setting ignition curves without dyno

[Clarence L.Snyder]

Bruce Plecan wrote:
> 
> -----Original Message-----
> From: Rick <rick at mafb.org>
> To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
> Date: Friday, November 13, 1998 4:47 PM
> Subject: Re: setting ignition curves without dyno
> 
> >Bruce Plecan wrote:
> >>Dynos are great for getting the cam events right. Well more prescisely
> they
> >>are great for doing everything but timing, and final mixtures.  They are
> >>worth every penny for doing anything other then
> >>timing, and final mixtures.  So if your buying dyno time for doing just
> >>those two items, you're not getting your money's worth in MHO...
> >
> >Why do you say this?? what is the BEST way in your opinion to get the right
> >timing down and final mixture??
> 
> Actual testing.  Bolt everything together, put it in the car, and tune it.
> The only way to load the motor as the motor will be run is after the
> installation.  Record the weather conditions, and make sure your
> corrections for IAT/Bar (as/is used are correct) even.  Engine dyno
> stuff is great for a starting point but, remember everything you do is
> being optimized for only that use (running on that dyno).
>    Yes, I get picky S---, about tune-up, that's just the way I am.  I've
> done numerous (NA)engines at 100HP/L that went 100,000 miles with min wear,
> ie, dress the valves+seats-rings-bearings, and go another 100,000....
> >
> >Rick
> >
A programmed rolling road is still "the best" as it is a controlled,
repeatable,"real world" situation. For those not aquainted with the
concept, it is a chassis dyno with a calibrated inertial component as
well as the restrictive or friction component. The ONLY way to test for
emmissions compliance, as well.
Too bad they are so expensive, not to mention rare. You can actually
program them for, say, a full throttle accelleration run up an 8% grade
with a 1 ton trailer behind your truck, with a 5 mph headwind - assuming
you know your co-efficient of drag and frontal area. Setting mixtures
and timing in this environment is the next thing to heaven, as EVERY
statistical change is relevent.
You are testing installed performance parameters under controlled,
simulated conditions.
Too bad I don't know where there is one for public use.