(02-07-2013, 09:00 PM)Ruan Wrote: I bet 300TDi nozzles set up properly in the injectors would be a good choice tbf, it's just that the fuel is so uncontrollable on the mechanical setups that you can end up with chronic coal-age...
The thing with even the SDi and I'd even go to say the 300TDi nozzles is that even past 3500rpm or so, you've got such a short time period to get the fuel in, you will struggle with "small" nozzles... DI engines suffer so badly from this, which is why you see so many engines making ALL their power at around 3-3.5k because if you try and get the fuel in past there, the peak temperature and pressure has gone by the time you've finished injecting...
With "big" nozzles you may want to up the break pressure a little (note this will add to injection retard, so map will need to be adjusted to compensate) to get great atomization... With the correct tuning, you CAN make big nozzles work well, it's usually poor tuning that causes smoke and gutless-ness issues etc...
That makes perfect sense as to why the power curve on that dyno print out (the one I posted) is so flat at the top end of the revs - can't get the fuel in so can't make any more power.
I think it was you who explained it to me before how IDI's are able to rev higher and make power up the top of the revs because there is still heat and pressure in the pre combustion chamber.
I'm pretty sure it was a guy with a mech pumped L series that tried the 200 or 300 TDi injectors, so that may have been the reason why it didn't perform so well. - The problem with ECU's vs mech pumps is that anyone can go out with some hand tools and fiddle with their fuel pump whereas people who want to experiment with ECU controlled fuel pumps can't really do a lot without getting the map tweaked every time they change something and it could get rather expensive unless you know how to remap ECU's yourself. Obviously you already know this but this is one thing I think that halts progress for some people.