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I had hear differet opinions on differet people, some said it can be down verywell on some particular engine, but other few dont think so.
Mainly problem of the conversion was to improve cooling system's effect, to allow engine output power as high RPM for much longger time compare to automobile. This is what I know.
So what is the turth? How they convert?
Many people have converted auto engines for aircraft use, but the only two in widespread use are Volkswagen and Corvair... both air cooled engines already similar to aircraft engines. Others have been used, for example Mazda rotaries, various V-8s, Model A Fords back in the old days, and some others, with varying degrees of success. As you say, cooling at sustained high power settings is usually the biggest issue, with torsional resonance issues also being a frequent problem (broken crankshafts, etc.).
So what did they do on thouse engines have already same cooling performance as aeroengine? Do they keep the original cooling system?Quote:
Originally Posted by Dana
Well, yes, they keep the same cooling system.
Let's look at the VW engine, which is opposed cylinders cooled in the automobile with air coming from above and down through cooling fins.
In an aircraft, it's the same, but done slightly differently. The air coming into the cowling from the front is cut in two horizontally, with baffling put between the layers. The top section is blocked off, making it high pressure, and the air has only one place to go - through the cooling fins of the cylinders. It works really well.
If RPMs are too high for the desired propeller, a Prop Speed Reduction Unit is used. It's essentially two pulleys of different sizes (the prop being put on the larger one) being driven by a belt (or even a gear).
There are a couple of companies selling converted Honda Fit engines for aircraft use. Time will tell us how well they work. The one vendor I spoke with at Oshkosh told me there were a few flying, and many more in air boats where they have been doing their development and testing.
From what I have read, the biggest problems with higher power installations has been the prop speed reduction units. People seem to have pretty good success with properly converted VW and Corvair engines.
Subaru engines are also very popular for use in aircraft.
Check out the FlySoob Yahoo group if you are curious:
https://groups.yahoo.com/neo/groups/FlySoob/info
-Dj
I don't think cooling is the major obstacle for converting an auto powerplant to aircraft use.
Thanks for recommond, It will be very helpful!Quote:
Originally Posted by deej
I just checked out the 914 VW engine maybe is you talk about, the vw company has several differet types of engines. 1991 cc, 81 kW (110 PS; 109 hp) at 5800rpm. I really want to know the actually temp during take off and cruise. Taking off usually use full power for approximately 5 min, I had see some auto oil cooling engine overheat during 5 min by output 100%power(ground test). And how many time can VW engine run as 80%power? I dont thinks without cooling upgrade It can keep normal temp too long. Because the performence like this will never be applied on automobile. Otherwise can i say air cooling has higher efficient than oil cooling?Quote:
Originally Posted by Frank Giger
Well, let's talk about the standard Type I Volkswagen engine, which is the most commonly used one.
Since I have one installed in my Nieuport 11, here's some pictures:
First up, here's how it's baffled - aluminum sheeting goes around the cylinders, cutting the engine compartment into two halves with the cowl.
http://www.darts-page.com/images/Nieuport/baffle006.jpg
The air is trapped in the upper portion, forming a high pressure area, and is forced downwards through the cooling fins.
I put my oil cooler beneath out in the prop wash for best effect, but loads of people put it back on the firewall for a cleaner look:
http://www.darts-page.com/images/Nieuport/cowl011.jpg
I have the biggest oil cooler on the market, as I live in Alabama and it gets darned hot down here.
With my present setup, I am actually a bit too efficient, the oil temps never getting above 160 degrees.
My engine is bored out to 1915cc, and on climb out I run about 3300 RPM.
One thing to keep in mind is that static ground tests may be more stressful as there isn't much induced airflow associated with forward movement. When you are climbing out, you may be seeing an additional 80 mph in air speed. I don't remember what the relationship between velocity and convective cooling is, but that little bit of extra airspeed could be very helpful in cooling.
