REFLECTOR: Oil cooler VG photo
Ron Brown
romott at adelphia.net
Sun Jul 16 18:56:57 CDT 2006
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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