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View Full Version : HKS700e in a model 3 with no cowling mods?



wildirishtime
11-16-2010, 12:30 PM
Has anyone installed an HKS 2cylinder in a Model 3 without
widening the cowling? Seems with those opposing cylinders you'd
never fit????

Mnflyer
11-16-2010, 06:24 PM
Hi wild, I did the conversion using an engine mount built by Lost Hill Aviation and the installation required a modification of the round cowl. On the left side a small bump of approx. 1" out by 2" long by 1" wide, on the right side a larger bump was required if you go to my album you can see the cut out I made before fiber glassing the bumps, a larger air outlet is needed in the bottom of the cowl for the cooling air to exit. Greensky's engine owl may allow you to use the round cowl with out modifying it but I don't know that for sure you would have to ask Gerry at Greensky.
If you would like to see more photos of the conversion let me know I have many.

wildirishtime
11-16-2010, 07:08 PM
Very cool thanks for the pointers to your photos they are helpful! That's easier than a 912 install from what I recall....

wildirishtime
01-28-2011, 12:29 AM
Can you comment on how much difference that 5hp loss made to your flying? Any? even noticable? Did you notice a change in climb rate? I'm starting to get more serious about the idea of 4stroke and the weight of the HKS is perfect!

Mnflyer
01-29-2011, 06:43 PM
60 hp is 60 hp whether its produced by a 2 stroke or a 4 stroke engine, but you are probably right about the HKS not preforming as well on a Powered parachute as the 582, the main reason being that on the PP prop diameter is limited to the prop cage diameter the HKS requires a longer prop to take advantage of its torque and power band, when a someone complains that the HKS only preforms slightly better than a 503 its just about always because they have the wrong prop on it they may even have a 503 prop installed. And comparing a 80 or 100 hp engine to a 60 is hardly a comparison its like saying a Rotax 912 in a Super Cub would be a dog vs a Lycoming 0-320 yea no doubt.
If your flying is going to be 5000' MSL + density Alt then one would need to look at the HKS 700T, 80 hp turbocharged makes 80 hp to 15000' cost is about the same as the asking price of most used 912 engines. It would new with warranty no worrying how it was operated, did it have a prop strike etc. I looked there are no $10,000 912's listed there is one $12 13 thousand one that's had a prop strike so you can figure another 3 to 5 thousand to make it airworthy.
Here's my disclaimer I have flow my Kitfox III with both the 582 and the HKS the HKS wins hands down all the way around. The cost per hour to run a HKS is 1/2 of that of the 582, fuel burn is 3 gph vs 4 / 5 for the 582 and with gas now over $3.40 that alone is a $5.10 to $6.80 per hour, overhaul cost for the HKS is $1500.00 for the parts if you are mechanical you can overhaul it yourself and the TBO is 1000 hrs, the cost to overhaul a 582 is more than $3000.00 and one can not do the crankshaft there self and overhaul TBO is 300 hrs. lets compare HKS OH cost per hr=$1.50 582 cost per hr.=$10.00.

av8rps
02-02-2011, 06:33 PM
A very interesting thread. As said earlier, isn't the internet great!

I think the HKS is a GREAT engine for any early Avids of Kitfoxes. As light as the early airplanes are the HKS will give them good performance. Plus, the 912's are marginally too heavy for the earliest airframes. I saw an Avid B model with a HKS on youtube that performed so well that I just had to e-mail the guy to learn more. I have an older 396 lb Avid A-model that I was thinking about doing something different than the older 532 I have in it, and after learning about the HKS put it in high consideration. However, the 532 makes that early Avid such a complete rocket ship (2,200 fpm ROC easy), and while the HKS will work well the 532 in this case would be hard to beat. But as mentioned earlier, you have to be fair when making comparisons. The HKS at 60 hp won't compare to the 532 at 73 hp (dyno proven).

Another thought on the engine choices for the early and light Avids and Kitfoxes....the jabirus work really well on those early airframes. I think the most important thing to understand about choosing engines is to match the engine to the airframe based on weight and horsepower. Study other successful examples and just make sure your choice provides the same horsepower to weight numbers.

Even though the early airplanes weren't designed to handle the weight of the 912ul or ULS, it sure would be fun to see what one might do in one of the super stol early airplanes....Aw heck, why not do a 914 right away? Can you imagine that? But I suppose it wouldn't make much sense to put a 35k engine in a 8K airframe?

wildirishtime
02-03-2011, 12:19 AM
Well there's some theories floating around from people smarter than me that an HKS with the 3.47 gear ratio paired with a long 3blade to make use of the extra torque would provide equal or better takeoff performance than a Rotax 582.......

Discuss.
:)