It sometimes boggles the mind how much power one can wring out of a diesel truck engine, and still make it live long enough to not rebuild it every year in competition. Was nosing around on the NTPA's website a while back, was an article in there on J.R. Collins' win in the Super Semi class. He runs a 1982 (I think) Mack Superliner with the 998 CID Mack V8. That year was the only year he had to rebuild his engine due to a mechanical problem, that Mack engine ran beautifully for nearly 30 years without issues. The thing to remember is, these engines only run at full load for about two minutes, tops, during a run......
Getting 3000 horsepower at 4000 RPM out of a truck engine is one thing, seeing how far one can go with a locomotive engine is another........
Randy Vos
"Ever have one of those days where you couldn't hit the ground with your hat??" - Waylon Jennings
"May the Lord take a liking to you and blow you up, real good" - SCTV
About 2 years too late to be referencing Peugeot....being a sportscar racing fanatic myself I can say that Audi has been running a different strategy lately with Toyota (and soon Porsche) running quite efficient petrol engines, they've given up fuel economy for the power AND torque afforded by a diesel running rich.
ML
carnej1 High speed race-tuned diesel engines have also become the standard for top level international Sportscar/GT racing, in fact the 24 hours of Le Mans has been one (overall not just class victory) by diesels for about a decade now....
High speed race-tuned diesel engines have also become the standard for top level international Sportscar/GT racing, in fact the 24 hours of Le Mans has been one (overall not just class victory) by diesels for about a decade now....
Being a racer, I am well aware of what Audi and Peugot have been doing with turbo-diesels in Sports Car endurance racing - beating the competiton with both power (really torque) and fuel economy.
Never too old to have a happy childhood!
Overmod BaltACDTop Fuel racing is a class of drag racing... He could have made the same point with respect to diesel drag racing, which is now a well-recognized niche in motorsports (separate from 'builds' for truck or tractor pulls). http://www.nhrda.com/Rec08/ET-TD.htm]Here is a link to the NHRDA Top Diesel record (ET 6.640). You can get a copy of the rulebook for this event here. Note that this is still timing for a full quarter-mile, and that the time record is NOT the speed record in a run... To put things in perspective, the Pro Street record is well under 9 seconds and the Super Street record 9.65 seconds -- with TRUCKS. Puts the whole 'muscle car' thing in a different light. Building engines for this service isn't really the right parallel for locomotive 'hot-rodding', though; I think the pulling engines represent a better technological source of ideas. And it is there, I think, that sequential turbocharging provides its best gains... as an example of design problems, if there is a driveline failure (relieving the load on the engine crankshaft) the engine will likely overspeed before the rev limiter can physically react.
BaltACDTop Fuel racing is a class of drag racing
He could have made the same point with respect to diesel drag racing, which is now a well-recognized niche in motorsports (separate from 'builds' for truck or tractor pulls).
http://www.nhrda.com/Rec08/ET-TD.htm]Here is a link
to the NHRDA Top Diesel record (ET 6.640). You can get a copy of the rulebook for this event here. Note that this is still timing for a full quarter-mile, and that the time record is NOT the speed record in a run...
To put things in perspective, the Pro Street record is well under 9 seconds and the Super Street record 9.65 seconds -- with TRUCKS. Puts the whole 'muscle car' thing in a different light. Building engines for this service isn't really the right parallel for locomotive 'hot-rodding', though; I think the pulling engines represent a better technological source of ideas. And it is there, I think, that sequential turbocharging provides its best gains... as an example of design problems, if there is a driveline failure (relieving the load on the engine crankshaft) the engine will likely overspeed before the rev limiter can physically react.
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
Parts pricing is a matter of policy. For instance; EMD puts all the overhead on new engine sales but keep the parts relatively cheap. CAT engines are notoriously cheap but they get you on parts. On another forum marine engines) someone stated that a CAT costs about twice as much per "hole" for a center section overhaul as an EMD. Then there is the labor, a CAT takes about 2 weeks for an overhaul while an EMD can be done in 4 days an important consideration when you need to be out making money. For locomotives they seem to have enough spare locomotives laying around that their is no rush.
In the case of EMD's F125 it may be more feasible to replace the C175 with a new engine when it wears out rather rebuild it.
