crushers
post ho
cool, good to know. thanks
turbo vs supercharger for 2B diesel, lots of mud and crossing creeks
- Thread starter Tin Tin
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That's funny, because your timing, chosen handle and comments say exactly the opposite.
If the Renault engine did produce power and economy, then it'd be in production. But it's not.
Modern technology hasn't yet broken the laws of physics.
Show us some data or some production engines.
Here's my data.
Zero supercharged diesels being produced for automotive applications.
I use that username because I have supercharged 2 diesel engines in the past. Both a turbo or supercharger will work for the O.P., the problem is that there isn't a lot of info on supercharging diesels as yet, (try ringing a cam company for a cam to suit a charged diesel), the cam events for a factory turbo engine are not really the best choice for the supercharged application if one wants to take advantage of the pressure ratio seen across the engine in the charged application, but can be used in a budget application without too much loss. Drivability is extremely good when the engine is always on boost, well worth the small drop in fuel consumption in my opinion. There was a time when you couldn't buy a factory supercharged gasoline engine too, so I'm not going to write off the factory produced supercharged diesel just yet, the aftermarket industry are investing heavily in this area and there are already a few different fitments available for those interested. The only reason that I don't run a charger on my diesel engine now is because of the noise produced by the cheap rootes type blowers that I ran, they sound great for the first week but can get on your nerves after a while. The turbo would be the easier option, but the charger would be a lot more interesting to play with. just my 2 cents!
I think part of the problem in this thread is that the definition of "better" varies depends on who's talking.
It is a simple fact that a turbocharger will beat a supercharger every time in BSFC - brake specific fuel consumption, i.e. the amount of power you get for the fuel you use. If you debate this its because you don't understand it.
... but...
Lets say you don't care about the fuel it takes to produce a given power level, and lets say you don't care about getting maximum power from your engine... maybe you're a Sheikh and own an oil well, for example... then maybe the very slight difference in the driver-seat feel is worth it to you.
Superchargers do:
a) produce much more power than an NA engine
b) perhaps offer a slight driveability advantage (almost nil compared to a well sized turbo)
Superchargers can't:
a) ever beat a turbo in terms of power per fuel consumption
b) reach the absolute maximum power levels that turbos can
It is a simple fact that a turbocharger will beat a supercharger every time in BSFC - brake specific fuel consumption, i.e. the amount of power you get for the fuel you use. If you debate this its because you don't understand it.
... but...
Lets say you don't care about the fuel it takes to produce a given power level, and lets say you don't care about getting maximum power from your engine... maybe you're a Sheikh and own an oil well, for example... then maybe the very slight difference in the driver-seat feel is worth it to you.
Superchargers do:
a) produce much more power than an NA engine
b) perhaps offer a slight driveability advantage (almost nil compared to a well sized turbo)
Superchargers can't:
a) ever beat a turbo in terms of power per fuel consumption
b) reach the absolute maximum power levels that turbos can
You'd better expand on that point. I say everything about supercharging diesels is known and that's why they aren't used.
What is the most modern diesel you've driven?
The reason I ask is modern diesels are on boost all the time. Even my 27 year old truck engine has 10psi boost from about 1200rpm. Drivability isn't a problem and we're not talking a small drop in fuel consumption. We're talking around 30%, maybe 50% along with lower power and torque.
Interestingly, supercharged petrol engines are also on the way out and for all the same reasons.
Just to point out, Mr Banks doesnt use a blower on his dragsters. He does on his jet boats as they are very much on/off throttle.
I think Banks has done great things for Diesel engines.
I must ask what you mean about modern technology and supercharging. Really all that is out there now isn't actually new at all. Centrifugal blowers have been around since almost the beginning - even in some WW2 aircraft and much earlier than that.
The problem is what was mentioned earlier in this thread as taken from that reference you gave and Dougal picked out the bit - its simply that the supercharger compressor drive is sourced from the crank, the turbocharger compressor drive is sourced by waste heat and to a lesser degree, exhaust stroke energy directly from piston.
This is a 5:1 difference, even using the same compressor technology. The difference is easly measured too. Just insert a EGT probe the the end of the exhaust pipe and measure the exhaust temps when engines are buring the same fuel load and the same mass of air is entering the air filter. You will note that the supercharged engine has much higher EGT's - this is where most of the difference comes from, wasted heat is used to source 80% of a turbos compressor drive energy and none of this is used in the crank driven supercharger.