Air flow truly effect on engine cooling especially fix wing aircraft. However, on helicopter the engine usually at the middle back, it can't accept as same amount air flow as fixwing that engine installed at front. But without test data, discussions are always empty in truth. If you can provide temperture record during both ground test and practical use based on same engine, that will be perfect to figure out how much can airflow do on engine cooling and that will very helpful.
Don't helicopters usually have cooling fans?
Great big ones they put on top of the engines. I mean the blades to the engine cooling fan are absolutely huge.Quote:
Originally Posted by c322348
Top View, it's almost impossible to provide the answer you're looking for, as every engine and every cooling set up is different.
I can tell you that my engine won't overheat sitting at an idle. Indeed, my main concern is ensuring the engine is warm enough for flight prior to takeoff even in 100 degree plus temperatures. Just one look at my cowl and engine provides the answer - it's a half cowl with an oil cooler the size of three ring binder right in the prop wash.
Indeed, my engine compartment is so open to prop wash and the plane is so draggy that I doubt the engine knows whether or not it is flying!
Your thinking is suprised, I never make rotor as a fan. But seriously the centre of rotor always rotate as slowest speed and blow only few airflow. But never mind.Quote:
Originally Posted by Frank Giger
The idea making a pressure area to trap airflow seems effective on small engine. How many power can it input at 3300 rpm? Compare to 100hp+ water cooling engine they usually run as 4500-5000, as you say different engine have different cooling, I think coolant efficency have more importance than airflow.
Most of people do instill a fan behind radiator. But not every oneQuote:
Originally Posted by c322348
Top View, you've got to ask a better question.
I'm guessing that English is a second language - and that you are excellent in it - but it is hard understanding exactly what you want to know.
For air cooled engines, like the VW (my 1915cc VW is around 90 HP) or the Corvair (about 120 HP, making it a good alternative to an O-200), they work about the same as certified engines.
For liquid cooled automotive engines, I'll defer to others. But in the end it always comes down to how the builder runs the cooling. Some are better than others. But it is always about airflow, whether over the cylinders and oil cooler in an air cooled engine or a radiator in a liquid cooled one.
My comment about helicopter rotors was a joke, btw. I often refer to my engine as the "loud fan up front."
The sole purpose is to keep the pilot cool. When it stops, you can actually see the pilot start to sweat! ;-)Quote:
Originally Posted by Frank Giger
Sorry about the ambiguity question. Turlly English is not my native langyuage and I just study it for few years, may not express exactly.Quote:
Originally Posted by Frank Giger
Briefly I want to figure out what kinds of cooling system can do better as same power output. But this question seems not significant, as you said it depends on how builders manage it.
Thanks for replied as plenty information, that already very helpful.
I am so surprised to NOT see the Viking Engine (Honda Derived) mentioned in this thread. If you get past Jan's rhetoric and see the results of a few hundred engines in service and development now with a 130hp and the 160+ Turbo. I believe he is producing 25+ engines a month. Yes. Jan has a past...and he has solved that problem with selling a plug-N Play engine assembly. Fully supported with mounts, cowlings and FWF supplies. Can't beat the price either. Friend here in NoCal has the West Coast service site has an engine ( 110) in a Sonex with I am sure 1000 hours on it by now. It moves the plane at VNE.
It may have been mentioned already is the heat transfer issue when a VW engine is pushed into the upper RPM numbers under load. A number of fixes are available to support this.
I *so* want to believe this. The claimed numbers and the price are exceptional. But there's that weaseley word "claimed". It scares the living daylights out of me, especially when it comes to something I'm going to bet my life on.
There's a lot to like: low-cost repairs, fuel injection, lost of power, liquid cooling making safe cabin heat a possibility, etc. But then I think of all those WWII Naval aviators who made it back despite losing major portions of their air-cooled engines and I think "what really matters to me?" That's when I get cold feet. We all complain about how conservative the aviation community is, but there's a damned good reason. With our small numbers, we don't have enough "volunteers" on the bleeding edge to get the kind of statistical sample needed to be able to reliably identify and correct the majority of the issues. I'm sure there are a few Viking customers who have 1000 trouble-free hours. What worries me is how many are going to have major issues just as the guys who bought into the Subaru conversions did a few years back. This time it may well be different. But past is prologue and, given the choice, I want a larger body of other peoples experience to refer to before I'll stake my life on certain things.
