Ecomodding a Cobalt SS/TC
 

I purchased a 2009 Chevy Cobalt SS/TC.

I decided that I would ignore all ecomodding until the car had a proper break in, which I concluded was best after it's first oil change.

7890 miles later that oil change is going to happen in a week or two.

ANYWAYS. The car has a well known engine, the GM LNF 2.0L Turbo 4cyl.

It's built for speed it's currently the record holder as the fastest factory FWD car to hit the 'ring, there are some vids of it to on youtube.

I bought it because speed and power doesn't have to come with a mileage price tag. I currently average high 27s in mixed driving and a generous helping of accelerator pedal. Experiments have shown I can get 37mpg on my daily commute with attentive driving, the right combination of stop lights and forgiving traffic. The turbocharger DOES NOT lend well to pulse and glide, or most other driving habits. It builds boost extremely quickly.

The car has a built in fuel cutoff when coasting in either 4th or 5th gear, however this may not be as efficient as idling and coasting, due to the nature of the beast we will see. Anyways, follow me along and if you have good input help me with a project to have a car that makes 300HP, runs 13s in the 1/4 mile and gets 40mpg daily driving.

I'd like to prove at a bare minimum the car can meet the EPA estimates for the XFE version of the same car.

An update.

At 8488 miles I have changed the oil, switched to a K&N drop in filter and adjusted air pressure to 38 front and 36 rear cold. I also removed the rear seat since nobody is ever in it. It weighs more than I expected, probably 80-100 lbs for backrest and seat together with seat belt assemblies.

The car is factory otherwise.

I had a baseline average with usual driving habits on the same route in the same weather of 31.6mpg.

After a tank of fuel my new average is 34.4mpg

I still haven't changed my driving habits but I don't speed either.

For those interested in knowing what tires I use, they are factory installed Continental ContiSport2 225 width i am not positive the aspect but I believe 35 on an 18 inch rim. They are not eco friendly tires but do roll well.

My next mods will include a coroplast of the underside towards the rear and removal of the high rise rear wing, for both weight and efficiency, though is it possible the wing helps?

Don't forget to add fuel logs for the car so we can keep up with your progress.

Can you show a profile picture of the vehicle/wing? Thanks

its almost dark out, let me go snap a pic of it

http://www.blackoperations.biz/Grey/PIC_0007.JPG
http://www.blackoperations.biz/Grey/PIC_0008.JPG
http://www.blackoperations.biz/Grey/PIC_0011.JPG
http://www.blackoperations.biz/Grey/PIC_0012.JPG

That's the car, didn't bother shopping out the plate...doesn't really matter I'm the only turbo cobalt owner in a 50 mile radius...

Anyways, the wing I discovered is actually at best 8 or 9 pounds, and it appears to have a purpose which is directing airflow not "downforce" just directing airflow slightly...I'm going to test it with and without, the look of it doesn't bother me if it was gone or stayed in place.

I also wanted to mention the reason why I think this car is a good choice. It has the holy grail of fuel injection.

Direct Injection. No need for injector cleaner, no fuel dumping, incredibly reactive to slight fuel and timing tunes and it has the most interesting idle I've heard from a 4 cylinder motor.

Pull the wastegate spring? :)

There are gonna be some fuel logs where my mileage won't be so good...ignore those ;)

I think those cars are pretty sweet.
I think this is a perfect formula for a small car.

Decent size, has the ability to be very very fuel efficent, yet a fast perfromance car when you want to have fun.

When they switched to turbo from the supercharger didn't they set it up to run off of 89 octane instead of requiring premium?

One thing I would suggest is look around online and see if the 15" steel wheels from the entry cobalts will clear the brakes on this car. if they do, you could go down to 15's and add some smooth wheel covers, would save some weight, rolling resistance, and add to the aerodynamics. Also there are plenty of 15" tires that will still give you good grip and improve your economy.

or you could get some light weight 15's.

either way with the right tires your handling would improve because you would be dropping alot of unsprung weight.

however those split 5spokes do look pretty boss

Ok the tire/wheel combo weighs about as light as it can be, no the factory brembos will clear no less that 17 inch rims, and even then it depends on the rim. The car can stop on a dime, and in the cobalt forums everyone has brake problems EXCEPT me, maybe it's cuz I never USE them huh? Everyone around here is a light to light driver, I drive a mile out, time my lights and adjust my speeds even if it means doing 30 in a 55 or 25 in a 45, I always end up with a nice cushion and long stretches without ever tapping the brakes in town.

