I love this subject and have contemplated turbo charging my 2180 for quite some time. I feel I have extensive knowledge of turbo charging systems as I have done extensive amounts of turbo and turbo engine work on automobile applications.
However, and not to slight anyone here, I don't think I would ever consider taking a turbo from one application and believe I could bolt it to my VW 2180 or a Corvair engine and expect success. I cut my teeth in turbo experimenting with automobiles. I will also credit much of the knowledge I gained came from many individuals involved in the Shelby Dodge Auto Clubs. Here is what I learned. Or, I could just cut to the finish and suggest that if you want to turbo your airplane, start with a proven turbo and engine application and then make minor modifications as you need. But back to what I learned. With a turbo several things are critical to it's success. I would say that the most important is proper air fuel ratio delivery and the ability to monitor that. In an aircraft , this would be highly critical. I think more engines blow up ( turbo or normally aspirated) because they get to a lean mixture condition. Adding a turbo makes this even more of an issue. For that matter, anything that increases horsepower makes fuel delivery very important. So, fuel injection would be my choice over a carb on this subject. I would also install an air fuel meter. You would also need to deal with the great deal of increased heat that a turbo creates. Both to your oil and probably even your air fuel mixture. Cooling the air fuel mixture can be done with and intercooler. The increase in oil temps would be a challenge to your oil cooler and oil delivery system. You may also need to deal with the fact that when you shut off the engine, all that hot oil from your turbo will drain down to your engine , thus increasing oil temps after shut down. The most reliable automotive turbo's use both oil and engine coolant to keep the turbo cool. You also need a reliable way to regulate the waste gate. Or in other words you have to be able to keep the turbo from overboosting. Again, I believe you need to monitor this with a guage. If not you will never be able to keep head gaskets on your engine. You would also burn holes in the tops of your pistons, burn valves and so on and so on. Speaking of valves, my experience leads me to believe that you would need to change the exhaust valves on your engine as well , in order to deal with the increased temps of combustion. This goes back to the idea of starting with a reliable engine turbo combination. I could go on and on with the subject of turbo charging. I would also say that I think it is the cheapest and best way to get more ponies and torque out of an engine. I also would guess that there are people on this list that know 10 times more then me on turbo charging. But I qualify my information with the years I spent experimenting with turbo in automobiles and that I was able to take a 2.2 four cylinder engine of 140 horsepower and develop a reliable dyno tested 360 HP with incredible amounts of torque. But, I did this using a tried and tested engine and turbo combination. I was able to take advantage of computerized controls for fuel delivery and waste gate controls. I was able to write my own computerized fuel tables and timing curves to assure air fuel mixture at various RPM ranges. This was all done via Engine ECU and interfacing a laptop computer. And the whole system seems a little complex for a KR2. I also need to mention that I struggled with all the items mentioned above. No big deal when on the ground ( ok maybe a few towing bills and head gaskets and parts and such) but I sure wouldn't want to have those issues in the air. I would still like to turbo an engine for my KR2. I am still unsure of the best, lightest and most reliable way to do it. Maybe I will start with some Rev Master turbo parts and go from there. Jeff York KR-2 Flying N839BG Home page http://web.qx.net/jeffyork40/ My KR-2 http://web.qx.net/jeffyork40/Airplane/ to see my KR-2 Email [email protected] ----- Original Message ----- From: "hussein nagy" <[email protected]> To: <[email protected]>; "KRnet" <[email protected]> Sent: Monday, November 21, 2005 7:40 PM Subject: Re: KR> Geared vs direct drive > Hello, Colin, > I always enjoy you comments on subjects, I am an observer to the KRnet , I bought a KR2 Boat with retractable gear and tail dragger, I have no experience of building A/C but opinion of experienced folks count, Now let ask you , I have the wing center Old aerfoil RAF48, Do you think the new aerofoil is woth it at this stage of the built, and changing to fixed gear better than the retract fo KR2, when the new aerfoil instaaled do you think that the elevator and the rudder will be resized. would like to know your opinion, > Best