The QSK in smaller sizes has been around a while in the 12 cylinder size (QSK 60) that parts should be readily available, same with MTU and CAT C175. The QSK 95 is only just going into production and the QSK 120 is only on paper but they all use the same cylinder "kits", fuel injectors,and so forth. The differences in the same engine family is:crankshafts, main bearing kits, water pumps,oil pumps, camshafts and so on.
Out of curiosity (and to save me the trouble of looking it up!) what is the actual piston speed of theQSK series (which have higher rotational speed but smaller stroke)?
The historical consensus is that the higher-power-density higher-speed diesels suffer in railroad use, perhaps when their maintenance requirements exceed the 'classical' requirements. A major factor cited in the failure of the Krauss-Maffei 'Amerika-Lok' diesel-hydraulics was the use of smaller high-speed diesel engines to get the necessary power density -- (this a separate issue from the warranty requirement problems on the hydraulic oil and Cardan-shaft bearings). I had thought that some of the 'advantage' from running the high-speed engines was that they shared parts and supplies with engines produced in great numbers (and hence with their parts costed-down and a relatively large aftermarket for supplies and maintenance compared to that for traditional locomotive diesels).
I confess I'm settling down with the popcorn to see what develops with all those locomotive proposals I see advertised in Trains and other magazines, which substitute a MTU or QSK or whatever as the prime mover of destiny... my guess is there will be more problems than long-term sales.
Back to a more reasonable level of power output such as applied to locomotives. A couple of years ago there was an article on boat diesel about about power density - horsepower per cubic inch - in relation to what the expected service life would be. The conclusion was that wear increased markedly above 30 hp per liter displacement or about 0.49 hp. per cubic inch. Both GE and EMD are about 25 hp. per liter. The Cummings QSK 95 at this rate would only be 2850 hp instead of the 4200 hp. that it is rated at which is about 44 hp. per liter. Both the competing high speed diesels, CAT C175 and MTU 4000 series are also in this range.
The other measurement for the purposes of comparison is piston speed. The arbitrary speed limit is 2000 feet per minute. EMD is about 1500 fpm for 645's and 1650 fpm for 710's and I think the GEVO is right at 2000 fpm. For locomotive line haul service statistically they only run at run 8 about 20% of the time. This means that even the high speed diesels will exceed these limits by very much.
In marine service where you can expect engines to run at full power for days at a time, GE downrated their engines to 900 rpm with a consequent loss in power to get a reasonable service life. MYU just settled a lawsuit against them by Alaska Ferries where MTU replaced all eight engines on the boats involved with two more for spares. The original engines were their model 595 which is now out of production being replaced by the 4000 series. The application was on two pump jet propelled cattaram boats that although have a top speed of 40 knots only traveled at about 32 knots (ahem) causing the engines to fail well within the warranty period.
In other words the engines on a top fuel dragster are more like liquid fuel rocket engines where the expansion of combustion gases is used to drive pistons rather than being accelerated through a converging/diverging nozzle.
Getting back to your original question, it sounds like an engined rated for 4400Hp for traction could be pushed past 6,000HP without much effort but at the expense of greatly reduced lifetime. In a similar vein, large piston engine aircraft engines could produce max power for 5 minutes (take-off and go around), perhaps 80% of max for perhaps 15 minutes (maximum except take-off) and cruise would be perhaps 60 to 65% of max.
- Erik
Top Fuel racing is a class of drag racing in which the cars are run on a mix of approximately 90% nitromethane and 10% methanol (also known as racing alcohol) rather than gasoline or simply methanol. The cars are purpose-built for drag racing, with an exaggerated layout that in some ways resembles open-wheel circuit racing vehicles. However, top fuel dragsters are much longer, much narrower, and are equipped with large tires on the back and small tires in front, all in order to maximize their straight-line acceleration and speed.
Top fuel dragsters are the fastest sanctioned category of drag racers, with the fastest competitors reaching speeds of 330 miles per hour (530 km/h) and finishing the 1,000 foot (300 m) runs in 3.7 seconds, or the full quarter-mile (402 m) in 4.4 seconds.
Because of the speeds, this class almost exclusively races to only the 1,000 foot (300 m) distance, and not the traditional 1/4 mile (1,320 foot / 402 m). The rule was changed in 2008 by the National Hot Rod Association following the fatal crash of Funny Car driver Scott Kalitta during qualifying at the SuperNationals, held at Old Bridge Township Raceway Park in Englishtown, NJ. The shortening of the distance was used in the FIA at some tracks, and for 2012 is now the standard Top Fuel distance. The Australian National Drag Racing Association is the only internationally recognized sanctioning body that races at 1,320 foot for the majority of races in Top Fuel.
