17-08-2012, 12:41 AM
But is the management THAT intelligent to drop iqs vs temperature, correctly in relation to temperature and the remap given... Surely by the time you've remapped it, unless you took your calibration to the north pole or Saharan desert, and did testing, surely you can only be certain that in the UK climate it would be OK... I don't know whether you adjust the maps that control this, I'm not totally knowledgeable about it...
The single biggest efficiency increaser I've seen is the increase of boost pressure when cruising from the VNT... Considering I've never replaced my injectors which have now done over 200k on the original nozzles which usually send mpg through the floor... It took my car from mid forties in mpg to well over 50...
With regards to calibration without emission restrictions... I was chatting to a friend tonight, GM make a locomotive engine, used in the BR class 60, 3300hp or so, it's got one of the best fuel consumption figures of any loco, even today! That's all because it was produced at a time when emission regulations weren't strict... However they are supposedly horribly bad on emissions due to the fact they're high compression and high boost, lots of thermal efficiency, but loads of NOx... Also they run chronic timing...
From my admittedly limited experiences of DI diesels, injection pressure has a big effect, but past 500bar or so, it's the law of diminishing returns...? The more you run, the harder you have to run everything else, to a point the gains become fruitless due to everything being over worked... Old vp37 tdis seem consume very much similar amounts of fuel to their newer PD and Piezo CR sisters, even though they're a much older design..
Id be very much interested to see where that point is... The more efficient you can make the injection system the better, but at some point increasing pressure more will consume so much energy, the increases in atomization and therefore economy become outweighed...
Hmm...
The single biggest efficiency increaser I've seen is the increase of boost pressure when cruising from the VNT... Considering I've never replaced my injectors which have now done over 200k on the original nozzles which usually send mpg through the floor... It took my car from mid forties in mpg to well over 50...
With regards to calibration without emission restrictions... I was chatting to a friend tonight, GM make a locomotive engine, used in the BR class 60, 3300hp or so, it's got one of the best fuel consumption figures of any loco, even today! That's all because it was produced at a time when emission regulations weren't strict... However they are supposedly horribly bad on emissions due to the fact they're high compression and high boost, lots of thermal efficiency, but loads of NOx... Also they run chronic timing...
From my admittedly limited experiences of DI diesels, injection pressure has a big effect, but past 500bar or so, it's the law of diminishing returns...? The more you run, the harder you have to run everything else, to a point the gains become fruitless due to everything being over worked... Old vp37 tdis seem consume very much similar amounts of fuel to their newer PD and Piezo CR sisters, even though they're a much older design..
Id be very much interested to see where that point is... The more efficient you can make the injection system the better, but at some point increasing pressure more will consume so much energy, the increases in atomization and therefore economy become outweighed...
Hmm...
