First Turbo Aerovee runup to WOT

[pfhoeycfi]

My first ground run-up to wot (wheels chocked) yielded RPM of 3056, MP of 36.8, oil pressure rose to 68.8 and the oil temp was at 104. I'm not sure what the initial numbers should look like. Having prob with my RDAC/MX1 so I do not have CHT or EGT therefore my run-up was kept very brief. I have the Sensenich climb prop from Sonex. My aeroinjector setup was per the manual with no additional adjustments made. Run-up was smooth. Idling ok between 800 and 900 RPM. No balking on top. No oil on the ground after...

Any thoughts on these initial numbers? Can I expect the RPM and MP to increase once I'm rolling?

Peter

[MichaelFarley56]

Peter, just out of curiosity, did you manifold pressure stabilize at 37" or was it still rising? Was that at wide open throttle?

If that's the case, it would appear that your wastegate blow off valve spring may need a little adjustment as most turbo owners can easily reach and even exceed the redline manifold pressure of 40" before they reach full throttle. When I had the turbo on my airplane, I could reach 40" at around 80% throttle (I live in the midwest at 1000' MSL). It may be worth a quick check to ensure your wastegate actuator arm isn't causing the wastegate itself to open just a little early.

Otherwise, your numbers look great! Good RPM and oil pressure was just fine, and it's good to hear your engine is running and idling smoothly. Sorry to hear about the MGL RDAC issues; I hope it's an easy fix for you!

Sounds like you're getting pretty darn close! Keep it up!

[pfhoeycfi]

Peter, just out of curiosity, did you manifold pressure stabilize at 37" or was it still rising? Was that at wide open throttle?

Yes I would say it was stable or very near so at WOT. The waste-gate is def seated tight with the engine off. I did purchase the blue spring that some here recommended but haven't installed it. The actuator still has the original spring inside. Perhaps I'll try that. I'm not sure how to adjust the actuator or if the stroke is even adjustable. I'll have to dig into that.

Thanks,

Peter

[NWade]

Peter - RPMs will change once you’re rolling, but MAP will not. So if you’re not seeing 40” tied down you won’t see 40” on the roll.

If your MGL supports recording, I highly recommend doing so for these run-ups. You can then download the recording and use the MGL BBTool after the flight to view your various engine parameters. The wastegate opening will appear as a very defined “plateau” / “flat top” in the MAP readout (as opposed to the “rounded hill” shape of the fuel flow or certain other parameters) if you smoothly and steadily advance to full throttle and then back it down again. See my posts on this site regarding engine MAP; IIRC I posted a few images of those recordings.

You can slightly adjust the wastegate opening by changing the pre-load on the actuator arm (I.e. how much tension or free-play the arm has at rest by changing its length), but IMHO that will only buy you 0.5” to 1” of MAP. If you are not seeing around 39” already, *and* you have ruled out things like intake leaks or leaks in your MAP sensor tubing, then a change in wastegate spring was the only way I could delay the opening long enough to get the full 40”. (Note however that the next spring up means you *can* hit ~42-44” MAP if you aren’t careful)

Hope this info helps,

—Noel

[XenosN42]

You can then download the recording and use the MGL BBTool after the flight to view your various engine parameters.

—Noel

A better tool is the 'Flight Data Viewer' http://www.JASFlyer.COM It supports all the data recording formats from MGL (including the MX1) and Garmin, Dynon, GRT, Adv. Flight Systems and Electronics International.

[pfhoeycfi]

I replaced the waste gate actuator white spring with the blue and now get 40" at about 3000 rpm. The MP would likely go to 43 - 45 if I let it. When I adjusted the throttle cable so that the MP is limited near 40 and I was surprised to see that the slide in the aeroinjector is only just past half open. Is this normal? I'm also questioning if limiting the aeroinjector slide travel by "shortening the cable" the best and safest way to do so. Or should the cable be adjusted to allow full open on the slide and limit the MP by keeping an eye on it,ie limiting by hand...which I think will be difficult at takeoff and climbout.

peter

[pappas]

Peter, I like your initial numbers. The change of springs did get you the MAP you want, good call. Don't adjust the throttle cable to limit the map, adjusting the throttle cable just limits how much air and fuel are delivered to the Aeroinjector. Adjust the throttle cable for full open, (assuming there is no balking, see the manual), and limit the MAP with the adjustment to the waste-gate actuator rod.

That should get you dialed in. And a lot faster than I got mine dialed in. Congrats!

[pfhoeycfi]

and limit the MAP with the adjustment to the wasre-gate actuator rod.

Thanks....I'll do that.
As it stands now there is no preload on the wastegate. Any additional adjustment, ie shortening of the actuator pushrod, will open the wastegate.

Peter

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