Today's Message Index:
----------------------
1. 10:49 AM - Re:912 Oil Filters (Michael Burson)
2. 03:32 PM - Allegro 2000, 912UL Initial Engine Test Run (Hugh McKay III)
3. 04:12 PM - Re: Allegro 2000, 912UL Initial Engine Test Run (Gilles Thesee)
Message 1
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| Subject: | RE:912 Oil Filters |
I've used a Fram PH3614 since my 1st oil change. 214 hours..
__________________________________________________
Message 2
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| Subject: | Allegro 2000, 912UL Initial Engine Test Run |
Gentlemen: Today I ran my Rotax 912UL for its first test run. The plane is
an Allegro 2000. Plane was anchored down, outside temperature 86 to 88
degrees F, bright and sunny, plane sitting on asphalt.
Here is the chronology of the results.
1. Oil system was vented properly.
2. Oil level checked. OK (Mobile 1 MX4T 10w-40 motorcycle oil)
3. Coolant level OK. (50/50 distilled water and Texaco Anti-freeze Coolant
Concentrate)
4. Started electric fuel pump.
5. Closed choke, (full choke)
6. Throttle in idle position.
7. Master switch on.
8. Ignition switches (2) on.
9. Started engine (engine started immediately).
10. Held engine rpm at 1000 for 5 min.
11. Oil pressure went to 5 bar on start.
12. After 5 min increased rpm to 2500
13. At 2500 rpm, oil pressure 4.0 bar, oil temp. 60 degrees C, cylinder head
temp. 100 degrees C, fuel pressure 0.3 bar (held this rpm for 10 to 15 min.)
I noticed the cylinder head temp gradually continued to rise.
14. After 15 min gradually increased rpm to 4000
15. At 4000 rpm; Oil pressure 4.0 bar, oil temp. increased to 120 degrees C,
cylinder head temp increased to 130 degrees C, fuel pressure 0.3 bar (held
this rpm for another 15 +/- min.)
16. At 4000 rpm checked both ignition (kill) switches. rpm drop was aprx.
100 rpm on each switch.
17. At this point the engine had been running for about 30 to 40 minutes
sitting on the ground with the cowling on and the ambient temp. at aprx.88
degrees F.
18. I then increased the engine speed to max throttle position and checked
the engine rpm. Max rpm was 4600 rpm. Held this speed for one minute. Based
on this number the existing Prop pitch (17.5 degrees by the Warp Drive
Protractor) needs adjusting to get the rpm up to the 4800-5100 range. I
assume I will have to reduce the pitch to do this (i.e. less pitch equals
higher rpm). How much less than 17.5 degrees I dont know. Im guessing
about 1 to 1.5 degrees.
19. At max throttle, 4600 rpm; oil pressure 3.4 bar, oil temp. 120 degrees
C, cylinder head temp 130 degrees C and rising, fuel pressure 0.3 bar.
20. Reduced engine speed to 1000 rpm for 3 min. for cool down.
21. Engine stopped.
Note: After engine shut down coolant in over flow bottle was boiling, and
there was evidence of overflow on the asphalt. I noticed that the specs on
the Texaco Anti-freeze coolant container showed that for a 50/50 mix ratio
and a 15 psi radiator cap (my cap is rated 1.2 bar or 17.2 psi), the boil
over protection is only 129.3 degree C. For a 60/40 mix ratio the protection
goes up only to 132.2 degrees C. This is the max. recommended mix ratio. If
the CHT gauge is correct I exceeded the boil over protection for the
mixture.
The Rotax Engine Operators Manual 10.2.1 states that the ratio of
anti-freeze to water should be increased if boiling should occur. I can only
go to a 60/40 and that only protects to 132.2 degrees C.
One thing that concerned me when I filled the engine cooling system, it took
less than one gallon (aprx. 3 quarts) of 50/50 mix to fill the system. This
seems to me to be a very small amount of liquid to cool the engine properly.
What is the proper volume of coolant in the Allegro 2000 cooling system?
Everything seemed to be normal except the CHT. Can any one help me with this
problem?
Hugh McKay in North Carolina
Message 3
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| Subject: | Re: Allegro 2000, 912UL Initial Engine Test Run |
--> RotaxEngines-List message posted by: Gilles Thesee <Gilles.Thesee@ac-grenoble.fr>
Hi Hugh,
> Gentlemen: Today I ran my Rotax 912UL for its first test run.....
>
> 1. Started engine (engine started immediately).
> 2. Held engine rpm at 1000 for 5 min.