I've had some involvement in supercharging a 4.2 Patrol (brother who now works for Detroit Diesel) way back in 1998, intercooled and 14psi. It was amazing at 1200rpm, really impressive. Its throttle response was the crispest Ive ever seen and it had almost no diesel knock when engaged. It kept causing my brothers ute to break the front CV joint in his off roading competitions. But, after 2000rpm it became breathless. Max was 130whp. He installed a turbo and picked up about 35hp! He's never looked back.
One more thing....
Because the diesel engine is very air hungry (requires much higher AFR's than petrol engines), this means there is even more load placed on the supercharging device (SC or Turbo), so what this means is that the desparity in performance between a SC and turbo is even wider for the diesel engine - lots of boost required if you want it to be powerful AND safe
When I tow, I have calculated that I need typically 380-450nm in normal cruisng (1850rpm/100km/h) and much more on hills. A naturally aspirated diesel of 4.2L capacity may produce around 280nm. To safely get the required torque needs around 8psi-14psi boost. What this translates to is this; even if you use the throttle postition based bypass on the SC, at this mode of operation the SC cannot be bypassed, it needs to be at full operation (you dont really want a positive displacement SC over 10-14psi, they range from a theoretical near 100% efficiency at say 0.1 Bar to 50% efficient at 1 Bar - approx, from memory, do your checks if you want exact numbers) and is actually at its most efficient point of operation (nothing is wasted past it in bypass since you need all the air). A turbo installed instead, even in this optimum situation (for a SC) will consume better than 10-15% less fuel than the SC, or at the same fuel load will make ~ 10-15% more torque. Since most SC are installed on diesels that never came with a turbo, most tend to be IDI. So, comparing a stock turbio DI to a SC IDI makes the situation even worse for the SC engine.
Dougal; you'll love this. The turbo calculator I developed takes into consideration the engine rpm and load dependant BSFC and the rpm dependant VE including allowance for intake temp...., So well does it work, that if I record the AFR, the Boost pressure and the engine rpm and road speed, the calc spits out my fuel conumption - and its correct within 5%!! *EDIT* I just realised I didnt need the BSFC for that, but the BSFC is used to tell me the engine torque required and wheel power; that has been measured to be accurate to about the same level.
There are many ways to paint an argument and I certainly dont care either way for one or the other for my personal use, I just want the better one for whatever the application is. I would be temped to use a SC only if no intercooler was fitted and boost was 0.33 Bar, where I would use a positive displacement blower and operate it at its high efficiency (80% or higher), and, only for a petrol engine, or neatly sit in the V of a 6.5 Chev diesel.... So many times I have considered twin charged, but the limited returns for the complexity always steer me to a single turbo. Having said that, I am considering trying a compound arrangement on a 1KD-FTV in the coming year with one of my high performance VNT 1KD-FTV turbos and the high pressure side... see how we go.
The same kind of power draw issues (but to a significantly lesser degree) are between wastegated and VNT turbos, at a typical 2000rpm they are similar, however the VNT kicks the wastegated turbos Butt at high rpm as the wastegate is wasting maybe 20-30% of the flow (or more). My cousins race truck with my VNT and VNT controller compared with with a really nicely matched Holset that I did calcs for, The Holset did 198kW (at wheels) at 3500, the VNT on same engine, same inj pump settings did 217kW. Boost was 40psi for both situations - very high AFR's for longeviety in desert style 40deg C racing. We were able to lower the VNT boost and still had better EGT's!! I should point out - no smoke, very lean compared to most high performance settings for the road. The engine was pulled down later after some major races for inspection; all looked as new.... even I was suprised. Also, we raced with the Holset not the VNT, in the end I couldnt get the EMF interference gremlins out of my controller.
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The O.P. has an older engine, how many people on this forum would be running a 2011 or 2012 diesel in their rig probably 1.....the later turbo diesels may be much better when it comes to turbo lag, but I can't see him fitting the computerized engine management system when he's after a system that can live through being immersed in mud/water. Economy isn't mentioned either, he is asking for a system that produces torque on demand, which a supercharger does very well.
I have driven a few different turbo diesels over the years, the 2004 mazda T.D. that I drove a year or 2 ago had about 4 seconds of lag before the turbo started to produce boost, the 2010 transit van had a good 2 seconds, and thats just the start of boosting, full boost took quite a bit longer. There is a good reason that engineers are trying their hardest to develop electrical assist on turbo applications- if you want instant boost you can't beat a crank driven charger.
