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  #51  
Old 09-20-2018, 04:58 PM
Lars Lars is offline
 
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Location: Davis, CA
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@ Dan, question: in charts B-XX, there are always two power curves, close to each other, with a legend on the right side implying that there are two sets of data being depicted, but I am not seeing anything explaining why two. What am I missing?

@ Tom, perhaps you know this already, in that case forgive the repetition. Early on when my RV was new and I was learning about optimizing my air cooling, someone pointed out to me here that a good way to find baffle air leaks is to remove the cowl, close hangar door, turn off any lights, then shine a flashlight from outside the baffles (reverse direction of airflow) inward. I found a few spots I'd missed, for example around the cylinder bases at the back baffle wall. Sealing the remaining spots with RTV dropped cruise CHTs about 10F.
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  #52  
Old 09-20-2018, 07:11 PM
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DanH DanH is offline
 
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Quote:
Originally Posted by Lars View Post
@ Dan, question: in charts B-XX, there are always two power curves, close to each other, with a legend on the right side implying that there are two sets of data being depicted, but I am not seeing anything explaining why two. What am I missing?
As usual, not much

The tests were conducted with three barrels of Swift fuel, two different 100LL fuels purchased at the local airport, and a specially manufactured minimum specification 100LL. The report mentions running all of them 5 or 6 times, but not presenting all the data due to volume. Some report plots are averages, notably detonation lean-outs (not posted here). For the rest, my understanding is that for each fuel type (referred to as Swift, 100LL FBO, and 100LLms) they presented two plots believed to be the most representative.

I removed the Swift and 100LL minimum specification plots and legends from the posted charts to reduce audience confusion. Here is the original version of the 2700-28" chart:



Entire report here:

http://www.tc.faa.gov/its/worldpac/techrpt/ar0853.pdf
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Last edited by DanH : 09-20-2018 at 07:17 PM.
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  #53  
Old 09-21-2018, 09:10 AM
tgmillso tgmillso is offline
 
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Location: Launceston, Tasmania, Australia
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Hi Lars. Yes, I've got this thing now as tight as a ducks b--- . The elephant in the room however is the fact that I did the common mod of lifting the oil cooler up an inch (plus the corner reinforcement and triangulation bracket back to the #4 cylinder head. My oil is running super cool, only just getting into the green range. It's more than 100degF by takeoff as I run a pre-heater, however on my last trip it only hit 168degF maximum, with on OAT of 48degF. I think I may have to look into taping of a bit of the oil cooler. That said, I noticed on the last trip that the temps were 10degF lower than they have been previously, even though the OAT and power settings were similar. I suspect things are moving in the right direction regard the engine breakin. I've just done my 5hr oil and filter change, and will get another run in this Sunday.
Cheers,
Tom.
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  #54  
Old 09-22-2018, 12:42 PM
Lars Lars is offline
 
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Quote:
Originally Posted by DanH View Post
As usual, not much

The tests were conducted with three barrels of Swift fuel, two different 100LL fuels purchased at the local airport, and a specially manufactured minimum specification 100LL. The report mentions running all of them 5 or 6 times, but not presenting all the data due to volume. Some report plots are averages, notably detonation lean-outs (not posted here). For the rest, my understanding is that for each fuel type (referred to as Swift, 100LL FBO, and 100LLms) they presented two plots believed to be the most representative.
Thanks, Dan. As usual, too much information is almost enough, sorta like horsepower

Quote:
Originally Posted by tgmillso View Post
Hi Lars. Yes, I've got this thing now as tight as a ducks b--- . The elephant in the room however is the fact that I did the common mod of lifting the oil cooler up an inch (plus the corner reinforcement and triangulation bracket back to the #4 cylinder head. My oil is running super cool, only just getting into the green range. It's more than 100degF by takeoff as I run a pre-heater, however on my last trip it only hit 168degF maximum, with on OAT of 48degF. I think I may have to look into taping of a bit of the oil cooler. That said, I noticed on the last trip that the temps were 10degF lower than they have been previously, even though the OAT and power settings were similar. I suspect things are moving in the right direction regard the engine breakin. I've just done my 5hr oil and filter change, and will get another run in this Sunday.
Cheers,
Tom.
I had a similar issue with oil temperature, cooler mounted as high as I could get it. Aluminum speed tape was required to get the temp above 180 F even on the hottest days. Without it in winter it won't go above 150 even at full power in level flight.

My engine is fairly similar to yours, I believe. 180HP parallel valve Superior-built Lyclone with P/A updraft fuel injection, dual LSE Plasma III ignitions, roller cam. As one might expect, cruise CHTs are OAT dependent, but range from 350-ish at altitude in summer down to barely cracking 300 during the cold months. I run lean of peak pretty much always. FWIW my full throttle sea level take-off fuel flow rate is 17-ish gph, again temperature (density altitude) dependent. On the hottest days here in the sea level Sacramento Valley it dips down to around 16. My fuel injection system is P/A's Sliverhawk product, and has never been touched since I bought the engine new other than idle adjustment. With the engine broken in (it's at about 700 hours now) and the mod shown below, I have to work to get the CHTs above 400F.

The mod is simply a half-round of stainless steel formed from thin sheet and screwed in place, an attempt to improve cowl exit airflow a bit (more like an RV-8.) It was worth somewhere on the far side of 10F on a full-power climbout. I had actual real data on that thing once, but it got lost during some life disruptions a couple of years ago, so I won't claim any hard numbers. I got the piece of stainless from a friend and hand-formed it, so almost no investment other than a little time.

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  #55  
Old 09-25-2018, 07:02 AM
tgmillso tgmillso is offline
 
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Location: Launceston, Tasmania, Australia
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Hi Lars. I have a row of #6 nutplates across a flange that is riveted to the lower firewall flange specifically for placing a exit flow ramp like you mentioned, incase I did encounter cooling issues. All I have to do is drill through the firewall for the top row of mounting screws. Although my temps are now down in a good range, I think I may still install it, as I'd be a fool not to take another free 10 deg F in cooling.
Tom.
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