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

[Adam Wade]

--- Ioannis Andrianakis <evotech at b-online.gr> wrote:

> When trying to get the best performance by road
> tuning, which gear ratio do you optimise for?

When dealing with the actual load/speed base map, I
tend to tune at the highest load possible (i.e.,
highest gear).  This tends to amplify symptoms of any
problems.

When testing "accelerator pump" maps, I test in lower
gears (2nd, say), as those maps are designed for
transient response, and the load on the vehicle
doesn't change as fast, nor will manifold vacuum drop
as much, at higher road speeds.

> Do you let the car cool down between runs?

As long as it is not overheating, no.  You want the
temperatures to be as consistent as possible.  To that
end, simply warm it up thoroughly before doing any
critical work (true on the dyno or the road).

> Stationary

I've found stationary, "no-load" testing tells very
little.

> So you come to the same point as using a dyno that
> you have to compromise between the different needs
> of the engine at same rpm and throttle oppenings but
> different acceleration ratios and history.

I can only speak for motorcycles, but even with ram
air systems, I've never found a "compromise" per se. 
I've found that sometimes you can make things a bit
better at the ends of the scale by having separate
mapping in some cases.  Ultimately, you have to
determine what is important to you; ease of tuning,
perfect "best power" everywhere and all the time,
economy, emissions...  Each has their place. 
Obviously, an acceleration map that is varied for
different gearings would perform better.

> Unless your car is a racecar and you have an ecu
> that can be mapped for every gear

I think most ECUs can be made to have the capacity for
such mapping (i.e., there's capability in the hardware
and enough room in the EPROM), while many don't
implement that.  It's certainly extra work to map an
ECU like that, but I don't think you need a racecar to
make it practical.

> and a dyno to simulate the whole race and
> datalogging to check you performance then your tune
> is not ideal, its close but not ideal.

Maybe I din't express this clearly in previous posts;
there's no such thing as an "ideal" way to tune. 
There are simply a lot of different methods and tools,
and what combination of those things is closer to your
goals than another is "better" for you and your
application.

> I have found that using a brake dyno(dynapack) and
> steady state tuning to get the map close and fixed
> acceleration ratio ramp tests(approximating road
> acceleration ratios) to optimise, I can get close.
> That is championship winning close.

My experiences are similar.

> But still I dont know how far from ideal I am.

Unfortunately, until we can take a series of very
accurate "snapshots" of exactly what is going on
inside the combustion chamber, we may never be truly
"sure".  Most such equipment does exist; it's simply
outside the reach of any but the best manufacturer and
research test installations.

> Wish I had more time,money and tools to achive
> a better tune.

I think we all do.  If we didn't want to know more,
and learn more, and do a better job, most of us
wouldn't be here.  ;)  Even me!  ;)

=====
| 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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