But thats only just above idle and more output than a turbo which is just an obstruction in the exhauist flow at that rpm
turbo vs supercharger for 2B diesel, lots of mud and crossing creeks
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But thats only just above idle and more output than a turbo which is just an obstruction in the exhauist flow at that rpm
Roscoe, I don't think you get this at all.
I did some 4th gear tests on my 4BD1T with my own built turbo on it.
40km/h in 4th gear is when I start to show boost on the gauge, 45km/h in 4th gear is when I hit 10psi.
This works out to 1050rpm starting to see boost and 1140rpm for 10psi.
From there 20psi at 2000rpm, 24psi around 2,400rpm.
40km/h in 4th gear is when I start to show boost on the gauge, 45km/h in 4th gear is when I hit 10psi.
This works out to 1050rpm starting to see boost and 1140rpm for 10psi.
From there 20psi at 2000rpm, 24psi around 2,400rpm.
Not when you dig up figures like these
On the 1.4bar chart(which is what they set the 1HZ at) it shows about 15kw power consumption with a volumetirc efficiency of 80-90%
I think you were quoting 60-70% and 70-80% for a turbo last week.
Your using engine rpm of 4000 which is nonsense because they will not do even close to that ,except maybe in 1st,which no normal driver would do.
In any case your turbo still requires the engine the to pump harder on the exhaust stroke to make boost but you conveniently leave that out of every post.
I also doubt you have ever spoken to anyone who has owned or driven a supercharged diesel.
Ive spoken to 2 mechanics who were very impressed with the dyno figures and driving characteristics of these engines. These guys had no connection with the company
Ive also been in touch with 3 owners who all gave glowing assessments of their supercharged 1HZs.
They had sold over 900 kits to diesel owners up to about 2006,so obviously others have had very different real life experiences with them
Some of their customers were fleet owners of landcruiser drilling rigs who also gave good reports
Stick to your books Dougal and make sure you take your aspergers medication.
I don't think you understand the source of my figures.
We have three fundamentals.
1. Engine size. This dictates airflow and boost pressure if the desired airflow is more than the engine consumes. From this we know airflow and pressure
2. Compressor power = airflow*pressure/compressor efficiency.
This dictates exactly how much power is requires to push the desired airflow through your engine. From this we know the power a supercharger sucks from the crank to deliver that airflow.
3. Diesel engine efficiency, this dictates how much power and torque a diesel can produce (maximum's) from the airflow it has.
The figures I have posted aren't "dug up", they are calculated from the above.
The results of these calculations show that superchargers are a terrible idea on a diesel engine.
The worlds diesel engine makers agree with me and that's why they all use turbochargers over superchargers.
Who is "they" who set up the 1HZ?
Either "they" are bad at maths or you don't understand their charts.
Power depends entirely on rpm. You can't quote a power consumption figure without an RPM attached. Without rpm we can however calculate torque.
Let's use 2000rpm
At 1.4 bar a 60% efficient supercharger on a 1HZ takes:
100% VE is 18.23 lb/min.
90% VE is 16.4 lb/min.
The power to push 16.4 lb/min of air against 1.4 bar (gauge) with a 60% efficient compressor is 24.8kw.
You and "they" say 15kw with no defined rpm, the maths says 24.8kw at 2000rpm.
But since you didn't state rpm, we can divide by rpm and get a steady torque requirement instead.
Torque = power/rotating speed.
= 24,800/2000*pi/30
= 118Nm.
It takes a steady 118Nm of crank torque to drive a 60% efficient supercharger at 1.4 bar.
That 1.4 bar would increase air density by 64% over stock, making the net torque gain around 188Nm. Of that 188, 118 is required to power the blower, leaving only 70Nm extra at the crank.
370Nm from 21psi boost on a 4.2L engine is awful.
I used 4000rpm in one example because that is the maximum power point of that engine. If you are interested in max power, then that's the rpm you find it.
Turbo's feed off exhaust temperature and pressure. The higher the temperature, the lower the pressure. Above 650C EGT's my turbo setups have produced more boost than backpressure.
