Gm Demonstrates Fuel-saving Engine Technology Breakthrough With Hcci-enabled Aura

[bc3tech]

http://www.saturnfans.com/cars/aura/...ine-technology

[Phaeton Driver]

Originally Posted by bc3tech

http://media.gm.com/servlet/GatewayS...35&docid=45489

Interesting. It was a very technical read. It seems like a lot of engineering for a little return. It was interesting the power claim for the 2.2L engine (180 HP).
Still, anything that can save 15% of the fuel is worth it if it dosent cost an extra $10K to get it.
Sounds like GM can adapt the technology to all of the OHC 4 valve engines (another nail in the 3.5's coffin)

[lbhskier37]

Its a lot of complicated work to make a spark ignition engine almost as efficient as a diesel engine. It can never be as efficient as a normal off the shelf diesel engine. I'm not sure why gm is so resistant to diesels in the US. They could achieve a 30% improvement in fuel economy across the board just by using currently developed and proven diesel technology. Plus a diesel engine would be far more robust than an HCCI engine because with a diesel you don't need nearly as precise control of injection, ignition, and cam timing. I don't see how an HCCI engine wouldn't cost as much or more than a diesel engine and in the end it would still only approach the diesels efficiency.

[bc3tech]

Originally Posted by lbhskier37

Its a lot of complicated work to make a spark ignition engine almost as efficient as a diesel engine. It can never be as efficient as a normal off the shelf diesel engine. I'm not sure why gm is so resistant to diesels in the US. They could achieve a 30% improvement in fuel economy across the board just by using currently developed and proven diesel technology. Plus a diesel engine would be far more robust than an HCCI engine because with a diesel you don't need nearly as precise control of injection, ignition, and cam timing. I don't see how an HCCI engine wouldn't cost as much or more than a diesel engine and in the end it would still only approach the diesels efficiency.

i still have doubts that diesel's efficiency offsets its routinely higher price....

but, i'm too lazy to do the actual math.

i also think part of the US' resistance to diesel lies in its cleanliness...

[lbhskier37]

Originally Posted by bc3tech

i still have doubts that diesel's efficiency offsets its routinely higher price....

but, i'm too lazy to do the actual math.

i also think part of the US' resistance to diesel lies in its cleanliness...

Diesel Jetta for example since it is the only car near Aura size that recently had a diesel to compare.

Diesel @ $4.20/gallon divided by 48 miles/gallon $0.088 per mile. For a 12k per year driver that is $1050 per year.

Gas @ $3.60/gallon divided by 25 miles/gallon $$0.144 per mile. For a 12k per year driver that is $1728.

So if you only drive 12k per year and diesel is $0.60 per gallon more you still asve $678 per year. That makes the payback of the $2000 price premium of the diesel engine take less than 3.5 years. If you drive more miles the payback takes less. As fuel prices increase in the next few years as long as the price difference between gas and diesel doesn't get crazy (which market forces probably won't allow) the savings grows.

The other thing that the EPA numbers don't really show is that with a diesel you get about the same fuel economy whether you drive like a grandma or drive like you stole it. We all know that isn't the case for gas engines.

On the cleanliness side, the new diesels that are coming out post 2006 are cleaner than any gas engine in all emissions catagories accept NOx. With NOx emissions they will be dirtier than PZEV vehicles like the Prius, but not any dirtier than any non-PZEV vehicle. Problem is when the EPA set up emissions for some reason they are very biased towards cleaning up NOx. NOx is very easy to clean up in a gas engine but very difficult in a diesel engine. Additionally if diesel cars do produce slightly more NOx than gasoline ones, it is more than made up for less NOx being created in production and transportation of the fuel because the diesel cars use less of it. On the other side of the coin, evaporative emissions are horrible on gas vehicles. Diesel fuel evaporates something like a 100th as fast as gasoline. Even in new gas cars where they are sealed, millions of gallons of gasoline evaporates every year from production to the filling station.

