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09-12-2011, 11:19 AM
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Join Date: Dec 2006
Location: Sumner, WA
Posts: 722
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Paul
You are right. Although my Vy is 95KIAS, I can climb at 110 to 120 and only lose 200 or so FPM. Although this does help, I can still get to 400 (CHTs) pretty easily on an 80deg day.
Dan
I should have worded that a little better. I meant, bring it over, I'd love to see it. Your airplane and results are awesome! What I wouldn't give to be your neighbor.
I'm guess what I'm saying is, I'm just regular guy that built the best airplane I could with what Van's gave me to work with. Perfect? Not even. Room for improvment? Definately. I've done all the normal stuff. Smooth the inlets, close one side of each eyebrow, verify good baffle seals, confirm good sealing on lower inter cylinder baffling, open up exit area a little (A model), etc. Various experienced RV builders along with A&P's agree it all looks pretty good.
I guess I'm just suprised at the wide spread of heating results with the same plane, same cowl, same baffling, and same engine. Some people have no problems, (Didn't do anything special) while hundreds of others have to fight it for what seems like years.
__________________
Jeff Bloomquist
Sumner, WA
PP-ASEL, IR
RV-7A
Flying
1150 Hours
Last edited by boom3 : 09-12-2011 at 11:21 AM.
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09-12-2011, 11:27 AM
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Join Date: Mar 2006
Location: Newport, TN
Posts: 7,496
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I second exactly what Jeff said. I sure wish Dan was here in my area to tell me how to fix mine!!!
Might have to take a day trip to see the "Cooling Doctor"....
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09-12-2011, 12:09 PM
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Join Date: Jan 2005
Posts: 369
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Paul,
Yes I can lower the temps a little by climbing faster than my normal 120 mph. We fly a lot of formation and matching my speed with others can be some of the cause as well as not climbing with WOT for extra fuel cooling.
Bob,
I have access to the Lasar timing box and checked timing just recently. FWIW, Lasar maintains you need to use fresh batteries each time you use their box.
Dan,
08A-KFFC--101 NM...ha.
Mark
__________________
Mark Strahler
RV-6 (Purchased flying)
KFFC-Peachtree City, GA
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09-12-2011, 12:54 PM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by strahler13
I am troubled with high cylinder temps on my initial flight of the day......Usually on my first climb out, my temps climb to about 430 deg, then level off and drop when leveling out. I can do a touch and go and the temps only climb to about 375. Normal cruise is about 360.
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Mark, yours is an interesting problem (first climb of the day only).
Are you sure you're comparing apples to apples? By that I mean do you hit 430F by pattern altitude on that initial climb of the day? Put another way, if the "go" in "touch and go" became a continued climb to some cruise altitude, would the temps eventually hit 430?
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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09-12-2011, 01:02 PM
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Join Date: Jan 2005
Posts: 369
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Quote:
Originally Posted by DanH
Mark, yours is an interesting problem (first climb of the day only).
Are you sure you're comparing apples to apples? By that I mean do you hit 430F by pattern altitude on that initial climb of the day? Put another way, if the "go" in "touch and go" became a continued climb to some cruise altitude, would the temps eventually hit 430?
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Sunday I climbed to 3500 ft (2,700 AGL) and hit 430 deg. Then straight and level for a few minutes until temps came down. Then into the pattern for a touch and go. On the TNG departure, I kept the same power and speed settings and the temps only climbed to about 385--with a "warm" engine. This is what baffles me.
Mark
__________________
Mark Strahler
RV-6 (Purchased flying)
KFFC-Peachtree City, GA
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09-12-2011, 01:40 PM
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Join Date: Aug 2007
Location: Houston, Tx
Posts: 163
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Oil issue?
Having not spent any time in my professional life with GA engines..
What your problem sounds like to me is a sticky thermal valve to the oil cooler. The oil in the engine may be up to the green but is the valve opening fully to the oil cooler at the right time?
My suggestion is to watch your oil temp/pressure on the first flight and on the TNG to see if it varies more than the given 25-50 degree range your CHT's give.
__________________
Bill S.
A+P, RV Dreamer + Schemer
RV-9 preplans in hand
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09-12-2011, 01:51 PM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
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I sure wish Dan was here in my area to tell me how to fix mine!!!.
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Jeff, Brian, if you walk around fly-ins with me as we talk to owners, you'll see me looking and feeling up inside cowls to check the fit of the baffle rubber. I've never met an owner with really, really nice rubber fit who also complained of high CHT. It is not the whole picture, but it is an indicator; you can bet the baffle tin was fitted and sealed, with everything just so.
The norm is conventional GA baffling tin, which is rarely tight or sealed. We're used to seeing it that way, and hey, it works fine on your Cherokee. Your A&P or local Old Crow looks at the same fit on your RV and declares it fine and dandy. What gets forgotten is that the Cherokee example is flowing vast quantities of mass through the cowl to make it work, while our tight little Vans cowls were designed with an eye toward minimizing cooling drag. The RV cowl just doesn't flow as much air, thus we must get maximum heat transfer to the air we do flow. We cannot afford leaks; every molecule must carry away heat.
If I were a cooling doctor I would, like your medical doctor, insert a thermometer in your exit as a very early diagnosis step. I'd be looking for high temperature cooling air.....or to be more precise, I'd want
(exit temp - OAT) / (CHT- OAT) to be 0.3 or higher. The 0.3 figure is not carved in stone (I'm still learning), but it's not far off. For sure higher is a good thing.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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09-12-2011, 02:17 PM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Quote:
Originally Posted by DanH
If I were a cooling doctor I would, like your medical doctor, insert a thermometer in your exit as a very early diagnosis step.
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OH NO
Visions of potatoes ------- make them go away AGGGGGGGG
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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09-12-2011, 02:26 PM
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Join Date: Oct 2005
Location: Vancouver, WA USA
Posts: 908
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Quote:
Originally Posted by DanH
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I also have no problem with cylinder temp at best rate from sea level to any height I like, I?ve done best rate to 15,500? in the hot summer desert many times with no issues, CHTs below 320. One note, my IO-360 A1A and Dan?s IO-390 have angle valve cylinders and oil squirting in the bottom of the pistons, these differences probably contribute to lower CHTs so it?s not exactly apples to apples.
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09-12-2011, 02:34 PM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Quote:
Originally Posted by Russ McCutcheon
One note, my IO-360 A1A and Dan?s IO-390 have angle valve cylinders ------
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Good point, I would be interested in looking at a parallel head, and an angle one side by side.
I suspect that due to the splaying of the valves, there is a lot more cooling fin area between the valve pockets.
Remember the issue of casting flash in this area, and the dramatic difference in CHT it made for those who cleaned it out???
Also, stop and consider where the CHT probe is located.
Wonder if any of the folks who are having temp problems are using a ring style sensor under the plug.
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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