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Discussion Starter #1
My car engine of choice is diesel. I own a 1993 Mercedes 300 td 2.5 and a 2004 VW Golf TDI.
These cars will last me a long time because I like to maintain them myself. The Golf needs to have
the 100k timing belt change soon and with it I will replace most of the moving parts linked to the
2 belts in the car.

All the talk about electric cars makes me wonder how these cars will deal with the power need of
AC and heating. Driving around in the winter cold or summer heat without AC or heating doesn't
sound very promising.

I'm waiting for a hybrid car that combines a diesel engine and electric system. This appears to me
the perfect solution for all our driving needs. A car like this should get at least 60 miles/gallon.

What you think?
 

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There are a few things that I've learned about VW-Audi hybrid systems and full EV.

They are set up for additional performance and better fuel economy, not optimized for economy.

The Audi hybrids use li-ion battery packs and run the AC to cool the batteries in the summer, a fan if it's not hot. Although they're advertised to go up to around 30 miles on the battery alone, that would require a full battery and no AC, mild speeds, etc. They cannot start by driving only on EV if it's too hot.

The Nissan Leaf uses a pre-heat mode and heated seats to pre-warm the car while it's still plugged in. Otherwise it would really drain the battery pack to heat up the cabin after you start moving. In addition, they've found that using the heated seats is less of a drain than using the battery to heat an element and then heat ice cold air with it.

The XL1 concept is VW's 2 cyl diesel hybrid and will be in production. However, the problem is how do you handle cold engine starts where all the emissions are? You would have to have a Chevy Volt type setup where the engine is a generator and just charges the batteries.

As you've probably heard, most the technology exists but it's not yet to the point where it can be not absurdly expensive and mass produced. Battery technology has a while to go as well.
 

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However, the problem is how do you handle cold engine starts where all the emissions are?
Chitty,

I don't quite understand what you're talking about here...could you clarify please?:eek:

:dunno
 

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Most emissions are during cold engine starts when the engine hasn't warmed up and the emissions system is not working. this is why the cat is so close to the engine. The closer the cat, the quicker the warmup. Some engines even have precats so they can place the main cat further downstream. A diesel takes longer to warm up because of less waste heat and the engine blocks are normally iron instead of aluminum which also takes longer to warm up. Further hurting the situation is that the engine manifold and turbo are cast iron which soaks up heat instead of going to the cats. As soon as the engine is off, that heat goes into the air, the cylinder head, and surrounding metal like the exhaust pipes.

The 15 minutes of driving in the winter it takes for the engine to fully warm up could be twice that in a diesel hybrid, or once the engine shuts off and the engine cools down, require a little more warm up again. Perhaps this would cause it to not pass emissions. This is just a guess. That twice number is just a number out of thin air. However, I recall reading somewhere that in modern cars, something like 90% of emissions are during cold engine starts. This should give you an idea of how effective modern emissions controls are.

The Prius has a heavily insulated coolant tank to help keep the engine warm and decrease warm up times. It can hold some heat for as long as 2 days. Maybe something like that could help. But that engine does not have as many obstacles to heat up.
 

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Got you now. Yes, you're right on all points. Now I see what you mean. Especially in colder weather that diesel engine might need to stay on to maximize efficiency and your Chevy Volt reference makes sense because that setup would allow the diesel to be useful during that time instead of just idling away to maintain heat. On the other hand though, it would be a very small engine and not super powerful so maybe they'll be able to thin the metal down some and put some insulated heat shields around to try to hold in that heat. Maybe there are ways to reduce warm-up to get close to the warm-up times of a typical gas engine, but it'll be tough especially when there are so many places for that heat to go given all the systems connected to the engine plus the exhaust manifold/pipes.
 

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Discussion Starter #6
Interesting info about the temperature of the engine and the emission level. I see now that it is important to keep the engine at optimal temperature for the emissions to stay low.

Looks like it wouldn't make any sense to turn off/on the diesel engine like the hybrids do with their
gas engine. Instead run the diesel engine at best efficiency and drive a generator that charges
the battery. Run the electric motor that drives the car from the battery, similar way all diesel trains
work. All other electric users, like AC run of the battery too.

Some heat from the diesel engine can be used to heat the inside of the car when the weather is
cold. Otherwise keep the diesel engine at the perfect temperature with insulation and a smart
cooling system. Shouldn't be the hard to do. Hope we see one of these cars soon from a major
car company.
 
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