REFLECTOR: engine question

[nmflyer1 at aol.com]

Lou, 

Aircraft leakdown tests are done at TDC. That really doesn't give you all the information you need. IF your cylinder taper was off & out of spec, you could see the pistons/rings leaking as they travel downward (this would not show up at TDC). Many times this causes not only power loss, but increased oil consumption. Sometimes you can verify this condition by noticing staining and scuffing on the piston skirts. 
The best way, of course, is to check the cylinder taper, 

Hope that helps. 

Kurt 



-----Original Message-----
From: Lou Stedman <stedmanlou at roadrunner.com>
To: Velocity Reflector <reflector at tvbf.org>
Sent: Wed, Aug 14, 2013 2:37 pm
Subject: REFLECTOR: engine question




On my last conditional inspection I found metal in my oil filter. After removing one of the cylinders I found the need to have my cylinders (4) taken down 10 thousands and new pistons put in. The total time since overhaul was just over 500 hrs. I have begun the break in period and have been pleasantly surprised. I am running 20W50 mineral oil and am not using near as much oil as I had expected. In the first seven hours I used one quart. Hoe that keeps up.
 
The thing that most surprised me is the increase in power. I could understand the increase if my compression figures were down but they were not. For the last three years I have been running mid to high 70’s. Previously, my max RPM at full throttle in level flight was about 2500. Now my max is about 2650. My max IAS before was about 155kt and now it is about 180kt. Nothing about the aircraft has changed except for the cylinders. Can anyone shed some light on this? I am happy but confused.


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