[Diy_efi] RE: Diy_efi digest, Vol 1 #413 - 12 msgs

[Adam Wade]

--- Dave Dahlgren <ddahlgren at snet.net> wrote:

> How long does it take for this to stabilize and get
> good data?

A lot depends on the length of your exhaust system.  I
used it with motorcycles, and it took about a half a
second for the exhaust gas readings to stabilize
enough for a clean reading.

> I had always thought and possibly incorrectly that
> they 4 gas analyzer was fairly slow in response
> time.

Oh, it would be totally unusable on an inertial dyno. 
then again, so would any tailpipe gas reader,
including an O2 sensor.  Most of the lag is the time
the gases take to get to the end of the exhaust
system.  If you had a port up near the cylinder head,
that time would be cut dramatically.  There would
still be more of a lag for a four-gas, but since an
eddy current dyno steady-states the speed and load of
the vehicle, you could wait indefinitely, as long as
you had sufficient cooling air.

> Are they faster now so a 3 or 4 second pull will net
> good data?

I can't speak for putting a probe down the tailpipe of
a car, but I can get a load/speed site accurately
analyzed on an eddy current dyno with a four-gas on a
motorcycle in that time period, consistently, yes.

> Most of the stuff I work on is pretty highly
> stressed so I am not so sure it would live through a
> 20 second pull at all the points that need to be
> programed.

Ugh, I wouldn't want to do that to a motor in any
case, but no, you should not have to do that.

> Most of the turbo stuff is over 1000 hp for a 3
> liter engine the 2.1 liters are around 800..

The only trick here is that I am not sure who makes an
eddy-current dyno that can handle that kind of
power...  If you were interested in going that route,
I could put you in touch with people who would know,
though.

The biggest trick, as I am sure you know, is getting
the exhaust gases as soon as you can so you don't have
to wait for them to come out the tailpipe.

=====
| Adam Wade                       1990 Kwak Zephyr 550 (Daphne) |
|   http://y42.photos.yahoo.com/bc/espresso_doppio/lst?.dir=/   |
| "It was like an emergency ward after a great catastrophe; it  |
|   didn't matter what race or class the victims belonged to.   |
|  They were all given the same miracle drug, which was coffee. |
|   The catastrophe in this case, of course, was that the sun   |
|     had come up again."                    -Kurt Vonnegut     |

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