Re :Intercooler/o2 volts/Injector constant

[Dig <turbodig@yahoo.com>]

I'm gonna combine a few replies, hope it's not too
confusing...

---->
Grumpy writes:

Just for those tinkering with turbos.
On a stock syclone (ie engine never opened up), last
week we ran from 97dF
to 130ish.  There was an add-on heater core for use
with the stock air to
liquid cooler.  This week ran without it, while
slightly warmer weather,
after using the same procedure the IAT went from 105
to 150s, during a pass.
I was amazed that little cooler made that much
difference.
Just makes ya wonder if it's the cooling area, or
increase in capacity that
makes the difference.
---->

I think the answer to that is *yes*. (both)

What I've found in playing with it is that the 
additional volume adds "capacitance" to the system;
and unless you're vigilant with the ice or a whole
lotta cool airflow, this can actually be a detriment.
After 3-4 rounds of eliminations at the track, it's
nearly impossible to get the IC temps back down
quickly between rounds. 

However, If you get a big 'ol beer cooler and throw
it in the trunk/bed, fill 'er with ice, and start
circulating... what a difference! I notice a lot of
the sub 10-sec GNs are doing this as well.

Along those same lines, I was driving a friend's Sy
in Detroit on a 97 degree day, and the IC temp read
about 120-128 at cruise. Hit a band of rain, and the
IC temp dropped to 76 within 3 minutes. I figured it'd
drop, but not 50 degrees.

Anyway, on to more EFIish stuff...

--->
Barry writes:
So:  -The Injector Flow value indeed is not used by
the ECU.
     -Changing the BPC vs EGR seems to be the
equivalent of a Injector Size
                        constant.
---->

Pretty much... that's what I've always used to play
with injector sizes and big fuel pressure. (I run
62 psi base or so on the Sy... 85 psi at WOT) The
0x328 constant is a leftover from another application
that they "borrowed" the fuel code from, I think.

You will need to pay attention to the DE and AE 
parameters... something I didn't do on early cals.
Watch your idle PW, too.


---->

Jim + Jeff Wrote:

<< While doing a WOT run, O2 volts were now steady
 at 946 to 986 (was 1016 before on some areas, no lack
of fuel now with 13 to
 15 psi) instead of falling off into the mid 800s with
the stock injectors.
 I would also like to add to those who >>

Do TGP's like it that rich?? you might gain more bny
leaning it out some.
 My 
GNB likes .790-.810
---->
 
I did a little research into this with a friend's
datalogger and a Diacom...

What I found was that, on the Sy we were testing,
the actual o2 volts measured by the Datalogger were
.192 lower than the Diacom o2. Not sure what the 
reasons for this are, but I suspect it has to do 
with the reference voltage of the A/D and the 
formula used to calculate o2 volts from the scan
data.

What I also found (from actual data compared to an 
NTK wide-band o2) was that the o2 voltage was not
repeatable on this vehicle. 980 mV during one
engine run session was 11.5:1 AFR, the next time
we ran it (on the same day, same temp condtions)
it was 12.4:1 AFR. There was no way you could 
guarantee what AFR a particular Diacom voltage
indicated, even on the same vehicle during the same
day.

What I *did* find interesting was that the trend 
of the Diacom o2 voltage at WOT followed the NTK
wide-band data exactly. The indicated range, however, 
is very small- you need to export the Diacom data to
Excel and graph the o2 data from 700mV to 1v or so.
The peaks and valleys show up quite readily, and
can be used to show lean/rich spots in a particular
cal. That-is, lean or rich relative to other points
in the run, since you don't really know for sure
where your max power AFR is.

With this, though, you can tune for a flat AFR curve
across the whole RPM range, then use fuel pressure
to dial the centerline of that curve to where it 
needs to be.

This was, again, on a Stock Syclone 4.3. I can't
say whether the results will be similar on a normally
aspirated motor since I don't have any data from one,
but it would be interesting to find out...


Later,

Dig
turbodig@yahoo.com
Northland Turbo Gathering I | May 13-14 | Sheldon, ND




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