So compare a turbo producing 20psi boost from 18psi exhaust drive pressure (that's the whole exhaust backpressure including the turbo) to a supercharger producing 20psi boost
Wrong on that one. In my career I have come across exactly one supercharged diesel. It was an underground loader used in a coal mine. They used a supercharger to give less hot exhaust exposed.
Why do you think that zero, not one, absolutely no diesel engine manufacturers produce supercharged automotive diesels?
Care to share these dyno plots and indeed the fuel consumption of these engines?
Personal attacks combined with mockery of those with Autism. Today we have witnessed a new low.
Did you by any chance mean 1.4 bar absolute? (6psi boost)?
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The only diesels I have seen with stock superchargers are old 2 stroke ones that need positive pressure just to idle. And if you are worried about getting a turbo wet on river crossings, just header wrap that thing really well.
It's worth noting that the blowers on those 2 strokes didn't increase charge pressure. When they needed more power they turbocharged them while still keeping the blowers.
A supercharger on a diesel is rubbish; sorry but thats just the way it is. The calcs don't lie.
I would also suggest you listen to Dougal's advice; he spends a lot of time helping people just because he likes it and he is a real engineer offering quality advice that works on paper and in reality. These are just heat engines, thermodynamics was well sorted years ago - which is why the calks always match the practice when all significant variables are considered.
Last week a guy who brought in his Nissan Patrol (spent $25K on supercharging it) dynode a whopping 388nm (at crank, corrected) using similar fuel to what we get with turbos and do closer to 550nm.... The guy is, as I type, ripping of the supercharger and fitting a turbo. Anyone here locally who wants to buy it PM me, Ill see if I can get his details. Its very funny - 388nm..... hahahaha Oh, the power was also garbage and the torque off the bottom started ok and then dove badly at 3k.
If you care about what happens between idle and 1200rpm, buy a SC, otherwise get a well setup turbo.
I would also suggest you listen to Dougal's advice; he spends a lot of time helping people just because he likes it and he is a real engineer offering quality advice that works on paper and in reality. These are just heat engines, thermodynamics was well sorted years ago - which is why the calks always match the practice when all significant variables are considered.
Last week a guy who brought in his Nissan Patrol (spent $25K on supercharging it) dynode a whopping 388nm (at crank, corrected) using similar fuel to what we get with turbos and do closer to 550nm.... The guy is, as I type, ripping of the supercharger and fitting a turbo. Anyone here locally who wants to buy it PM me, Ill see if I can get his details. Its very funny - 388nm..... hahahaha Oh, the power was also garbage and the torque off the bottom started ok and then dove badly at 3k.
If you care about what happens between idle and 1200rpm, buy a SC, otherwise get a well setup turbo.
This is where the term "blower" came from. Because the pressure was low, they were doing the scavenging, blowing in the fresh air charge
As Dougal said, they have a bypass typically and a turbo designed for better than 1:1 pressure ratio of intake/exhaust is fitted
My younger brother works for Detroit and still rebuilds the occasional 8V92 etc
diesel supercharging
There are STILL a lot of old wives tales when it comes to supercharging diesels, I remember when turbo's first appeared in a big way back in the 80s, turbocharging was seen as some kind of idiotic mod that would melt your pistons before you even got out of the driveway! Superchargers work well on a diesel engine, low revving engines need lots of boost down low because thats where they generally spend most of their time 1000 to 3000 revs. When calculating drive loss for a supercharger vs turbo one has to understand that you can drop the boost pressure when running a crank driven charger to get the same airflow through the engine (no power robbing backpressure in a properly designed system), add in the fact that crank driven chargers are approaching the efficiency figures of turbo's and things are starting to look interesting! Here's a few engineers who walk the walk: http://www.dieselpowermag.com/tech/...ments/page:1dp_supercharge_your_diesel_truck/
The newer Magnusen chargers are well designed chargers for a diesel instalation, the internal butterfly valve allows the charger to freewheel when boost isn't required, so the parasitic loss is virtually zero!