The tires supposedly average 20-24K miles before change, I have done the math, at the rate my tires are wearing I won't "require" a change by state law until 70K.

one mod Im interested in is fog light cavity inserts that deflects airflow, although all told it may not be that much of a difference. The car is quite aerodynamic already. I plan to focus primarily on drivetrain, synthetic fluids, gear ratios, underbody smoothing, and weight reduction. I drive this car 128 miles, 5 days a week, so even small mods are welcome. If anyone has input for this unique car, I'm all ears. I've read through the ecomodding for beginners, 100 tips/65 tips and very few actually APPLY to this car. The design of the engine the forced induction and direct injection make this car a puzzle for most. I have the equipment to do tunes, so that is the first place I am going to look, analyzing everything and seeing where I can shape the fuel map and timing to suit the sweet spot in my daily drive, the 57-67 mph sweet spot I usually drive within 90 percent of the trip is where I want to trim things if I can.

For the person who said 89 octane, this car can accept any 87 or higher fuel you put in it, however, ambient temp and humidity seem to play hell on this car's overall performance and even mileage, where it affects a normal car, it is amplified with the forced induction. I escape this by running 93 octane, the car then utilizes full timing and cam phasing. We don't have 91 octane here, and 89 is actually 90. WIth the price difference being negligible and doing the math, I pay maybe 15 cents more a fill up for my car to behave perfectly when the weather is hot or humid...or both.

I can guarantee you your fuel maps are set to be too rich. Prettty much every turbo motor is. But if you can get that down to where your still safe, you will notice a big jump in economy numbers.

ill be installing thermocouples before and after turbo to monitor these things, I am a bit worried about EGTs when adjusting timing and fuel maps...

Get a wideband O2 sensor to monitor your A/F ratios. Don't want to run your turbo beast too lean when you re-tune the computer.

Gotta love the turbo 4's huh? Ultimate compromise between speed and economy. You dont hear much about cylinder deactivated v8s anymore huh?

nope, I fear the v-8 will become a very expensive option and have a HUGE tax associated with it.

If they could get an active management v8 setup to shut down when you stop like a prius does, that would cause a huge increase in intown economy ratings.

to answer your comment. The car comes with a factory wideband sensor.

And the car has everything on my personal checklist...

Blow the doors of a mustang gt...check
Blow the doors of a Honda...check
Looks good...check
Turbo...check
Direct Injection, Accurized MAF and Wideband O2 sensors...check
34mpg in a car designed to go very fast, make very hard turns, and stop on a dime...priceless

If you get that kind of mileage and don't use the brakes and time the lights, don't speed. You must drive like my grandmother... WHY do you own a SS/TC ???

Buy a smart car !

Why? Why not? Really it's the only sensible GM product out right now, everything else they have is a poor attempt at "green". This is probably the only turbocharged 2+ liter engine to get this kind of mileage. I am not particular about being eco friendly, I was more being mindful of gas prices and my budget for distance driving.

The turbocharged ecotec is a sure bet in the market right now, the LNF motor won design awards, it has been in the racing scene for 3 years now, 4 if you count the Saturn Sky Prototype. No matter how you look at it, on paper it is the most efficient conventional internal combustion engine available right now. If you measure output versus fuel consumption it would really make you think twice about hybrids.

And Binger was right, the maps are too rich. Since they don't test emissions here, I wasn't particularly worried about high NOx levels here running lean. The fuel map is set to run lean under certain conditions, namely manifold vacuum and rpm. The temperatures are stable and low, right around 850F during normal driving. Stock was even lower at these demand levels, around 700-750F. According to every bit of research I can get my hands, anything under 1100 will not significantly shorten turbo life. I can get away with lean conditions due to direct injection and a water jacketed turbocharger. I keep a close eye on oil and water temps.

