|
|
I will bet a coke or two that this is related to intake charge temp,
which in his installation may be unmonitored. I cant remember if we
(when I was actively working with him on his build) put a
thermocouple on the intake or not - the Mistral Intake I bought had
3 ports on the throttle side for "stuff". I remember putting two of
them to the intake manifold pressure sensors, and may have put the
third one to a thermocouple, but unknown if Chris had wired up and
calibrated that, or if it actually was just plugged with a threaded
blank/cap.
Couple that with a boosted engine, minimal airflow over the
intercooler. Also... how many inches of MP is Chris actually
getting? I remember he says he has 3lb springs in the wastegate, so
that SHOULD be 6" of boost.. so a max MP of 36". If he's getting
anything more than that, then something is out of calibration or its
not a 3lb spring.
Using universal gas law, PV=nRT, and playing with a gas law
calculator calculator, I dont know if I missed something.. but a 70F
degree day (294 degrees Kelvin), standard pressure 29.92" (760 torr)
boosted to 36" (914 torr) and keeping the volume constant, I got a
charge temp of 175 F. If you boost to 45" (15" extra boost, 7-8
lbs) you get a charge temp of 336 degrees F. This does not account
for waste heat from the turbo wheel heating up the compressor by
direct conduction.
That means (if my numbers are right), the air leaving the turbo to
the intercooler is 175 degrees F or more. With no airflow over the
intercooler, the only heat loss minimal radiation and conduction, so
you still have VERY HOT AIR going into the combustion chamber, which
predisposes you to detonation tremendously.
On 3/4/2011 10:39 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
|
|