# Engines to replace the dominance of Rotax

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#### erkki67

##### Well-Known Member
Through K.Armstrong an English gentleman, I got the idea to have a closer look at an engine manufacturer;

http://m.gk-engine.com/products

they have more then one engine that could replace the 503 and 582 and with some mods even the 912s.

#### billyvray

##### Well-Known Member
A gentleman online is working on a belt driven version of the 850cc v-twin right now. Kevin Armstrong on Youtube.

#### Armilite

##### Well-Known Member
Through K.Armstrong an English gentleman, I got the idea to have a closer look at an engine manufacturer;

http://m.gk-engine.com/products

they have more then one engine that could replace the 503 and 582 and with some mods even the 912s.
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You're going to find out, almost all Bike/ATV Engines have to Small of PTO for Plane use and most Bike/ATV and other Brand of Sled Engines don't have the Bosses needed for any Gear or Belt Drive. Hirth & Simonini both offer many different Engines to cover almost every HP want. Very few AirPlanes today can use an Upside Down 2 Stroke today. Some can be Adapted with usually an Exspensive Adapter Plate. Many of these Newer Engines haven't been run Upside Down either. So if you like being someone else's Test Pilot, I would stay with what you know Works. There are many Older Rotax 277UL, 377UL, 447UL, 503UL, 532UL, 582UL, 618UL, Kawasaki 340/400/440/500/550's laying around cheap that can be Rebuilt & maybe even Updated. Rotax 277's were made 1980 to 2006/08. 503's were made till 2003. 250's and 377's, 440/447's, and 503's are Still made New in Russia. Kawasaki 440 and Suzuki 440's are still made last I knew.

Simonini sets the World Bar in Singles with a 400cc 54hp@6500rpm.

#### blane.c

##### Well-Known Member
HBA Supporter
Looks like most of the engines you are looking at from the web address are 4 stroke. My opinion is that to compete for that engine size with the competition, 4 strokes will need an EMS, Fuel Injection and be Turbo-Supercharged. Direct drive isn't practical at the RPM's necessary to obtain reasonable power to weight ratios so a propeller speed reduction system will also need to be part of the solution.

#### Vigilant1

##### Well-Known Member
Yamaha RX1, Genesis, Apex and Phazer snowmobile engines
Yep, there's been a lot of good work done with these, and some seem to be quite promising as airplane powerplants (with a PSRU). Even if run well below normal redline they could still give up/weight as good as conventional acfy engines.
But for widespread use (i.e. a standardized conversion with kit parts, instructions, support, etc), used engines from snowmobiles probably not be practical. I wonder what new crate engines from Yamaha would cost (if they were available). We

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#### Armilite

##### Well-Known Member
Until any of these different Engine Manufacturers, and People, who do these different Engine Conversions for Airplanes, has lots of Engines (100+) with High Hours at least (300hrs+), used on Actual AirPlanes, you're just being their Test Pilot. What may work ok on an ATV, Bike, Go Cart, etc., may not hold up well in Airplane use. Rotax's have Millions of Flight Hours being used on Planes for 35+ years, also being used on Jet Skies, Water Pumps, Generators, etc. So be very careful of all the hype out there. 300hrs is Simple for any of these People to achieve in a proper Test Cell. 300hrs/24hrs = 12.5 days if ran Continiously. 300hrs/8hrs = 37.5 Days. Once most Engines are properly broke in on the Ground in a Test Engine Cell and then ran Continious for 8hrs at say a 75% load, if it hasn't Failed by then it will usually be ok, that it could then be then mounted on a Plane for further Testing. 300hrs @ 75% Power say 3gph = 900 Gallons of Gas minimum. Engines & Gear/Belt Drives that have never been used on Aircraft should have more Ground Testing to simulate being used on an Airplane, Hung Upside down if a 2 Stroke, Tested at different Angles to Simulate Accents & Decents. Every Type of Engine is different so they can have different Weak Points.

