182 hp from a 2.2 litre Subaru is about 82 hp per litre. 115 hp from a 1.2 litre Rotax (the 914) Is about 96 hp per litre. The Subaru’s not that stressed by comparison. Must be more to the story than that.
TK Sent from my iPad > On 29 Dec 2019, at 5:37 am, Mike Stirewalt via KRnet <krnet@list.krnet.org> > wrote: > > Postings are scarce on KR net this holiday period so I'm putting this in > for anyone that's bored. > > I admire you guys with your Subarus. A lot of engineering complexity > goes into getting these engines to work well in an aircraft. Besides the > thrust bearing issue Max Power is discussing, other Subaru issues are > water cooling, turbocharging, reduction drives and through using these > mechanical features, squeezing a huge amount of power out of such > relatively small displacement engines - 2.2 litres - roughly the same as > a GP 2180 or Revmaster 2100D. Instead of getting the rated 76 HP at 3400 > RPM of a GP2180, the Suburus are pulling 182 HP from an engine of roughly > the same displacement. > > I had a hangar neighbor, a retired aircraft engineer/designer, really put > his heart and wallet into an EA-81 turbo installation on his Europa over > a period of 10 years. He used the Marcotte PSRU (I've earlier > incorrectly posted that he used the Eggenfeller). The Europa was > designed for a Rotax but Wayne was attracted to the idea of using more > power and making a really high flyer out of it with lots of range. He > made many enhancements such as additional fuel capacity and added all the > available factory options and, of course, put a dual GRT panel in it > along with a plethora of back-up instruments. A really first class > effort that taxed his excellent engineering skills. It took a lot of > ingenuity to sculpt into the stock Europa design the radiators and > plumbing necessary for the Suburu. The front end came out looking > rather bulky and not very sleek looking but it was engineered well. When > finished the engine ran well for quite a few hours on the ground and even > ran well enough for Wayne to fly it up to the designated airport for > flying off the 40 hours. Since it was a monowheel, he had a landing > mishap in a crosswind so brought it back to Gillespie to install the > tri-gear option that's offered for the Europa. After running the engine > some additional time on the ground, when he again was headed to the 40 > hour fly-off airport, the engine disintegrated shortly after takeoff. > Wayne, although he had been doing very little flying while building this > plane, landed it on a busy freeway without mishap and had a flatbed truck > bring it back to his hangar. The engine had broken a timing gear and > swallowed some valves and he hadn't the heart or trust in it to re-build > it. He trashed it and all his elaborate plumbing, reshaped the cowling > and put in a Rotax. He then sold it to a fellow who flies it (N951EU) > out of Apple Valley. Wayne retired to the Ozarks. > > Pictures at this link show what it looked like with both the Suburu and > the Rotax cowlings. > > https://tinyurl.com/rckpda3 > > Discussing things afterwords the concensus seemed to be that trying to > squeeze so much power out of a 2.2 liter engine frequently causes failure > due to heat and stress. Mainly stress. Same thing that kills people > kills engines. Sometimes the reduction drive is also a factor. > > https://www.nbcsandiego.com/news/local/small-homemade-plane-lands-on-stat > e-route-67/1928901/ > > What boggles the mind is how the automotive industry manages to make > reliable engines by doing the same thing - developing huge horsepower > numbers from very small displacement engines. I think they get away with > it because the engines, while rated at a high HP, spend their lives > loafing along at very low power settings - unlike engines used in > aviation applications. The fastest production car in the world (until > recently . . . it's always changing), the Koenigsegg Agera RS, gets its > 1160 HP out of a 5 liter V8, about the same size engine as what's in my > Olds 98. > > Mike > KSEE > ____________________________________________________________ > Simple Trick Is Improving Men's Love Lives > Med Journal > http://thirdpartyoffers.juno.com/TGL3141/5e07aec070a72ebf4186st02vuc > _______________________________________________ > Search the KRnet Archives at > https://www.mail-archive.com/krnet@list.krnet.org/. > Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. > see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change > options. > To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org _______________________________________________ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org
