Ground run shroud

[RV8RIVETER]

Originally Posted by LarryT

What engine RPM and MP were you using? Did you sweep the area around the aircraft pretty carefully? I prefer to be moving before I have my prop turning over 1800 RPM because it is quite easy to suck up a rock and ding it.

Do you have approximate dimensions of your shroud or did you just eyeball it?

.....but I expect that running at high power for an extended time period would meet with similar objections from the same people.

Larry T

Most of the time spent above 23 inches and 2400 rpm. From there gradually increased to 25/2500, 26/2600 and then about 5 min at full power.

Size. See first post, 1 sq ft per cylinder, so 4 cyl is 4 sq ft. Mine is more like 4.2 sq ft due to how I eyeballed it.

Yes we swept the ramp very thoroughly. In a 3pt attitude there is quite a bit of ground clearance, but who wants to take chances. Nothing on the prop but bug guts.

The comment about the neighbors was kind of toungue in cheek. Quite a few turned out, to what was making the noise, but no real complaints. We live on airpark after all. Made sure late morning and would only run one time a day. If you are worried I would ask around about what time is best. It probably didn't help to be so close to the hanger with the door open. Makes a nice megaphone for the opposite side of the runway.

[Snowflake]

Are you tying your tailwheel too? Those 2x4 wheel chocks won't hold much at 2400rpm...

[RV8RIVETER]

Yes we did. The neighbors ramp has 1/2" J bolts ( I think) sunk in the ramp to use as tie downs. Very interesting, when we untied it we found the bolt bent over about 10 deg and no one ever saw the tail come off the ground. Stick was full aft all the time.

[rv8ch]

Hi Wade, do you still have the images of your ground run shroud? They seem to be lost on the imageshack.us site. Thanks, Mickey

[rmartingt]

Yes, I'm very interested in this as well

[okdonn]

I wonder if it was something like this?
http://rv7preflight.blogspot.com/ -scroll down to the 2nd December 2011 post.

[svyolo]

I will be breaking my engine in on the ground as well. Googling and you tubing ground engine run shroud or something similar will show some good examples. Also airboat Lycoming pics also use something similar.

It looks very easy to do. Just the problem with the noise. The other benefit is you are testing your entire engine installation on the ground, instead of with your pink body several thousand feet in the air.

[chaskuss]

Originally Posted by okdonn

I wonder if it was something like this?
http://rv7preflight.blogspot.com/ -scroll down to the 2nd December 2011 post.

Perhaps it's just the perspective, but I don't see an oil cooler mounted on that shroud. For those that have their oil cooler mounted on the engine mount or the firewall all you really would need is to duct some scat tube to your oil cooler installation.

Charlie

[rv8ch]

Found this one - I guess it's what is being suggested. Seems simple and solid.

[Marc Bourget]

I couldn't open the photos but will search for and check the reference.

IIRC, test clubs provided the important benefit of reducing the effect of harmonics in the crank if ran "unloaded"