David,
Where are you injecting the water? Here
are the few facts I think I know
about water injections.
- Water
is better for detonation prevention than an alcohol mix.
- Alcohol
mixture allows timing advance and more HP.
- Injection
in the intake some distance before the engine block = more cooling.
- Injection
at the block = better detonation margin.
- Windshield
wiper fluid is a good alternative to dealing with methanol. Usually about
40% alcohol.
- With
a 100cc / 200 psi injector placed about 20” before the engine block
my temp drop to between 15-20F above OAT. No intercooler at 40”MP.
Also a good wideband is very useful. http://www.jdmpartswholesale.com/product/plx-dm-5-wideband-o2-52mm-display-sm-afr-combo-black
It’s my most used instrument. Any unusual sound and my eyes immediately look
at the gauge. I have also experienced a slight roughness using water and
leaning (using the wideband) clears it up. I’m also running Tracy’s timing
curve. Playing with the timing curve under boost is way out of my comfort zone.
I don’t won’t to be dependent on the water injection system to keep
the engine together under high boost.
Bobby
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of David Leonard
Sent: Sunday, August 28, 2011
10:24 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] How to tune
with ADI?
Ok, So I have the new ADI system installed and working....
I think?
Some of you smart racing guys probably have experience with ADI.
Most of the instructions that come with tuning it are directed toward
car guys that have computers and knock sensors. All they do is turn the
system on and the computer allows more advance because I is not sensing any
knock. The only real advise I have so for for me is that I should be
running just less than the amount of ADI that it takes to bog down the
engine. My system is a fixed flow so I don't have much choice but it
seems to be about right. If I use straight water (which I did for initial
testing), the engine bogs after about 10-15 seconds of ruining the ADI
system. But when I uses a 50/50 mix of water and denatured alcohol (too
hard to find methanol around here, but close enough) the engine does not bog.
So assuming my amount of ADI injected is about right, now I am supposed
to be able to lean to better power and advance the timing a little. But
how much? For the last testing flight I was using EGT for lack of a
better guide. When the ADI comes on, my EGT drops by about 30 deg C, and
there is a hint of roughness to the engine. I can then lean a little and
the roughness clears up. For my test flight I leaned until my EFT came
back up to where I normally limit it (890 deg C). But if I then add 5
more inches of MAP, there is still a hint of roughness even at 890 deg and I
get the sense that it wants to be leaned a little more. But I am afraid to do
that... We are talking 45" MAP and 7300 RPM here (185 KTS indicated
(Vne) and climbing at 500 fpm).
So here are my questions:
Is EGT a useful tool here, and does leaning to get the EGT back to 890
make any sense?
Since Methanol will do such a good job at preventing detonation, is it
safe to lean further toward best power (peak EGT)? (note, that will be hard on
the turbo... I need to remember to bring the spare one to Reno)
How much advance do you think i can add? I was
previously ruining 5 deg ahead of Tracy's
recommended initial set up. Can't give a number because the EC2
retards the timing with higher MAP's. How much, I have not heard. I
can easily add one deg at a time using Ed's EFI monitor. But without a
knock sensor am really in the blind.