Quote:
Originally Posted by islanderman7
Alex what do you mean that the FI smooths the throttle response? Can you elaborate more as compared to a the carbureted.
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I meant that a power commander installed on a FI bike smooths the throttle response compared to a FI bike without a power commander. In terms of carbs versus FI, many folks still feel that a good carb setup provides smoother throttle response than some FI systems, but most folks agree that FI has gotten much better over the years and the best ones are as good or better than carbs.
Carbs, being purely mechanical devices that are finicky but still rather simple, can't perfectly meter the fuel/air mixture at all points of operation from full throttle low revs to part throttle high revs and all combinations in between, let alone taking into account different temperatures and pressures. They do a reasonably good job at full throttle for peak power, and they do a good job at idle when they are synced properly.
Fuel injection, which today generally means computerized fuel injection, provides the engineers the ability to very finely decide how much fuel is required depending on throttle position, current engine speed, temperature, air pressure, and likely a few more factors. It can also decide exactly when to apply the fuel to the mixture. However, all of this flexibility is tuned on a production bike to meet emissions. And meeting emissions means the bike is not optimized for best performance, or even smooth performance. It can be particularly bad in part-throttle situations in low to mid revs. What a power commander does is piggyback on the normal engine computer, to instruct the injectors to provide more fuel than the ECU would provide otherwise. When people talk about dyno mapping for a power commander, what they are really doing is tweaking those settings at every 500 RPM or so to optimize power. It looks like +2, +4, +3, +1, +0, etc all the way up the rev chart, the numbers mean how much additional fuel is provided at that point in the curve. The benefit of a power commander on a stock (FI) bike is that the throttle response is smoother, and perhaps there is a small, very small, increase in power at the top end. But if it's 1 hp on a 110 hp 600cc, it's alot. What the power commander is more useful for is if you've opened up the exhaust and the intake, you can add fuel to take advantage of the other changes you've made.