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jb92563
Joined: 23 Mar 2007
Posts: 314
Location: Southern California
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 Posted: Tue Apr 01, 2008 7:22 am Post subject: UltraStar Engine tuning |
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I have 2 different CHT probes that are giving me different results.
I swapped probes and now the old probe is reading 420 on the formerly under 400 cylinder(Front cyl) so I can conclude its the old CHT sensor is off for some reason(Maybe my extension has to much resistance).
My new probe from Aircraft Spruce reads as expected.
After correction(swapping back and forth) I am really getting:
CHT Front Cyl: 390
CHT Rear Cyl: 360
EGT: 1350
RPM: 6190
Still a little hot on the EGT and one cyl....perhaps too lean still.
History Note: I honed the rear cylinder and installed new piston/rings after repairing a mild seizure. Cuyuna ULII-02
Perhaps I should hone a cross hatch into the front cylinder as well to improve oil adhesion and cooling.
I found my Cuyuna Manual and for the elevation
and Temperature it recommends the #280 Main Jet.
The Standard was #300 it seems.
I wonder if the 280 is richer than the 300?
I suppose I should try my needle setting first though to see what effect that has on the CHT and EGT.
I might also have too much prop since I thought max static RPM was supposed to be about 6300-6500 so it can unload up to 6800 in the air.
Any tips on how to go about getting my numbers in line.
I think a little richer and less prop if necessary seems the way to go.
(I have a wood 2 blade Ritz prop...easy to modify)
I though during the initial full throttle I got it up to 6500 for a second so perhaps that also indicates a lean condition as the extra fuel from idling ran out and then stabilized at 6190.
Also read that ~1400 rpm is the recommended idle so the engine does not load up with too much fuel during an idle power decent.
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Ray
Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider
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herbgh(at)nctc.com
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| Posted: Tue Apr 01, 2008 7:39 am Post subject: UltraStar Engine tuning |
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Seizures normally leave some aluminum on the cylinder walls...I
always ,twice now, swab the affected areas with muratic acid to etch
away the aluminum before honing.. Herb
At 10:22 AM 4/1/2008, you wrote:
| Quote: |
I have 2 different CHT probes that are giving me different results.
I swapped probes and now the old probe is reading 420 on the
formerly under 400 cylinder(Front cyl) so I can conclude its the old
CHT sensor is off for some reason(Maybe my extension has to much resistance).
My new probe from Aircraft Spruce reads as expected.
After correction(swapping back and forth) I am really getting:
CHT Front Cyl: 390
CHT Rear Cyl: 360
EGT: 1350
RPM: 6190
Still a little hot on the EGT and one cyl....perhaps too lean still.
History Note: I honed the rear cylinder and installed new
piston/rings after repairing a mild seizure. Cuyuna ULII-02
Perhaps I should hone a cross hatch into the front cylinder as well
to improve oil adhesion and cooling.
I found my Cuyuna Manual and for the elevation
and Temperature it recommends the #280 Main Jet.
The Standard was #300 it seems.
I wonder if the 280 is richer than the 300?
I suppose I should try my needle setting first though to see what
effect that has on the CHT and EGT.
I might also have to much prop since I thought max static RPM was
supposed to be about 6300-6500 so it can unload up to 6800 in the air.
Any tips on how to go about getting my numbers in line.
I think a little richer and less prop if necessary seems the way to go.
(I have a wood 2 blade Ritz prop...easy to modify)
I though during the initial full throttle I got it up to 6500 for a
second so perhaps that also indicates a lean condition as the extra
fuel from idling ran out and then stabilized at 6190.
Also read that ~1400 rpm is the recommended idle so the engine does
not load up with to much fuel during an idle power decent.
--------
Ray
Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Riverside County, CA
Do Not Archive
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http://forums.matronics.com/viewtopic.php?p=174138#174138
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jb92563
Joined: 23 Mar 2007
Posts: 314
Location: Southern California
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| Posted: Tue Apr 01, 2008 10:09 am Post subject: Re: UltraStar Engine tuning |
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Thanks Herb,
Thats exactly what I did thanks to your suggestion here about 6 months ago to use the Muriatic Acid.