#### dcstrng

##### Well-Known Member
Until any of these different Engine Manufacturers, and People, who do these different Engine Conversions for Airplanes, has lots of Engines (100+) with High Hours at least (300hrs+), used on Actual AirPlanes, you're just being their Test Pilot... Every Type of Engine is different so they can have different Weak Points.
Like many, I’m not (psychologically) a Rotax fan; but they’ve stuck with the aviation hobbyist for decades now -- arguably refining the product and moving along as the application moves; usually to heavier, more-complex aircraft. The notion of the better motorcycle engines is appealing to me and power like the R-1 (I liked the Z11 series – Kawasaki) seem attractive, but unless you own a small machine shop and a modicum of skills to match, it isn’t something most of us can safely tackle from an airworthiness standpoint – it is one thing to chuckle through a power-out at 103 speeds, yet another to white-knuckle at LSA speeds and can be a whole lot more breathtaking when the stall speeds approach 60mph or so… and as Jab and UL (etc.) have shown, it is difficult to knock the Rotax cowboy off the saddle… I think about the only engine that has come close is the VW-Beetle in years gone by… but that was from an era when at least one shade-tree wrench in five actually has VW experience – not the case any longer, so while skilled folks may get an R-1, or such, nicely assembled, I don’t see enough interest/abilities/skills/passion to reach critical mass…

#### blane.c

##### Well-Known Member
HBA Supporter
You need to consider multi-engine, more smaller engines. You can operate multiple engines that have a EMS. The computer could even be programed to open and close the cowl flaps so the pilot workload is diminished to observing that the temps and pressures are correct and would only need to step in manually if a correction was needed. It is easier to find two 60hp engines or three 40hp engines than one 120hp engine that will work for an aircraft.

The biggest problem with multi-engine has been pilot workload to keep the engines within operating parameters, with EMS it is no longer as big an issue.

#### Vigilant1

##### Well-Known Member
The biggest problem with multi-engine has been pilot workload to keep the engines within operating parameters, with EMS it is no longer as big an issue.
In the non-Pt 103 world, I think another big problem will be the cost/hassles of getting a multiengine rating. I suppose if a particular small/cheap multiengine design became popular that folks could train in it rather than renting hours in an Apache, but it is still a considerable barrier.
Also, two 60 HP engines will generally weigh more than one 120HP engine. Three 40 HP engines will generally weigh a lot more.
Still, I'm a fan of the multiple small engine idea, I do think it has merit--provided that the design can operate safely with one engine out.

#### blane.c

##### Well-Known Member
HBA Supporter
Because engine manufacturer's are now putting time limits on their engines, so they will have to be inspected every ten years it is going to get harder and harder to find an engine that hasn't had the cases split in 30 years. Private ownership and operation of certified engines is going to become more expensive. Finding safe alternative power is imperative to the continuation of experimental aviation. What's wrong with putting two VW engines AKA Cri-Cri mount on the front of a Pietenpol?

#### Doggzilla

##### Well-Known Member
HBA Supporter
Surprised someone hasn't Frankensteined one together like the Napier Sabre from the Typhoon.

Has a huge advantage in that it has no significant first or second order vibrations due to the opposing cylinders being so balanced.

24 cylinders too complex, but 4 or 8.... maybe not.

#### lr27

##### Well-Known Member
snip
What's wrong with putting two VW engines AKA Cri-Cri mount on the front of a Pietenpol?
I find this a compelling argument1:

Those are some heavy weights to hang at the ends of sticks. Wonder just how much effort to engineer it right?

------------
1 Lacey M-10C, and yes, those are two VW's.

