Re: Spark Plugs
If there is misfiring in the engine then a more intense spark may help the burn start up in a more stable manner. Misfiring just like detonation is not always detectable by human feel or hearing - so though the base engine may appear to be running fine and then after the ignition hop up may yield power giving the impression of a power gain, when in fact it is a recovered loss.
There is no relationship between spark intensity and speed of flame propagation. Let me put it this way.. Taylor, Blair, Heywood, Lumley... none of them ever mention anything remotely related to spark intensity affecting burn rate. What they do mention as factors to burn speed are all the usual - AFR, charge turbulence as directly related to engine speed, cylinder geometry and chamber design. All they say about ignition is that it is a start to the burn.
There is a relationship between spark intensity and when the flame propagation begins, IF the original spark wasn't intense enough to carry out the job it was supposed to be doing in the first place. If the original spark was doing its job, then the difference between normal plug and fancy plug ranges in mere us-time / fraction of a degree, as mentioned.
It potentially leads to earlier start of combustion, not that combustion is any faster.
Any time you make combustion significantly faster, you experience big gains in power because more of the force can be applied closer to the optimal crank angle. This is not what's happening, no matter how intense the spark is. To maximize gains, on top of the shorter combustion event, you need to shift ignition again to re-center 50% mass fraction burn over the optimal point, yielding best torque.
Kistler makes some offert sparkplug adapters that allow you to fit the sensor next to the sparkplug. Maybe you can get those?
We don't have a intruded mule engine on which we test plugs or other individual components. We have an engine cycle analyzer that is specifically designed to work with our SF-902 engine dyno as well as the older 901. It references crank angle to non-intrusive sensor-on-plug system. It is not a system that allows you to use other plugs, so I don't think it can be of help in the tests you seek to conduct.
In any case we don't use it much at all because of all the distortion of even the finest components in both the lower and upper assembly at near 5 digit RPMs and 32m/s mean piston speeds. The harmonics are crazy and piston position is never really known esp the furthere away from the crank snout you get. Charging variances between cylinders also starts to occur because of the valvetrain distortion with even the cam core twisting!
Dyno cell time is also at a premium with all the stuff going on daily. Would need a fairly substantial project to squeeze something like this in on.
yendor said:
If there is misfiring in the engine then a more intense spark may help the burn start up in a more stable manner. Misfiring just like detonation is not always detectable by human feel or hearing - so though the base engine may appear to be running fine and then after the ignition hop up may yield power giving the impression of a power gain, when in fact it is a recovered loss.
There is no relationship between spark intensity and speed of flame propagation. Let me put it this way.. Taylor, Blair, Heywood, Lumley... none of them ever mention anything remotely related to spark intensity affecting burn rate. What they do mention as factors to burn speed are all the usual - AFR, charge turbulence as directly related to engine speed, cylinder geometry and chamber design. All they say about ignition is that it is a start to the burn.
There is a relationship between spark intensity and when the flame propagation begins, IF the original spark wasn't intense enough to carry out the job it was supposed to be doing in the first place. If the original spark was doing its job, then the difference between normal plug and fancy plug ranges in mere us-time / fraction of a degree, as mentioned.
It potentially leads to earlier start of combustion, not that combustion is any faster.
Any time you make combustion significantly faster, you experience big gains in power because more of the force can be applied closer to the optimal crank angle. This is not what's happening, no matter how intense the spark is. To maximize gains, on top of the shorter combustion event, you need to shift ignition again to re-center 50% mass fraction burn over the optimal point, yielding best torque.
Kistler makes some offert sparkplug adapters that allow you to fit the sensor next to the sparkplug. Maybe you can get those?
We don't have a intruded mule engine on which we test plugs or other individual components. We have an engine cycle analyzer that is specifically designed to work with our SF-902 engine dyno as well as the older 901. It references crank angle to non-intrusive sensor-on-plug system. It is not a system that allows you to use other plugs, so I don't think it can be of help in the tests you seek to conduct.
In any case we don't use it much at all because of all the distortion of even the finest components in both the lower and upper assembly at near 5 digit RPMs and 32m/s mean piston speeds. The harmonics are crazy and piston position is never really known esp the furthere away from the crank snout you get. Charging variances between cylinders also starts to occur because of the valvetrain distortion with even the cam core twisting!
Dyno cell time is also at a premium with all the stuff going on daily. Would need a fairly substantial project to squeeze something like this in on.