I had some visible aluminum stuck to the cylinder wall but barely any scratches so i was able to simply disolve the aluminum with the acid.
Replaced the melted piston and rings, honed it smooth to fix the slight scratching, put a x-hatch patern in with the hone and its running great now....even cooler than the front cylinder apparently.
Worked like a charm!
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_________________
Ray
Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider
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jb92563
Joined: 23 Mar 2007
Posts: 314
Location: Southern California
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| Posted: Mon Apr 07, 2008 1:06 pm Post subject: Re: UltraStar Engine tuning |
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Now the saga continues.
I have 2 new CHT's installed and a bunch of jets from 270 to 310 that I tried last weekend.
Seems that the new #300 jet is better than the old one and results in somewhat lower temps especially on the EGT.
With all the other jets the temps go up or down as expected.
I believe the 290 or 300 jets are optimum, resulting in 1225 F on the EGT max which is less than the 1250 F maximum recommended.
However, the rear PTO end cylinder does fine at only 320 F the front cylinder consistently goes to about 435 F +- depending on the Jet.
I will need to take that cylinder apart and hone it, perhaps replace the rings and improve that situation some how.
I also tightened the redrive belts since I noticed a bit of slip and now I get 6000 rpm max so I may need to trim the prop a bit to get the rpms up to the recommended 6200-6300 rpm.
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Ray
Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider
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Dana
Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA
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| Posted: Mon Apr 07, 2008 2:27 pm Post subject: UltraStar Engine tuning |
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At 05:06 PM 4/7/2008, jb92563 wrote:
| Quote: | However, the rear PTO end cylinder does fine at only 320 F the front
cylinder consistently goes to about 435 F +- depending on the Jet.
I will need to take that cylinder apart and hone it, perhaps replace the
rings and improve that situation some how.
|
Assuming you've done the obvious and swapped the CHT's, something's
definitely wrong. How do the plugs look?
I doubt it's ring related. A crankshaft seal seems a more likely culprit,
have you done a pressure test? Could be the intake manifold or cylinder
base gaskets on that cylinder, too, check the cylinder base nut torques.
Another far out possibility... where did this engine come from? If it was
previously set up as a tractor engine instead of as a pusher, it could have
the wrong fan installed... in which case it'd be trying to pull air from
the rear (PTO) end of the engine and fighting the prop blast, instead of
pushing it from the front, so the front cylinder could well be running
hotter (though that's a LOT hotter!)
-Dana
--
Ask not what you can do for your country, but what your country is doing
to you.
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jb92563
Joined: 23 Mar 2007
Posts: 314
Location: Southern California
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| Posted: Mon Apr 07, 2008 5:46 pm Post subject: Re: UltraStar Engine tuning |
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What kind of pressure test? Crank case ? Cylinder pressure?
What is the procedure?
I'll check the plugs tomorrow.
Jack Hart suggested the carb could be rotated incorrectly.
I did rotate the carb so that it would be level in flight.
Maybe it should just be mounted in line with the crank shaft as it probably comes from the factory.
Is yours rotated at all?
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_________________
Ray
Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider
Do Not Archive |
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Dana
Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA
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| Posted: Mon Apr 07, 2008 6:43 pm Post subject: UltraStar Engine tuning |
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At 09:46 PM 4/7/2008, jb92563 wrote:
| Quote: | What kind of pressure test? Crank case ? Cylinder pressure?
What is the procedure?
|
See the Cuyuna service manual in the Kolbultrastar Yahoo group files
section. Basically you seal off the intake and exhaust ports, pressurize
the crankcase, and see that it holds pressure for several minutes.
| Quote: | I did rotate the carb so that it would be level in flight.
Maybe it should just be mounted in line with the crank shaft as it
probably comes from the factory.
Is yours rotated at all?
|
No, mine's square with the engine. If it was a carb issue it would affect
both cylinders equally.
Another quick test is to get a can of spray carburetor cleaner. While the
engine's running, spray it on the gaskets (cylinder base, intake
manifold). If the rpm changes, that gasket is leaking.
-Dana
--
"A designer knows he has achieved perfection not when there is nothing
left to add, but when there is nothing left to take away." -Antoine de
Saint-Exup,ry
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