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Q65A
Age: 66 Joined: 17 Apr 2007 Posts: 1769 Location: Central NJ
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DE60LF
Joined: 03 Oct 2007 Posts: 142 Location: Albuquerque, NM
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Posted: Wed Aug 13, 2008 10:18 am Post subject: Re: Diesel Electric Hybrids 101 |
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There is one thing that I have a question about: is a smaller engine always better? I think that really only applies to series hybrids.
New Flyer uses a Cummins ISL engine in their GM Allison parallel hybrids. ABQ RIDE reports around 4.5 mpg with their DE40LFRs. San Joaquin RTD, operating Gillig hybrids with Cummins ISB engines, reports about the same fuel economy. From what I have heard, the New Flyer hybrids have a faster acceleration. Therefore, I wouldn't say that a smaller engine is necessarily always better. |
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RailBus63 Moderator
Joined: 16 Apr 2007 Posts: 1063
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Posted: Wed Aug 13, 2008 2:43 pm Post subject: Re: Diesel Electric Hybrids 101 |
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DE60LF wrote: | There is one thing that I have a question about: is a smaller engine always better? I think that really only applies to series hybrids.
New Flyer uses a Cummins ISL engine in their GM Allison parallel hybrids. ABQ RIDE reports around 4.5 mpg with their DE40LFRs. San Joaquin RTD, operating Gillig hybrids with Cummins ISB engines, reports about the same fuel economy. From what I have heard, the New Flyer hybrids have a faster acceleration. Therefore, I wouldn't say that a smaller engine is necessarily always better. |
It depends on the planned usage of the vehicle. Tests to date have generally shown that series-hybrid buses are better in stop-and-go traffic than parallel-hybrid buses. As the linked article notes, the engine in a parallel-series bus will get its greatest usage in higher speed driving, so it may be argued that a large engine is 'wasted' if the bus is purchased for use in a busy urban area. |
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DE60LF
Joined: 03 Oct 2007 Posts: 142 Location: Albuquerque, NM
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Posted: Wed Aug 13, 2008 3:03 pm Post subject: Re: Diesel Electric Hybrids 101 |
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RailBus63 wrote: | DE60LF wrote: | There is one thing that I have a question about: is a smaller engine always better? I think that really only applies to series hybrids.
New Flyer uses a Cummins ISL engine in their GM Allison parallel hybrids. ABQ RIDE reports around 4.5 mpg with their DE40LFRs. San Joaquin RTD, operating Gillig hybrids with Cummins ISB engines, reports about the same fuel economy. From what I have heard, the New Flyer hybrids have a faster acceleration. Therefore, I wouldn't say that a smaller engine is necessarily always better. |
It depends on the planned usage of the vehicle. Tests to date have generally shown that series-hybrid buses are better in stop-and-go traffic than parallel-hybrid buses. As the linked article notes, the engine in a parallel-series bus will get its greatest usage in higher speed driving, so it may be argued that a large engine is 'wasted' if the bus is purchased for use in a busy urban area. |
Of course, comparing Albuquerque to NYC is a huge difference. I can see why the series hybrids (Orion VII HEV) would do better there. Here in Albuquerque, traffic is nowhere near as heavy as it is in NYC, so parallel hybrids may possibly do better here.
Why would be the reason why New Flyer's GM Allison parallel hybrids buses use a Cummins ISL engine rather than thie ISB? Perhaps NFI is trying to keep costs down by not having to use a different engine than their diesel counterparts. As I stated, ABQ RIDE gets about 4.5 mpg with their GM Allison parallel hybrid DE40LFRs with Cummins ISL engines, while San Joaquin RTD gets about the same mpg with their Gillig BRT parallel hybrid buses with Cummins ISB engines.
The only New Flyer parallel hybrids that have Cummins ISB engines are the DE40i Invero buses in Aspen, Colorado. And of course, New Flyer's new ISE/Thundervolt series hybrid version of the DE40LFR also uses the Cummins ISB. |
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