The approximately 500 cu. in. engines with Roots type superchargers operating at high boost levels consume fuel at 15 gallons per run. Engines receive a 'top end' rebuild after every run (new pistons and connecting rods). In normal full throttle operation the cylinders are filled with fuel almost to the level of hydostatic lock up and the engines produce in excess of 8000 HP during their competitive runs.
erikemImprovements in motors and power electronics might make turbo compounding practical for locomotive engines. The turbine would drive a high speed alternator and could be located where it can take the best advantage of exhaust gas enthalpy. The compressors would be driven by motors and also located to give the best airflow for the intake. The excess power from the turbines would be added to the output of the traction alternator during steady state operation and the compressor motors could borrow power from the traction alternator to spool up faster than a straight turbocharger.
The problem, I think, is that the amount of horsepower gained by this is minimal in comparison with the cost and complexity. Even the Wright Turbo Compound only added about 300 effective shp from the compounding, and deploying a 'split system with electric drive only adds to the cost, complexity, and control issues. There's also the issue that because diesels are more efficient, the exhaust gas enthalpy is lacking at part-load; this accounts both for the early Elliott multiple-turbo approach UP was playing around with (to decrease effective turbo lag) and the geared overrunning transmission in EMDs that 'motors' the turbocompressor until there's enough exhaust to drive it from the turbine...
On the other hand, you have a nifty answer to Alco smoking, if you motor the turbocharger briefly prior to advancing the fuel rack... the compressor load will probably not ramp up to very many hp before the rising exhaust pressure takes over, if I remember correctly. That is a sizable electrical load, but one which could certainly be accommodated briefly off the output (recitified or unrectified) of the traction alternator, or supplied from a reasonably sized battery or supercap source. Then you can start harvesting the turbine power as desired.
There have been a number of very well-thought-out recovery-turbine systems for trucks; Volvo had a particularly good one. In my experience, these eventually gave up trying to produce effective amplification of shaft horsepower and instead used the system to drive ancillary loads and 'hotel power' to reduce parasite drag on the prime mover. That is in my opinion the 'first best use' of the technology ... but its use on working locomotives is more limited, and there's less perceivable 'bang for the buck' beyond the comparatively small-scale provision of cab amenities, control systems, etc. when running.
With the advent of low-NOx regulation, the 'critical' exhaust temperature above which nitrogen-oxide production became relatively low -- I remember the 'threshold' being somewhere around 1436 degrees F (given the compression ratio in diesel engines). As it turned out, in order to achieve Tier IV compliance (which is 2.6g/hp/hr, sorry about the mixed units) manufacturers went to a SCR solution... which made it relatively less important to achieve low NOx during combustion by methods such as use of EGR to keep combustion temp peaks low. Cummins, for example points out that they can maintain best-power combustion in the large QSK engines and depend on an enhanced aftertreatment to meet the standards up to 2015.
“Combining cooled EGR with SCR provides a very effective solution to balance NOx reduction between the engine combustion and exhaust aftertreatment,” says Kevan Browne, Cummins. “This enables the optimum point of fuel efficiency and performance to be maintained in the ‘sweet spot’ for longer than an SCR-only approach can achieve. The engine EGR rate is rebalanced for the Tier 4 Final engines.”
So at least in theory it might be possible to have a MORE 'hopped-up' diesel engine under Tier IV than previous levels... if you are willing to use a bit more DEF or whatever, and mingle it effectively with the exhaust gas prior to the SCR. Seems a fair tradeoff to me... just as long as those ridiculous regenerated particulate filters can be gotten rid of! ;-}
I mentioned the similarity of tractor pulls and drag racing to point out that longevity was not a primary concern with tractor pulls, though I'd suspect that running time between overhauls is longer for tractor pull engines that top fuel dragster engines.
My engineering Thermodynamics prof commented on NOx production going up sharply with gas temps above 2700F, and wouldn't be surprised that it goes up with pressure as well. OTOH, I do remember squirting a solution of urea into a beaker of NO2 to clear out the brown haze in a freshmen chem lab in '73.
