Turbos

[buickanddeere]

Okay. . .  I've found a blower, got it adapted to the engine. . . just trying to figure out what to do with the damn drive belts!



I know, I need to be more serious about this, just can't help myself!

  Give the blower a quarter turn.

[compig]

Locate the blower on top of the alternator instead !!

[jsw123]

[oliver90owner]

As I see it:

Thermodynamics predict that the higher the compression (higher the air charge temperature, etc etc) the more efficient the energy conversion will be.  There are limitations to any particular engine - like lubrication, size of bearings, (loading issues, etc), cooling... the list goes on.

Some of the power is always used to drive the supercharger.  It works throughout the rev range.  No power is required from the mechanics to drive a turbo which could be effectively stationary at idle, but it does have to contend with high temps - hence the oil supply is for cooling as well as lube and probably the cooling is the more important issue.

A blower can give as much pressure boost as you would wish - just need different designs for different pressures - it is, after all, only a large air compressor.

So blowers tend to increase bottom end torque and turbos only come into their own further up the rev range and generally need a waste gate on a variable speed engines where a large percentage of the available energy recovery will be lost IF good boost is required at lower revs.

Comparing the designs for a fixed speed engine will be vey different than a variable speed one.

Most fixed speed engines use a turbo (probably without a waste gate) these days.  They are correctly sized for that one speed (that one exhaust gas velocity).  Most engines do not need the slow speed boost, so why use a blower or a turbo which will have to waste some of the waste gas energy (via the waste gate).

There is no problem in metering the oil flow to a turbo (or the pressure) and having an auto engine shut-down on fault.

Overall, it seems irrelevant to a 6/1.  The engine is designed for longevity at that specific power outut.  Longevity and simplicity are the virtues of the design.  There will always be someone who wants more out than they put in.

Regards, RAB

[jzeeff]

I understand the "make it into something it wasn't intended to be" thing, but I also think that there is some market for a small, reasonably priced diesel engine for generator use that is extremely efficient and has long life - if you runs hours every day one can easily save more in fuel than the engine cost.   A turbo is probably a necessary part of this.   

Also: long stroke, low rpm, high piston speed, high compression, high pressure DI, piston and combustion chamber coatings to retain heat, thin, low tension rings, right-sizing (average output and peak output are close to the same), tuned intake and exhaust, high swirl, single cylinder, etc.

[buickanddeere]

As I see it:

Thermodynamics predict that the higher the compression (higher the air charge temperature, etc etc) the more efficient the energy conversion will be.  There are limitations to any particular engine - like lubrication, size of bearings, (loading issues, etc), cooling... the list goes on.


Regards, RAB

  At partial power levels high intake temps are ok and even desirable. However at near to full power the intake air must be cold. The diesel engine converts chemical energy via heat into mechanical power. The greater the delta T in the combustion chamber , the more power and efficiency. Lower intake temps tend to reduce NOX pollution instead of using EGR. Aoso reduces over heating valves and turbine power wheels.   

[oliver90owner]

B&D,

I wasn't referring to the actual air intake temp - yes colder = more mass per unit volume = more combustion oxygen and lower temps = less NOx

I was referrring to the combustion air temperature after adiabatic compression - the higher the intake pressure (boost), the higher the combustion air temperature, the higher the burn temperature etc.

Regards, RAB

[buickanddeere]

B&D,

I wasn't referring to the actual air intake temp - yes colder = more mass per unit volume = more combustion oxygen and lower temps = less NOx

I was referrring to the combustion air temperature after adiabatic compression - the higher the intake pressure (boost), the higher the combustion air temperature, the higher the burn temperature etc.

Regards, RAB

   Still the same problems. Combustion chamber air temp during injection should only be high enough to obtain reliable ignition. Higher temps only stress the engine and reduce efficiency.

[compig]

The point being made is that the higher the temperature of the air from the turbo compressor the higher the combustion temperature.

[buickanddeere]

The point being made is that the higher the temperature of the air from the turbo compressor the higher the combustion temperature.

  What makes power and efficiency is the difference in air temp from the moment of injection to peak air temp, the delta T. An engine going from 500F to 1300F, a change of 800F is making far more psi/torque/HP/efficiency. V.s the otherwise identical engine with an injection air temp of 900F and 1300F peak.