I looked into this and came away with the theory that there are things a VW does really well, and things it doesn't - and in at least one case I know of I was shaking my head at the selection of a VW at all.Quote:
It may have been mentioned already is the heat transfer issue when a VW engine is pushed into the upper RPM numbers under load. A number of fixes are available to support this.
For light aircraft like mine, a VW is a perfect fit. At a fully loaded (with pilot and fuel) weight of 700 pounds and a fat airfoil that makes for a really effective wing, I'm not demanding much out of my engine, climbing out quickly to around 2,500 or 3,000 ft. AGL in less than five minutes (on a hot summer day) and then cruising around at half throttle the rest of the time.
Throw my 1915cc direct drive set up into a plane twice as heavy with a less effective airfoil and I could see trouble coming. The engine would have to be run at much higher RPM's all the time, and problems might pop up. It's a matter of not asking too much from the engine for what it's designed to do.
Bunkie. I understand your hesitation about the Viking. I am not in anyway affiliated with Viking and am only a follower of the product and have seen a number of installations. That said the Issue with the Subaru engines Jan sold were fundamentally around the very topic we are addressing in the threads - heat - or shall I say cooling. Jan sold the engines - done....when things did not go well the engine, not the installation, was held at fault. Added to that he was financed too tightly and he went under leaving a few buyers without engines and and no relief. The community is not kind to businesses that fold up and leave them hanging. you many have read the comments. [This is not how I would chose to operate and now that the business is doing well I would pay back the offended buyers and request deletion of the webpage. But it is not my business]
His new business/product model uses a well designed and proven engine and has released a second gen block (130) and a designed for turbo engine (160+) which is still in beta. Added value is the availability of a designed for cowling and an integrated cooling system as part of the engine package. It is truly a plug and play installation (module) that requires very little installation and no engineering. Even an EFIS system is available designed for the engine at fair market price.
Jan has a large inventory of PSRU parts but seem to be doing very little service. It, like the VW and Corvair engines, are experimental. Unlike the VW engines the engine cores are OEM vs racing derivatives.
So, if you (collective) feel anxious about using an experimental engine in your experimental aircraft then go ahead and get a certificated engine.
That was one issue, but not the only one. There have been internal problems with the PSRUs, problems with the spline shaft that connects the PSRU to the engine, problems with the valve timing setup (the original variable valve timing inside the engine was disabled and the timing gears were altered, and this alteration has been problematic), the initial engine timing map in the computer is incorrect and needs tweaking, etc. Note that these problems were not builder installation issues. There is a wonderful group of talented individuals (community members) that have worked around these issues, and today I think it is a fairly good engine package, but there was a lot of work that needed to be done after the initial purchase to get to this point for the EZ30 six cylinder engine. There are now several of these flying with hundreds of hours, and some with over a thousand. There are still some ongoing concerns with the PSRU but those are being worked on.Quote:
Originally Posted by Jim Heffelfinger
Two of the engine types sold, the Sti and the EZ36, have been abysmal failures. I do not know of any that are safely flying. On the other hand, the original four cylinder packages that were sold seem to have had a good success rate.
fyi, fwiw.
My VW has a stock core.
Jim, I'm not anxious about experimental engines in general, I'm almost certainly using a Corvair, but I'm not at the decision point yet. Jan Eggenfelter left a bad taste in a lot of peoples mouths. Just for that alone, I would be very hesitant to do business with him. As I said, I really like the premise of the Viking engine, really, I do. the difference between it and a Corvair is the large body of experience with it. The problems are, for the most part, known and addressed. Another important point is that the Corvair is frozen in time. It's a bit counter-intuitive, but automotive engines are changing rapidly and there's a chance that new versions of an engine can introduce new problems. The Corvair is a known quantity.