Scania K230UB acceleration
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Originally posted by Powered_By_CNG:
In my opinion, the best city bus engine has 6 cylinders, (a) variable geometry turbocharger(s), displacement of between 10 and 12-litres, a power rating of between 185kW and 240kW available at as low as possible engine speed, and 1100Nm or greater torque available between 1000-1400rpm or wider. The engine should be hooked to a 5-speed ZF transmission with a high-speed diff. The top speed should be electronically limited.
Regards,
DaveMercedes-Benz OM457HLA coupled with ZF6HP592C is the best!
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The OM 457 hLA (as well as the previous OM 447 hLA) is quite a good engine. The 220kW version used on SMRT's OC 500 LEs develops a whopping 1000Nm already at 600rpm (idle speed) and over 1100Nm by 800rpm. Mercedes-Benz diesel engine have traditionally featured very flat torque curves for the best driveability.
Regards,
Dave -
Originally posted by SBS n SMRT:
for free tickets???
Siao la.. Fast also want to complain, slow also want to complain. I muz say some Singaporean had nth better to do. -
Originally posted by chickenlittle2:
Siao la.. Fast also want to complain, slow also want to complain. I muz say some Singaporean had nth better to do.They should know BC had a schedule to adhere to
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So do most buses have their speed limits electronically controlled?
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Originally posted by lianamaster:
So do most buses have their speed limits electronically controlled?
yah.....speed limitator caps speed at 60kph
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Originally posted by SBS n SMRT:
yah.....speed limitator caps speed at 60kph
Oic....
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Originally posted by Powered_By_CNG:
The OM 457 hLA (as well as the previous OM 447 hLA) is quite a good engine. The 220kW version used on SMRT's OC 500 LEs develops a whopping 1000Nm already at 600rpm (idle speed) and over 1100Nm by 800rpm. Mercedes-Benz diesel engine have traditionally featured very flat torque curves for the best driveability.
Regards,
DaveSo is that why MB buses can take-off from the bus-stop with a full load fast?
Seen O405s with OM447hLA engines around the mountainous regions of Germany alot.
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Originally posted by Raraken:
So is that why MB buses can take-off from the bus-stop with a full load fast?
Yes. The OM 447 hLA and OM 457 hLA engines have high torque output even at engine speeds close to idle. High torque (pulling power) is critical for acceleration with a full bus load of passengers.
Regards,
Dave -
LTA requires all buses to be capped at 60kph. In fact, i notice many BN buses are going above 60.
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Originally posted by SBS9888Y:
LTA requires all buses to be capped at 60kph. In fact, i notice many BN buses are going above 60.
They alter speed limitator
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Originally posted by Powered_By_CNG:
The Scania DC9 engine has a very wide band of engine speeds where maximum torque is available. Maximum torque of the base-model (DC9 16 230 Euro 4) engine is 1050Nm @ 1100-1500rpm. The engine runs optimally at engine speeds between 1100rpm and 1700rpm although quite often the maximum engine speed is limited by transmission settings.
In contrast, the engines in the Volvo B10Ms have a very narrow band of engine speeds where maximum torque is available. The THD102KF has 1050Nm (same as the DC9 16 230) but maximum torque is available only at 1400rpm. The torque curve drops substantially below and above 1400rpm. In order to obtain the best acceleration from the THD102KF, the driver needs to use the power of the engine and allow engine revs to remain high.
In my opinion, the best city bus engine has 6 cylinders, (a) variable geometry turbocharger(s), displacement of between 10 and 12-litres, a power rating of between 185kW and 240kW available at as low as possible engine speed, and 1100Nm or greater torque available between 1000-1400rpm or wider. The engine should be hooked to a 5-speed ZF transmission with a high-speed diff. The top speed should be electronically limited.
Regards,
DaveThanks for your reply, Dave.
I did not take note of the current B10M torque band when I was with SBS. Are you referring to the THD101GC instead? Because I do experience pretty good acceleration from 1200 rpm for the THD102KF. In fact many drivers hardly drive at higher revs, unless overtaking or overcoming steep slopes with heavy loads, or just to have some fun.
The THD101GC engine of earlier B10M indeed require reving due to narrower power bands.
According to the Scania website, the K230UB maximum power is attained at 1800rpm, which means that the ZF gearbox should upshift at 1800rpm at maximum acceleration. I think I can safely assume that the acceleration for the K230UB should be better than the B10M at narrower gear ratios and same torque ratings.
I agree with you that city driving, power band should be wide. It makes driving more pleasurable.
So the only thing that can get in the way of better acceleration is the unladen weight. Do you agree?
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Originally posted by Powered_By_CNG:
The OM 457 hLA (as well as the previous OM 447 hLA) is quite a good engine. The 220kW version used on SMRT's OC 500 LEs develops a whopping 1000Nm already at 600rpm (idle speed) and over 1100Nm by 800rpm. Mercedes-Benz diesel engine have traditionally featured very flat torque curves for the best driveability.
Regards,
DaveAt 220KW, it should be one of the most powerful engine to be used in a rigid single decker city bus, especially in SG roads. Wonder why the use of such a powerful engine.
