Power brakes on gas engine vehicles use a vacuum booster, which needs engine vacuum to operate. A 12vdc electric motor could be used to run a vacuum pump for the brake booster, running off the battery while the engine is stopped. Seems like a lot of unnecessary complication just to let the engine stop for a few seconds or maybe a minute while waiting for a stop light.
The HVAC blower motor already operates from 12vdc power from the battery, so no change there.
The AC compressor operates via belt drive from the crank pulley. A different AC compressor system would have to be used that operates via a separate 12vdc motor, drawing power from the battery. I suppose some kind of clutching system could be used to let the engines belt drive the compressor when the engine is running and disconnect it from the belt and let the electric motor run the compressor while the engine is off. Again, seems like a lot of unnecessary complication just to allow the engine to stop while waiting at a stop light.
The alternative would be to use a conventional belt drive compressor and simply let the AC compressor stop while the engine is stopped. If the AC system is already cold, not having the compressor on for that short time shouldn't have too much effect on the cooling of the cabin, unless you're in heavy stop and go traffic on a very hot day...
The water pump operates via belt drive from the crank pulley. If the engine stops for every stop light, that means no water is circulating through the engine and radiator to help cool the motor while it is stopped. That doesn't sound like a good plan to me, especially for anyone who lives in a hot climate and even more so when there is also heavy stop and go traffic involved. Another bad scenario would be after having just pulled a load up a grade and there is a long red light at the top of the hill. Your engine is sitting there boiling with no water flowing, while you wait for the light to turn green.
So the alternative would be to have a similar clutched electric motor to operate the water pump while the engine is stopped, as described above for the AC compressor. So far there are 3 extra unnecessary electric motors involved in operating this car, one each for the AC compressor, water pump and power brake booster.
We can assume that the power steering pump won't be needed while stopped at a stop light, so loss of power steering is a non-issue, so long as you don't need to turn the steering wheel while stopped. This would be very aggravating if you're trying to maneuver the car in a tight area, stopping, looking and assessing the situation and turning the wheel to change direction while stopped, especially while backing in a trailer.
So now we need yet another clutched electric motor, to operate the power steering. Again, seems like a lot of unnecessary complication, just to allow the engine to stop while the car is stopped momentarily.
A good question would also be, how many seconds does it take for the engine to re-start after you push the gas pedal to go? Also, how many seconds, if any, do you have after the car stops, before the engine stops?
I think the alternator will have to be an extra high output one, to re-charge the battery after all these electric motors have been drawing juice off the battery while the engine is stopped. The battery will also have to be extra high capacity, or maybe 2 batteries will be needed.
Really, I doubt this start-stop feature is going end up adding any measurable real-world gas mileage to an average use car. Possibly tailpipe emissions may be less, but then even I doubt it is enough to justify such a complicated system.
SoCalDesertRider wrote: Power brakes on gas engine vehicles use a vacuum booster, which needs engine vacuum to operate. A 12vdc electric motor could be used to run a vacuum pump for the brake booster, running off the battery while the engine is stopped. Seems like a lot of unnecessary complication just to let the engine stop for a few seconds or maybe a minute while waiting for a stop light.
The HVAC blower motor already operates from 12vdc power from the battery, so no change there.
The AC compressor operates via belt drive from the crank pulley. A different AC compressor system would have to be used that operates via a separate 12vdc motor, drawing power from the battery. I suppose some kind of clutching system could be used to let the engines belt drive the compressor when the engine is running and disconnect it from the belt and let the electric motor run the compressor while the engine is off. Again, seems like a lot of unnecessary complication just to allow the engine to stop while waiting at a stop light.
The alternative would be to use a conventional belt drive compressor and simply let the AC compressor stop while the engine is stopped. If the AC system is already cold, not having the compressor on for that short time shouldn't have too much effect on the cooling of the cabin, unless you're in heavy stop and go traffic on a very hot day...
The water pump operates via belt drive from the crank pulley. If the engine stops for every stop light, that means no water is circulating through the engine and radiator to help cool the motor while it is stopped. That doesn't sound like a good plan to me, especially for anyone who lives in a hot climate and even more so when there is also heavy stop and go traffic involved. Another bad scenario would be after having just pulled a load up a grade and there is a long red light at the top of the hill. Your engine is sitting there boiling with no water flowing, while you wait for the light to turn green.
So the alternative would be to have a similar clutched electric motor to operate the water pump while the engine is stopped, as described above for the AC compressor. So far there are 3 extra unnecessary electric motors involved in operating this car, one each for the AC compressor, water pump and power brake booster.
We can assume that the power steering pump won't be needed while stopped at a stop light, so loss of power steering is a non-issue, so long as you don't need to turn the steering wheel while stopped. This would be very aggravating if you're trying to maneuver the car in a tight area, stopping, looking and assessing the situation and turning the wheel to change direction while stopped, especially while backing in a trailer.
So now we need yet another clutched electric motor, to operate the power steering. Again, seems like a lot of unnecessary complication, just to allow the engine to stop while the car is stopped momentarily.
A good question would also be, how many seconds does it take for the engine to re-start after you push the gas pedal to go? Also, how many seconds, if any, do you have after the car stops, before the engine stops?
I think the alternator will have to be an extra high output one, to re-charge the battery after all these electric motors have been drawing juice off the battery while the engine is stopped. The battery will also have to be extra high capacity, or maybe 2 batteries will be needed.
Really, I doubt this start-stop feature is going end up adding any measurable real-world gas mileage to an average use car. Possibly tailpipe emissions may be less, but then even I doubt it is enough to justify such a complicated system.
I am the original OP re. this thread.
X2 re. your post.
As I said in the beginning, the 'announcement' of a 'stop start' feature being on the 2013 Ram 1500 made me LOL!
It will 'kill' Ram 1500 new sales from 2013 onwards, because unless all the ancillaries are kept opearating at 100% when 'at the lights', the truck is useless!
Already in my view, the Ram 1500 2009 onwards, mushy rear coils have now caused the manfacturer to offer an 'available' factory fitted 'air suspension!' BAND-AID. I am positive that if the Ram 1500 until now had rear leafs, there would be NO 'factory fitted rear air suspension' availability from 2013 on.
Chevrolet Silverado 1500 LTZ 2007 (new shape)
4x4 Crew Cab VORTEC MAX (L76) 6.0L V8 4L70E 4.10 axle
factory NHT Max Trailering Package.
2010 Coachmen Freedom Express 280 RLS
"...a Waldorf Salad?, sorry we are fresh out of Waldorfs!".......BASIL FAWLTY.
The claim of the 3.6l with the 8 speed transmission is 20% better:
Would be:
about 16 to 17 city
about 19 combined
about 24 highway
---------------------
Ford 3.5 ecoboost:
17 City
19 Combined
23 Highway
---------------------
Many of the tricks used on the Chrysler can readily be implemented by Ford on a 1 year cycle.
I believe you're making a mistake there comparing the 3.6 pentastar v6/8 speed auto with all the other enhancements to only do 20% better than the previous 5.7 hemi with none of the enhancements. Id bet the hemi will better the ecoboost in mpg, and the 3.6 will do better yet.
2010 Cougar 322QBS 5er
2007 Dodge 3500 SRW Megacab, 4x4, 5.9L Cummins, 3.73, 48RE auto HYPERTECH MAX ENERGY or DIABLO PREDATOR tuning MBRP 4" Turbo back Scangauge2 for Boost, Coolant temp, Rail press & Trans Temp
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