larry(at)macsmachine.com
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 Posted: Tue Jun 28, 2011 6:30 am Post subject: [Probable Spam] Fwd: Zenair601HDS Stratus/Ram cooling proble |
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Ron,
I use a gage that Warp Drive makes for setting the pitch. It’s accurate to half a degree and you should have one. I have a spare one if you want it. Send me your address and I’ll mail it to you.
My pitch is based from the top longeron, not the propeller center line. The gage is set by presetting the desired degrees, clamping the gage on the end of the prop and adjusting the blade to get the bubble level on the gage. (Very accurate & consistent) Just add or subtract the difference from level on the longeron. My longeron are 2 degrees nose up (tri-gear) and pitch has to be adjusted for that to get level flight.
I’ve not made any radiator intakes for a while, so I pitched the mold. I still have the form for the intake and could make a new mold if you want one. I couldn’t do one until sometime after Oshkosh. I have to get $200.00 for the intake as it represents two full days work plus materials. It does eliminate turbulence at the radiator opening and provide better flow on the negative side of the louvers which results in better cooling by 7 degrees or more plus the 5 you get with the louvers. The radiator is set behind the firewall 32 inches and I’ve flown with it both up front and back where it is now. The CG is better with it back there owing to the weight of the Subaru. I like the look of it as well. Study the radiator construct on my engine page for minor changes you would need and let me know if you want an intake.
Other thing that helps get rid of engine temps is exhaust wrap. Not so hard to do, but it keeps heat in until it gets out the exhaust.
Larry McFarland
601HDS at www.macsmachine.com
From: owner-stratus-list-server(at)matronics.com [mailto:owner-stratus-list-server(at)matronics.com] On Behalf Of ron hansen
Sent: Monday, June 27, 2011 11:51 PM
To: stratus-list(at)matronics.com
Subject: [Probable Spam] Fwd: Zenair601HDS Stratus/Ram cooling problem
Thanks, Larry.
I think I have the mixture problem solved. Ram did a dyno test and measured exhaust components and said they were good. 101 measured HP was also nice. After repairing the broken valve seat and other damage that caused, Ron Carr at Ram dynoed the engine first with the timing per Stratus specs and only got 83HP. Then he changed (advanced) the timing to his specs and it came up to 101HP. Now it runs stronger, cooler, and burns less gas.
I haven't thought about prop setting. I have the same Warp 3 blade set to 12.5 degrees relative to the prop hub, not the horizon. Is that how your pitch is measured? I get 4875 RPM on early takeoff roll. I can't hold brakes at full throttle. What takeoff RPM are you getting at 17.5 degrees? Climb is great even at max GW of 1320#. I still don't quite get to 5300 RPM in any flight regime other than a descent so I figured I was about right. I've tested lower and higher pitches, but not since the rebuild that added so much HP. I can certainly play with prop pitch again and see what happens. Although I think I will probably need a major rebuild of the radiator, before I do that I may do things like prop pitch, lower the antifreeze component from 50% to 25%, and try "Water Wetter" which seems to have sound followers that say it works and few downsides that I've seen.
I see your radiator is moved well back vs. the Zenith plans. Do you know how much that helped the cooling and are you still making the glass intake to sell? The rest seems fairly straight forward. I built from scratch so although I was hoping to avoid another major change and just fly, I can do the work if needed.
Thanks again for the help,
Ron
---------- Forwarded message ----------
From: Larry McFarland <larry(at)macsmachine.com (larry(at)macsmachine.com)>
Date: Mon, Jun 27, 2011 at 6:41 PM
Subject: RE: [Probable Spam] Zenair601HDS Stratus/Ram cooling problem
To: stratus-list(at)matronics.com (stratus-list(at)matronics.com)
HI Ron,
The cooling issue is very common, but coolant temps should never see more than 200 on a hot day in a perpetual climb. My cowl opening just ahead of the oil pan for some reason cools better in a climb than going fast flat and level. As you’ve done the jetting, you might consider the propeller pitch. My Warp Drive 70-inch 3 blade set for 17-1/2 degrees per their instrument does a much better job of cooling flat out at or near
120 mph. The pitch allows lower rpms, better speed. I trim nose down carefully to get best speed by setting rpms to 4300 for best fuel burn until the rate of climb gage indicates level flight. You feel the center of lift move slightly back on the wing and get optimum cooling this way too. Odd, I flew for a year or more before realizing that trimming in the last bit of down elevator at a cruise rpm would increase performance and cooling so much. Used to also worry that the nose was always slightly up before discovering this.
I seldom fly flat out as there’s no way to justify the fuel burn and engine wear at 5000 rpm.
Note the links show the hole in front of the oil pan and heat from the exhaust pipes is fed cool air either side of the cowl looking straight in
at aluminum sleeve clearance aluminum. They made a significant difference.
http://www.macsmachine.com/images/completion/full/601ezclosefrtrt.gif
http://www.macsmachine.com/images/cowling/full/cowelfrtlower.gif
Hope this helps,
Fly safe
Larry McFarland 601HDS at www.macsmachine.com
From: owner-stratus-list-server(at)matronics.com (owner-stratus-list-server(at)matronics.com) [mailto:owner-stratus-list-server(at)matronics.com (owner-stratus-list-server(at)matronics.com)] On Behalf Of ron hansen
Sent: Monday, June 27, 2011 5:53 PM
To: stratus-list(at)matronics.com (stratus-list(at)matronics.com)
Subject: [Probable Spam] Zenair601HDS Stratus/Ram cooling problem
Hi listers,
I've been quiet a long time due to life interfering with my plans, but I need some help. I had about 60 hours on my 601HDS with a Stratus on it. I was fighting temp. issues from the start, adjusting the carb jets and such. I had Ram modify the heads before it flew. Anyway, I never went past the Stratus 230 deg. "water temp" redline, but often approached it. Taxiing in after 60 flight hours I broke a valve seat and later learned broke a piston. I have not been pleased with Stratus support for years so I had Ram Performance rebuild the engine. He also made some other changes and it now runs stronger and cooler, but still not cool enough. I moved the "water temp" probe from the Stratus setup in the cylinder head dry-hole to actual water as it comes out of the engine. Ram says water temp redline should be 220 deg. and the engine should run at the thermostat setting of 190 deg. Research I've done would indicate the same for long engine life.
Anyway, I still get water temp climbing to 220 a few minutes after takeoff on a warm day and I suspect it would go higher. My radiator is the stock Zenair radiator installed per plans. Gaps are sealed. Coolant is 50/50 per instructions. I'm beginning to think the Zenith setup is not suitable for a 100HP engine that is water cooled. The Rotax they designed it for only uses water to cool the heads.
I don't want to ruin my new Ram-rebuilt engine. It is running really well: stronger, cooler, lower fuel burn......but it's not running at the temps it should do to a weak cooling system. If anyone has data or ideas that would help I would appreciate hearing from you. I recall all sorts of discussion from years past (this plane took me many years to build from plans), but I can't remember where all those ideas ended up. I know some were abandoned, but others probably solved some or all of the problem. I've gone through the archives, but you never know if you're missing something important that came later.
Thanks,
Ron Hansen
Los Angeles
601HDS, Ram-Rebuilt (formerly Stratus) Subaru EA8101
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