Improvements in motors and power electronics might make turbo compounding practical for locomotive engines. The turbine would drive a high speed alternator and could be located where it can take the best advantage of exhaust gas enthalpy. The compressors would be driven by motors and also located to give the best airflow for the intake. The excess power from the turbines would be added to the output of the traction alternator during steady state operation and the compressor motors could borrow power from the traction alternator to spool up faster than a straight turbocharger.
erikemHugh MacInnes in his book "Turbochargers" stated that diesel engines can take a huge amount of boost as long as the charge air is kept reasonably cool He was speaking from experience with engines modified for tractor pulls, which is, as far as the engine is concerned, not all that different from drag racing.
They can, and they do. The 'catch' here is that the amount of achievable increase of boost is severely limited by the size of the engine. Perhaps my favorite case of 'overkill' was a three-cylinder Kubota in a 'racing' lawn tractor -- it was documented as providing over 750hp, which is an interesting power-to-weight ratio for a riding mower...
The question is whether the additional boost (in terms of charge oxygen) can be translated into meaningful piston thrust and hence into usable torque at the crank. In a compression-ignition engine running at very high boost, the torsional stresses in the crank can rapidly rise dramatically (as the stress to perform compression is counter to the stress after firing, and both stresses are distributed according to where the adjacent loads (from other cylinder events on the crank) are. The 16-cylinder Alco 244 was, I believe, notorious at breaking cranks for this reason (and I strongly suspect the turbo characteristics had some role in this).
Cranking up the boost can lead to more than a little improvement in fuel efficiency. Not many people run twins for fuel efficiency (I was one) but Ford conducted some experimentation with ceramic coatings in the 1970s that produced some fairly dramatic economy results. This is like an analogue of the Rankine cycle for IC motors; the energy 'recuperated' from the exhaust heat is returned to the intake charge. Some of it is (necessarily, but grudgingly) 'thrown away' in the intercooler, but whatever remains is just as capable of providing expansion during the right part of the power stroke as the heat energy from combustion. Engines that can be massively overbuilt, studded, etc. can be run with very high "boost pressure" (up to what provides effective stoich with the higher fueling rate, and limited by cooling of critical engine parts) and achieve remarkable fuel economy.* But as you might imagine the 'wear and tear' resulting from the peak pressures involved, which are of relatively short duration but are very high, are more substantial than most 'fuel savings' could possibly justify...
* Note that I do not mention emissions. High overboost is really, REALLY bad for emissions, particularly NOx emissions. That is a primary reason why you don't see it discussed often, just as for very high compression ratios in other types of motor.
Overmod There are other effects -- notably 'cavitation' -- that rise up alarmingly with increases in unit power beyond a certain point. Cavitation effects were a definitive reason for the demise of the 265H, and IIRC were a thorn in the side of the 6000 HP GEs.
There are other effects -- notably 'cavitation' -- that rise up alarmingly with increases in unit power beyond a certain point. Cavitation effects were a definitive reason for the demise of the 265H, and IIRC were a thorn in the side of the 6000 HP GEs.
First time I heard about the adverse affects of cavitation was from a late 1960's installment of Gus Wilson's Model Garage in Popular Science. In that story, the town fire department was having their engines eroded by knocking induced cavitation, where the knocking was caused by cheap gasoline being sold by the town skinflint.
Hugh MacInnes in his book "Turbochargers" stated that diesel engines can take a huge amount of boost as long as the charge air is kept reasonably cool He was speaking from experience with engines modified for tractor pulls, which is, as far as the engine is concerned, not all that different from drag racing.
Done with a bit of finesse, hot-rodding a diesel by cranking up the boost from a turbocharger can lead to a slight improvement in fuel efficiency.
EMD took the 567 well past 3,000 HP in tests back in the early 1960's but it shortened the life of the power assemblies to unacceptable levels.
I'd love to know what the upper limits are with today's engines as well.
jcburnsI know that if you have too much cavitation, the Soviet Subs will spot you and blow you out of the water.
Different cavitation. This is the one that I originally saw discussed with respect to the old 7.3 Power-Cerebrovascular Accidents back in the day... and I assumed it was something about the circulating coolant wearing away metal somehow, until I found out the actual mechanism involved.
