Buying Tips for Performance Chips

Chips, handheld tuners, engine control units; they are all used to change the power output of an engine and the shifting of automated (automatic and automated manual) transmissions. The problem is how to choose based on their claims. Based on a friends 997 Porsche Twin Turbo shopping experience, there are certain things to be aware of and questions to ask if you're new to modding your car and there are no clear choices.

It's easy enough to buy on owners recommendations and write-ups in the forums. Not everyone is of the mindset for maximum horsepower though. Some don't even want to void their warranty. Go figure. Sometimes ownership of the car determines your choice. Not so with an LS1 Fbody (Camaro/Trans-Am). There are a ton of choices written up here.

The biggest controversy is horsepower claims. Where do the numbers come from and how are they measured? Keep in mind the biggest horsepower gain isn't always the best choice for your application.

Factors to consider are numerous. Will quality be affected? If supercharged or turbocharged, will the sparking life be shortened? Will there be an octane sensitivity other than a simple race gas tune? Is dyno tuning allowed for more exact and correct tuning or is a "canned" tune all that is available? Perhaps both are possible. Sometimes other vehicle electronic controls are tapped to control the level of the tune from stock to tuned to race gas. For example of this is using the cruise control button to select the tune. Sometimes, you just don't have a choice and have to go with what's available.

Are the horsepower claims taken directly from flywheel or from the dynometer? If taken from the flywheel, the implication is that the engine was removed and tested under controlled conditions. A time consuming and expensive process but more accurate.

If taken from the dynometer, and quoted as an estimated flywheel increase, what percentage loss are they calculating? Keeping in mind there are minor variations in production tolerances for horsepower ratings. One engineering team said 2% is allowable for their line of performance engines. An engine can also make more power when running cool vs. at normal operating temperature vs. running hot or "heat soaked". Taking all this into consideration, claims AND your results can vary wildly.

Was the car modified with intake and exhaust changes that show a greater horsepower enhancement than bone stock? Was 91 octane gas used vs. 93 octane? California is stuck with lousy 91 octane gas and therefore the goofballs at C.A.R.B. (California Air Research Board) dictate the octane auto manufacturers must comply with, among other restrictions. But other parts of the country have 93 octane available at the pump and there is and that allows for a little more power if tuned for it.

It's possible your emissions may be affected negatively. But that is why the "stock" tunes remain accessible. The performance aspect of the tune may not comply with emission requirements. But many times, the car will get better mileage.

As far as warranty concerns, some say their modified tune doesn't leave a trace when the car comes in for warranty work. Some manufacturers may claim otherwise. Well known BMW tuner Dinan matches the manufacturers' warranty and has a relationship with BMW. If your fellow owners have history, and there are a lot of established ones, enjoy that extra kick in the back and head snap with those shifts!
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Have a question about cars you would like answered? Want to know about performance, racing, modifying, shopping, makes, models, events, etc? Ask me here: AskRobAboutCars@gmail.com and I'll do my best to answer your question and publish it here on Examiner.com!