The superchip?
June 23, 2005 11:08 AM   Subscribe

Are the fancy aftermarket chips for your new truck too good to be true?

A friend is buying a new diesel truck and is very excited about adding an aftermarket computer chip. Others are claiming increased power and gas mileage (to the tune of 6 miles per gallon). If this is for real, why don't the manufacturers install them in the factory? I'm sure they'd love to advertise such a dramatice mileage increase.
posted by MotorNeuron to Travel & Transportation (5 answers total)
Best answer: Some are legitimate, many others are not. Is the truck turbocharged? It's generally easy to extract more power from a turbocharged engine by increasing the boost from the turbo. The downside is increased wear/tear on the turbo and higher chance of detonation. Fuel mileage can be increased by leaning out the fuel mixture on cars/trucks with computer controlled fuel injection. From the factory, cars tend to run rich (lower air:fuel ratio) to be safe, because the extra fuel keeps the combustion temperatures down. Leaning out the mixture will increase power slightly, increase mileage, and push you closer to the danger zone of detonation.
posted by knave at 11:30 AM on June 23, 2005

By the way, a 6mpg gain is significant and unlikely, in my opinion. I'd like to hear about it, if he did actually gain that much.
posted by knave at 11:51 AM on June 23, 2005

Best answer: The Cartalk Guys have talked about various alterations and whether they were snakeoil or not and one thing they have commented on several times is that many people who do these things DO see an improvement... because in a subconscious desire to get the positive result, they alter their driving style. Less jackrabbit starts and stops could very possibly get you 6mpg.

On the flip side of the question, why wouldn't a manf just install something in the factory, there ARE tradeoffs made by auto manufacturers on many matters. There are a near infinite number of choices they can make and they certainly could pass up something that got you better mileage but resulted in higher in-warrantee repair costs, for example.
posted by phearlez at 12:14 PM on June 23, 2005

I once interned at a diesel engine design shop, although they didn't make engines for trucks.

People who bought our engines would often switch chips to get more power or whatever performance boost they were after.

The reason the maker did not ship with the more powerful chips is that the material used in the lower powered engine was not rated for the high power. Thus, with a more powerful chip, the engine would wear out faster, or at least require more maintenance.

Again, I'm not saying this is true for the road vehicles.
posted by achmorrison at 1:30 PM on June 23, 2005

Also, the factory settings are tuned to meet emissions standards.
Don't some American states mandate an emissions check every year? (California maybe?)
If the chip causes the car to fail that test, I think there are fines.
posted by atrazine at 3:30 PM on June 23, 2005

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