Usually high powered engines are used for long distance overland travelling whereby buses hit around 100km/h to 140km/h.
I assume the unladen weight of the OC500LE is around 11 ton. Coupled the engine with the ZF gearbox, I believe the acceleration can be quite blistering.
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Originally posted by Powered_By_CNG:
The OM 457 hLA (as well as the previous OM 447 hLA) is quite a good engine. The 220kW version used on SMRT's OC 500 LEs develops a whopping 1000Nm already at 600rpm (idle speed) and over 1100Nm by 800rpm. Mercedes-Benz diesel engine have traditionally featured very flat torque curves for the best driveability.
Regards,
DaveAt 220KW, it should be the most powerful engine to be used in a rigid single decker city bus, especially in SG roads. Wonder why the use of such a powerful engine.
Usually high powered engines are used for long distance overland travelling whereby buses hit around 100km/h to 140km/h.
I assume the unladen weight of the OC500LE is around 11 ton. Coupled the engine with the ZF gearbox, I believe the acceleration can be quite blistering.
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I did not take note of the current B10M torque band when I was with SBS. Are you referring to the THD101GC instead? Because I do experience pretty good acceleration from 1200 rpm for the THD102KF. In fact many drivers hardly drive at higher revs, unless overtaking or overcoming steep slopes with heavy loads, or just to have some fun.
I have found that the THD102KF isn't as good as previous generations. The THD100D (used on Volvo B58s, B59s and early model B10Ms) was the best.
According to the Scania website, the K230UB maximum power is attained at 1800rpm, which means that the ZF gearbox should upshift at 1800rpm at maximum acceleration. I think I can safely assume that the acceleration for the K230UB should be better than the B10M at narrower gear ratios and same torque ratings.
In normal everyday traffic, how often does one push a bus engine to 1,800rpm? The answer is generally rarely ever unless the transmission is ill-suited to the task at hand. An engine with high torque at low engine speeds as well as a suitable transmission with suitable programming are therefore required for good in-traffic acceleration characteristics. In order to calculate the optimal up-shifting engine speed, it is necessary to investigate passenger comfort levels (read: shifting comfort) as well as specific fuel consumption of the engine at various speeds. Up-shifting at 1,800rpm is unnecessary - operating an engine at or above it's 'rated' speed (yellow to red on the tachograph) results in high fuel consumption and unnecessary engine wear. It is therefore wise to ensure that the engine operates within its 'green zone' as much as possible. At the same time, it is also unwise to operate an engine at speeds below the 'green zone', as again fuel economy, performance, engine life and smoothness suffers. Allowing an engine to run below the 'green zone' also promotes 'hunting' - where the transmission is constantly 'between gears' - resulting in poor passenger comfort levels.
In order to understand why new buses may not perform the same as older buses, it is necessary to understand the concept of torque reduction. Many new engines are fitted with OBD (On-Board Diagnostics) systems that monitor the health of the engine as well as the exhaust output. In order to guarantee low emissions levels, some engines are 'cut back' at low speeds under full load. If the OBD system detects an engine fault, the torque output of the engine is also reduced. From experience, newer buses require more frequent servicing to ensure reliable operation.
Remember, official engine power and torque figures are measured under ideal circumstances.
So the only thing that can get in the way of better acceleration is the unladen weight. Do you agree?
As above, there are more variables than you think. Modern buses, with all their creature comforts, safety and emissions control gear will almost always be significantly heavier than previous generations of buses.
Regards,
Dave -
Originally posted by SBS9888Y:
alot of bndep ones esp 36, as usual, tuned that way, i plan to submit a complain to lta soon.
When did u take sv36 may i noe coz i dun noe c any acceleration past 55km/h...
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Originally posted by Powered_By_CNG:
I have found that the THD102KF isn't as good as previous generations. The THD100D (used on Volvo B58s, B59s and early model B10Ms) was the best.
In normal everyday traffic, how often does one push a bus engine to 1,800rpm? The answer is generally rarely ever unless the transmission is ill-suited to the task at hand. An engine with high torque at low engine speeds as well as a suitable transmission with suitable programming are therefore required for good in-traffic acceleration characteristics. In order to calculate the optimal up-shifting engine speed, it is necessary to investigate passenger comfort levels (read: shifting comfort) as well as specific fuel consumption of the engine at various speeds. Up-shifting at 1,800rpm is unnecessary - operating an engine at or above it's 'rated' speed (yellow to red on the tachograph) results in high fuel consumption and unnecessary engine wear. It is therefore wise to ensure that the engine operates within its 'green zone' as much as possible. At the same time, it is also unwise to operate an engine at speeds below the 'green zone', as again fuel economy, performance, engine life and smoothness suffers. Allowing an engine to run below the 'green zone' also promotes 'hunting' - where the transmission is constantly 'between gears' - resulting in poor passenger comfort levels.
