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- This topic has 7 replies, 5 voices, and was last updated 13 years, 4 months ago by RONALD BENNETT.
11/11/2009 at 8:13 pm #41252
While randomly searching the world of WWW., I ran into a r/c car site. These guys run .12 and .21 sized engines but pursue the engine mods quite differently than we do. It seems that they use some engines that we commonly don’t see (such as the Novarossi and a hot rodded OS) and do some fairly interesting things to them. Look at the attached picture of the crank…
So, if you have some time to waste, glance thru some of the links and look at the photos of the internals of the engines. Big mods to the crank as well as wierd porting ideas (such as “the fangs”). Now, I don’t know if they work, but it is interesting. Plus, while we have stuffed the cranks for the last 30 plus years with a brass insert they commonly use RTV!
11/11/2009 at 10:16 pm #48158Steve LandyParticipant
John, do you have any specs on these beasts? HP @ rpm? Has anyone put a ff prop on one of these and recorded the results? I, too, see a lot of these car engines on eBay and often wonder…..11/11/2009 at 10:22 pm #48159Scott LapraikParticipant
John, I’ve been looking at the specs. on some of the O.S. car engines and they are quite impressive. The low end ones are rated at 30k rpm while the full race ones are listed at 38k. I’m looking at obtaining a .12 OS CVR and working with Bob Mattes modifying it for FF. Bob says he’s done this to a couple of car engines before. Should be interesting. Steve the O.S. engine web site has full specs. for there engines.
Scott11/11/2009 at 11:41 pm #48160
I really have no knowledge on these engines. They do turn them up alot tho and looks like they typically run 20-30% nitro in them. When I read a bunch of their comments it seems that they spend $250-500 on engines. The guts look pretty nice, with either ABC or AAC P/L sets, ceramic bearings, shorty tuned pipes, and looks like many run pipe pressure.
One of the articles was discussing the use of slots on the squish band that run axially from the combustion chamber to the edge of the head. The Cyclon .061 uses these and the thinking behind this is that the flame will travel thru the slots for more complete combustion of fuel trapped there. The interesting part of this is that on the Speed Talk website (big car engne stuff) there was a good discussion on using this same slot idea on SB and BB Chevy stuff. They ran the slot from the exhaust valve to the cylinder wall. After doing this, the coloration on the piston showed much better coverage. Now, whether it gave more power is somewhat unknown but they did seem to think that it did…11/12/2009 at 12:05 am #48161DAN BERRYParticipant
The car guys will also run ’em with low oil content. Longevity isn’t such a big deal, maybe.
Jerry Wagner, in Florida, has a plane maybe 400″ with a 10 or 12 buggy engine in it. I can tell you guys, it goes like a bat outta hell. Joe Clawson has a small car engine but i don’t know if he’s got a plane built yet.11/12/2009 at 3:02 am #48162
Yeah, you are right on the oil deal- I saw somewhere in all the talk of 5% castor and 5% synthetic….One time I mixed up some 60% nitro/8% “mystery oil” and 35% methanol….I ran it in some TD 049 and it ran just fine- Not sure what the oil was but it was synthetic and it did work, at least in that instance. Would I run 10% oil in anything good? Probably not…11/12/2009 at 3:09 am #48163DAN BERRYParticipant
George Aldich told me that he made a lot of money repairing engines that rc guys said only neede 15% oil in the fuel.11/12/2009 at 11:39 pm #48164RONALD BENNETTParticipant
Some general thoughts and experiences with car engines for aero use. A number of control line speed fliers have long been using the Novarossi 5-port .21 for .21 Proto and .21 Sport Speed – right now, it is the “engine of choice” for .21 applications. Some, including me, are working with the OS V-Spec B .21 engine with some success. Scott Newkirk is working on the rb Concepts .15 for A speed and a few are trying the Orion WASP .28 for B Speed.
Most car engines are designed to run a small flywheel and a very light engine load, and run in the mid-30,000 range. But, when you load them up with a prop, they drop of dramatically. They achieve their performance in low load application with a 7 to 9 intake ports (works of art to look at these liners), yielding high HP at high RPM but low torque. I’m not going to get into 2-cycle compression engine theory here but more turbulence give more torque and more fuel/air yields more RPM/HP.
John’s photos do a great job of showing the workmanship that goes into building a crankshaft – trick flow, radius-ed transitions, and tungsten weighs for balance, for example. The other BIG problem with car engines for aero use is that in cars, never sees side loads (like when the prop hits the ground), and all have been turned back to accommodate a flywheel/clutch unit. This make them prop to breaking and leaves very little for a thrust driver (prop hub) or threads to mount the prop. Nvarossi makes an aero crank version of their 5-port .21.
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