regards > Nagy > Jacksinville, Florida > 904-543-8183 > > Colin Rainey <[email protected]> wrote: Netters > This debate about best engines for experimentals, and whether to turbo, whether to Gear drive/PSRU or direct drive has been going on for a while now, and I suspect will probably continue, kind like the Ford/Chevy debate (Chevy is best, LOL ). I am NOT going to take sides of whether a builder should choose auto or aircraft engine, normally aspirated or turbo, or direct drive or PSRU. All these things are in the archives, and found in literal volumes in other writings, both Internet and books like, "Auto Engines for Experimental Airplanes" by Robert Finch, just to sight one example. There are many others. > > What all Netters, especially you new members need to take to heart is that engine selection is VERY important. Looking at certified aircraft, you will see that it it the single most important factor when considering an aircraft's present value, how many hours on the engine. Of all the expense of owning an aircraft, once it is completed, the most money you will spend will be for the engine, and its up keep/maintenance. Turbo charging is the cats meow for cheap horsepower, but just ask Orma Robbins about how this "enhancement" comes with its own unique set of problems to deal with and overcome. Also, the article sighted states that turbo charging generally adds at least 50% more power. This is out right fiction! The best that I have seen proven by dyno runs is approximately 40%, and this is with associated engine modifications, AND the use of an inter cooler, which is not mentioned in the article at all. B&M, Vortech, Banks Turbo-charging, and Paxton all report similar > values for their "bolt-on" systems. I am not saying that a turbo or supercharger cannot add 50% or more power, but that rather that bolt on systems do not give that kind of increase, and do not want builders running out and buying a turbo for their engine expecting to get a 50% increase in power and torque by just hacking the exhaust in order to add the turbo. > > The same rules hold true for direct drive vs PSRU. There are definite benefits to a PSRU, but to set one up on a 2.2 to 1 reduction, just to achieve maximum horsepower from an engine from a dyno run, and say that is best does not take into account all phases of flight for the engine, only take off. That is the only time you will use max power. This amount of reduction although it makes the max power available according to the dyno, it does not allow for a reasonable rpm for cruise. This is because the prop will be slowed to 2000 to 2100 rpm, which begins putting it below its cruise efficiency speed. Just compare certified props that are made to run in this range of rpms. They produce max thrust at near redline, and produce best cruise thrust at 75 to 80% engine power. This puts the prop at around 2300 to 2400 rpms on a 2750 redline. This puts the engine in the re drive at 5060 rpms for the 2300, and 5280 rpms for the 2400 rpms at the prop. Now your engine is running > just like the Rotax family of engines and can expect the same life, or simply 50 to 100 hour maintenance intervals with a major a max of 500 hours out. It also makes the combination "peaky", where basically you spend literally all your time at or near peak rpm. > > Robert Finch's book details a lot of engines that have been successfully used in direct drive configuration; the Buick V8, the VW family, the Corvairs, and several others mentioned in his book. In larger aircraft that have more generous weight allowances for the engine, the more complicated and heavier engines have a good appeal. BUT for our applications, in order to stay in the RECOMMENDED weight range of engines AND their output, direct drive offers the best answers, and air cooled the simplest installation. Above all, it takes research and study to decide and engine install, and talking to other actual pilots of those engines. Don't get sucked into the trap of some fancy numbers calculations and good advertising on one web page where one engine is presented as the experimental airplanes dream engine. There are a lot of "assumptions" and over generalizations made at the expense of the builder. No quick answers here. It takes years to build a KR, take enough time to > study your engine completely BEFORE spending any money. > > > Colin Rainey > [email protected] > EarthLink Revolves Around You. > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to [email protected] > please see other KRnet info at http://www.krnet.org/info.html > > > > > nagy hussein > > --------------------------------- > Yahoo! FareChase - Search multiple travel sites in one click. > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to [email protected] > please see other KRnet info at http://www.krnet.org/info.html >
