Engine Choice...

I have been thinking about engines for this project for over a year. On one hand, you have the tried and true Rotax 912ULS 100hp. This is the "standard" SuperSTOL engine. The least expensive Rotax option, as such, probably 90%+ of the SuperSTOL and Highlander fleet have these engines installed. They work well and are relatively inexpensive. It's a great engine choice. However, they're naturally aspirated (triple carburetors) and are a little under powered for out West.

Then there are the more expensive 912IS fuel injected and the 914 turbo versions. When I purchased my kit a year ago, I thought at that time I would be going with the 914 turbo as I live out west and anticipate flying in the mountains at some point. However, what I really wanted was a fuel injected AND turbo charged engine.

When the new Rotax 915 finally hit the market the end of 2018, I was really excited because it fulfilled both of my requirements of being fuel injected and turbo charged. As a bonus, it has more horse power too, 141hp. However, it is the most expensive Rotax model with installation costs ranging as high as $60k. Not an option.

Of course, There are "other" non Rotax manufacturers out there, namely Titan, which produces a 180hp engine, Unfortunately, it's so heavy it requires a SuperSTOL XL to be able to install them. Naturally, those were not an option for this project and none of the "other" manufacturers (Jabiru, Subaru, VW, Honda, Continental, Lycoming, etc.) seemed to be of consideration for similar reasons.

Then there is Steve Henry who has been flying behind a Yamaha snowmobile engine for years now with great success. He started out with the RX1 engine and is now flying the APEX. He really likes the APEX and has actually designed a firewall forward kit for the Highlander and SuperSTOL specifically for the 2006-2010 Yamaha Apex engine. He has been working on the development of this engine for aircraft use for several years. In addition, in conjunction with Steve, Teal Jenkins (Skytrax) has designed a gearbox (PRSU) that mates to the Yamaha engine replacing the Rotax C gearbox that was previously used. This Skytrax gearbox is much more robust and can handle much greater horse power while swinging larger diameter propellers than the Rotax box. The Yamaha APEX and Skytrax PRSU is proving to be a winning combination.

Last but not least is Edge Performance out of Norway. They have been modifying Rotax engines for years and have an excellent reputation for quality. Their flagship product up to now has been the  pumped up 912ULS Rotax with 154hp that is fuel injected and turbo charged. This engine made me reconsider my Rotax 914 choice and in fact, I was planning to go with it until I learned that Thomas (Edge's CEO) was getting involved with Steve Henry and the Yamaha Apex engine project. After exchanging several emails with Thomas about both the Edge 154hp Rotax and then learning about the upcoming EPEX (Edge's version of the APEX) which is to remain fuel injected but have a turbo added, I finally made a decision.

That decision is to go with the Edge Performance  EPEX Yamaha Apex 150hp fuel injected/turbo charged engine for the SuperSTOL. Thomas says this engine should conservatively generate 160-170hp continuous with 210-220hp takeoff power. He is currently building Steve Henry's APEX that will be 300hp which Steve will use for competition. This choice requires me to find an Apex engine here in the US, then ship it to Norway for Thomas to work his magic. While that is going on, I'll pick up the firewall forward kit from Steve Henry that has all the specific parts required to make it work in the SuperSTOL.

Of course, it would be easier to just purchase an APEX engine (if you can find one) however, it is not easy to verify that it runs or nothing is wrong with it. Also, most engines for sale will not have all the necessary parts, oil coolers, ECU, electrical harness, etc. So purchasing a complete sled makes sense because you can easily verify that the engine runs and performs as it should and you'll be sure to get all the parts! However, you'll have the sled chassis to dispose of, once you remove the engine. In this scenario, the ability to have a verifiable running engine with all the correct parts outweighs any downside. Now, even though the plan is to have Edge Performance totally rebuild the engine, I think acquiring the lowest mileage sled I could find is just a good idea... so, the search was on.

After several months, I came across a Craigslist ad for a 2010 Apex Mountain with 619 miles on it. The problem was that it was in another state, 500 miles away. As with all things Craigslist, buyer beware. So, I had to verify, the best I could, that the sled was actually what the seller said it was. That's a problem when your 500 miles away, so you do the best that you can. Ask tons of questions, get pics...

and choose to make the exchange at a Yamaha dealer, Santa Fe Motor Sports. I was able to call the dealer in advance and talk with service personnel. They agreed to look at the sled for me when we made the exchange (thanks Dominic). I think I hedged my bets the best I could. The seller didn't have a problem meeting at the dealership or them looking it over, which made me feel a lot better about the transaction and made it a lot less likely to be a scam. So, we struck a deal and I set about making arrangements to go get it.

After catching a very early flight to Albuquerque Saturday morning, I picked up a Penske truck and drove to Santa Fe Motor Sports. I met Brandon and Dominic and discussed the sled. When Jon (Seller) arrived with his son Aden, I asked Dominic to look it over and render his opinion. It only took him a few minutes to know the sled was good. It turns out that the sled was originally purchased from Santa Fe Motor Sports and they were familiar with it.

After a little head scratching about how to get the sled from Jon's trailer into the truck, we decided to back the truck up to his trailer since the height difference was only about 5-6 inches. Jon backed the sled up into the truck and with help from Brandon we were able to wrestle the sled into place. After strapping it down we completed the exchange, executed the bill of sale and title. We were able to verify with the store that we had executed the title properly which was really nice. Then, I immediately left for Phoenix.

Eight hours later I arrived back home with the sled undamaged. It was a long day.

Sunday, I pondered how to get the sled out of the truck? Finally, I made a ramp out of 2x6's and a sheet of plywood I had on hand. I used the Ford F450 to tie off to and pulled the sled out of the truck onto the plywood ramp. I was able to use my engine hoist to lift the front of the sled allowing me to slide a couple of Eastwood dollys under the front skids. I was then able to lift the back of the sled off the plywood so I could remove it. Once clear, I placed a 1000lb capacity Harbor Freight furniture dolly under the track and let the sled down on it. Perfect, a mobile sled.

Then came the cleaning. I pressure washed it to see what I had purchased. It came clean and looks pretty good. Starts and runs really nice. I'm delighted with my purchase. It's so nice, I really hate to take the engine out!

MOD – Split Rear Baggage Panel

I removed the weights and level from the piece and checked to make sure everything was aligned and cured. I then marked and drilled the lip for the lock plates. Deburred the holes and then dimpled them to receive the flush rivets. I riveted the lock plates into place. I installed the bottom rear baggage panel and then the top to check fit. Everything was in order and fit as it should.

With both panels in place I verified the boundaries of the pieces in relation to the fuselage tubing to make sure there was enough room to apply covering in the baggage area. Some very minor trimming was required on both panels as well as rounding the corners. I then deburred all edges, holes and corners with a sanding block. I reinstalled both panels to verify fit, perfect.

MOD – Split Rear Baggage Panel

I trimmed the upper rear baggage panel to give about 1/16^th of an inch spacing between the upper and lower panels. I measured and cut a couple of stiffeners to be Hysol’d to the lower panel to act as a lip for the upper panel to rest on when in place. This serves double duty as a lip and as an attachment point. 

Once cut to size, I bent a half inch of the stiffener to 90 degrees effectively making an L bracket. I prepped both surfaces to be joined and Hysol’d them together. I placed a 48” level on them with a couple of 5lb plates on top to hold the pieces in place while they cure overnight. I will drill and install three lock plates to the lip once the Hysol cures. This will provide three more screws along the seam joining the upper and lower halves together.