SonexBuilders.net

Looking ahead to an engine installation, (It will be a while. Just lining up ducks) I gather the Waiex is prone to being tail-heavy.

So far I've lost 3lbs by making an aluminum fuel tank, and have the potential of taking off more than a couple of pounds with a lithium battery. I'm guessing a total weight savings of 10 plus lbs. All of this, of course, only makes the CG issues worse.

To offset the lost weight in the nose, and to address some of the structural issues found in a clearanced stock VW block, my plan calls for the use of an aluminum crankcase, manufactured with stroker crankshafts in mind and wider cylinder bosses. The aluminum cases weigh in at about 45lbs.

Is there anyone out there that hasn't assembled their engine yet that is willing to weigh their magnesium case and report back? The difference may be greater than I expect and might not be a viable option.

Fat, dumb, and happy here @Area 51%

https://www.kustom1warehouse.net/New_16 ... 101025.htm

This says that the mag case is 17 lbs lighter than an aluminum case. That matches everything I've read before.

I have a standard magnesium case but if I were to do it again, I'd probably take the weight hit go with a CB performance aluminum case.
They come drilled & tapped for full flow and HVX mod ready, and are filled in behind #3 from the factory.
Only downside (apart from the extra weight) is that they tend to run slightly hotter than standard magnesium cases, or so I've been told.

If I were to build a VW powered plane, I'd go with an aluminium case for strength and added piece of mind.

Not that I've spent a lot of time searching, but the only cases I have come across are the EMPI units. Are there others out there?

Also, what is the HVX mod? I'm familiar with the "Bubble Top" and the #3 modifications to the aluminium blocks.

Thanks for the thoughts.

I'm not sure where the majority of the cases come from these days (although I did hear they were going to or stopped making magnesium cases). I would imagine a great deal of aluminum cases are Empi which usually means "made in China". In a lot VW circles Empi is synonymous with garbage. I've found that to only be partially true. I would thoroughly inspect any VW part I was about to put on my plane. Chinese manufacturers aren't known for their quality control. (think sand still in the parts form the casting process)

The HVX mod is an attempt to get the VW to throw more oil out to the heads to reduce temps if memory serves which I believe was for racing applications. You might think "Racing stuff? I want that!!!" but a good deal of the mods are aimed at high revving engines turning 5000+ RPM. I don't know that many of them would be applicable to an aircraft engine spinning at a slower rate.

I like the aluminum case for a couple reasons...It won't go up like a sparkler if something gets too hot (burning magnesium will turn night into daylight). Aluminum is a stronger than mag which should withstand the stresses of the aircraft application better.

All just my opinion.

vwglenn wrote:The HVX mod is an attempt to get the VW to throw more oil out to the heads to reduce temps if memory serves which I believe was for racing applications.

Not for racing... http://bobhooversblog.blogspot.com/2007 ... -mods.html

vwglenn wrote:I'm not sure where the majority of the cases come from these days (although I did hear they were going to or stopped making magnesium cases).

That was a rumor a few years ago, that production of the Mg case would end very soon. In fact, the magnesium cases are still being produced in Brazil.

I have a VW based street buggy, and am no stranger to EMPI parts, both good and bad. As with all Chinese manufactured things, you must inspect and/or fix them before use.

I'm still leaning toward the aluminum case, however, as it appears the U.S. machinists working for Sonex might have dual citizenship anyway. The examples that jump to mind are the clearances that were cut into the oil galleys, eccentric prop hubs, and spitting spark plugs as if they were watermelon seeds.

Back to my original thought. Does an extra 10lbs in the engine compartment do any harm to weight and balance in a Waiex?

Haio-Haio-Chi from Area 51%

This is of course my two cents only, so please take it for what it's worth....

Personally, I don't see how adding 10 lbs to the engine compartment will make much of a difference. As long as you can keep the engine less than the 200 lb max weight as recommended by Sonex, I'd guess you're okay.

When I installed the turbo on my AeroVee, it was a weight addition of approximately 22 lbs and the airplane flew great. On a Waiex, shifting the C.G. forward slightly actually made things a little more stable.

Again, just my two cents!