turbo vs supercharger for 2B diesel, lots of mud and crossing creeks

[blownoiler]

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 **** all over the results of a supercharger on the same engine.

How much power it takes to get the same airflow through the engine would be a more valid comparison, because you can get the same airflow with less boost when running a more efficient exhausting system, a percentage of the power lost to drive the crank driven charger is gained on the more efficient exhaust side. An engine that has been optimised for a turbo won't show optimum results with a crank driven charger when the engines breathing requirements are designed for a turbo system. I think that it's reasonable to assume that the large majority of folks in this forum drive 4wd's that get close to these consumption figures, some better some worse, the money saved by not buying a more expensive newer (or new) vehicle can buy a huge amount of fuel, so losing 10% fuel efficiency is worth it if it means that the laggy old turbo diesel gets transformed into a beast and is kept because it is now great to drive , but thats just my opinion, obviously people make their own choices.
I see you have already decided that the turbo figures will "**** all over the results of the supercharged engine" , I'm obviously conversing with the wrong engineer here, I'm really looking for someone who has optimized their engine to suit a crank driven charger, and "results" include the drivability of the engine in question.

 

[Dougal]

How much power it takes to get the same airflow through the engine would be a more valid comparison, because you can get the same airflow with less boost when running a more efficient exhausting system, a percentage of the power lost to drive the crank driven charger is gained on the more efficient exhaust side.

Do you have data to support this?

What is really interesting at this point, is an Aussie on another forum spent last month trotting out exactly the same theories. Turned out he'd been reading books about high rpm petrol engines with large valve overlap.
Didn't apply at all to diesels which run minimal valve overlap and can't make appreciable gains through exhaust scavening.

What is even more interesting is your time of response suggests you are also in Australia.

In short, the difference in diesel engine airflow between turbo backpressure and supercharger backpressure is about 3% at the worst case. This 3% is completely drowned out by the superchargers lower efficiency as a compressor, which means it needs higher boost numbers to get the same air density.

An engine that has been optimised for a turbo won't show optimum results with a crank driven charger when the engines breathing requirements are designed for a turbo system.

Please post data to support this statement.

I think that it's reasonable to assume that the large majority of folks in this forum drive 4wd's that get close to these consumption figures, some better some worse,

The average landcruiser uses around 12 litres per 100km. More when towing or driven in the cold, less when driven carefully at low speed cruise.
Your fuel consumption is around 7km/l or 14 litres/100km which is at the worst end of the spectrum.
My worst ever fuel economy was 6.5km/litre when I was towing 3 ton. This is your norm.

the money saved by not buying a more expensive newer (or new) vehicle can buy a huge amount of fuel, so losing 10% fuel efficiency is worth it if it means that the laggy old turbo diesel gets transformed into a beast and is kept because it is now great to drive , but thats just my opinion, obviously people make their own choices.

Please post photos and power/torque specs of your "beast". I'm pretty sure we can find someone here with an older turbo diesel producing more power and torque while also getting way better fuel economy.

I see you have already decided that the turbo figures will "**** all over the results of the supercharged engine" , I'm obviously conversing with the wrong engineer here, I'm really looking for someone who has optimized their engine to suit a crank driven charger, and "results" include the drivability of the engine in question.

Yes, the last 100 years of diesel engines confirm that turbochargers always beat superchargers. It would take an idiot to expect a different outcome using the same hardware.

Good luck with your quest. A good starting point would be any data that supports your cause. So far you have shown none, nothing, zip, nada, nichts.

Mods, please lock this thread.

 

[amaurer]

Mods, please lock this thread.

Aww, we're enjoying this!!

 

[blownoiler]

Do you have data to support this?

What is really interesting at this point, is an Aussie on another forum spent last month trotting out exactly the same theories. Turned out he'd been reading books about high rpm petrol engines with large valve overlap.
Didn't apply at all to diesels which run minimal valve overlap and can't make appreciable gains through exhaust scavening.

What is even more interesting is your time of response suggests you are also in Australia.

In short, the difference in diesel engine airflow between turbo backpressure and supercharger backpressure is about 3% at the worst case. This 3% is completely drowned out by the superchargers lower efficiency as a compressor, which means it needs higher boost numbers to get the same air density.




Please post data to support this statement.