As far as fuel economy goes, I expected to get horrible consumption figures after I fitted the rootes blower, I mean it's well known that the rootes design is at the low end of the efficiency scale, and there are rumours going around about how much of a parasitic drag these blowers supposedly are, yet I only dropped 1.5 litres per 100 k. I didn't drive for economy, it was such a buzz to have a powerful engine under the hood I made the most of it. I often took of from a standstill in 2nd gear as first gear was now too low- around 2 seconds from standstill to high revs along with substantial neck strain, if I was chasing economy then lower numerical diff ratios would have given better figures. Another huge benefit of running positive boost at idle was that I could now run multi fuels, even used/filtered engine oil burnt very well when injected into the chamber, along with used cooking oil etc.etc. All of a sudden it became apparent that it was much much cheaper to run on free fuels when supercharged....you can't do this with a turbo without getting large amounts of white smoke when boost drops off, so in the real world superchargers have many advantages over turbo's , well worth a try!
I have driven a few different turbo diesels over the years, the 2004 mazda T.D. that I drove a year or 2 ago had about 4 seconds of lag before the turbo started to produce boost, the 2010 transit van had a good 2 seconds, and thats just the start of boosting, full boost took quite a bit longer. There is a good reason that engineers are trying their hardest to develop electrical assist on turbo applications- if you want instant boost you can't beat a crank driven charger.
As far as fuel economy goes, I expected to get horrible consumption figures after I fitted the rootes blower, I mean it's well known that the rootes design is at the low end of the efficiency scale, and there are rumours going around about how much of a parasitic drag these blowers supposedly are, yet I only dropped 1.5 litres per 100 k. I didn't drive for economy, it was such a buzz to have a powerful engine under the hood I made the most of it. I often took of from a standstill in 2nd gear as first gear was now too low- around 2 seconds from standstill to high revs along with substantial neck strain, if I was chasing economy then lower numerical diff ratios would have given better figures. Another huge benefit of running positive boost at idle was that I could now run multi fuels, even used/filtered engine oil burnt very well when injected into the chamber, along with used cooking oil etc.etc. All of a sudden it became apparent that it was much much cheaper to run on free fuels when supercharged....you can't do this with a turbo without getting large amounts of white smoke when boost drops off, so in the real world superchargers have many advantages over turbo's , well worth a try!
I'll jump in with anecdotal information to soften all of these figures.
It seems to me that all of this discussion is how quickly you can accomplish boost. With proper turbo choice you can get extremely early boost in a 3B. My 2B with a GT2052 turbo boosts almost immediately. If I had to spit a number out I'd say literally half a second to a full second and you're at minimum 7 psi.
Keep in mind these are tractor engines and getting 7psi almost instantly is pretty remarkable.
My last opinion is in regards to cost and trouble installing. A 3B turbo is pretty easy to put on, but a blower sounds like it would be a pain to install. It's hard enough to find the right crank pulley to install power steering and AC on one of these engines. It doesn't matter how powerful the engine is if you're stranded out in the backcountry because something breaks down because a complex system is too hard to fix while out there. In my opinion that risk is just too high.
It seems to me that all of this discussion is how quickly you can accomplish boost. With proper turbo choice you can get extremely early boost in a 3B. My 2B with a GT2052 turbo boosts almost immediately. If I had to spit a number out I'd say literally half a second to a full second and you're at minimum 7 psi.
Keep in mind these are tractor engines and getting 7psi almost instantly is pretty remarkable.
My last opinion is in regards to cost and trouble installing. A 3B turbo is pretty easy to put on, but a blower sounds like it would be a pain to install. It's hard enough to find the right crank pulley to install power steering and AC on one of these engines. It doesn't matter how powerful the engine is if you're stranded out in the backcountry because something breaks down because a complex system is too hard to fix while out there. In my opinion that risk is just too high.
It appears you are basing your entire opinion on two turbocharged diesels.
The OP's engine is similar vintage to others on this forum.
Suggest you read the reponses of those running the GT2052 turbo that I sized for the 3B.
Zero electronic controls, just a well matched wastegated turbo. They talk of instant boost, but despite doing all the sizing work, I've yet to drive one.
My 1985 vintage truck engine has 10psi boost from 1150rpm. The only way I could get 2 seconds lag would be planting the foot from idle in 4th gear.
