On Fri, Apr 30, 2004 at 09:50:20AM -0700, Paul M. wrote:
> Fuel injection is great (and very modern cars, with
> their incredible digital systems that can adjust
> engine management in real time) are really good, but I
> still love the throttle feel of a car with carbs.
> Push the pedal in a little bit, and a little bit
> happens. Push the pedal in more, and more happens.
> Somewhere along the line, that was lost with fuel
> injection. It's finally starting to come back now (I
> just drove a buddy's BMW M3 and it feels wonderful),
> but it's taken a long, long time.
>
> The only "vintage" exceptions to this I have found are
> some of the mechanically-injected cars like the Alfa
> Romeo SPICA system and some of the
> Kugelfischer-injected Porsches.
>
> But for my money, I still love me some carburettors!
I've not driven any "vintage" fuelie cars.
Granted, the whole point of my post was an excuse for a cheap
pun. However, when I was trying to dial in the carb on the blower, I
installed an O2 sensor and would watch that while driving. It was
amazingly educational, watching what happened, and noting things like
how much richness affected fuel consumption.
Unfortunately, it wasn't until after I had installed it I learned
about the difference between a standard and a wide-band sensor. If you
want to learn about what it going on in your motor, I highly reccomend
installing one and watching it as you drive. I suspect that you can
save yourself a lot of dyno time dialing in your car by watching one.
The other bit of instrumentation I want to add is EGT probes down the
air injection ports, so I can get per-cylinder data.
I had always labored under the misconception that SUs do not lean out
when you step on the gas. Unfortunately that is not at all true, and
when running on the edge of detonation or preignition, it can be
critical. I don't know if this leaning out on "tip in" is exacerbated
by the blower, but I ended up following Joe Cuerto's advice and
plugging off one of the ports on the carb piston.
Since embedded systems and computer controls are what I do
professionally, I'd love to have someone pay me to design and build an
engine management system. But failing that, I can't help but notice
the (at least theoretical) advantages of closed-loop control systems.
A lot of the old fuel injection systems were open-loop. They'd measure
various parameters and take a guess at how much gas was needed. Modern
FI, reads the output of the O2 or AFR sensor and adjusts mixture
accordingly.
--
Girling is not a verb.
lrc@red4est.com http://www.red4est.com/lrc
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