[metgol]

Originally Posted by bc3tech

i still have doubts that diesel's efficiency offsets its routinely higher price....

but, i'm too lazy to do the actual math.

i also think part of the US' resistance to diesel lies in its cleanliness...

That's the exact thinking of most Americans. They only see how much it is costing them at the moment, not over time.

[lbhskier37]

Additionally I just looked up the Opel Vectra fuel economy ratings for the 1.L diesel engine. 49mpg highway, 31mpg city. That is in US gallons! With an engine that has 148hp and 235ft/lb of torque. And that is already an out of date engine without a lot of the newer diesel technology. A newer generation advanced commonrail engine would likely do quite a bit better. VW has claimed their new commonrail engine will give about a 12% boost in economy vs their previous generation engine.

So in other words adding the emissions scrubbing technology that is needed for diesels in the US is adding about 12% to the the efficiency of the diesel engine which already was 30% better than an equivalent gas engine. The HCCI technology is only going to add 15% to a gas engines efficiency making it still no where close to a diesel engine.

[Jon Boy]

Originally Posted by lbhskier37

Diesel @ $4.20/gallon divided by 48 miles/gallon $0.088 per mile. For a 12k per year driver that is $1050 per year.

Gas @ $3.60/gallon divided by 25 miles/gallon $$0.144 per mile. For a 12k per year driver that is $1728.

Where are you getting these mileage numbers? The 2.4L Aura is rated at 25 mpg combined. If the HCCI engine is 15 percent more efficient, that should bump that up to 28.75 mpg, right?

It looks like the most recent diesel Jetta available in the US is rated at 33 mpg combined under the new EPA test.

[lbhskier37]

Originally Posted by Jon Boy

Where are you getting these mileage numbers? The 2.4L Aura is rated at 25 mpg combined. If the HCCI engine is 15 percent more efficient, that should bump that up to 28.75 mpg, right?

It looks like the most recent diesel Jetta available in the US is rated at 33 mpg combined under the new EPA test.

Those numbers I posted are real world highway numbers for the 2006 Jetta. The EPA ratings for the previous diesels were completely off. The 2006 was rated at 42 highway, but the only way you only got 42 highway is if you forgot to shift to 5th gear. Then when they changed the EPA rating system they just knocked the same percent off the 2006 Jetta rating as they did every other car making the EPA rating even more unrealistic.

[K-1]

Originally Posted by lbhskier37

Those numbers I posted are real world highway numbers for the 2006 Jetta. The EPA ratings for the previous diesels were completely off. The 2006 was rated at 42 highway, but the only way you only got 42 highway is if you forgot to shift to 5th gear. Then when they changed the EPA rating system they just knocked the same percent off the 2006 Jetta rating as they did every other car making the EPA rating even more unrealistic.

So, what makes you think the '08 EPA rating for the 4-cyl AURA is "realistic"? A little apples-to-oranges, don't you think? Do the same comparison with the gas engine getting 34mpg.

Diesel @ $4.20/gallon divided by 48 miles/gallon $0.088 per mile. For a 12k per year driver that is $1056 per year.

Gas @ $3.60/gallon divided by 39 miles/gallon (34 + 15%) $0.092 per mile. For a 12k per year driver that is $1104.

[tackepj]

In addition, a Jetta TDI oil change will run you about $60--quite a bit higher than your average gasser's oil change. Diesels might run forever but maintenance can be frightening. Earlier TDI engines required timing belt replacements every 40k miles, but I think that's since changed.

Don't misunderstand--I like diesels a lot--but there's a lot to consider when you're doing the economics.

I find it somewhat amusing when those (not necessarily anyone here) who malign the benefits of mild hybrids talk about how quickly one can overcome the additional cost of a diesel. In terms of actual payback, they are quite similar.

[bc3tech]

Originally Posted by metgol

That's the exact thinking of most Americans. They only see how much it is costing them at the moment, not over time.

believe me i'd have done the math if it was going to impact my pocket book (read: if i was considering a diesel). but i'm not, so i didn't.

