400hp w210, om606 Turbo or 320cdi?

Naturally-aspirated

16

01-12-2011, 07:56 PM #12

I have everything from OHV Lucas single stage IDI through Bosch EDC to the PD unit injecto and CR3 common rail engines I work on (I don't run a PD/CR mainly just because I have too many cars and the CR VAG are brand new, they never used 1st/2nd gen using the unit injector instead).

You are correct that atomisation gets better with pressure rise. But it's a reverse exponential curve, from early pressures like 100 bar IDI nozzles the jump to 300 bar enabled DI engines to ignite and atomise. PD then jumped to around 2,000 bar (around 7 times the pressure) and emissions cleaned up if I recall from euro 3 to euro 4 but couldn't pass euro 5 so they moved again to CRv3. Also, you'd think it would be better atomisation, more efficient but it lost 5mpg on average and had to have a cambelt twice the size and special oil there was so much drag on the engine creating these huge pressures.

There is (for performance anyhow, not necessarily emissions) a sweet spot whre more pressure will just create more drag and there is an argument for putting in the fuel quick, but in large particles so they burn for a while. Fuel in small particles explodes quickly, bad for stress on the engine. Also very high pressure requires very tiny nozzles, so it's often a long duration of injection which means optimum timing cannot be adhered to.

So, I'm for the control system but may want to have far larger nozzles running a lower pressure - something around 500bar will still be cleaner than 1st gen di's but be more efficient and a lot easier to pump more fuel I think, if you don't have to pass it through such a narrow hole that it requires 2,000bar to get it to pass!

Greg.

(01-12-2011, 07:34 PM)Riverstick
(01-12-2011, 06:35 PM)greg123 Who will remap your trans shift pattern for you?

Extrude honed nozzles are generally not as good as off the shelf larger ones as it's hard to match them all, I use nozzles from Bosio and the like for performance (or Bosch, but larger) but I haven't experience of this on the cdi. The principle is the same though. I would also like to half the injection pressure, there is a lot of drag from running such a high pressure on the pump and atomisation is better, but not that much better, than 300bar IP engines. Something half way in between the two would still run just as well but have less sacrificial load on the engine - my di runs super clean on 300bar old school injectors, you'd still be running around double that pressure or more!

Greg.

Not sure yet Greg as its difficult to get someone to do that over here....auto boxes are not that overpopular and most workshops are only interested in rebuilding/resetting them to OEM specs. I have a friend who does engine remapping so I'll enquire from him. I noticed some of the finnish guys on here write their own maps. The US is the home of the automatic and they seem to have the way of upgrading and improving OEM 'boxes and torque converters with great results. I'm sure someone here can put us right on that front.

Correct me if I'm wrong but I was led to believe that the higher the injection pressure,the better the combustion/atomization/efficiency/power/particulate yields....particularly as you climb the hoorsepower table? I know driving the high pressure pump requires a significant ammount of energy but we were told the benefits far outweighed that.

What DI have you?

This is the link to the Extruded honing process...has anyone any experience of this?

http://dynomitediesel.com/user_pages/0_b...l?page=The Honing Process