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#### Armilite

##### Well-Known Member
Like many, I’m not (psychologically) a Rotax fan; but they’ve stuck with the aviation hobbyist for decades now -- arguably refining the product and moving along as the application moves; usually to heavier, more-complex aircraft. The notion of the better motorcycle engines is appealing to me and power like the R-1 (I liked the Z11 series – Kawasaki) seem attractive, but unless you own a small machine shop and a modicum of skills to match, it isn’t something most of us can safely tackle from an airworthiness standpoint – it is one thing to chuckle through a power-out at 103 speeds, yet another to white-knuckle at LSA speeds and can be a whole lot more breathtaking when the stall speeds approach 60mph or so… and as Jab and UL (etc.) have shown, it is difficult to knock the Rotax cowboy off the saddle… I think about the only engine that has come close is the VW-Beetle in years gone by… but that was from an era when at least one shade-tree wrench in five actually has VW experience – not the case any longer, so while skilled folks may get an R-1, or such, nicely assembled, I don’t see enough interest/abilities/skills/passion to reach critical mass…
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Rotax Engines have been used in SkiDoo Snowmobiles since I think the early 60's and have been the Leaders in the Snowmobile Industry and Winners in many Snowmobile Races since the 60's. At one time, there was over 400+ different Snowmobile Manufactures and they all used about 20-25 different Snowmobile Engines from different Engine Manufactures. We have went from 400+ to just 4-7 in the Whole World, Skidoo, Yamaha, Arctic Cat, Polaris, are the Big (4) and there was a brand made in Russia, and one made in China also. Some of the Big (4) had other Brand Names like Skidoo, had Lynx.

The Big (4) Bike Companies, Yamaha, Kawasaki, Honda, Suzuki, make some of the best Engines out there for BIKE's. But those Bike Engines haven't really been Tested in the Airplane World. Some of these Big (4) Bike Manufactures do, or did have a line of Snowmobile Engines at one time, Yamaha has their own Snowmobile Engines, Kawasaki had their own Snowmobiles and Sold their Engines also as Industrial Engines, and sold them to other Snowmobile Manufactures to put in their Sleds, the main (2) that were used on Ultralights was the 340/440 Engines, Suzuki had their own line of Snowmobiles at one time and their Engines were also used in Arctic Cat's for many years. Arctic Cat started making their own Engines a few years ago.

Snowmobile Engines usually make the best choice account they were designed to be used in rough environments and have a HD PTO for a Large Heavy Clutch, which is taken off and replaced with a Prop. Bike Motors PTO's were not Designed for that. Most Engine Cases were not Designed with the Bosses needed for the Gear or Belt Drives to be attached.

All of these Engine were not Designed Specifically for Airplane use, but were Adapted to be used! Not Designed for Continuous use for Hours at Higher Rpms! A Snowmobile, Bike, ATV, Off Road Cart, etc., Speed up, Slow Down, Speed up, Slow Down, Stop, Speed up, Slow Down, Stop, etc. Average trail Speed is 25-35mph so there not Turning High Rpm! Most Fan Cooled Engines are rated at 7000rpm in Sleds, Water Cooled are rated at 7750-8000rpm! For Airplane use there reduced to Max 6500rpm today by most Manufactures, and that's for just 2-3min for takeoff and then reduced even more. None of these Companies have done much of anything to Improve them since their Introduction. Hirth came out with their own Brand of Synthetic Oil. Hirth & Simonini have used Nikasil Cylinders, Rotax has never switched their UL motors to use them. None, have used the Advance Engine Coatings or Bearings out today.

