Two issues . . .

[MS19087]

Having put a few hours on the engine after first flight last week I am having a few issues - any thoughts or comments would be appreciated.

Background: IO-320 w/ Sensenich FP prop running one mag (Left) and one Plasma II (right) - Rated HP = 165.

1) Large rpm drop on both R&L when doing mag check: 150 rpm drop when Plasm is turned off, 130rpm drop when mag is turned off. This is way off - This should be more like 50-75 when Plasm is turned off, and nothing when mag is turned off.

2) Static RPM is 2250 @ 28" - right in spec. Flying WOT, I could only spin it up no more than 2350! Now I do not have main pants on yet, but Im still 350 RPM short of redline (250 short of Sensenich prop limit). Sensenich says even a re-pitch would get me only 25 rpm. LSE suspects leaky MP - that was pretty much ruled out. Others suggest timing is off. I checked the tach with a digital optical unit and it is spot on. I will check timing with my A&P on both units this Tuesday.

Has anyone seen a similar situation? I want to resolve this before continuing Phase 1 testing. Suggestions??

[Radomir]

you have all the fairings on?

[chaskuss]

Originally Posted by MS19087

Having put a few hours on the engine after first flight last week I am having a few issues - any thoughts or comments would be appreciated.

Background: IO-320 w/ Sensenich FP prop running one mag (Left) and one Plasma II (right) - Rated HP = 165.

1) Large rpm drop on both R&L when doing mag check: 150 rpm drop when Plasm is turned off, 130rpm drop when mag is turned off. This is way off - This should be more like 50-75 when Plasm is turned off, and nothing when mag is turned off.

Mark,
What type of spark plugs are you using with the magneto and the EI? What is the spark plug gap for the plugs on each?

Originally Posted by MS19087

2) Static RPM is 2250 @ 28" - right in spec. Flying WOT, I could only spin it up no more than 2350! Now I do not have main pants on yet, but Im still 350 RPM short of redline (250 short of Sensenich prop limit). Sensenich says even a re-pitch would get me only 25 rpm. LSE suspects leaky MP - that was pretty much ruled out. Others suggest timing is off. I checked the tach with a digital optical unit and it is spot on. I will check timing with my A&P on both units this Tuesday.

Has anyone seen a similar situation? I want to resolve this before continuing Phase 1 testing. Suggestions??

Check your fuel flow reading and see if they are within spec. Perhaps you are not getting sufficient fuel at high RPMs?

Charlie Kuss

[Kyle Boatright]

Check your mixture. The mag drops (IMO) may be indicative of a lean condition.

Regarding the low RPM at max throttle, a lean condition and the lack of wheelpants might explain both.

[Walt]

Try leaning during the run up, a rich mixture will cause excessive rpm drop on both sytems. A lean mixture will usually cause stumbling when advancing the throttle.

[Jerry Cochran]

Now I do not have main pants on yet,

How about the leg fairings? In my case I picked up 15 mph when all the pants and leg fairings were installed. I have an IO-360 CS.
Your FP prop could be overworking itself with all that drag.