Piston Slap: The Italian-American Job

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.