When run to high (enough) power, parts of the engine structure serve as foci for vibrational energy at high frequency (up to ultrasonic range). This causes small bubbles to form and collapse in adjacent coolant, and the energy involved wears away the adjacent metal surface -- it's surprising how strong the shock waves are at accomplishing this. (I've seen at least two projects trying to use this effect to generate thermonuclear fusion, which gives you some idea of that... ;-})
I don't have full tech references to this with reference to the 265H, but Don Oltmann surely does...
What the ah...heck is "cavitation" in a diesel engine. I know that on smaller CAT diesels that they get up to one horsepower per cubic but they only have a service life of 10 hours.
erikemI'd suspect that the ultimate output with a hot rod chip would be limited by how much fuel the injectors can push into the cylinder per power stroke.
More to it than that.
First, does the 'hot-rod' chip involve easing the rpm limit? That can't be increased very far without producing all sorts of problems with inertial effects, and the 'standard' traction alternator may not be happy operating beyond a certain increase.
Second, more fuel requires more oxygen (which is, roughly, only 1/5 of intake air mass) so most of what your 'hot-rod' chip will produce will be smoke unless you increase... well, it's going to be the charge-air pressure. And without a WHOPPING increase in intercooling, that is going to involve much higher intake-manifold pressure (to get the necessary charge density) which in a compression-ignition engine then gets multiplied proportional to the compression ratio... I'm not sure you can 'stud' an EMD power assembly enough to make that worthwhile.
This is separate from the starting of an orbital-insertion program for power assemblies, which is what I'd expect to be the predominant product of any significant increase of locomotive-engine horsepower. Hopefully that can receive some Government funding -- we can speculate on the railroad equivalent of the stuff on the Voyager probe, perhaps...
BaltACD GE's ES44AC gets 4400 hp for the Main Generator from it's prime mover while it is also producing additional Horsepower to power all the accessories (air pumps, Aux. generator etc. etc.). We know that is not operating anywhere near it's maximum mechanical stress as it has been 'de-rated' so that it can produce it's rated horsepower for the life of the prime mover. Presuming that one wanted to 'tune' the prime mover for MAXIMUM horsepower, what kind of HP could be produced, at the expense of longevity. We already know GE can 'tune' these EVO prime movers with a computer chip change - both CSX and NS have derated their DC traction EVO's to 4000 HP from the 4400 HP they were delivered with. So with a 'hot rod performance' chip, what sort of HP could be expected? What would the life expectancy be? How much would fuel economy suffer?
GE's ES44AC gets 4400 hp for the Main Generator from it's prime mover while it is also producing additional Horsepower to power all the accessories (air pumps, Aux. generator etc. etc.).
We know that is not operating anywhere near it's maximum mechanical stress as it has been 'de-rated' so that it can produce it's rated horsepower for the life of the prime mover.
Presuming that one wanted to 'tune' the prime mover for MAXIMUM horsepower, what kind of HP could be produced, at the expense of longevity. We already know GE can 'tune' these EVO prime movers with a computer chip change - both CSX and NS have derated their DC traction EVO's to 4000 HP from the 4400 HP they were delivered with.
So with a 'hot rod performance' chip, what sort of HP could be expected? What would the life expectancy be? How much would fuel economy suffer?
According to an item I read in TRAINS at the time, when GE was road testing the first production ES44AC's they did some runs with the units "Chipped up" (i.e engine settings tweaked) to 5,000 HP Net HP. So there is some growth potential in the 12 cylinder GEVO power plant and it is conceivable that a higher power rating may be offered in the future.
Whether the additional fuel consumption is "worth" the motive power performance improvements gained from the 600 extra Horsepower remains to be seen.....
I would opine that 6000 HP into the main alternator would be within the realm of possibility but fuel economy would drop appreciably (the extra HP would have to come from somewhere), maintenance expense would probably go up and life expectancy would also drop.
For comparison, the engine on a high-performance drag racer puts out an obscene amount of horsepower, but it has to get rebuilt after no more than a minute of peak performance.
I seem to recall a Trains article by someone in the E-L mechanical department commenting on the strange sounds he was hearing from a load test on an SD-45 diesel engine. The load meter stated that the engine was putting out 5,000HP, where normal rating was 3,600HP for traction.
I'd suspect that the ultimate output with a hot rod chip would be limited by how much fuel the injectors can push into the cylinder per power stroke.
Our community is FREE to join. To participate you must either login or register for an account.