- Thu Apr 26, 2012 3:22 am
#302909
Less air in the engine means less fuel burned. If you bolt on parts that allow more air in, especially on an ECU that isn't tuned for it, you will hurt mpg.
Increasing an engine's power increases mpg only under certain circumstances. If you live in a hilly area, and find that you are heavy on the throttle from frequent stops, then increasing the engine's output helps you get up to cruising speed faster. The point after you've backed off the throttle is where you achieve your best fuel economy.
An engine requires all of it's hp to accelerate and then only 8-12hp to cruise. If you've increased the output beyond what is necessary you burn excess fuel while cruising.
If you have a 1.5 liter 8 valve engine and find that you frequently require lots of throttle, your best bet is to get a small turbo. NOT AN N/A SETUP. You boost under acceleration but under cruise you're at atmospheric pressure. Turbo setups are complex and expensive, so if cost savings is your only goal, it will never make sense. But if a mix of performance and economy is what you're after, then you can piece together a setup from late eighties junkyard parts and create quite a little monster. Ultimately, it's the quality of the engine management and tune that will determine your success or failure.