----- Original Message -----
Sent: Monday, July 18, 2005 12:13
PM
Subject: [FlyRotary] EM-2 and fuel flow
questions
Greetings,
First, I still haven't
tried the auto tune yet, but should give it a full test when I build the new
intake. I wasn't going to do the intake now, but since my garage is full
of stuff that should be outside in the destroyed screen room, I can't really
work on the Kolb. Frequent readers will also realized that I didn't need
much of an excuse :-)
Tracy, I'm happy to
report that I've seen no further wacky behavior on the EM-2 since installing
the new software. Before, it had a tendency to display wildly incorrect
numbers on occasion, such as 60 gph, and the only fix was to turn it off and
back on. It also used to show fuel flow when the engine wasn't
running. So far, so good on all that. Thanks!
Ahh... some good news for a change! : )
Yesterday, I was showing
24.5 gph at 8000 ft and WOT. Let's hope that's not true :-) Now
that I can get serious about getting this set correctly, I looked at the FF
cal. I presume the 151 number is set for the stock Mazda "460"
injectors. From what I can tell from the archives, Mazda doesn't use
standard practice for rating these, and in fact, they seem to test much higher
when using standard methods. One example I found was someone who had 4
of these "460" injectors tested, and they each flowed 520. When I take
520, compared to my current 400 injectors, there's a 23% difference, so I'll
raise the 151 cal factor by 23% to 186 and see what that gives me.
It's also interesting to note that taking 23% off my 24.5 gph figure gives
18.9 gph, which is far close to what I'd expect at max
power.
My experience matches yours in the injector flow
department. Mazda is either sandbagging or conservative in their
rating. I'm only seeing less than 50% duty cycle on the 440/460 (forget
which) 2nd gen NA injectors at best power mixture (~ 12 : 1 A/F) at WOT &
sea level. FF is around 22 GPH, RPM 7300.
Now for a
question- I've seen figures for Brake Specific Fuel Consumption (BSFC) in
the .55 range for a non-turbo rotary. If I were going to use
this factor to calculate HP from fuel flow, what mixture would I need to
be at? Is this for best power, 14.7, or does it even
matter?
Yes it matters and the EC2 tries to estimate BSFC if
you have an O2 sensor attached. The BSFC constant in the EC2 is the
median at 14.7 : 1. This is all just my best guesses so don't sue me if
you don't get lab grade results right off the bat. Juggle BSFC factor in
the EC2 if you need to.
Another question for
Tracy- Does the Max HP figure do anything other than changing what is
displayed on the screen for HP? I would presume the % power figure
should always be correct, but if you put the wrong max HP factor in, then
your displayed HP would be wrong.
The calculated HP displayed is based on Fuel flow and
calculated BSFC. The % power is based on calculated HP
divided by the max HP factor. If you rate the engine lower in max HP,
you could see more than 100% power displayed.
Final question for Tracy-
How much did John pay you to sabotage Buly's EC-2 :-)
This is
based on a calculation involving how long John is laid up and unable to fly
and how many times I have to sabotage Buly's EC2. :-
))))
Tracy
(still waiting for my LS1 replacement coil)
Thanks,
Rusty (catching up to Ed
on the intake count)