|
|
Just wanted to mention that the EC2/3 does back the ignition timing off when the MP goes over 30" Hg. It's not a step function but backs it off gradually as the MP goes up. It's backed off about by ~12 degrees when the MP gets up to about 54" Hg. Whether this is the correct curve I don't know but it's the best guess I could make without doing any turbo testing myself.
Tracy
On Sat, Mar 5, 2011 at 11:58 AM, Kelly Troyer <keltro@att.net> wrote:
Guys,
One other point that I forgot to mention was ignition timing..........It is my understanding
that turboed engines should not use excessive timing advance and that the higher the
boost the less timing advance is needed (or wise).........As I recall ignition timing as high
as 27 + degrees BTDC has/is used for naturally aspirated rotarys.........Lynn has stated
many times that 20+ degrees BTDC is actually plenty for most use and not much more
than that probably should be used for our turbo engines............Again Lynn jump in here
and give us the straight info..............
Kelly Troyer
"DYKE DELTA JD2" (Eventually)
"13B ROTARY"_ Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold
"TURBONETICS"_TO4E50 Turbo
Sent: Sat, March 5, 2011 9:56:53 AM
Subject: [FlyRotary] Re: Knock sensor and indicator
John, Chris,
I just remembered one other tidbit of info from our rotary guru Lynn.........One of
his informative posts on fuel and the effects of octane ratings stated that as you lean
the auto fuel that many of us use (87 to 91 octane) that the flame front is slowed and
this mimics the effect of lead in fuel (100 octane+) and makes the leaned auto fuel
less prone to detonation at the same time lowering EGT temps........I see no reason
this cannot work the same way with our turbo engines...........Hopfully Lynn will jump
in here and give us the straight info if I have this wrong...........
Kelly Troyer
"DYKE DELTA JD2" (Eventually)
"13B ROTARY"_ Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold
"TURBONETICS"_TO4E50 Turbo
From: Kelly Troyer <keltro@att.net>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sat, March 5, 2011 8:50:51 AM
Subject: [FlyRotary] Re: Knock sensor and indicator
John,
As you said Chris's problem is probably a combination of factors..........You mentioned your
intercooled intake temps being about 130F during climb..........Info I have about intercooling
used 130F as a desired max boosted intake temp..........What are your typical intake temps at
cruise and what manifold pressures (or PSI) do you use at takeoff, climb and cruise........Also
what is your EGT at cruise ?.............
Thanks,
Kelly Troyer
"DYKE DELTA JD2" (Eventually)
"13B ROTARY"_ Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold
"TURBONETICS"_TO4E50 Turbo
From: John Slade <jslade@canardaviation.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sat, March 5, 2011 7:54:20 AM
Subject: [FlyRotary] Re: Knock sensor and indicator
>Perhaps too much ignition timing or mixture problems such as spending to much time at best
>power mixture (1700+ f EGT) instead of richer than best power before leaning quickly to lean of peak EGT.
Yes, possibly. I always run rich, especially during run-up and take-off. By running rich, I mean I turn the mixture knob to 2 or 3pm. My EC2 is adjusted as best I could, and seems to keep the mixture about right, - but I still turn it rich for high power ops. My EGT alarm is set at 1750, and I occasionally have to reset it and back off the throttle during climb. Perhaps I'm being too conservative here.
Its been a while since I checked it, but I seem to recall intake temp (after the intercooler) being around 130 during climb. The airflow to my intercooler could/should be improved.
It's possible that Chris is overdoing the static high power runs. I mostly did mine during high speed taxi tests and was always mindful of the temps. I think I read that Chris runs high power static for 15 mins at a time. I never
ran full power static for more than a minute or two.
No - I don't aggressively lean at cruise - I set the mixture at 12 and let the EC2 do it's thing. Besides - Chris hasn't reached cruise YET, so I doubt it's that. As you say - it has to be timing, mixture or intake temps, or a combination of the three, possibly combined with "destructive testing" on the ground (which I did in the air :).
Chris - what oil are you using? I used Mobil dino oil during initial testing and Mobil 1 thereafter.
Regards,
John
On 3/4/2011 11:39 PM, Kelly Troyer wrote:
John,
Chris is using Tracy's apex seals (2mm) which are fairly tough and is only using
about 3 psi boost so any ideas on what is causing detonation ?............Perhaps too
much ignition timing or mixture problems such as spending to much time at best
power mixture (1700+ f EGT) instead of richer than best power before leaning
quickly to lean of peak EGT..........What EGT temps do you routinely see during
takeoff, climb and cruise ?..........Do you aggressively lean at cruise ?............
Thanks,
Kelly Troyer
"DYKE DELTA JD2" (Eventually)
"13B ROTARY"_ Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold
"TURBONETICS"_TO4E50 Turbo
From: John Slade <jslade@canardaviation.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Fri, March 4, 2011 4:30:29 PM
Subject: [FlyRotary] Re: Knock sensor and indicator
On 3/4/2011 4:43 PM, Kelly Troyer wrote:
> engine runs reported by Chris at high manifold pressure, high coolant temps and as you mentioned > probably high intake temps with little or no airflow across the intercooler............. I did many, many
engine runs and high speed taxi tests prior to flight, often with the temps at the limits. On occasion I was able to hear "pre-ignition" and back off the throttle. There was no sign of damage to my seals - but mine are 3mm 'indestructible' seals from Tracy.
John Slade -- Homepage: http://www.flyrotary.com/Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html
|
|