> 3. Oil pressure went to 5 bar on start.
> 4. After 5 min increased rpm to 2500
> 5. At 2500 rpm, oil pressure 4.0 bar, oil temp. 60 degrees C,
> cylinder head temp. 100 degrees C, fuel pressure 0.3 bar (held
> this rpm for 10 to 15 min.) I noticed the cylinder head temp
> gradually continued to rise.
>
I would have shut down long before that.
> 1. After 15 min gradually increased rpm to 4000
> 2. At 4000 rpm; Oil pressure 4.0 bar, oil temp. increased to 120
> degrees C, cylinder head temp increased to 130 degrees C, fuel
> pressure 0.3 bar (held this rpm for another 15 +/- min.)
> 3. At 4000 rpm checked both ignition (kill) switches. rpm drop was
> aprx. 100 rpm on each switch.
> 4. At this point the engine had been running for about 30 to 40
> minutes sitting on the ground with the cowling on and the
> ambient temp. at aprx.88 degrees F.
> 5. I then increased the engine speed to max throttle position and
> checked the engine rpm. Max rpm was 4600 rpm. Held this speed
> for one minute. Based on this number the existing Prop pitch
> (17.5 degrees by the Warp Drive Protractor) needs adjusting to
> get the rpm up to the 4800-5100 range. I assume I will have to
> reduce the pitch to do this (i.e. less pitch equals higher rpm).
> How much less than 17.5 degrees I dont know. Im guessing about
> 1 to 1.5 degrees.
> 6. At max throttle, 4600 rpm; oil pressure 3.4 bar, oil temp. 120
> degrees C, cylinder head temp 130 degrees C and rising, fuel
> pressure 0.3 bar.
> 7. Reduced engine speed to 1000 rpm for 3 min. for cool down.
>
IMHO, 40 minutes on the ground seems quite an ordeal for a first engine
run. Especially with the temperatures you achieved. 130C seems to me
way too high.
One thing common to any piston engine, is they need to be treated with
care at the beginning of their operating life. And you don't want to
thermally load them during the run in period.
If it were my engine, I'd do short runs progressively increased in RPM
and duration, with a careful monitoring of temperatures. And I would
stop as soon as they climb too high. Adequate airflow is key.
When building a 4-seater project, I conducted a thorough cooling
investigation, and designed a radiator duct which performs very well,
with great ease of adjustment.
See :
http://contrails.free.fr/engine_refroid.php
http://contrails.free.fr/tunnel_en.php
>
> 1.
>
>
> Note: After engine shut down coolant in over flow bottle was boiling,
> and there was evidence of overflow on the asphalt.
>
This is no surprise.
First start, run 30 seconds, shut down, check everything.
Then resart for a few minutes, without allowing the temps to exceed the
lower authorized range, shut down, check, etc...
> I noticed that the specs on the Texaco Anti-freeze coolant container
> showed that for a 50/50 mix ratio and a 15 psi radiator cap (my cap is
> rated 1.2 bar or 17.2 psi), the boil over protection is only 129.3
> degree C. For a 60/40 mix ratio the protection goes up only to 132.2
> degrees C. This is the max. recommended mix ratio. If the CHT gauge is
> correct I exceeded the boil over protection for the mixture.
>
It's not the boiling that harms the engine, but high CHT. To the
contrary, boiling helps reducing temps, that is as long as there is
coolant to boil, and not for 40 minutes. You definitely need cooling
airflow to correctly reject heat from the engine.
>
> The Rotax Engine Operators Manual 10.2.1 states that the ratio of
> anti-freeze to water should be increased if boiling should occur. I
> can only go to a 60/40 and that only protects to 132.2 degrees C.
>
> One thing that concerned me when I filled the engine cooling system,
> it took less than one gallon (aprx. 3 quarts) of 50/50 mix to fill the
> system. This seems to me to be a very small amount of liquid to cool
> the engine properly. What is the proper volume of coolant in the
> Allegro 2000 cooling system?
>
> Everything seemed to be normal except the CHT. Can any one help me
> with this problem?
>
The Rotax 91X series are very enduring engines, so you may hope you did
not really damage your engine.
I would suggest you start again the right way :
- Download the applicable cooling SBs and service letters from the Rotax
website and read them thoroughly.
- Seek the advice of a knowledgeable Rotax mechanic, engineer or dealer.
- Check for adequate engine and radiator installation.
- Do not do long ground runs with no cooling.
Best of luck,
Regards,
Gilles Thesee
Grenoble, France
http://contrails.free.fr
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