Chevrolet Cruze Eco Question???
 

So If I buy thing Cruze Eco 6 speed manual it has a 1.4 liter turbo. Can I engine off coast this kind of vehicle without the turbo exploding? Or hurting the engine?

What do you guys think?

...engine OFF coasting is not a good idea (especially at high speeds) because the turbocharger (which is physically mounted *in* the exhaust manifold) is cooled (coolant) and oiled (oil) by the same coolant and oil that services the rest of the engine.

...if the engine's OFF, so are the cooling and oiling of the turbo, which is VERY co$tly to replace.

...yes, I have a Cruze 1.4LT, an LTZ model, not an Eco, however.

Why would you want to?

As Old Tele man says its not good for the turbo. However, you could work around this by using an electric oil pump. You'd need some nifty way of controlling it as well.

Doomz78, check out this thread on EO(ff)C-ing a turbo'ed car. It was meant for turbodiesels, but the same applies to gassers. The bottom line is that you can kill your turbo'd engine, but you should coast in neutral first for a few seconds to allow it to cool down. This pretty much limits your EO(ff)C to loooong coasts, but even then it may still be worth it.

For example, if I'm driving in rolling hills then I try to have 2-4 engine on coasts between engine offing to make sure there isn't too much (thermal) stress. I don't kill the engine if the coast will be less than 500 meters, unless I'm coasting to a red light. On the other hand, it would have been a sin to keep my engine on during 5-6km coasts in the Austrian Alps, ah...

...unfortunately, there's a BIG difference between a turbocharger bolted onto an exhaust manifold (most other cars and trucks) and the Cruze which (literally!) has it's small turbocharge actually bolted *into* its exhaust manifold (for both turbo "lag" reduction as well as quicker catalytic converter "lite-off").

...if the OP hasn't read-up on the 1.4LT engine in his Cruze, he might consider visiting some of the Cruze forums, such as CruzeForumz.com and CruzeTalk.com, etc.

Just let it cost in neutral instead of turning it off. It will save some wear and tear on your turbo and starting motor.

Can we assume none of the cautions are applicable if you haven't spooled the turbo up within 30 seconds of turning the engine off?

...how "slow" are you driving? it's active between 1850-4900 rpm.

There's no boost gauge? There's a big difference between cruising at 2000 rpm and boosting at 2000 rpm. The turbo only spools a fraction of the time you're in that rpm range, right?

The turbo on the Cruze is making full boost (something insane, IIRC) right around 2000 RPM's after starting to spool at about 1800 RPM's. That's one of the reasons those cars MOVE when the go-pedal is hammered. The Eco really loves getting the snot revved out of it thanks to the long gears.

Making the turbo not spool on this car is very hard. And the car is a real slug off-boost since it's a 3200 lb car lugged around by a 1.4l engine. It's designed to have the boost to get any meaningful acceleration out of it. Just something that Cruze hypermilers will have to work around.

...yes, there is no boost gauge, neither mechanical nor digital on the dashboard display.

...the torque curve is perfectly "flat" between 1850-4900 rpm. Here's the SAE HP & torque graph from the CruzeForumz.com. To my eyeballs it looks like they actually "run" on the boost between those two limits--probably to get the necessary HP out of such small displacement for such heavy (3200 lbs) car:

http://eogld.ecomm.gm.com/images/lig...e_luj_0311.jpg

...and, notice how "flat" the torque curve continues to be beyond 5500 rpm (after a slight drop)!