The average landcruiser uses around 12 litres per 100km. More when towing or driven in the cold, less when driven carefully at low speed cruise.
Your fuel consumption is around 7km/l or 14 litres/100km which is at the worst end of the spectrum.
My worst ever fuel economy was 6.5km/litre when I was towing 3 ton. This is your norm.



Please post photos and power/torque specs of your "beast". I'm pretty sure we can find someone here with an older turbo diesel producing more power and torque while also getting way better fuel economy.




Yes, the last 100 years of diesel engines confirm that turbochargers always beat superchargers. It would take an idiot to expect a different outcome using the same hardware.

Good luck with your quest. A good starting point would be any data that supports your cause. So far you have shown none, nothing, zip, nada, nichts.

Mods, please lock this thread.

I didn't get my build dynoed, sorry to disappoint you with no sheet.
That Aussie guy you mentioned could be onto something , if we can increase the flow through the head then the charger doesn't have to put out as much pressure to get the same flow figures. Less boost = less power consumed by the charger. I wonder what the real parasitic loss would be if flow were optimized. It seems strange to me that the Renault engineers are not only using a crank driven charger for an economy engine, but are also using the charger for the top end power! Maybe one of these could be the answer : Green Car Congress: Fallbrook Technologies Inc. developing variable speed supercharger drive using its CVP technology

I don't believe that crank driven chargers have reached their pinnacle just yet, Obviously Mr. Banks thinks so too!

 

[Dougal]

I didn't get my build dynoed, sorry to disappoint you with no sheet.
That Aussie guy you mentioned could be onto something , if we can increase the flow through the head then the charger doesn't have to put out as much pressure to get the same flow figures. Less boost = less power consumed by the charger. I wonder what the real parasitic loss would be if flow were optimized. It seems strange to me that the Renault engineers are not only using a crank driven charger for an economy engine, but are also using the charger for the top end power! Maybe one of these could be the answer : Green Car Congress: Fallbrook Technologies Inc. developing variable speed supercharger drive using its CVP technology

I don't believe that crank driven chargers have reached their pinnacle just yet, Obviously Mr. Banks thinks so too!

Not only do you have no dyno sheet, you have no description at all of your beasts peformance.
At least the Aussie had a a 2LT and a "killer hill" which it could do 90km/h up.

Renault have not sold a single supercharged diesel and your new link is for petrol engines.
I cannot find any supercharger kits for sale on the Banks website either: Cold Air Intake - Diesel and Gas Performance Products

 

[blownoiler]

Here it is: Supercharge Your Diesel Supercharged Duramax Diesel Photo 1

 

[Dougal]

Here it is: Supercharge Your Diesel Supercharged Duramax Diesel Photo 1

That is from the same article you linked to first time around. The one where they say this about supercharging.

Stepping up the ladder a bit in our idea ladder is that of running a supercharger as the only source of compressed air. This isn’t that great of an idea, either, mainly due to the fact that most diesel engines benefit from very high-pressure ratios (lots of boost). Superchargers are very effective in the 5- to 15-psi range, but beyond that they start to sap a lot of power. A large centrifugal supercharger operating at 50 psi might take upward of 500 hp to drive! A turbo of the same size would take about 100 hp at the most, so it’s clear who the winner is. The only way we’d run a supercharger as a single would be in a low boost (less than 30-psi) application with a healthy dose of nitrous oxide to make up the airflow deficit.

You are so short of material, you've repeated yourself already.

I'm sure you also missed the NOS part.

 

[crushers]

mods, please don't lock the thread. there is some good tech info flowing here ...
i have to agree with Mr Kiwi on this one.

<that is one ugly engine, i don't care how much HP it puts out, i wouldnt have it under my hood.>

 

[goldchaser]

^^^^^^^^^^^^^^^^^^

Is this the motor Rosco's putting in his ute?

 

[blownoiler]

turbo drive losses

I have asked an engineer to calculate the horsepower needed to drive a typical turbo setup, I will post the info when I get it!

 

[Dougal]

I have asked an engineer to calculate the horsepower needed to drive a typical turbo setup, I will post the info when I get it!

This will be interesting. Does he/she know how many engineers are here waiting to check their work?

