Chevrolet Cruze Eco Question???

[99LeCouch]

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.

[gone-ot]

...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:



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

[Tygen1]

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.

[Fat Charlie]

Originally Posted by SentraSE-R

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?

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.

[SentraSE-R]

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.

[EdKiefer]

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 .

[doomz78]

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.

[cfg83]

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

[EdKiefer]

Originally Posted by cfg83

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 .

[gone-ot]

...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!