Originally Posted by K-1

So, what makes you think the '08 EPA rating for the 4-cyl AURA is "realistic"? A little apples-to-oranges, don't you think? Do the same comparison with the gas engine getting 34mpg.

Diesel @ $4.20/gallon divided by 48 miles/gallon $0.088 per mile. For a 12k per year driver that is $1056 per year.

Gas @ $3.60/gallon divided by 39 miles/gallon (34 + 15%) $0.092 per mile. For a 12k per year driver that is $1104.

and now the payback on the $2000 premium for the diesel jetta is going to take you almost 10 years. who owns a car for that long anymore?
heck even at 34mpg (no HCCI improvement) you'd be getting $0.105 for $1260, for a 4+yr payback of the $2000 diesel premium. that's nearly the length of most financing offers, and over the length of most leases. throw into the mix the cost saved on a gas engine in maintenance as already pointed out, and it'll take even LONGER to recover that $2k premium.

not to mention the Jetta's an import, and we all now how those maintenance costs compare on average anyway for things other than oil changes

[lbhskier37]

Originally Posted by K-1

So, what makes you think the '08 EPA rating for the 4-cyl AURA is "realistic"? A little apples-to-oranges, don't you think? Do the same comparison with the gas engine getting 34mpg.

Diesel @ $4.20/gallon divided by 48 miles/gallon $0.088 per mile. For a 12k per year driver that is $1056 per year.

Gas @ $3.60/gallon divided by 39 miles/gallon (34 + 15%) $0.092 per mile. For a 12k per year driver that is $1104.

I didn't compare an Aura anywhere in my comparison. I was comparing a gas Jetta to a diesel Jetta because that is the only recent car that has had both a gas and diesel.

So now in your comparison, you have nicely proven my point. An HCCI Aura would have a higher fuel cost than if they just brought over the already existing 1.9L CTDi engine from the Vectra. And an HCCI engine is not going to be significantly cheaper than a diesel. Now if VW going from their 1.9L last generation diesel to a 2.0 commonrail engine got a 15% improvement in fuel economy (they are claiming, no numbers so far), it isn't too much of a stretch to assume GM could get 15% more out of thier diesels by going from a last generation 1.9L to a commonrail 2.0L. So add 15% to the Vectra fuel economy and you get 56mpg and a fuel cost of $900.

I'm just pointing out that GM could bring over the engines that they already sell elsewhere in the world and get better fuel economy than this HCCI stuff will ever provide. I see people on here drooling over HIDs and other nice features GM puts in the Vectra but won't give us, I am drooling over the engines!

[lbhskier37]

Originally Posted by tackepj

In addition, a Jetta TDI oil change will run you about $60--quite a bit higher than your average gasser's oil change. Diesels might run forever but maintenance can be frightening. Earlier TDI engines required timing belt replacements every 40k miles, but I think that's since changed.

Diesels don't cost anymore maintenance than a comparable gas engine. The timing belt has nothing to do with it being a diesel, many OHC engines have belts that need replacing. And the Jetta diesel uses the same oil as their gas engines. You are correct that a VW in general is more costly to service, but that has little to do with the engine and more to do with it being a VW. GM could bring us the Opel diesel engines and they would cost no more to service than the normal GM engines.

[K-1]

If you want a diesel Vectra, import one and STFU. Diesels are not going to catch on in the U.S. in a near enough time to make a difference. Query some people outside your diesel circle. They'll readily accept a gas engine with near diesel efficiency than an actual diesel. As much as you'd like to make it so, diesels aren't even on the map for the vast majority of consumers.

[tackepj]

Originally Posted by lbhskier37

Diesels don't cost anymore maintenance than a comparable gas engine.

Ask your average VW TDi owner. Maintenance costs are considerably higher than VW gas models--it's not really up for debate. 40k mile interval timing belts are a VW TDi exclusive--no gas engine requires them that often.

