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Hybrid Vehicles Chevrolet Tahoe and GMC Yukon Hybrid Chevy Tahoe/GMC Yukon Hybrid
301 messages, Last post on Nov 23, 2009 at 10:58 AM
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Replying to: pear69 (Nov 07, 2007 10:26 pm) I really don't see how this could be an issue. The engine is still water cooled and all cooling channels still get the same amount of coolant flowed through them whether they are firing or de-activated. The heat build-up / differences between cylinders will not be significant enough to make things out of tolerances. Look how much air cooled engines expand and contract without issues. Since this is a water cooled engine, it's true that the tolerances will be tighter, but then, the operating heat range is smaller as well, with or without deactivated cylinders. Plus, like other have said, they are de-activated for very short time periods and if the 'brain' is deactivating them, it means you are on a very low power situation so the other cylinders are likely barely working at all. Basically in a coasting or idling work mode rather than a "make power" mode like when accellerating. At which time, all cyclinders will be working anyway. This technology has been around for quite a while (in everything from 4 stroke auto engines to two stroke outboard boat motors) so it's nothing new. No doom and gloom needed. |
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Replying to: galvang (Nov 09, 2007 8:02 pm) Since Toyota has abandoned LiIon for the 2009 Prius Refresh, I would be shocked if GM solved the problems inherent with current LiIon batteries. |
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Replying to: galvang (Nov 09, 2007 8:02 pm) Ford was originally going to put a hybrid powertrain in the Explorer. They halted the concept because it turned out that they could achieve the same MPG increase with a 6 speed transmission. A Ford Explorer is probably 2000 lbs lighter than a Yukon at full load. The point is that it takes a lot of energy to push that kind of mass up to speed, and I don't think that a 3 ton gas/electric hybrid is necessarily going to provide enough MPG savings and/or power.
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Replying to: stevedebi (Nov 12, 2007 1:50 pm) Both of these are significant accomplishments.
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Replying to: kdhspyder (Nov 12, 2007 5:09 pm) Both of these are significant accomplishments." I understand your point, but I will wait to see what MPG the vehicles get in actual useage. The same point was made about the Sierra Hybrid P/U, and it was dismal in actual performance. If the difference is 1 MPG that is not a "whole lot of fuel saved for the country"... 
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Replying to: stevedebi (Nov 12, 2007 5:21 pm) Actually, it is when you are talking about such low mileage vehicles. It's more about percentage increase and number of gallons saved and not mpg increase. If real world numbers in a vehicle improve it from 15mpg to 16.5mpg, that is a real world increase of 10%. Toyota camry (I4 engine) is rated at 31 hwy vs Toy. Cam. Hybrid rated at 38 hwy (I don't know what the real world numbers are). That is a about a 23% increase. However (and it's a big however), look at the number of gallons of gas burned over 15,000 miles in a year. Changing from 15mpg (1,000 gallons) to 16.5mpg (909 gallons) saves 91 gallons a year. Changing from 31mpg (483 gallons) to 38mpg (394 gallons) saves only 89 gallons a year. What this shows is the planet would be way better off focusing on getting an extra 1 or 2 mpg out of the worst gas mileage vehicles rather than getting more mileage out of already high mileage vehicles. If they got the same 23% mileage improvement on the trucks, the difference would be even more obvious. Now you'd save 187 gallons a year. Of course, ideally, everyone would change the type/class of vehicle they drive to a smaller and inherently better mileage class, but if that is not going to happen, the real "world saving" differences will be seen improving the gas guzzlers and not the gas sippers. This has all been outlined before, but it was worth repeating because it is not an obvious train of thought. It's really all about using less gallons of gas a year. Improving the worst of the worst will prove far easier (and have a far larger impact) than improving the best of the best.
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Replying to: chadx (Nov 13, 2007 9:27 am) Yes, agreed. This should be our first order of business as a tion, actually 2nd IMHO. 1st.. Every government vehicle Federal or State must be either a hybrid or diesel. 2nd. Every BoF SUV must use the 2-Mode or similar technology 3rd. Every truck must be a diesel 4th. Within 7 yrs all the older technology vehicles must be off the road.
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Replying to: kdhspyder (Nov 13, 2007 3:02 pm) 2nd. Every BoF SUV must use the 2-Mode or similar technology 3rd. Every truck must be a diesel 4th. Within 7 yrs all the older technology vehicles must be off the road. Wait a minute, some people may call that communism. I don't. Agreed, something is got to be done. Above may be some crucial steps. You might want to include some of the tougher CAFE standards which the auto companies are against. Every bit counts for the larger gas-a-hog trucks or SUVs whether we save 1 mpg or more. With gas prices in some areas in CA hitting close to $5,00 a gallon and slated to go higher every bit counts. A good time to overfill your air in the tires by a few pounds to add some extra MPG on your vehicle. That seems to work well for me. Saw a good show in CNBC "Street Signs"  along with Brian Williams during NBC Nightly News. They were broadcasting out from a Chrysler MFG plant in Detroit. The Chrysler plant was spitting out trucks every minute or so. The plant was somewhat automated with robotics, looked pretty amazing on TV. Just curious, why didn't CNBC/NBC visit the GM plant where the Hybrids are being built?? Perhaps no cameras or news reporters allowed?? Too bad. Other than that, the shows were well produced. Pardon my ignorance, but what does BoF stand for? Yea, I know I've been living in the west coast too long.
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Replying to: galvang (Nov 13, 2007 10:15 pm) This is what most SUVs are, a body on a truck ladder frame. OTOH the newer lighter and more fuel efficient vehicles are Crossovers. These are similar or even larger inside but they use a unibody construction like a car does. The first Crossover was the RAV4 back in 95. The first large volume Crossover was the Lexus RX300 which was an SUV body on a Camry frame. Instead of getting 15-16 mpg most crossovers get 20-23 mpg.
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Replying to: kdhspyder (Nov 14, 2007 7:00 am) Truck frame vs the crossover unibody construction. Ala, Ford Exploder Vs. Buick Enclave. Got it thanks. The Yukon is BoF.
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