Odd apparent ignition timing requirements

[JulianEdgar]

No I haven't. Can post it here if someone wants to look at it very closely.

[SportsCarRacer]

I strongly suspect it is the one valve operation with large degree if charge motion. Have seen similar on 996 gt3 engine when in low lift short duration mode (only about 25% of full lift)...above 3500ish rpm it needed 20deg Less timing or knk was runaway!!!.Moving to hilift at thus point restored sensible spk timing.
I work for large auto oem in calibration & previously eng devt....we run cmcv (chg motion control vlvs) which induce charge motion at otherwise unstable cam timings to gain some chg motion with very dilute cyl fill (from internal egr by cam vct). Many papers on this behaviour.
cutrently work on 2l turbo gtdi with 10 cr, 259 kpa map and 91ron fuel!!! But all in the name of ECOnomy....spk values are single digit adv bef tdc or up to -15 (deg AFter Tdc)....especialky at low rpm high load.
can you control the vtec valve actuation to prove it out? Can you retard the inlet cam 30 ir so deg at this point(if you have boost) and gain same det relief from miller effect? Miller is boosted atkinson to regain the lost tq and keep the increased eff of short comp long exp strokes.
I thought insight was atkinson cycle? Is it DI or Pfi?
Strongly suggest lots if chg motion, more cyl fill (from boost), leanish afrs & high thermostat temp for economy are all driving you heavy in the direction of det.....overcompressed as we say....

[JulianEdgar]

Yes I think what you say is correct - lots of swirl with the one valve inlet operation in VTEC-off mode. However, I seem to have it all working pretty well now, with better low-down torque than the factory ECU provided.

The Insight is conventional cycle, port fuel injected.

Thanks for your thoughts.

[SportsCarRacer]

No worries. Every day with modern engine gtdi turbo engines we see confounding stuff that goes what has been many decades if engine calibration thinking. The strive for improved Fuel economy with increased performance but more stringent emissions means we are in a golden age of spk ign engine devt!
GTDi engines are rivalling diesels in the passenger markets, unthought of even as recent as 08-09.

I applaud your project and am interested in you keeping us updated.

Your previous auto projects have often be unorthodox Julian, but the logical devt process you have followed should demonstrate the benefits if thinking outside the box.

u often say, when asked why buy motec, is that the power of the hundred series ecus (and my m1 devt ecu!!!) Is limited mostly by your imagination....something your project succinctly demonstrates, along with many other lateral thinking contributors here!

PLEASE KEEP US UPDATED WITH YOUR PROGRESS!

Could I suggest adding a precis if your project in the motec "user projects" forum, as a foil for many less technically interesting projects