The Walking Eye writes:
Sajeev, I was reading (a recent) TTAC diesel engine thread and got to thinking about what it would take to slap a small diesel into my Cobalt. I’ve got the super base model w/ the 5-speed and so long as I get good gas, I get really good mileage out of it. However, I’m from IN and we’ve got crappy gas with extra additives that kills my mileage from 10-20% depending on the time of year. If I decide to do this, I’d aim for a small engine with around 150 hp and mileage in the high 40s.
I guess my main question is, how involved would this project be as far as other equipment that would need to change along with the engine? New tranny, computer, driveshaft, etc?
Sajeev responds:
Pushing small GM platforms to their peak efficiency, eh? Are you the ghost of Smokey Yunick?
You have a fascinating idea. I was fortunate to cover the Society of Automotive Engineer’s Challenge X competition. Credit where it is due: my X-citing discussions with the good people from GM Powertrain came to mind after reading your question.
Me thinks that finding a good diesel motor in the States will be impossible, so you’ll need a European vacation. Luckily, the GM nerds and SAE kids already did it. The Chevy Equinoxes used by those engineering students had the full range of GM’s powertrain family at their disposal. Which, at the time, included the FIAT 1.9-liter CIDI engine.
It would make for an absolutely wicked Cobalt Diesel Frankenstein-mobile. If your transaxle won’t work, the SAE students found a six speed unit in GM’s arsenal that will. Or, at least did.
You’ll need all of the Fiat’s wiring and computer(s), or a standalone ECU that’s worth more than the trade-in value of your Cobalt. Then you’ll buy/make a new fuel system, and the necessary particulate filters to make your Diesel Cobalt nearly as enviro-friendly as a stock Chevy. If you care about the environmental impact of your efforts, of course.
Oh, and it may never run right, even after spending tens of thousands on parts. I’d recommend getting a used Jetta TDI ($17,000) instead. Or drive what you got, and enjoy carefree operation and super low emissions.
Bonus! A Piston Slap Nugget of Wisdom:
Perhaps this parallels the reasons why GM didn’t make a go of the Fiat relationship. If so, here’s a question to the FIAT-crazed Bob Nardelli: will you support the Chrysler Tech—who fixes Neons and HEMIs—when they can’t figure out WTF is wrong with a misfiring Punto?
And what about five years from now? If not, don’t expect the consumer to spend their cheddar at your dealerships.
Sajeev, he mentioned a driveshaft. I think he may have wanted to give the Cobalt a RWD conversion also. You left out the details for that.
My recommendation would be to find a Chevy diesel pickup, take out a bit of the wheelbase, and put the Cobalt body on top.
Sajeev already said what needed to be said, so I’m going to ask a wacky OT question: what about a liquid propane conversion? Apparently you can buy kits for older cars, would it work for a fuel-injected Ecotec? It might burn cleaner than your crapped-up Hoosier gasoline.
and the necessary particulate filters to make your Diesel Cobalt nearly as enviro-friendly as a stock Chevy. If you care about the environmental impact of your efforts, of course.
IN won’t care. No emissions testing in the Hoosier state woot!
If he lives in lake county IN then he get the same crappy gas the rest of Chicagoland does.
there was a film clip on the topgear website about dropping a VW TDI into a old rabbit.
but frankly I think he would better off takeing a trip to Mexico and buying a Diesel there and bringing that back.
a diesel rwd cobalt. interesting. but good luck with that.
Even if it was technically doable, you might run afoul of the EPA or local authorities for modifying the car. What seems like a great idea to you runs counter to laws on the books about lifting the hood for more than an oil change.
If the owner’s looking for a project, why not develop a water injection system? I remember reading Smokey Yunick’s column in Popular Sciences from the 80’s where people put together systems by themselves to gain significant (I can’t remember an exact number) mileage increases. Smokey would advise that the driver remember to turn it off the water injection system a bit before turning off the engine though, otherwise the water might cause corrosion in the cylinder liners.
Did Jeff Gordon’s crew do the paint job on that Cobalt in the picture?
I’m not sure about the FIAT engines, but I know the Germans have slightly modified fuel systems here in the US vs. their European counterparts. Apparently the diesel fuel here, even the ultra-low sulfur stuff, has way more sulfur than the European diesel. Something to consider if you decide to actually go threw with it. I wouldn’t however.
When Smokey sings…I hear violins!
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no_slushbox : Sajeev, he mentioned a driveshaft. I think he may have wanted to give the Cobalt a RWD conversion also. You left out the details for that.
My recommendation would be to find a Chevy diesel pickup, take out a bit of the wheelbase, and put the Cobalt body on top.
Ugh, this sounds painful. Better off with FWD to get his targeted goal of 150hp and high 40s for MPG. That automatically disqualifies many (if not all?) right-wheel-drive diesel motors.
That used Jetta looks better and better in my book.
friedclams : Sajeev already said what needed to be said, so I’m going to ask a wacky OT question: what about a liquid propane conversion? Apparently you can buy kits for older cars, would it work for a fuel-injected Ecotec? It might burn cleaner than your crapped-up Hoosier gasoline.
Mileage will be an issue, if I remember my time as a student with the Chrysler/SAE Propane Vehicle Challenge correctly. I don’t recall LPG having the thermodynamic efficiency(?) of gasoline…but I’ve forgotten a lot of stuff in the past 12 years.
And good luck having a propane tank (at 100+ psi, you cannot use the stock system) with any serious range in the stock location. You’ll need the stock place and a big chunk of the trunk for this project.
But maybe LPG conversions have improved since the days of Chrysler’s Propane Vehicle challenge. I’ll be open to it.
