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Unread 10-06-2007, 08:44 PM
rsdiol rsdiol is offline
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Default PFS and also LASAR ignition?

Is it true that a PA28 140 with an installed PFS should not install the Unison LASAR ignition system?

If so, what is the reasoning?

I have a PA28 140 with the PFS ceramic short stack and was considering adding the LASAR ignition.

Thanks,
Ron
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Unread 10-08-2007, 09:50 AM
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tstrohmayer tstrohmayer is offline
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Arrow PFS and LASAR

Ron,

My understanding of LASAR ignition system is that it operates by gathering data from the running engine (RPM, MAP, and sometimes CHT) and compares that to data in a pre-defined look-up table. Then, based on those parameters, it decides how to fire the spark (amount of advance, spark duration, spark energy). The effectiveness is partially based on how similar your engine is to the "standard" engine that was used to create the look-up table.

The LASAR system has never been mapped for an engine equipped with a PFS exhaust system. This means that the decisions being made by the LASAR control unit are being based on inputs that it never expected to see. The PFS exhaust changes the RPM, MAP, CHT and horsepower relationships, making the pre-defined lookup table inaccurate.

This isn't to say that the LASAR ignition will not work on your airplane with the PFS exhaust, but our own testing and some customer feedback has shown that the combination of the two mods can yield less than the optimal result from either.

On the other hand, I believe we have some customers that are using both mods and are happy with the results. Unfortunately, since every engine is different, there's no way to know for sure without trying it.

One of the reasons for the creation of this forum is to post actual experiences with various mods. If you decide to go with the LASAR, please post your results, as I'm sure you won't be the last one to ask.
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