Interesting thread, I also read through the TDI EOC thread.
To the OP, I think your a little crazy to go EOC'ing a brand new car under waranty...If you are trying to drive a car to get great mpg, it's probably because you want to save money. If you want to save money, then why are you buying a new car that gets much worse mpg than a 1988 Honda?
I work with Turbos and do some failure analysis. However the only turbo vehicle I own is a 7.3 Turbo Diesel Excursion. I've had the chance to dyno a 7.3 while checking turbine housing and bearing housing tempature vs. EGT. At 1100 degree EGT, post turbo, the Turbine housing was around 650-700 degrees and the bearing housing was around 500-550 degrees. This was under a high load on the dyno, thus the high EGT. High EGT is associated with High Load. I wouldn't get caught up on how much boost you are making.
I don't really like the idea of using an electric pump, to many failure modes associated with that, and you'd have to create some significant pressure to get any real benefit, and that would take quite a bit of electricity to make that psi.
Turbo seals are more like piston rings than O-rings. They are designed to always leak a tiny bit to keep them lubed. They are very durable and are difficult to damage, the bearings should die from coking long before the seals, key word is should.
I could definatly see P&G being a potential problem, but as said, it's all about the tempature of the bearing housing and oil, additionaly if you are at high boost (high turbine rpm) and just cut the engine, you would loose oil pressure on a shaft turning 150,000rpm or more! That's not a good idea at all.
I see plenty of hot shut down issues. It starts as a varnishing of the shaft and bearings, then gets worse as the varnish builds and can eventually lead to wear and excessive shaft motion and then.....That being said, you typically have to abuse the turbo very badly to get varnishing, ie. hot shut down and worn out oil. Keeping a good and fresh synthetic oil in the engine goes a loooong ways towards preventing these issues. Blah Blah Blah....you get the idea.

I'm a bit crazy, so I would probably EOC, then tear down the turbo regularly to see what's going on. If you can manage the load, temp's and turbo rpms, you could probably do it without causing varnish.

That's what I do. That and I always seem to be changing the oil- small turbos like to drink the stuff, so I never give it a chance to run out and always keep it fresh.

That torque/hp graph sure does look like the mild (6 psi?) turbo's boosting in the whole 1950-4900 rpm range, alright. Wayne Gerdes said P&G doesn't work with the Cruze. I guess we know why, now.

Guys don't even bother to look if its not making boost . On a much larger turbo's (more mainstream) they generally "idle" at like 20k rpm and under full boost go to 100k .
I don't know on the Cruze but since its smaller, closer to valve exit and very responsive the idle speeds could be higher .
Don't shut engine off and let it cool down if you were pushing on it .

Don't know if there still around but there were add in electric pumps to prime and run after engine shutdown, along with bunch of turbo timers which just don't let engine turn off till xx time after key is pulled .
Never used the add-in pumps but they supposedly worked .

I will end up buying the base engine for 2700$ cheaper. The difference in gas between the 1.8 base car and 1.4 turbo eco model is maybe 400$ a year.

And the base has 16 inch tires. (Cheaper maintenance)

So it would take 6 years to pay for the difference in price with better mpg of the eco model.

With the price of tires I will round out the difference at about 7 years.

And I can engine off coast with the 1.8 liter. I am very certain that I can achieve the Eco MPG numbers with the base model with tire inflation, and my scan gauge 2 and just basic hypermiling techniques. I may be able to supass them actually.

That's the side im leaning on now. Base model.

doomz78 -

Yeah, the base model sounds like a good compromise. It seems like a lot of the new eco-tech cancels out some of our strategies. I'd hate to lose EOC in order to pamper the turbo.

Maybe you could slowly get your hands on the Eco aero-options over time. I would hope that the closing grill could be just "hooked up" and the ECU/PCM would recognize it and use it, but maybe that's asking the software to be too flexible.

CarloSW2

I doubt very much you could do that without firmware update "if" ECU the same .
well the base 1.8L in 3400lb vehicle sound like it be slugish . I think I would get something else, lighter . hell even accord 2.4L is only 3100-3200 in low trim .

...some people with manual Cruze Eco's are getting into the 50+ mpg's, so all isn't lost.

...but, the automatic Cruze Eco's are nowhere near that successful!

the 1.8 liter base model is 3150 lbs roughly. Im a hypermiler, so sluggish is what I do anyways. Its my driving style. The front grill is black and all i do is use gorilla tape on the grills for a block and I will install my scan gauge 2 and use my PSI inflation strategy to match the ECO's mpg. The accord is not as good on gas and it is more expensive.

I tend to look at best value for money. And I care about safety since I have a little one. The Cruze is a smart compromise in every category in my opinion. At 17000 CAD... In my opinion its a steal.

When I look at a new purchase I look at maintenance cost. Safety. (if you're dead hypermiling means nothing) MPG, Insurance cost, Since te base isnt a turbo model ins will be cheaper.

Nothing a (partly) (removable) grill block can't solve ;)

I'd have it delivered with good LRR tyres, if the regular Cruze doesn't come with them as stock.

Being in Canada, you could get the Michelin Energy Saver LRR tyres.
IMO the best compromise between eco and fairly decent handling.