The 03/04 vintage bounty diesels I've driven had about a 1000rpm power band and are probably the worst example of a peaky turbo diesel.
Nothing, lots, time to change gear. Repeat.
The 1.5 litre/100km fuel economy penalty from your supercharger is huge. I can tow a 1 ton trailer for a similar penalty. You still haven't given any other details on the setup.
Starting in second gear isn't impressive. Better get that neck looked at.
BTW, your white smoke when off boost is because your injection timing is too retarded. It could be fixed in minutes while still running a turbo.
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It might be a good time to consider why engineers are developing electrical assist on turbo's Dougal, maybe you could help them to save a few million in development costs with your no-lag calcs! Like I already mentioned earlier, when running a supercharger the increased in-cylinder pressure at idle is sufficient to run fuels other than diesel, like used filtered engine oil, with no visible smoke emitted from the tailpipe. Used engine/vegetable oil is usually free, costs a few cents a litre to filter, which puts the crank driven charger in the most economical system to operate category. The white smoke comment that I made referred to a turbo engine trying to idle on used engine oil, with no boost there just isn't enough heat in the chamber to burn it properly.
In the mid 90's engineers were playing with electrical assist turbos.
Since then I can't name two production engines with it. It's simply not used.
In my immediate family we've got 8 diesel cars, ranging in age from mid 80's to late 2010.
Of those one is a computer controlled sequential/compound system.
Three are computer controlled VNT turbo's.
One is a vacuum controlled VNT turbo.
Three are wastegated turbos.
None have a lag problem. What are these lag calcs you are on about?
No-one in their right mind runs used engine oil through their injection pump.
As I already stated. The white smoke at idle means your injection timing is too far retarded. Advance the timing and the white smoke will stop. No supercharger needed.
Do you have anything real to add to this thread?
Data?
Performance figures?
Production supercharged diesels?
Because if not, you're just wasting everyone's time. Just like Roscoe was earlier.
The electrical assisted turbo is still being investigated, here's some info from 2007 Browser Warning
Here is an article that includes some graphs for transient torque response, note the big improvement with the assisted turbo! Browser Warning
Quite a few people run used motor oil through their pump/ engine nowdays, it lubricates the pump much better than low sulphur diesel, and please don't tell me that your uncles fathers wife wrecked his pump doing this , if the oil is properly filtered then it would more likely extend pump life.
White smoke at idle.....I dont get white smoke at idle , so there is no need to change the injection timing, when I run heavy oils for fuel I get white smoke at idle when running a turbo, because there isn't enough heat in the chamber to burn heavy oil, when running a supercharger the boost at idle provides enough heat to burn the heavy oil-hence no smoke!
You must sell turbo's for a living, you sound like a dodgy used car salesman with your lagless turbos and incorrect calcs!
No links ....try Browser Warning do a search for electric assist turbos,
autospeed dot com
Autospeed dot com has the articles on electric assist turbos, can't post a link here!
Autospeed dot com has the articles on electric assist turbos, can't post a link here!
Still hasn't made production and likely never will. It's not relevant to this debate.
When oil is considered too dirty to run your crank bearings, why in hell would you want to run it through your injection pump and injectors? The two closest tolerance and most expensive parts on your engine.
You would have to filter it to clear before all the abrasive carbon particles were removed. I can guarantee you aren't filtering it that well.
Do you understand the relationship between compression temperatures and injection timing? Your response above says no.
Essentially you have fitted a supercharger to an undisclosed engine and taken a ~15% fuel consumption hit because your timing was too retarded for the fuels you were trying to use.
Nope and I don't believe you understand any of the calcs well enough to call them incorrect.
Can one of the mods please lock this topic?
Because a new technological turbo assist prototype hasn't made production by a larger scale manufacturer doesn't mean anything , much, more time and dollars should improve efficiency/build cost for what is essentially a crank driven supercharger.
FILTERED used engine oil is fine to run as a fuel, if you can't work out how to pump it through a 1 micron filter then that shows your lack of practical application down here in the real world! I wouldn't run it through a turbocharged engine though, there is too much unburnt fuel left over after the combustion event, hence the clouds of white smoke when your turbo does a seal and starts blowing engine oil into the intake, a crank driven charger can allow FILTERED used engine oil to burn completely , great economy there!
