forced induction & torque converter

[theboss]

anyone running a forced induction lister clone here?? just curious to know..

 

a small engine..with electrically controlled super / turbo charger setup will have good efficiency at low loads which are probably continuous and can accommodate demand based high loads which are probably intermittent or during part of day. A good size radiator will keep heat away.

I heard of someone on Orkut using auto torque converter in his generator. Can make out its benefit and how will he manage his rpm unless the governor is coupled with alternator shaft. Because with a torque converter in between, the alternator rpm can easily fall when heavy loads are turned on as well a speed differential can exist between both. Therefore the governor must monitor alternator shaft rpm not the engine. Its hard to visualize, all i can think off is an engine with rapidly fluctuating speeds.

[cujet]

Our aircraft use a device called a CSD, or constant speed drive. It drives the generator at a constant speed, no matter the engine speed. I think they cost about 250,000 dollars each. They are not torque converters. They are hydraulic pump/motor systems that are swashplate actuated. They are not all that reliable on aircraft. I would never consider something like this for a lister.

Better to use a variable speed engine to make DC power to charge batteries and/or drive an inverter. That way, the engine can idle when no load is present. Conversly the engne can really speed up under high loads.

Forced induction is interesting. I think a twin is better suited for this. But at this point, the only saving grace of the listeroid is lost, Simplicity!

[phaedrus]

Because the lister types operate at constant speed it is possible to achieve "forced induction" with a tuned intake - just a piece of pipe. By interupting the flow with a butterfly valve the effective boost can be varied. To take advantage of the boost properly it might be necessary to increase full rack fuel supply. However there might already be enough excess fuel capacity (I suspect that there is).

In a real world application my hunch is that the butterfly would need three positions: air off (overspeed trip) , air disrupted, wide open.

Fella could do the two running positions with a current transformer and a relay to invert the transformer output.

Overspeed ya kin do with a spring and pawl.

[mike90045]

Because the lister types operate at constant speed it is possible to achieve "forced induction" with a tuned intake - just a piece of pipe.

Any idea on how this would be tuned, or what it woud be like :  14' of 2" pipe ?  Air filter at the remote end of the pipe, or the engine end ?  Flex coupling at the engine end ?

[phaedrus]

Phaedrus' thoughts: Of course the problem is a calculus problem - several interacting variables. But an ideal is not necessary. Clean air enters a pipe. The pipe is fairly straight and holds a constant cross section. Diameter is whatever's close to the as-built manifold - say 1 1/2 inch american standard sched 40. Start with a long pipe. Because the engine rocks as it fires an expansion joint is very desirable at the coupling to the head. Make up a plenum - a piece of 2" pipe, about a foot long with both ends closed and a pressure gauge to measure the internal pressure delta over atmosphereic pressure. open the pipe through a small tube, say 1/8 copper, to the intake valve area so that the slugs of air pressure will slowly average out in the plenum - so you can see what's "hitting" the valve. With engine running at design speed note pressure. shorten pipe, repeat. graph readings. when pressure is maximum you are there. This ought to get one close enough to "supercharge" 1 or 2 psi  This is opinion only, but that's how they scavenged some marine 2 stroke ship engines in the 1920's - it ought to work well enough. I would start with a 20 foot length of pipe set up on saw horses and just cut away, but a guy could do some research and maybe find some formulas for a rough idea of pipe length. These are related to the formulas contained in utterpower cd on exhaust muffler design. Exhaust pulses can, in theory, be used to augment this process, but there's a lot more to fiddle and possibly some corrosion or carbon problems too.

[Doug]

# 24 hydraulic hose is close to 1 1/4 inches without the corrosion problems I bet a larger hose and some fittings could be used to make a Lister version of my manifold and then be easily tuned but trimming the hose....

Doug

[rcavictim]

Use 1-1/2 inch or 2 inch PVC  plastic well pipe.  This comes in big rolls and is cheap.  I have just such a `supercharger` in the development stages myself but haven`t done anything with it in the past months, that is a winter project.  You can leave the plastic pipe in a 4 foot coil if you like.  Put the filter on the far intake end farthest from the engine.  I was tuning mine for 1800 RPM to work with a one cylinder diesel operating a generator.  I forget what exact length I calculated but it was out in the 20-25 foot range.  If you make a section of it as a trombone you can fine tune it in length once installed to compensate for seasonal air temperature changes.

