Wes's Onex #89

[WesRagle]

HI Guys,

I haven't seen any oil seeping from around the bolt head. There is evidence that Scott put a bead of grey RTV under the bolt when he assembled the engine. It's still on there and seems to be sealing.

Wes

[WesRagle]

Hi Guys,

I've been in the boonies bonding with my new airplane. My intent was to get the airplane trimmed up for straight and level flight. However it's been 80 Deg. F. at morning civil twilight for some time now. That's 15 to 20 degrees hotter than it was for my first flight. So, those temps that were OK on first flight turned RED with the ambient temperature increase. Suffice it to say that I got ahead of myself. The first step with a VW conversion is getting the temps under control ;-)

I'm on my third revision of the outlet "scoop". This one seems to be working pretty good. The hottest CHT stays below 375 at WOT and runs about 350 in cruise. The coldest CHT (front cylinder) is right at 300 in cruise. I think I can improve a bit more but not sure I should.

Oil Temp has been a problem. I have only been able to climb 2000 ft., level off, and fool around for about 10 minutes before the Oil Temp hits 230. I have a firewall mounted oil cooler that will also provide cabin heat. The cool air is provided by a NACA vent on the side of the cowl.



I was sure that the little cabin heat flapper valve was too restrictive causing my oil temp problems. So ..., I tried to make the output less restrictive by drilling holes in the output plenum the appropriate size for snap plugs. That would allow me to regulate the oil temp as necessary by removing or replacing snap plugs.



That had zero effect. Nothing, nada ...

So, it must be the input air supply. I had a small piece of aluminum and some double sided tape at the hangar so I tried this ..



Presto ... a 25+ deg drop in oil temperature. I was able to get in a 45 min flight this morning with oil temperature never busting 215 and holding about 205 in cruise.

I'll try to refine the scoop so it doesn't look quite so cheesy. It might become a part of my summer running gear but I'll make it removable since it probably won't be needed in the winter months.

The VW only has 5 hours of combined flight and ground running so I expect the temps to come down some. We'll see.

Forever Forward,

Wes

[wlarson861]

With a new vw engine you should expect high heat until it breaks in. I had high temps (CH) until I hit about 30 hours then they started getting cooler as i built a few more hours. The biggest effect was getting the electronic ignition dialed in.

[WesRagle]

Hi Bill,

The biggest effect was getting the electronic ignition dialed in.

Scott set the timing. I haven't messed with it. I will check it in cruise next time up.

Thanks,

Wes

[Gordon]

Hummel Engine Timing........

Just to add to Wes's comment on ignition timing......."Scott set the timing".

Scott Casler in Arizona is the builder of the Hummel engines and he runs every engine on a test stand BEFORE shipping to the customer.

The ignition timing should be correct.

Gordon.........Hummel 2400.......Onex C-IODB

[WesRagle]

Hi Guys,

I made some minor mods to the Onex cooling systems and flew for a couple more hours. Since I think of the Onex as the Harley I never had, it doesn't bother me too much to hang little shiny metal things off of it :-)

I refined the oil cooler scoop a little:



I enlarged the outlet scoop and truncated the bottom sooner to allow for a less cluttered path for exit. I also ran the sides all the way to the firewall. Maybe that will keep outside air from filling the low pressure area.



It's not quite as gaudy as it looks in the pic but it is pretty big. Both of these mods are easy to undo/change as needed after break in.

I also made an attempt to seal the valve cover cutouts. Not a perfect seal but pretty good.



I ran manometer tubes through the cabin heat flapper and out a recently acquired hole in the oil cooler plenum :-) The high pressure tube was routed through a blast tube and taped flat to the rear bulkhead of the baffling. The reference tube was taped to an oil cooler hose and basically just dangling in space behind the engine.



Took it up for a test flight yesterday. I climbed to 2000' AGL (~5000 ft DA), leveled off and throttled for 3000 RPM cruise. I let everything stabilize for about 4 minutes and then noted temperatures. Oil Temp 197, hottest CHT 327, EGTs in the mid 1200's, and pressure drop across the baffling 6.5 in. H2O. 6.5 is what Capt. Google says is needed to cool an O-360. BTW, I do have the CHT probes as close to the spark plug as I could possibly get them.

There was one disappointing number. I pulled the high pressure tube off of the manometer to get a reading of cockpit pressure relative to forward of the firewall. It was negative 1.2 in. H2O. I was hoping it would be positive. Oh well, the CO sensor in the cockpit has never come off of zero. I'm not going to worry about that.

This morning I took another 1 hour flight. I was able to do 4 full stop landings and taxi back without temps being the least bit threatening.

I can quit worrying about temps for now and get back to rigging issues and learning how to fly this airplane.

It's way too early to report much performance data. However, I can report one number. I have been able to regulate climb speed on takeoff very close to 100 MPH indicated. RPM locks in on 3400 and the GPS vertical speed reports anywhere from 950 to 1050 ft. per min. 3400 is where the engine makes peak power so that would explain (what I consider to be) the excellent climb rate. And I did verify again that WOT in level flight will blow right through 3600. I'm obviously under propped but right now I don't think I care. With this prop I'm set up for maximum T&G/Hr. That is touch and goes per hour. A very important performance parameter for this airplane.

Forever Forward,

Wes

[lgsievila]

Glad things are working for you Wes-I told you the Onex would be a blast. Good numbers for the heat in Weatherford!

[WesRagle]

HI Loren,

Good to hear from you. Yes, this is a lot of fun. I do have to remind myself that while "First Flight" is a major milestone, it's not the end of the project.

Good numbers for the heat in Weatherford!

Actually, the airplane is in Olney Tx. right now. Usually just me and the crop dusters next door. A good place for me to work my way back to proficiency.



Wes

[flyingbear]

Neat idea WES. My R2300 has almost 1000 hours on it and I still add no oil between changes. Mine is on the belly though....a little bit every flight, mostly from push rod tube seepage.
Glad things are going well for you
Glen ONEX 131

[WesRagle]

Hey Glen,

Neat idea WES. My R2300 has almost 1000 hours on it and I still add no oil between changes. Mine is on the belly though....a little bit every flight, mostly from push rod tube seepage.
Glad things are going well for you
Glen ONEX 131

What's a neat idea? The edging on the valve cover cutout?

Wes