Originally Posted by lbhskier37

And the Jetta diesel uses the same oil as their gas engines.

Not according to VW.

[lbhskier37]

Originally Posted by K-1

If you want a diesel Vectra, import one and STFU. Diesels are not going to catch on in the U.S. in a near enough time to make a difference. Query some people outside your diesel circle. They'll readily accept a gas engine with near diesel efficiency than an actual diesel. As much as you'd like to make it so, diesels aren't even on the map for the vast majority of consumers.

So few would rather have a 55mpg diesel Aura than a 38mpg HCCI Aura? I'll bet if they put both on the lot I could tell ya which ones would sell. Especially once gas is going for $4+ per gallon. Diesels aren't on the map for most consumers because no one knows about them. We get bombarded with advertisements bragging about 35mpg Aveos and 29mpg Avengers and how "fuel efficient" they are, not knowing that in Europe an Aveo would be below average for fuel economy.

[K-1]

Originally Posted by lbhskier37

So few would rather have a 55mpg diesel Aura than a 38mpg HCCI Aura? I'll bet if they put both on the lot I could tell ya which ones would sell. Especially once gas is going for $4+ per gallon. Diesels aren't on the map for most consumers because no one knows about them. We get bombarded with advertisements bragging about 35mpg Aveos and 29mpg Avengers and how "fuel efficient" they are, not knowing that in Europe an Aveo would be below average for fuel economy.

Yep. Diesel = "Eew... smelly."

38mpg HCCI AURA = ~$22k with $3-4/gal fuel or $2-3/gal E85 fuel
45mpg diesel AURA (55mpg '08 EPA rating in La-La Land maybe) = ~$28k with $4-5/gal fuel

[lbhskier37]

Originally Posted by K-1

Yep. Diesel = "Eew... smelly."

38mpg HCCI AURA = ~$22k with $3-4/gal fuel or $2-3/gal E85 fuel
45mpg diesel AURA (55mpg '08 EPA rating in La-La Land maybe) = ~$28k with $4-5/gal fuel

Why would a diesel be $6k more than an HCCI engine? $2k max would be the premium for a diesel engine over a standard gasoline engine, and you know an HCCI engine would also come with a price premium.

Ethanol is a joke and is only cheap because we are paying for it out of our taxes in government subsidies.

If you've noticed the price spread between gas and diesel is not $1 and has gone down. That price spread will continue to go down and there is no reason to believe diesel will remain above gas in the long term.

And for the EPA rating, the Vectra is rated at 49mpg highway with an out of date diesel engine. Put a modern commonrail engine in it and 55mpg wouldn't be out of the question.

[K-1]

Originally Posted by lbhskier37

Why would a diesel be $6k more than an HCCI engine? $2k max would be the premium for a diesel engine over a standard gasoline engine, and you know an HCCI engine would also come with a price premium.

The Duramax upgrade on the HD trucks is $7k, I believe. I was actually being generous.

Ethanol is a joke and is only cheap because we are paying for it out of our taxes in government subsidies.

An emerging renewable fuel proposition needs to be subsidized to survive against Big Oil. Last I checked, your diesel is still imported, thus degrading our GDP. Pick your poison.

If you've noticed the price spread between gas and diesel is not $1 and has gone down. That price spread will continue to go down and there is no reason to believe diesel will remain above gas in the long term.

Yeah, it's only $1+/gal more expensive for 8 months out of the year. There's no indication that diesel prices won't keep increasing with the price of oil. Up demand a bit and we'll be enjoying winter prices all year round. Renewables, hydrogen, electricity - our "long-term" future is combination of these, not diesel.

And for the EPA rating, the Vectra is rated at 49mpg highway with an out of date diesel engine. Put a modern commonrail engine in it and 55mpg wouldn't be out of the question.

We live in the United States, there is no '08 EPA-rated diesel Vectra here, out of date or modern.