- Joined
- Jul 27, 2010
- Messages
- 5,820
- Reaction score
- 927
- Location
- Blouberg, Cape Town
- Bike
- KTM 890 Adventure R
As BoosterPlug dealer I had a lot of questions on the effect of aftermarket pipes: What is the effect of an aftermarket pipe and filter on a bike's engine? Will it damage the engine? Why does the BoosterPlug work so well in combination with aftermarket pipes and filters?
Jens Lyck from BoosterPlug answers:
Most aftermarket filters and exhausts will flow a lot more air at higher RPM, but at low RPM's the difference between the resistance in the original exhaust and the aftermarket system is minimal - so in low RPM conditions, the AFR (Air/Fuel Ratio) is almost the same.
Good News: In a modern fuel injected bike, there's no risk of damaging the engine by running it too lean when you install an aftermarket exhaust or K&N filter - because the O2 sensor in the exhaust will adjust the mixture back to the original AFR in all closed loop situations (Higher RPM).
Constant medium and high RPM are closed loop operation, and the O2 sensor is in charge here.
The BoosterPlug is active in open loop conditions (which is idle, low RPM and during acceleration and engine braking. See the BoosterPlug.com website for a full explanation on open loop and closed loop).
But as the aftermarket parts will flow slightly more air in low RPM conditions too, the drivability will be even worse than on the stock bike. Normally we see the open loop AFR increase from around 14,4:1 (stock exhaust) to 14,5:1 with aftermarket exhausts fitted, and now you really need the small controlled fuel enrichment from the BoosterPlug to restore the smooth throttle action and to prevent the engine to stall easily.
Because the AFR difference (between the stock system and the aftermarket parts) is relatively small in open loop conditions, the BoosterPlug works with all combinations of exhausts and filters on the bike (the BoosterPlug is only active in open loop).
You are far worse off if a Power Commander was installed, where the O2 sensor is removed/bypassed - and then changed the exhaust. Now you would have to dyno and set up the Power Commander correctly again to avoid running the engine too lean all the time - with the risk of damaging the Whengine.
So, the fact that the BoosterPlug works in cooperation with the O2 sensor in the exhaust makes it possible for our device to cover all combinations of exhausts and filters.
Jens Lyck from BoosterPlug answers:
Most aftermarket filters and exhausts will flow a lot more air at higher RPM, but at low RPM's the difference between the resistance in the original exhaust and the aftermarket system is minimal - so in low RPM conditions, the AFR (Air/Fuel Ratio) is almost the same.
Good News: In a modern fuel injected bike, there's no risk of damaging the engine by running it too lean when you install an aftermarket exhaust or K&N filter - because the O2 sensor in the exhaust will adjust the mixture back to the original AFR in all closed loop situations (Higher RPM).
Constant medium and high RPM are closed loop operation, and the O2 sensor is in charge here.
The BoosterPlug is active in open loop conditions (which is idle, low RPM and during acceleration and engine braking. See the BoosterPlug.com website for a full explanation on open loop and closed loop).
But as the aftermarket parts will flow slightly more air in low RPM conditions too, the drivability will be even worse than on the stock bike. Normally we see the open loop AFR increase from around 14,4:1 (stock exhaust) to 14,5:1 with aftermarket exhausts fitted, and now you really need the small controlled fuel enrichment from the BoosterPlug to restore the smooth throttle action and to prevent the engine to stall easily.
Because the AFR difference (between the stock system and the aftermarket parts) is relatively small in open loop conditions, the BoosterPlug works with all combinations of exhausts and filters on the bike (the BoosterPlug is only active in open loop).
You are far worse off if a Power Commander was installed, where the O2 sensor is removed/bypassed - and then changed the exhaust. Now you would have to dyno and set up the Power Commander correctly again to avoid running the engine too lean all the time - with the risk of damaging the Whengine.
So, the fact that the BoosterPlug works in cooperation with the O2 sensor in the exhaust makes it possible for our device to cover all combinations of exhausts and filters.
