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-   -   How should I tie down RV-7 for engine run in? (https://vansairforce.net/community/showthread.php?t=79049)

dsmithlib 11-17-2011 08:13 PM

How should I tie down RV-7 for engine run in?
 
The good news: it's finally time to run the engine for the first engine run.

The bad news: My rebuilt O360 has new ECI Titan cylinders that have never been 'run in'. So, I need to fire it up and run at some pretty high RPM and temps for the first 60-90 minutes to start the ring seating process properly.

The bottom line is that I need some best practice advice on how to hold back my RV7 with the Catto prop spinning fast. I have considered tying the tailwheel to my Honda Pilot.

Should the tail be lifted so as to not create pressures under the wing?

Would you ever use the wing tie downs to hold back under full power? I was thinking I need to hold the gear legs somehow?

Other suggestions for run-in, break-in always appreciated.

Ideas appreciated......

hydroguy2 11-17-2011 08:30 PM

tie down the tail to the ground. chock the wheels. and Minimize the ground time.

DanBaier 11-17-2011 08:38 PM

With my new jugs that had never run before (replaced 4 due to group B ECi) the initial ring seating took place in only about 3/10ths of an hour (based on CHT dropping significantly). These were the Nickel-Carbide cylinders.

I had only done two brief starts of the engine before launching (albeit not the first flight) - limiting each to less than two minutes or 275 on CHT - whichever came first. (CHT doesn't necessarily tell you what the temperature is on the cylinder wall.) The first start to check for leaks; wait a day, and the second start to make sure I could get enough power for takeoff; wait a day, and fly.

The way I understand it, if you ground run the engine for 60 - 90 minutes without some serious cooling shroud precautions, you could bet on glazing the cylinders. Your best course would be to get high power (more than 75%) but without too high a CHT temperature. Too low power and the rings don't seat - you get blow by and the cylinders glaze; too high a temperature and the oil cokes on the cylinder wall and the cylinders glaze. ECi has some downloadable info on engine break in and so does Mattituck.

I know it's an answer to a question you really didn't ask - just another $.02 for good measure.

Dan

erich weaver 11-17-2011 09:10 PM

Ditto on what Dan said. Don't be doing any significant time on the ground at high power. Sucky huh? Think about it what it's like with a new plane AND a new engine.

Erich

Kyle Boatright 11-17-2011 09:12 PM

Quote:

Originally Posted by dsmithlib (Post 597102)
The good news: it's finally time to run the engine for the first engine run.

The bad news: My rebuilt O360 has new ECI Titan cylinders that have never been 'run in'. So, I need to fire it up and run at some pretty high RPM and temps for the first 60-90 minutes to start the ring seating process properly.

The bottom line is that I need some best practice advice on how to hold back my RV7 with the Catto prop spinning fast. I have considered tying the tailwheel to my Honda Pilot.

Should the tail be lifted so as to not create pressures under the wing?

Would you ever use the wing tie downs to hold back under full power? I was thinking I need to hold the gear legs somehow?

Other suggestions for run-in, break-in always appreciated.

Ideas appreciated......

Dave,

Here are ECI's procedures. Since you have their cylinders, I recommend following their procedures.

http://www.eci.aero/pdf/BreakInInstructions.pdf

Page 6 is where the most relevant procedures begin.

I think you will be VERY unhappy with your results if you attempt to run the engine for a lengthy period on the ground. There isn't enough airflow to properly cool the engine, so you won't be able to maintain a high enough power setting to seat the rings. All you'll do is glaze the cylinders.

Low Pass 11-17-2011 09:36 PM

Fly it. You don't want glazed cylinders. Been there, done that.

Unless you have a test stand with proper cooling system and a way to load the engine, you're making a mistake trying to break in an engine on the ground.

MauiLvrs 11-17-2011 11:07 PM

What LowPass said...
You don't want to rebuild your rebuild O-360.:eek:
You can't properly break it in on the ground without damaging the engine
Quote:

Originally Posted by Low Pass (Post 597132)
Fly it. You don't want glazed cylinders. Been there, done that. ....


turbo 11-18-2011 05:16 AM

good thing you posted this. now go out and do the right thing!!!!! :p

pkill 11-18-2011 11:34 AM

Hello Dave,

All good advice above…. Plus any ground run discussion is probably not complete without this video…

http://www.youtube.com/watch?v=EHt6nYTdmRQ

pk

JDRhodes 11-18-2011 12:42 PM

Quote:

Originally Posted by pkill (Post 597328)
Hello Dave,

All good advice above?. Plus any ground run discussion is probably not complete without this video?

http://www.youtube.com/watch?v=EHt6nYTdmRQ

pk

Good grief - Yeah, don't do THAT!


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