Achieved 18.8mpg on urban cycle

[dnb]

I had a target of 20 mpg urban cycle and 30mpg on the M-way, but I'm still quite pleased about getting to nearly 19. 

Before VEMS the car did 16mpg urban cycle. 
After VEMS, but before the rebuild & wild cam it did 19.5mpg, but the engine produced about 100 less bhp than now...

Where would be a good place to look to gain the extra economy? (without altering my driving style - this is about the car, not me!)  I'm using lean burn on cruise, but it's never really cruising in urban conditions.  Also, I'm pretty close to MBT in at least half the ignition table now.  Maybe I need ion sensing to really be sure about this...  

[MWfire]

Ion sensor will reduce consumption, but maby 1-2%.
You can add erg valve or hot air(taken over exhaust manifold) when you crusing. Valve can be control via misc output.

[Jorgen]

Do you use overrun fuel cut?

Maybe a misc out can be used to fully open the idle valve when in overrun to make the engine braking less violent. Those who has driven a light car with a big engine know how brutal it can be.

Be careful with acc enrichment.

Do you have an MSD 6A or better?

Close to MBT on a US based V8 in low load conditions? Somewhere around 45-50deg advance at 50kPa?

Jörgen

[dnb]

I do usually use overrun fuel cut, but it's switched off at the moment due to the extreme brutality you talk about, and the little fact the diff and driveshafts are almost dead... 

Is there any reason why the idle valve can't be made to open under these circumstances?  I can't easily use a misc out to open it because it's a stepper.

Accel enrichment is tuned nicely based on datamining my log files - no major rich excursions any more, so the throttle response is good too, so is the reason why the diff is being killed.  I have very little self restraint leaving junctions when no-one's around...

I have 034 Motorsport coils with standard VEMS IGBTs.  I am running about 40 degrees at 50kPa above 3000 RPM, but ramps down sharply to 15 degrees for idle.  No sign of misfires yet, but I'm not convinced I'm at MBT at low loads yet.  They'll happily run with a huge dwell if necessary - provided there's time to fit it in.

The high and mid load stuff was all done on a dyno, so I'm fairly confident about that being MBT.  The engine is severely knock limited at high RPM and high load due to it being high compression and me only having 95 RON fuel...