CHT's drop 50?!!!!

RV8Squaz · #1 08-14-2016, 06:30 AM

Yesterday I took my airplane up for a test flight after installing my repaired LSE Plasma III and I'm very happy with the results. Overall, my CHT's dropped about 50?F.

For background info, see this thread, particularly my last post, message #66 here:

http://www.vansairforce.com/communit...=140211&page=7

Before the repair, my temps would hit 410-425 by 5000' during climb and I would have to level off and let things cool before continuing the climb. In cruise the temps would settle right around 400? running an excessively rich mixture.

For my test flights, I wanted to try worst case conditions. I launched in the middle of the afternoon with the OAT at 92?. I flew two 30 minute legs, KFFC-KPXE-KFFC, with about 30 minutes on the ground at KPXE. On the second leg, after being heat soaked, I took off and climbed straight to 10,500 while maintaining 100 KIAS. The hottest it got was 385? In the climb and in cruise the hottest cylinder settled at 360 at peak EGT mixture. I tried various altitudes and mixtures and generally saw 345-360?. VICTORY!!!

I want to thank Scott Card again for his original posts. My problem and resolution ended up being IDENTICAL to his situation. His posts and the other contributors to the connected threads have been especially helpful in getting though this. Thank you!

rv8guy · #2 08-14-2016, 06:41 AM

now that's progress!!

scard · #3 08-14-2016, 07:12 AM

How about that! I'm seeing similar results with a borrowed unit. Ours hasn't gone back to Klaus yet, but probably will soon.

Ed_Wischmeyer · #4 08-14-2016, 11:29 AM

Talked to the Lycoming tech rep at Oshkosh, and at least got the O-320, maximum allowed sustained CHT is 435. Don't remember peak allowed CHT.

rayagriflite · #5 08-15-2016, 09:12 AM

If I'm seeing similar results...is there a method to determine if my Plasma needs service? Did the bad capacitor show up with just a mag timing check?

I checked the other thread, just didn't see much posted except the bad capacitor.

DanH · #6 08-15-2016, 09:42 AM

Quote:

Originally Posted by rayagriflite

If I'm seeing similar results...is there a method to determine if my Plasma needs service? Did the bad capacitor show up with just a mag timing check?

Standard setup check from the manual. Run it at 1000 RPM or so. Point a timing light at the marks. It should show base timing (20 or 25 BTDC depending on engine model) with the MAP sensor hose disconnected and open to the atmosphere. If your timing is advanced, you have a bad box.

rayagriflite · #7 08-15-2016, 10:22 AM

Understood. Thank You.

Finley Atherton · #8 08-15-2016, 02:45 PM

Quote:

Originally Posted by rayagriflite

If I'm seeing similar results...is there a method to determine if my Plasma needs service? Did the bad capacitor show up with just a mag timing check?

I have the panel mounted Lightspeed timing display and it accurately displays the timing advance. Not sure though if it would display accurately if there was a fault in the brain box?

Fin
9A

DanH · #9 08-15-2016, 04:34 PM

Quote:

Originally Posted by Finley Atherton

I have the panel mounted Lightspeed timing display and it accurately displays the timing advance. Not sure though if it would display accurately if there was a fault in the brain box?

Dunno Fin. I know the timing light doesn't lie

vic syracuse · #10 08-15-2016, 05:15 PM

The timing meter is reliable. I have one as well.
Dan, I don't think at idle it will read 20 degrees or 25 degrees. It is usually advanced quite a bit at 30 or more.
If you disconnect the manifold pressure line from the controller it will read low, usually 16 degrees. A quick check without using a timing light, and the associated danger, is to just disconnect the manifold pressure line while the engine is idling. You will notice a very substantial drop in RPM's if it is working correctly. If it is stuck at the high advance, there will be no change in the idle rpm's.

Vic