Presuming you'll get the same engineer to calculate supercharger drive requirements for the same airflow (i.e. slightly higher boost for the supercharger). What guidelines did you give for a "typical turbo setup"? Engine size, VE, rpm, boost, EGT, compressor efficiency, turbine efficiency, engine BSFC?

 

[blownoiler]

This will be interesting. Does he/she know how many engineers are here waiting to check their work?

Presuming you'll get the same engineer to calculate supercharger drive requirements for the same airflow (i.e. slightly higher boost for the supercharger).

Here are the theoretical engine specs Dougal, have a chop at it yourself and we should get close to the same figures:

Using a free flow (n.a.) extractors/exhaust system as a base, and 2 p.s.i. backpressure in the exhaust manifold/system would be a realistic figure to start with. To round off the figures the engine has a 100mm bore and 100 m.m. stroke, 4 cylinder 4 stroke with a 20-1 compression ratio. If I have 20 p.s.i. backpressure in the exhaust manifold while producing 10 pounds of boost at peak revs (4000) how many horsepower are consumed by the pumping loss of 20 psi of exhaust pressure?

 

[Dougal]

Man, this coincidence is getting stronger.

The user on 4btswaps trolling the same arguments was running a toyota 2LT with a supercharger.
A quick google search for "blownoiler" shows a profile on other forums also running a toyota 2.4 diesel.

Same arguments, same engine, same country.
Guess I'll just call you Fourex from now on. That's the handle you use on 4btswaps.com
Roderunner/Roadrunner is another username of yours.

So your setup is a rebuilt 2L toyota running 5psi on a supercharger:
Vehicles converted and successfully running on WVO - Page 8

As you've stated here, that engine is in a surf/4-runner with a manual and gets 20mpg. You are changing the oil every 4,000km.
Jeepers, it'd be cheaper to run a petrol.

Your build thread is here:
Toyota 4WD Surf Owners :: View topic - Supercharge your 2.4

Running 8psi boost and getting 90-100C intake temps. That equates to a compressor efficiency of 48 to 55%.
That's the cause of your terrible fuel economy right there.

You fitted a lightened flywheel to a 4 cyl diesel?
I see you also fitted a Hyclone at some point.

This thread says your 2LT turbo wasn't giving 1psi until 1800rpm. I can see why you think turbos are terrible. You've owned the worst setup ever sold:
http://dahn.webcity.com.au/~toy49040/forum/viewtopic.php?p=217220&highlight=#217220

 

[blownoiler]

Man, this coincidence is getting stronger.

The user on 4btswaps trolling the same arguments was running a toyota 2LT with a supercharger.
A quick google search for "blownoiler" shows a profile on other forums also running a toyota 2.4 diesel.

Same arguments, same engine, same country.
Guess I'll just call you Fourex from now on. That's the handle you use on 4btswaps.com
Roderunner/Roadrunner is another username of yours.

So your setup is a rebuilt 2L toyota running 5psi on a supercharger:
Vehicles converted and successfully running on WVO - Page 8

As you've stated here, that engine is in a surf/4-runner with a manual and gets 20mpg. You are changing the oil every 4,000km.
Jeepers, it'd be cheaper to run a petrol.

Your build thread is here:
Toyota 4WD Surf Owners :: View topic - Supercharge your 2.4

Running 8psi boost and getting 90-100C intake temps. That equates to a compressor efficiency of 48 to 55%.
That's the cause of your terrible fuel economy right there.

You fitted a lightened flywheel to a 4 cyl diesel?
I see you also fitted a Hyclone at some point.

This thread says your 2LT turbo wasn't giving 1psi until 1800rpm. I can see why you think turbos are terrible. You've owned the worst setup ever sold:
http://dahn.webcity.com.au/~toy49040/forum/viewtopic.php?p=217220&highlight=#217220

Dougal is a stalker lol, Ive done many experiments over the years, and yes, tried to share the results when people show some interest, yet you can't even do a single calculation for the parasitic loss from a turbocharger! Thanks for nothing!

I still own that car, and yes the turbo is an antique design, but so are many of the later factory builds. do you really think that the people on this forum drive 2012 model x5s? My 93 isuzu has terrible lag too, as did the 04 mazda I drove. Don't get me wrong here, turbo's are the best thing that happened to the diesel engine, but I think that people want to explore other options regardless of your position on this issue. This thread is getting a lot of veiws, that must tell you something!