[mike90045]

How do the engines tolerate this extra power - I assume they will burn more fuel with the extra getting slammed in, and will output more heat, so what about the valves, and bearings getting even more of a sledgehammer impact ? Even the combustion chamber and head bolts, will they take that extra load ?   Or are they so grossly overbuilt this is of no concern ?
  Mike  (Los Angeles, California)  [just getting my feet wet here, reading up  about these, prior to purchase]

[rcavictim]

How do the engines tolerate this extra power - I assume they will burn more fuel with the extra getting slammed in, and will output more heat, so what about the valves, and bearings getting even more of a sledgehammer impact ? Even the combustion chamber and head bolts, will they take that extra load ?   Or are they so grossly overbuilt this is of no concern ?
  Mike  (Los Angeles, California)  [just getting my feet wet here, reading up  about these, prior to purchase]

A simple ram air effect intake pipe supercharger isn`t gonna suddenly make the Lister or other small diesel smoke the tires, but what it can do is raise volumetric efficiency a bit and that equates to higher fuel efficiency at existing power levels!!!!  Don`t look for jaw dropping performance gains.  Effect will be subtle.  Like many things in engineering the cumulative effects of a bunch of little improvements can make a noticeable difference.

I doubt that 10 PSI max boost will cause any problems in a properly sealed Listeroid if one puts on a actual mechanical supercharger or a turbo.  The main worry I`d have was weakness in the head gasket seal.  These engines use a LOT more metal per HP than any automotive engine and stuffing the air intake on car engines is not usually a problem within reasonable limits.

Has it been mentioned that one can find GAST rotating vane pumps in industrial applications that can be used for engines like this as a stuffer?  Also another potential source of cheap pumps are pollution A.I.R. pumps from large V-8 vehicles at the wrecker.

[phaedrus]

If memory serves the largest A.I.R. vane type pump that GM was making in the late 1970's was 31 cubic inches per revolution...

I like the hose ideas. Much more compact and less troublesome to trim.

[4x4_Welder]

A vane pump, supercharger, etc has very little effect on a diesel-  the 2stroke GMs used one simply for scavenging, and bypassed it at higher rpms. 
Turbos are much more efficient, especially on a diesel.  They are only there when they are required, and they are not constantly trying to shove air in needed or not, constantly dragging on the engine. 
Extra air by itself won't hurt the engine, but it won't help it either-  you need to add fuel to increase the power.  Possibly make a calibrated diaphragm to open the fuel rack a little more as the pressure increases.  I wouldn't a DIY turbo setup without an EGT probe for sure, though-  extra fuel means much, much higher exhaust temperatures, and the temp can rise significantly before excess smoke shows up. 

[phaedrus]

The idea I had in mind was simply to retain, to some extent, the sea level power output at modest elevations above MSL, eg <10,000 feet, by using the innate and simple method of ram air "supercharging" by tuning the intake. Running at sealevel with a tuned intake might yield some small amount of power - maybe 100 watts (better pumping means less loss), but it's too small to be important. Actually increasing the power output is another ballgame, as you say, and the thermodynamics is clear - turbo's the best way. There's a Canadian guy who put a turbo on a 6-1.... But a serious boost turbo would create a serious problem I think...

My 'speriments with full rack on my 6-1, ie overloaded, indicate to me that there is considerable excess fuel capacity in the as-built configuration. They also revealed that the transient accelerations associated with overload are severe - the engine-generator-coolingtank-silencer-stack assembly and foundation rocked violently - and alarmingly! In the designed speed range a 6-1 is limited to something like, well, 6 hp. But at, say, 7000 feet it may be possible to get enough air by ram-air tuning of intake and maybe a bit of charge cooling to make the sea-level 6 hp. Fella looses about 20% at 7000 feet in a NA engine and my opinion is that all of or most of that can be got back without the complex mechanical solutions that are necessary in variable speed machines. There is some slight efficiency improvement at elevation due to exhausting to a lower pressure, so making full 14.7 SL air isn't quite necessary.

[Doug]

I wonder what I gain 7000 feet below sea level.....

Doug

[xyzer]

I wonder what I gain 7000 feet below sea level.....

Doug

Good cooling! Keeping water out of the fuel will be a problem!
Dave

[rcavictim]

If memory serves the largest A.I.R. vane type pump that GM was making in the late 1970's was 31 cubic inches per revolution...

I remember their introduction to consumer vehicles in the 70`s certainly DID cause a revolution, an underground one of owners disconnecting them and removing the horsepressure robbing drive belts.