Lycoming
>>>> tells me that the system is designed for around 4 feet of tubing, and
>>>> that
>>>> this installation is completely nuts (my words... they are more
>>>> diplomatic).
>>>>
>>>> Sooo... to avoid loosing another summer of flying... I'm now willing to
>>>> consider installing a second cooler.
>>>>
>>>> Any thoughts are welcome - and thanks for the good suggestions!
>>>>
>>>> Dave
>>>> ----- Original Message -----
>>>> From: "Scott Derrick" <scott at tnstaafl.net>
>>>> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>>>> Sent: Saturday, July 15, 2006 8:57 PM
>>>> Subject: Re: REFLECTOR: Oil cooler VG photo
>>>>
>>>>
>>>>
>>>>
>>>>> Dave,
>>>>>
>>>>> I have Std RG, and had an IO360 200 HP engine in it. Standard oil
>>>>> cooler. When I bought the plane I had temp problems. Bad ones.
>>>>> Couldn't
>>>>> run any where near 75% power without over heating.
>>>>>
>>>>> I did the following which allowed me to run 75% any time of year and
>>>>> normal cruise temps were 190, I even had to cover up some of the oil
>>>>> cooler in the winter to get the temps above 180.
>>>>>
>>>>> 1.) Put turning vanes in the oil cooler duct and smoothed out the
>>>>> duct,
>>>>> especially the exit. You don't want turbulent air downstream of the
>>>>> cooler.
>>>>>
>>>>> 2.) Got very anal about air leaks in the engine cowl/baffling. Any
>>>>> hole larger than 1/4 inch must be plugged. Also be sure the silicone
>>>>> baffles are pressed against the engine so that the air pressure will
>>>>> tighten them against the heads. Lowering your CHT's will have a
>>>>> dramatic effect on your oil temps.
>>>>>
>>>>> 3.) Run LOP. I installed a Lightspeed Ignition that provided such
>>>>> good
>>>>> complete fuel burn I could run 75 degrees LOP which dropped my oil
>>>>> temps
>>>>> 5-10 degrees from a similar ROP power setting.
>>>>>
>>>>> Scott
>>>>>
>>>>>
>>>>> Dave Nelson wrote:
>>>>>
>>>>>
>>>>>> Wow is this both interesting and pertinent to me... I've been
>>>>>> battling
>>>>>> oil temp issues for the past two summers on my std rg - I'll try the
>>>>>> VGs tomorrow.
>>>>>>
>>>>>> In the meantime, since I'm getting desperate - for those of you that
>>>>>> have succumbed and added a second oil cooler - where did you mount
>>>>>> it? Where do you get intake air?
>>>>>>
>>>>>> Thanks.
>>>>>>
>>>>>> Dave
>>>>>>
>>>>>> ----- Original Message -----
>>>>>> *From:* Laurence Coen <mailto:lwcoen at hotmail.com>
>>>>>> *To:* reflector at tvbf.org <mailto:reflector at tvbf.org>
>>>>>> *Sent:* Saturday, July 15, 2006 12:46 PM
>>>>>> *Subject:* REFLECTOR: Oil cooler VG photo
>>>>>>
>>>>>>
>>>>>> Mike,
>>>>>>
>>>>>> Here is an attached photo of the VG's. The top VG should produce
>>>>>> a clockwise vortex and the bottom one should be counter
>>>>>> clockwise. I have no idea as to why you felt a "flutter". The
>>>>>> only effect I experienced was cooler oil and nothing else. I
>>>>>> felt
>>>>>> that my arrangement should stuff air into the oil cooler
>>>>>> opening. A 20 degree drop in temperature would logically tend to
>>>>>> support the theory.
>>>>>>
>>>>>> I hope this is of some help.
>>>>>>
>>>>>> Larry Coen
>>>>>> N136LC
>>>>>> SE/RG Franklin/IVO
>>>>>>
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>>>>>>
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>>>>> like
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>>>>>
>>>>> Thomas Jefferson to G. K. van Hogendorp
>>>>> Oct. 13, 1785. (*) ME 5:181, Papers 8:632
>>>>>
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>>>>
>>>>
>>>>
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>>
>
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>
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>
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