There are STILL a lot of old wives tales when it comes to supercharging diesels, I remember when turbo's first appeared in a big way back in the 80s, turbocharging was seen as some kind of idiotic mod that would melt your pistons before you even got out of the driveway! Superchargers work well on a diesel engine, low revving engines need lots of boost down low because thats where they generally spend most of their time 1000 to 3000 revs. When calculating drive loss for a supercharger vs turbo one has to understand that you can drop the boost pressure when running a crank driven charger to get the same airflow through the engine (no power robbing backpressure in a properly designed system), add in the fact that crank driven chargers are approaching the efficiency figures of turbo's and things are starting to look interesting! Here's a few engineers who walk the walk: http://www.dieselpowermag.com/tech/...ments/page:1dp_supercharge_your_diesel_truck/
The newer Magnusen chargers are well designed chargers for a diesel instalation, the internal butterfly valve allows the charger to freewheel when boost isn't required, so the parasitic loss is virtually zero!
Here's another: Focus - Automotive Engineer
That first link doesn't want to work, here it is: Supercharge Your Diesel Truck! - Diesel Power Magazine
Do you have any production examples of supercharged diesels?
BSFC charts to show how efficient they are?
Dyno plots to show how powerful they can be?
Because after 100 odd years of diesel engine development, pretty much everything has been tried and either proven or abandoned.
Superchargers, they got abandoned. Turbochargers, they were proven.
Pretty much because that power robbing backpressure; robs a lot less power than a supercharger pulley does.
There's a lof of talk on the internet about supercharged diesels, but not much else.
That little experimental engine in your link isn't just supercharged, it's twin-charged with a turbocharger as well. Also 2 years on it's not in production.
Did you read that article? Here is what they say about running just a supercharger:
Diesel Power said:
Not postive at all.
But what I'm most interested in, is: "Why someone would join up with the username "blownoiler" specifically to post in this topic?"
Do you have a commercial interest in supercharged diesels or do you have your own supercharged diesel which is truely awesome?
Or are you just one of Roscoe's mates?
supercharge your diesel
I'm not here to argue with you Mr. Dougal, just pointing out the po0tential of a supercharged diesel engine. The street diesel engine and modern supercharger are a great match. Maybe you would like to email Gale Banks and tell him that his supercharged engines are smelly and lack power, or explain to the Renault engineers that superchargers don't produce economy or top end power, because you can devise a calc that says so, It's time to let go of past misconceptions and enjoy what modern technology has to offer.
I'm not here to argue with you Mr. Dougal, just pointing out the po0tential of a supercharged diesel engine. The street diesel engine and modern supercharger are a great match. Maybe you would like to email Gale Banks and tell him that his supercharged engines are smelly and lack power, or explain to the Renault engineers that superchargers don't produce economy or top end power, because you can devise a calc that says so, It's time to let go of past misconceptions and enjoy what modern technology has to offer.
crushers
post ho
subscribed to watch the fun ...
If you truly wish to win an argument here you need to post some charts and numbers to back up your opinions, calling names and arguing just for the sake of arguing wont get you far...
crushers
post ho
well, i don't usually agree with Mr Kiwi but in this situation i would go with the turbo for the application stated in the OP.
i have yet to see a turbo crack and i have personally driven hard off road and then through deep cold mountain water with no ill side effects.
the SC adds complexity to the system with belts and tensioners.
KISS principle.
i am sure Greg or Dougal can crunch the numbers for a turbo that comes on fast low down.
<we installed a turbo off a 2LTE onto a 3B and the results were excellent for the off road 60>
i have yet to see a turbo crack and i have personally driven hard off road and then through deep cold mountain water with no ill side effects.
the SC adds complexity to the system with belts and tensioners.
KISS principle.
i am sure Greg or Dougal can crunch the numbers for a turbo that comes on fast low down.
<we installed a turbo off a 2LTE onto a 3B and the results were excellent for the off road 60>
crushers said:
Hi crushers,
I played around with some different kind of turbo's an my opinion is that the 17201-67040 (2e generation kz engine) is the best option to go on a 3b. Don't have any faith in supercharger on a diesel....
Regards
Mike
Sent from my iPad using IH8MUD... fun starts where the road ends