The LPG conversion would probably be easier, since you should be able to keep the engine…not sure if a re-flashed ECU is in order here, but I expect it is.
My grandfather used to run LPG in a dual-fuel setup back in the 70’s. He would buy a new GMC pickup and take it right from the dealer to the propane place for the conversion. They’d throw a big-ass 50 gallon tank in the bed and hook up a switch inside to change from LPG to gasoline. But those old 454’s had carbs, not fuel injection and computers running them so the conversion was much easier.
There was a power penalty with LPG as well, which is one reason he kept the gasoline option as well. He pulled huge travel trailers through the mountains, and would always switch to gas when he started uphill.
One big bonus was the huge range he got. With the 50-gallon LPG tank and dual gas tanks, it was a long, long time between fill-ups. Nowdays, you’d have to sell a kidney to fill it up, but it was reasonable back then.
ScottMcG : The LPG conversions from yesteryear are nothing like the new ones. Most (all?) of those carbed systems were gaseous phase injection, as propane needs 3-4x more pressure in a fuel system to become a liquid. And carbs don’t like those kinds of pressures. By the time the propane reaches the intake runners, its already a gas.
LPG in modern, EFI applications shoot liquid propane right before the combustion chamber, just like most cars today. The perk is that once LPG leaves the injector, it goes from liquid to gas, making a cooling charge and allows for denser air and more power…than the old school carb conversions.
The downsides are that the new conversions are pretty expensive, and LPG has lost traction to the Ethanol boondoggle, Hybrids and other alternative fuel ideas.
And, performance wise, using our current gasoline infrastructure actually works better. (even though we all hate to admit it)
I worked (off and on) for two years on the Challenge X project at one of the participating schools. In our Equinox, we had the diesel hooked up to an f40 6-speed transmission. This combination is identical to the configuration in an Opel Vectra. I never saw the engine separate from the transmission, so I do not know if the Fiat diesel shares a GM bellhousing pattern.
If the Fiat diesel shares the Ecotec pattern, it would easily bolt up to the f35 in the Cobalt SS Supercharged/Turbocharged. I’ve seen some reference to the f35 and f40 sharing mounts, so the f40 itself may bolt up to Cobalt SS mounts. You’d likely be on your own for engine mounts and axles, though.
Computer/Wiring would likely be a nightmare. The Fiat diesel is drive-by-wire, so the accelerator has to come with the setup. Making the necessary modules talk to each other could be overwhelming. We had access to the pcm programming, but I can’t get that for anybody…too many non-disclosure agreements.
So if you really want a small diesel, then it’s what Sajeev said – just buy a Jetta TDI.
By the time you spend the money to buy another car (Jetta) or modify your vehicle in one way or another, —which I’m assuming you’ve read what it will take and are now against the idea— you will spend more money than you’ll save on the fuel mileage. If you have the “super base cheap model” that my sister has, then it’s the XFE model and you should be able to get mileage well into the 30s if you drive it right. If you don’t have the XFE, then you can most likely put the smaller tires from the XFE on your Cobalt and remove the spare, which is pretty much the difference anyway. If you go that route, make sure to pick up a can of fix a flat, just in case.
@Sajeev
Regarding the bottom of your article, “et tu, Sajeev?”
FromBrazil: Let’s hope my translator worked correctly…não uma possibilidade.
But I listen to everyone in this business. And you can learn a lot from service techs.
Philip Lane : I worked (off and on) for two years on the Challenge X project at one of the participating schools. In our Equinox, we had the diesel hooked up to an f40 6-speed transmission. This combination is identical to the configuration in an Opel Vectra.
Thanks for posting, Philip. That was the combination I drove and (tried) to reference for this question.
Glad to see it could work, but in your more experienced opinion, shouldn’t be pursued.
To answer questions w/o attributing them:
I hadn’t considered a RWD conversion but wouldn’t be averse to it.
The “super base model” is a 2008 prior to the debut of the XFE. It’s an 08 LS w/o any options. Yes, I’m a glutton for punishment. (BTW, it’s actually pretty fun to drive for me)
This was more a thought exercise than a practical one, however thank you Sajeev. I did a little research on it, which is what ultimately prompted me to send in the question.
Thank you to all the B&B who responded. My gut feeling was that it would be vastly cost prohibitive to convert it and Sajeev’s response and yours cemented that.
Now, how about slapping a turbocharger on it? :)
friedclams :
what about a liquid propane conversion? Apparently you can buy kits for older cars, would it work for a fuel-injected Ecotec?
I know somebody with a 2001 Astra with the 1.8 Ecotec and a LPG kit. Stuff like that is available everywhere in Europe.
The Walking Eye : Now, how about slapping a turbocharger on it? :)
Probably not a good idea, since its more cost effective to get a new SS model with a better suspension, wheels, seats, etc and already has a turbo and a boost friendly short block.
Now if you find a wrecked SS for cheap…
Oh and thanks for picking our collective brains. Piston Slap doesn’t work without questions from the B&B.
May I interest you in a LS4 swap?
http://www.ls1tech.com/forums/ls4-front-drives-2005-2009-108/
I remember being in the student SAE in college. GM gave out Chevy Corsicas to schools that submitted a proposal that seemed plausible to them. Back in the 80’s the challenge was to convert a V6 Corsica to run on methanol/gasoline, i.e. M-85. One of the issues was to heat the intake so you could get the fuel to burn properly. We took the electronics from the Ford Instaclear windshield clearing system to allow the alternator to run unregulated so we could use electric heaters to warm up the intake for better cold running. I have the same feeling now that I did then…GM was looking for some R&D on the cheap!!