I haven't been on in a while, tommorow I'll dig out my gas receipts, I've been keeping track. I'll post everything for the past month, that is all post tuning.

OK, I think the question on most people's mind (like motogp) and myself would be "why would you buy the "turbo" if you drive around like a little old lady. never breaking the speed limit, timing the lights....
why not buy the regular Cobalt LT, or LS or even better the XSI
It just makes no sense to me, why you would need to buy the Turbo??
(in Canada, the Turbo is about $5000 more than an LT)

I have a friend that owns a Mustang V8 & he drives like my mom, why would he not buy the V6?
I guess I just don't understand the logic behind this?

I do like to have fun with it, BUT I have a very long commute to work. I did alot of reserch and learned alot about GM's direct injection endeavors, test drove a few and read alot about their fuel economy, epa says 30 and that's coming from a turbocharged car.

Is it so much to ask to have power on tap, and get very good economy in any situation your not choosing to use all that power, peak power output should not dictate fuel economy and this car fits that bill very well. Alot of people get lost on smaller engines, lower power levels and they don't understand that an engine's efficiency is dictated by its operating load range not it's peak outputs. I make well over 300HP with the tune, yet gained additional mpg in the process. It really is a win win with this car. You can have your sport compact and rather than killing its efficiency with bolt ons and turbo kits, it's an out of the box eco friendly sporty car. And that's why I bought it, it fits closest to my commuter life AND my weekend pleasure drives.

I understand your choice:thumbup:

Thank God there are more people out their like me!!!

oh and to add to that, you gotta remember, this engine is built for turbocharging, so it will last a very long time if it's taken care of and driven at least a bit less harsh than it's design intention, at least more so than the XFI model.

Uhm, All the Caddillac engines do it, Most of the cars w/ V8's from the big three have it as an option or standard, (Hemi's)

Its called Variable Displacement technology. They skip fuel injectors in a pattern to keep all the engine warm and not dry spin any cylinder.

Its how the Northstar engine works and manages to go in limp mode if it loses coolant and still drive 100 miles.

Dave

armygreywolf -

This is pretty neat. Racing enthusiasts will sometimes have two cars, one for racing and one for ecomodding. It reads like you did your homework and found a balance that allows for the best of both worlds in one car.

Apologies if it's already been asked, but is there any way to bypass the turbo for increasing MPG? I think I already know that the answer is NO from other threads I have read in the past, but that would be my holy-grail interest.

CarloSW2

You bought a car that was engineered in Germany at the famous Nuremberg race circuit, designed to corner hard and drive fast. Makes no sense if you intend not to drive aggressively. You want to improve your hp to 300, which would cost you thousands of dollars. But your not even going to use the 260hp you have.
My 06 SS/SC got better gas mileage then my 09 SS/TC dose.
Looks wise there is no real difference between any of cobalts, they all look the same only the rims are different. If you wanted something a little sportier the 2.4L SS with 177hp would have been way better choice for fuel eco. But i do think for eco would have been the XFI model.

The SS/TC dose NOT blow the doors of the
Mustang GT
0-60 5.5 Sec.
Top Speed 145 mph

Cobalt SS/TC
0-60 5.7 Sec. some articles say 5.5 ?
Top Speed 160+ without the big wing...

http://wrmag.nextautos.com/issue/46/145
http://wrmag.nextautos.com/issue/41/35
http://www.roadandtrack.com/assets/d...risonchart.pdf

How many times have you "blown the doors" off of a Mustang?

Ok, to respond to all at once, first, to the Multi-Displacement V8s. It's still a V8, it is still reciprocating against friction, vacuum, consuming energy to increase economy, sorry it can be done better than that. It'd be the arguement of saying I only need one lung, I have two, but need one, are you as efficient with one as you are with two at half the capacity? No of course not, neither is an engine that's alternatively firing cylinders to reduce consumption, the first generation MD Hemi actually got pretty bad mileage.

