[VeyronSuperSprt]

Originally Posted by Sutripta

Check out

Any further developements on the Miller Cycle?

Highly probable. But as is the case with most manufacturers, details are never disclosed until the product has been in commercial production for some time. As of now,even the torque and bhp figures haven't been released!

[thoma]

Originally Posted by thoma

I didn't fully understand, what exactly is enhanced /changed (if any) so that the compression ratio is found out that it can be reduced?

So, was it mostly for starting that the comp ratio kept higher earlier?

Okay, my question seems immature, reading just the Babbage article and not the Mazda one, as provided by @Sutripta. The article clearly explains:

There are two main problems that have been preventing the spread of low-compression-ratio diesels regardless of these merits. The first is the fact that when the compression pressure is reduced, the compression temperature during cold operation is too low to cause combustion, preventing engine-start. The second is the occurrence of misfiring during warm-up operation due to lack of compression temperature and pressure.

Further, the gist of improvements that counter the above issues are

The newly adopted multi-hole piezo injectors allow for a wide variety of injection patterns. Precision in injection amount and timing increases the accuracy of mixture concentration control, ensuring cold-start capability. Hardware-wise, the injector is a high-spec type capable of a maximum of 9 injections per combustion. Along with the three basic injections: pre-injection, main injection, and post-injection, different injection patterns will be set according to driving conditions. Definite engine-start even with a low compression ratio is attributable to this precise injection control and also the adoption of ceramic glow plugs.

and

Any misfiring that may occur during warm-up operation after engine-start is prevented by adopting a VVL (variable valve lift) system for the exhaust valves. A single combustion cycle is sufficient for the exhaust gas temperature to rise. Given this, the exhaust valves are opened slightly during the intake stroke to regurgitate the hot exhaust gas back into the cylinder, which increases the air temperature. This promotes the elevation of compression temperature, stabilizing ignition.

[Diesel_convert]

Other than nox improvements, what other benefit?

Don't you lose thermal efficiency lowering compression ratio?

They can probably save weight elsewhere instead of the engine block by making it weaker. Lol 50,000 mile two year engine warranty anyone?

Switch to aluminum body panels maybe...

[DWind]

As I understand, the new Diesel engines lower the compression ratio (for Nox Reduction and better combustion) but compensate for it by even higher rail pressure. can somebody confirm change in CR pressure?

[Diesel_convert]

Originally Posted by DWind

As I understand, the new Diesel engines lower the compression ratio (for Nox Reduction and better combustion) but compensate for it by even higher rail pressure. can somebody confirm change in CR pressure?

I think the part about better combustion is misleading.

It's better combustion in terms of nox production not in terms of mean effective pressure or peak thermal efficiency.


You can see this in Mazda's graph about friction mean effective pressure, which I think is brake mean effective pressure.


Cr pressure, number of nozzles, number of injections only affects spray pattern and atomisation/ mixture formation.

The same advancement in cr technology can be applied to higher compression ratios with better results.


Sorry about the rant as an enthusiast I cannot get over losing efficiency over nox production.