Lasar

[rv72004]

The Lasar has a optional CHT probe system to retard timing if temps get too hot. If I use this I have to get the dual probe CHT as required. I have spoken to some who say its not needed.
What have others done ?
Where can I buy the dual J probe M5340-03 to use with my engine system and Lasar together ?

[Rosie]

I've been running LASAR since hour #1 on my O360-A1A and do not have the optional CHT probe system installed. I've never had a CHT temp problem, now 2400+ TTSN Rosie

[AlexPeterson]

From a practical point of view, the temperature feedback is not needed, provided you are monitoring CHT's. However, if your controller is set up to use one, it will not work without having the probe installed. You should be able to dig around on Unison's website to find out which models use it.

I would suspect that you can get the probe from Unison, the manufacturer.

[tacchi88]

Had 900+ hrs. with LASAR on my Arrow when sold. It had the temperature probe, and the more information the computer can absorb, the better LASAR is able to perform. Without the probe, timing reverts back to base timing above 2500 rpms, where as with CHT it works throughout the entire range. Managing timing is a wonderful aid to our primitive engine, the more info the better.
If we had TPS, Knock sensors, and a host of others such as our autos have, we would gain even more performance, and economy. Full FADEC would even be better, managing timing, and fuel as well.
T88
RV10/LASAR

[walter]

Originally Posted by tacchi88

Had 900+ hrs. with LASAR on my Arrow when sold. It had the temperature probe, and the more information the computer can absorb, the better LASAR is able to perform. Without the probe, timing reverts back to base timing above 2500 rpms, where as with CHT it works throughout the entire range.

I beg to differ. The only thing the CHT probe does is to begin to retard
the timing once the engine gets to a CHT of 450. The probe was designed
for Certified aircraft. It's not needed in our experimentals. Without it, you
control the CHT temperatures by increasing mixture, reducing power or a
combination of both. Without the probe the timing continues on it's merry
way to 45 degrees BTDC as MP and RPM dictate along it's fixed timing curve.
You have no control over it save for the MP and RPM input, which you do have
control of. This is one of the reasons I ditched my LASAR system and went
with P-mags. Soon enough, we will be able to control timing from within the
cockpit with P-mags. And we can affect the timing advance now on the
ground.

As stated before, make sure you ask for the "brain box" which does not
require the CHT probe. If you would like, I will sell you my complete LASAR
system for a bargain basement price. I have yet to find the time to put it
on e-bay. It's a great system but I wanted something more "experimental"
that I could manage my CHT temps with, hence the P-mags. And I'm talking
basement prices here. New LASAR sytem is $2500. I'll sell my system that
only has 25 hours on it for $1250 complete. Pls, contact me offline.

[tacchi88]

I believe you have some erronious information. The non CHT LASAR is indeed available for certified AC, and nowhere does Unison market an "Experimental only" LASAR. As to the CHT information, it is used throught the operating range of the engine. One feature is the avoidance of the "shock cooling" effect, in which the CHT version will maintain reasonable engine operating temperature, and opposed to extreme cooling of cylinder head temp.
Managing timing requires many bits on information, the more info is available, the better the selection of required timing. Unfortunately for our antique engines, we are liminted.
I know of at least one occasion where the CHT probed LASAR saved the pilots bacon. He complained of loss of power. An engine check revealed low compression on one cylinder. Compression loss was due to a loosened exhaust valve seat. The cylinder was the CHT probed. Subsequent checks on the remainder of the engine revealed cracks on on the remaining cylinders including one with a loose intake seat. The cylinders where "repaired" by a less than reputable shop. Cylinders since replaced with new ECIs, to date same engine has logged more than 1000hrs. LASAR/w CHT, still ticking away.
T88

[gmcjetpilot]

Originally Posted by tacchi88

If we had TPS, Knock sensors, and a host of others such as our autos have, we would gain even more performance, and economy. Full FADEC would even be better, managing timing, and fuel as well.
T88 RV10/LASAR

TPS, throttle position sensor is not a hard thing to but does nothing on its own. However a Knock sensor on an air cooled engine with 5 inch diameter pistons, I dare say, is impossible.

Knock sensors use vibration or sound transducers. On an air cooled engine noise and vibration are too great to use these sensitive sensors, at least to date. Who know in the future, but in a Lyc if you are detonating you are already in trouble due to air cooling and large bore pistons. The solution thankfully is easy, don't detonate, which is operate so we're well below detonation margins.

Cheers George