And to "motogp34" First, to tune the car cost $656.88, I bought the HP tuners cable and program so I could at least have a look at the tables and make minor adjustments, the price also includes the availability of proven tunes for certain amounts of power, all available for download, it even includes the ability to "live" tune the car via datalogging and uploading to HPtuners so their staff can custom tune your car remotely. A mobile mustang dyno at Capitol Raceway outside of Baton Rouge logged just over 300WHP and 313 lb-ft TQ. At this very same track I had an enjoyable weekend, which is where an almost factory 2006 Mustang GT got his butt handed to him. He had the intake, the exhaust, maybe a programmer, I doubt anything else, and he was on street tires.

As I said initially before an obvious attempt at trolling, this car is DUAL purpose.

Things I have done so far include removal of the trunk interior, removal of unnecessary plastics, the spare tire and jack, An HPTuners custom tune with a lean cruise feature. Muffler delete, which was the heaviest thing thus far on the car, at least 50 lbs. I have also added corrugated plastic sheeting, black in color via aluminum rivets to the dead space behind the air damn in front of the tires, while cutting a small directional vent towards the inside of the brakes. I have also added the same material while avoiding the exhaust to everything behind the rear axle. I had also tried wing removal, it turns out I actually LOST .9 mpg on two tanks in the same general conditions with it removed, has since been reinstalled. I also run 43 psi front, 46 rear. I fixed the rear brake problem most SS/TCs seem to have which is nothing more than a lack of lubrication when it was factory installed, that alone gave back .5mpg. The presence of a boost/vacuum gauge gives me a great tool to measure my driving, this is probably the best thing for me in the eco-sport quest.

And yea, I've embarrassed many cars on the track, I don't need to list, but the Mustang is on it, the Camaro SS is on it, the charger SRT8, challenger SRT8, v8 s10, 8100 Vortec Silverado, Several Hondas, including the newer K20 Civic, and an unknown year Eclipse GST, who by chance is also an ecomodder, and he is on this forum...i wish I could remember his screen name, I don't believe the eclipse is on his eco car list though, I've looked for eclipses.

In any case, the car has more than 15K miles on it, I've had no problems with it other than the brakes which was an easy fix, and the shift linkage, which was a warranty fix. I haven't yet broken my 40mpg goal, but I hope I can.

And one last thing, show me a Mustang "faster" than this car, from the factory that can match it's efficiency, or at least come near it's efficiency. OR better yet, HP for HP, find another 300HP car that can break 30mpg. Or at least Chevy's 260SAE BHP and the epa rated 30. The point is I bought it because it is quick, it is nimble, it's efficient and not as expensive as having two cars for two different purposes.

I end up with long term rental cars a lot due to work.

Caddy CTS, Dodge Pickup(Hemi) Seemed to do well for their size, weight etc.

Not saying VDT is the answer but its pretty cool how well it works...

Dave

I was taking about stock for stock, not who's done what to what on a track.
Who cares if the car matches its efficiency, its all about 0-60 or top speed and how fast it goes around the track...

stock for stock I'd still give the nod to the Cobalt SS/TC, not because I own one, but because I've seen it, being in the service for a while you get to see most of the latest cars and go fast stuff guys buy when they get back from Iraq, one such was a brand new mustang gt, it was pretty quick, but the weight of the car is just not ignorable. I had him as soon as I shifted into second. He got me on a launch every single time for obvious..wait a tic, aren't we supposed to be ecomodding? Ahah, anyways, yea, I don't wanna diverge too much here.

I'm very close to 40mpg, my avg and tank avg mpg is all over, but my commute mileage (the actual durations I attempt to be frugal, which is 5 days a week hehe) stands just shy of 38mpg. If anyone can read through this and give me an idea, I'd be grateful, cuz next is tires.

I find it hard to believe you lost mileage taking the big wing off, when is produces to much drag and it wont reach top speed with it on ?

who said it won't reach top speed with it on, it does destabilize because of it's flexibility, but the car has no problem reaching 162 stock with it mounted. And I believe it works like diverters found on SUVs it's designed more to direct flow in a uniform direction, the way the cobalt is designed, I believe without the wing it produces a dirty air current when air mergers between the roofline and the door. Kinda obvious the way the antenna vibrates in the vortex , probably even worse without the wing, though I wasn't paying close attention to that particular detail. GM had no problem with a recorded top speed on the 'ring at 163MPH during the test lapping. The wing isn't the issue I think it has alot to do with conditions whether or not the car will behave, it is extremely susceptible to cross winds, reduces my mileage, even when I slow down to compensate, more than it should IMHO, that's the only downfall of the car, if that engine was in a honda, I'd bet on 40mpg for sure by now. Cobalt didn't really have aerodynamics in mind, oh well though.