 

[Dougal]

Here are the theoretical engine specs Dougal, have a chop at it yourself and we should get close to the same figures:

Using a free flow (n.a.) extractors/exhaust system as a base, and 2 p.s.i. backpressure in the exhaust manifold/system would be a realistic figure to start with. To round off the figures the engine has a 100mm bore and 100 m.m. stroke, 4 cylinder 4 stroke with a 20-1 compression ratio. If I have 20 p.s.i. backpressure in the exhaust manifold while producing 10 pounds of boost at peak revs (4000) how many horsepower are consumed by the pumping loss of 20 psi of exhaust pressure?

Your figures are BS so the results will be too. Garbage in, garbage out. No turbo system runs 2:1 at steady state.

Suggest you go back to helping your mates install their HHO systems.

 

[blownoiler]

Your figures are BS so the results will be too. Garbage in, garbage out. No turbo system runs 2:1 at steady state.

Suggest you go back to helping your mates install their HHO systems.

I tried many different levels of boost with the charger, 2,4,6,7,9, to see what effect it would have, tried various fuels, (and yes hho was also tried), injected water , methanol, petrol, among other liquids.
The 4000 kay oil changes work out cheap when you buy oil on special for $1 to $2 a litre, $15, per change with filter, thats good value.
How are the calcs coming along for the turbo parasitic drag?

 

[iggi]

This thread is getting a lot of veiws, that must tell you something!

It should tell you that lots of us enjoy reading Dougal's explanations of turbo theory, plus your defense of using superchargers just adds a comical twist to the whole thing.

 

[Dougal]

yet you can't even do a single calculation for the parasitic loss from a turbocharger! Thanks for nothing!

There is no parasitic loss. A parasite is something that takes and never gives back. A good example of a parasitic loss is reading these posts. That time is gone forever.

If you wanted to know how much drive power a turbo requires, well I've already done that on 4btswaps.com for you. But the effort was wasted. Maybe you didn't understand, maybe you just wanted to ignore the results because they show again that turbochargers are better.
Either way, you are still trolling the same arguments.

This thread is getting a lot of veiws, that must tell you something!

It's the car crash effect.

For those interested, worked example of 2LT supercharged vs turbocharged is here: http://www.4btswaps.com/forum/showt...k-pressure-and-wastegates&p=192813#post192813

 

[blownoiler]

There is no parasitic loss. A parasite is something that takes and never gives back. A good example of a parasitic loss is reading these posts. That time is gone forever.

If you wanted to know how much drive power a turbo requires, well I've already done that on 4btswaps.com for you. But the effort was wasted. Maybe you didn't understand, maybe you just wanted to ignore the results because they show again that turbochargers are better.
Either way, you are still trolling the same arguments.



It's the car crash effect.


For those interested, worked example of 2LT supercharged vs turbocharged is here: Turbos, back pressure, and wastegates - Page 6

I see you have been busy editing!
Quote"Crank power turbocharged = 80.7 -10.7 = 70kw
Crank power supercharged = 80.7 -13.5 = 67.2kw" Unquote

Thankyou, thats all I was after. Now where does the extra power come from after parasitic losses are taken into account? As far as I can work out it has to be more airflow across the head, which allowed me to turn the fuel up, I can't think of any other reason for the extra power, may7be you can help here Dougal?

 

[Dougal]

I see you have been busy editing!
Quote"Crank power turbocharged = 80.7 -10.7 = 70kw
Crank power supercharged = 80.7 -13.5 = 67.2kw" Unquote

Thankyou, thats all I was after. Now where does the extra power come from after parasitic losses are taken into account?

If by "extra power" you mean the turbo doing better, it's because it takes 2.8kw less to drive than the supercharger.
Remember this example was using best case numbers for the supercharger and worst case for the turbo. A turbo setup which hits best efficiency at that flow will give another 10-20% power.

Why are you just now reading a post that was put in front of you 3 weeks ago?

As far as I can work out it has to be more airflow across the head, which allowed me to turn the fuel up, I can't think of any other reason for the extra power, may7be you can help here Dougal?

As much as I'd like to improve the airflow through your head, all the methods that come to mind are illegal in most countries. Even Australia.