eBay & Craigslist is a Good place to fine Sled and UL Engines, and www.Barnstormers.com and by using a Good Search Engine like www.searchtempest.com to searh from your Zip Code. I have never Paid more than $250 for any Good used Sled Motor from the 70's, 80's, 90's. The 503F was made till 2003, the 377F/380F and 440F was made till around 2008, as was the 277F. The Big Dog 670 was the last Provision 8 Engine made 1992-1999. 670HO was only made 1998-1999. The 580/582/583 Sled Engines were made till 1999. The 521 was made till 1992, and the 617 was only made about 2-3 years, I think 91-93. The 670 came out in late 1992 but had a Crank issue and are ver rare to find, the Good ones are 1993-1999. The 521 Types were 89hp@7750rpm, 580 Types were 97hp@7750rpms, the 617 Types were 106hp@7750rpm, the Standard 670 was 115hp@7750rpm, the 670HO was around 122-125hp@7750rpm. A 377 and 380 36hp@7000rpm is the same Engine, there was a 380HO used 11.2cr 48hp@7000rpm only made for oversea Sales and Alaska. There was a 521/532UL HO Type that used 12.5cr. Almost all Water Cooled Skidoo's used 11.5cr. Kawasaki/Suzuki 340/440/500/550's are basically the same Engine that all Share the same Lower end. Kawasaki did have an A Type, B Type, and C Type. Not sure if Suzuki did that. You have to look at the Case Ports! The A Type is what most People used on Airplanes, account it was Sold also as an Industrial Engine by Kawasaki. 440's(436cc) were around 40hp@6500rpm with a Muffler same as the Rotax 447UL(436cc) were rated. Never seen one actually Dynoed. The main Trouble with the Kawasaki/Suzuki 440 Engines is Nobody ever made a Good Tuned Pipe for Airplane use Max 6500rpm. Some Kawasaki/Suzuki's had a Big Boss around the PTO, some didn't. They used an Adapter Plate with the Rotax A Drive which isn't made today, so you have to buy a Used A Drive or use a Belt Drive. If the Kawasaki 440's were 40hp@5800rpm with a Muffler as many people Claimed, you could use 436cc/40 = 10.9cc = 1hp if using a Muffler to give you a Ball Park HP Number! The faster you turn it the more HP it will make. I would Increase the Carb Size. 340cc/10.9cc = 31.2hp 436cc/10.9cc = 40.0hp@5800rpm! I believe that was with a Chaperal #4 Sled Pipe. 500cc/10.9cc = 45.9hp 550cc/10.9cc = 50.5hp The Kawasaki 440A is a twin-cylinder, two-stroke engine. The two cylinders are placed in an in-line configuration. It utilizes a single ignition system using a coil and points. It has a displacement of 436cc (26.61 cubic inches) and has a dry weight of 65 lb, 7 lb lighter than the ROTAX 447. Specifications (440A) This was the Industrail Motor. General characteristics Type: twin-cylinder, two-stroke engine Displacement: 436 cc (26.61 cu inches) Dry weight: 49 lb (22 kg) Components Valvetrain: piston ported Fuel system: Mikuni 34mm slide-type carburetor Oil system: premixed oil and fuel Cooling system: air cooled Reduction gear: aftermarket reduction drive for aircraft use Performance Power output: 38hp (28 kW) at 5000 rpm Kawasaki's 340/440/500/550's were offered as Free Airs, Fan Cooled, Water Cooled, Single Plug, and Dual Plug. I have never seen a Rotax B Drive myself mounted on a Kawasaki, but here is an Adapter Plate I have it labeled Kawasaki Adapter Plate, but I don't know where I found it many years ago. J-Bird deals in Kawasaki and makes some Belt Drives for them. There is a guy on eBay Selling New Belt Drives for rotax's and Kawasaki's. #### Attachments • 63 KB Views: 9 • 47.3 KB Views: 9 • 44 KB Views: 9 • 32.7 KB Views: 8 #### BBerson ##### Light Plane Philosopher HBA Supporter I was thinking a new two-cylinder snowmobile engine, direct drive, would be about 35hp at 4500rpm to 5000rpm. No need to get the max rpm and ear splitting prop tip and engine noise at the higher 6500 direct drive of the old days. A simple can muffler should work at that lower rpm, same as an R/C giant model. For$1500-\$3500 new, that is about as cheap as can be expected.
This would be for the low drag ARV* types, like the Moni that also had a direct drive 2-stroke.

*ARV (Air Recreation Vehicle)

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#### pictsidhe

##### Well-Known Member
To detune a 2 stroke, you need to shrink the ports. Otherwise you will be looking at some very disappointing torque and hp numbers. You can usually drop the ports by machining the bottom of the cylinder. But you can rarely go very far with that before the piston is sticking up past the top of the cylinder at TDC. If you can find a crank with a slightly shorter stroke, more can be done.