In order to understand why new buses may not perform the same as older buses, it is necessary to understand the concept of torque reduction. Many new engines are fitted with OBD (On-Board Diagnostics) systems that monitor the health of the engine as well as the exhaust output. In order to guarantee low emissions levels, some engines are 'cut back' at low speeds under full load. If the OBD system detects an engine fault, the torque output of the engine is also reduced. From experience, newer buses require more frequent servicing to ensure reliable operation.
Remember, official engine power and torque figures are measured under ideal circumstances.
As above, there are more variables than you think. Modern buses, with all their creature comforts, safety and emissions control gear will almost always be significantly heavier than previous generations of buses.
Regards,
DaveAfter this explaination, I am sure there is a difference drawn clearly between that of a city bus and a sports car.
Often I see a K230UB at 1000-1100 RPM+ when cruising on the sixth gear at 60 km/h as opposed to a OC500LE at 1200 RPM+ when also at the same speed. It may be also true to say that in comfort levels, on a Scania there would be this feeling that the gears are going to downshift any time, plus the tell-tale sign of low engine speed vibration/sound, while on the Mercedes, it seemed comfortable to think that the bus will be able to maintain at the 6th gear even with the same gradient both models encounter.
Then again this may be a case to case basis as tuning of different vehicles count as well.
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Originally posted by Powered_By_CNG:
I have found that the THD102KF isn't as good as previous generations. The THD100D (used on Volvo B58s, B59s and early model B10Ms) was the best.
In normal everyday traffic, how often does one push a bus engine to 1,800rpm? The answer is generally rarely ever unless the transmission is ill-suited to the task at hand. An engine with high torque at low engine speeds as well as a suitable transmission with suitable programming are therefore required for good in-traffic acceleration characteristics. In order to calculate the optimal up-shifting engine speed, it is necessary to investigate passenger comfort levels (read: shifting comfort) as well as specific fuel consumption of the engine at various speeds. Up-shifting at 1,800rpm is unnecessary - operating an engine at or above it's 'rated' speed (yellow to red on the tachograph) results in high fuel consumption and unnecessary engine wear. It is therefore wise to ensure that the engine operates within its 'green zone' as much as possible. At the same time, it is also unwise to operate an engine at speeds below the 'green zone', as again fuel economy, performance, engine life and smoothness suffers. Allowing an engine to run below the 'green zone' also promotes 'hunting' - where the transmission is constantly 'between gears' - resulting in poor passenger comfort levels.
In order to understand why new buses may not perform the same as older buses, it is necessary to understand the concept of torque reduction. Many new engines are fitted with OBD (On-Board Diagnostics) systems that monitor the health of the engine as well as the exhaust output. In order to guarantee low emissions levels, some engines are 'cut back' at low speeds under full load. If the OBD system detects an engine fault, the torque output of the engine is also reduced. From experience, newer buses require more frequent servicing to ensure reliable operation.
Remember, official engine power and torque figures are measured under ideal circumstances.
As above, there are more variables than you think. Modern buses, with all their creature comforts, safety and emissions control gear will almost always be significantly heavier than previous generations of buses.
Regards,
DaveThe THD102KF is more fuel efficient and torquey than the THD101. I draw my comparisons purely from driving experience. It was also quieter and briskier, though now age is starting to show in most THD102.
I have not had the chance to get behind the wheel powered by a THD100. I have got behind a B57 with an Allison box.
Please describe to me about the THD100?
It is true that most drivers, even myself drive along the green band. But there will be times high acceleration power is needed; heavy load and taking on a steep slope. What most city drivers need is acceleration, even braking effect and a firm steering. These features will greatly reduce driver fatigue.
Except for current generations of buses with Euro IV or V engines which are paired with closely spaced gears, there was no difference in the ZF gearbox used in the THD101 and THD102. Even the Nissan Diesel U31 of 1980s uses the same ZF4HP500 (correct me if I am wrong).
I will love the hear more of your sharings on the newer Euro V engines. You must have kept abreast on the developments over the years.
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Yup, UD's are also using 4HP500's. ;)
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Originally posted by BB2001:
The THD102KF is more fuel efficient and torquey than the THD101. I draw my comparisons purely from driving experience. It was also quieter and briskier, though now age is starting to show in most THD102.
I have not had the chance to get behind the wheel powered by a THD100. I have got behind a B57 with an Allison box.
Please describe to me about the THD100?
It is true that most drivers, even myself drive along the green band. But there will be times high acceleration power is needed; heavy load and taking on a steep slope. What most city drivers need is acceleration, even braking effect and a firm steering. These features will greatly reduce driver fatigue.
Except for current generations of buses with Euro IV or V engines which are paired with closely spaced gears, there was no difference in the ZF gearbox used in the THD101 and THD102. Even the Nissan Diesel U31 of 1980s uses the same ZF4HP500 (correct me if I am wrong).
I will love the hear more of your sharings on the newer Euro V engines. You must have kept abreast on the developments over the years.
even the B10M MKIIs used ZF4HP500.
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Originally posted by nenepokey:
even the B10M MKIIs used ZF4HP500.
Actually can someone explain to me why the MKII's ZF sounds different from all the other ZFs?