Calcs: Tell me how you calculate the parasitic drag of a turbo system please, pumping the exhaust gas into a 20 psi manifold requires quite a few horsepower, let alone into a manifold with 40 or more pounds per square inch, yet you consistently leave this loss out of your equations! Please explain !
Perhaps you could give me some camshaft timing figures suitable for a 8-1 pressure ratio engine, (that would be 8 pounds of boost and 1 psi exhaust backpressure), one for horsepower and one for economy ! 2 cams to try.
Horsepower costs fuel, if you want to go faster you have to burn more fuel, it's simple really!
The fuel consumption drop was from 22.5 m.p.g. to 20.1-that would be a 10.6% drop, how did you calculations get you 15%? You are 33% out on that one!
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It appears you haven't read a single word I've written. So I'll write answers below which say exactly what I've already written in this thread.
They haven't made production on any scale and likely never will.
1 micron filters will not remove the abrasive carbon particles which colour used engine oil black.
You need to filter the oil until it is visibly clear to remove those, you are clearly not doing this.
Turbocharger seals do not function in the way you think they do, nor does combustion on a healthy turbo engine leave unburnt fuel.
It appears you have no idea what exhaust pressure turbochargers run at. Suggest you read this thread as those figures have been stated.
Turbochargers at best points run higher boost than drive pressure. As Graeme has stated in the applications he has looked at a turbocharger requires 1/5th of the crank power that a supercharger requires to deliver the same boost.
What are you on about now?
A more efficient engine produces more power from the same fuel. Turbocharging makes engines more efficient.
That is appalling fuel economy. I thought you'd be getting roughly what I get.
They haven't made production on any scale and likely never will.
1 micron filters will not remove the abrasive carbon particles which colour used engine oil black.
You need to filter the oil until it is visibly clear to remove those, you are clearly not doing this.
Turbocharger seals do not function in the way you think they do, nor does combustion on a healthy turbo engine leave unburnt fuel.
It appears you have no idea what exhaust pressure turbochargers run at. Suggest you read this thread as those figures have been stated.
Turbochargers at best points run higher boost than drive pressure. As Graeme has stated in the applications he has looked at a turbocharger requires 1/5th of the crank power that a supercharger requires to deliver the same boost.
What are you on about now?
A more efficient engine produces more power from the same fuel. Turbocharging makes engines more efficient.
That is appalling fuel economy. I thought you'd be getting roughly what I get.
The typical diesel engine oil is full of carbon particulate, and yes it gets pumped through your bearings, particles of 1 micron or smaller arn't really of consequence , thats why the standard fuel filters on most diesels don't filter to a particle size below 1 micron and typically filter from 5 to 10 microns.
Combustion of fuel in the typical mass produced automotive diesel engine isn't 100%!
The very large majority of diesel engines in use have much higher backpressure than your willing to admit, but if you want to calculate your figures to suit a laggy aftermarket set-up then your figures are of no use to anyone much .
The fuel economy figures are typical down here in the real world, much more common than your downhill coasting with a tail wind fuel consumption figures. I can get much better figures by dropping cruise speed and driving for economy, but don't.
It's obvious that you have a bias when it comes to the turbo vs crank driven charger discussion, what a shame, a lot of people here would like to see an unbiased comparison so that they can make their own minds up about which type of charging will suit their application/driving conditions. If you can calculate the power needed to drive a crank driven compressor then why not do the drive loss figures for a TYPICAL turbo set-up, like a 80 series cruiser for example?
Yawn.
Perhaps you can enlighten us with all the details of your setup. This will maybe show why your fuel economy compares to Graeme's 100 series with over 800Nm or my Isuzu powered rover with around 550Nm with either vehicle towing another car on a trailer.
I have run with backpressure gauges, I'm not guessing at figures. I know what they were.
Cold acceleration, double boost (40psi drive, 20psi boost).
100km/h cruise, ~1.5 times boost (12-13psi drive, 8-9psi boost).
2000rpm full torque, drive is under boost (18psi drive, 20psi boost).
I'm not biased, I present the facts which include how much power it takes to run a supercharger. These show the problems superchargers have on diesel engines.
You have presented no facts or data at all. Except for fuel economy figures which can be beaten by petrol vehicles.
Put drive and boost gauges into an 80 series and I'll tell you exactly how much power the turbocharger is using. Along with how much comes from heat and how much from pressure.
One thing I can guarantee up front. They'll piss all over the results of a supercharger on the same engine.