I read a review on the SS/TC about the big wing produces to much drag and wont reach top speed, so i figured it would get the worst gas mileage ? I drive a little aggressive, So i ordered a 09 without it...

Do you know of any 17 rims that will clear the brembos ?

I was also told that the SS/TC has a learn down computer, meaning that it doesn't matter what mods you add to the car it will only produce 260/260 unless you retune the car.

Have you tried the car with just the small wing ?

Nothing I've found, BUT you can shave them, then any 17 except OZ will fit. It's very very close, but most will fit just fine. I want 17s because I want drag radials...is that too much to ask ;)

There is something about the wing, I really don't have a clear answer for you, whether variances in road conditions, weather, or I just drove slower (not likely) I really got better fuel mileage with it on.

Two things you should do as soon as you have the chance. One is to remove the muffler, it's not quite 50 lbs of dead weight and there is just a little bit more open tone to the exhaust, the turbo does good to keep it quiet anyways. Two, buy some of that corrugated plastic sheet, Cover up everything under the trunk out to the bottom lip of the ground effects use large head rivets or something equally strong enough to handle constant wind road elements and rain. I also did the front but may have lost a bit of intercooler efficiency. It's actually rated higher in capacity than what it comes with from the factory. Next, and probably the only true benefit without any real work involved, a tune.

Ohh and you wanna see awesome, pump your tires up to 40 front/38 rear. The factory conti sport2s are ok, but they take overpressure pretty well. Anyways, I haven't got terribly evasive yet, If you walk by the car, it looks like a Cobalt...pretty much stock, go underneath it and it's obvious I've been making an effort to keep it somewhat aerodynamic.

boost control
 

I did a little research on turbocharging and I thought you might find it useful. From what I gather, you would be able to install an electronic boost controller along with a wastegate set for a (much) lower boost threshold. If you coupled this with a dual map ecu, you could theoretically have one map for lean burn/maximum economy and another for spirited driving, perhaps even bumping power up into the 310 hp range (at least that's what a solstice gxp is capable of with the same engine, an ecu upgrade and bolt ons). I would expect a virtually no boost 2L ecotec with direct injection and your driving style to consume little fuel on your commute and many mustangs on the weekend.

It's taken me six months to figure out tuning on direct injection turbocharged engine. I have been very very conservative and for a long time I was using a PsychoSteve tune without a single problem (one of the people I believe knows his stuff without question.)

Anyways, my ECM was "locked i.e. certain factory settings are not accessible with the tuning software I had. I have since acquired the same software Vince uses and unlocked the fuel pressure tables, and some other useful things. The car at present is just under 300WHP with quite a bit more torque than I had previously. I have also upgraded the intercooler, downpipe to a (gasp) off road only catless downpipe. These are my only mods at present tune not withstanding.

The tune itself is much like the Trifecta tune, simply stating it has the aggressive tune and the eco tune. The eco tune is tamer, mostly because I use cam phasing and timing to give the engine the longest possible duration to take in air and least amount of time to get rid of it. This slows down the turbo, demand for fuel to keep the mixture in the right spot is also minimized. Theres so much I just don't understand completely about tuning yet I am not comfortable distributing tunes for other people at present. Besides, my tunes are slightly tamer than even superchips.

Anyways, because the engine can phase the cams, it is forced induction, small, direct injected, and I use all synthetic fluids, I put myself at 40mpg regularly now. My goal has been achieved. Sorry for the run away monolouge guys but If there is ANYTHING y'all would like to ask about direct injection, tuning or forced induction I'll do my best with it. And I will have updated pics for the car when the weather presents me with a brighter day.

Ohhh I forgot, I removed the wing entirely and opted for 5 roof mounted vortex stabilizers since then even though they don't do that much at the speeds I drive cleaning up the air movement over the roof in even a small way helps.