mtntopgeo

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Over the past few months, I've noticed a number of OS .12 CVR engines, selling for cheap, on the auction site. Comparing specs to some of the latest OS .12 car engines, it appears that they might have gotten obsoleted??? Bought a couple of them, both in like new condition. One had a rotary carb, & some sort of "super duper" aftermarket head; only paid $20 for it. Threw a chunk of aluminum in the lathe & made a prop driver, & prop nut. No other mods. Ran tests with only one prop (APC 6.5x5) and two fuels. (15%, & 33%). The 15% gave 20K, but on the 33%, ran out of needle (no muffler for press. tap, & no crankcase press tap.) I'm quite optomistic. Now I see that a CVR crankcase was advertised as "for .12/.15". My, things are starting to get interesting!!!. Thinking of a large (270 sq.in. ?) SWR ..... Getting old(er) so quick, & still so many toys to check out. ....... George K.

combatpigg

My Feedback: (3)

George, $20 is incredible!
If you can find a light enough slab of 3/8" balsa, 6" wide, 36" long, you could carve a nice wing out of that. Otherwise, I just made a wing for a .15 by stacking thick "ribs" and strips of wood along the perimeter over a 1/16" sheet outline and sanded the ribs with a long board to a decent looking shape. Once I was happy with the shape, sheeted the top with 3/32", which left enough meat for further refining of a smooth airfoiled shape. It went pretty quickly, which is more important than anything....

Japanman

I would expect there engines to go pretty decently, I think they are very direct descendants of the CZ11 pylon engines: In fact I suspect the first "small" O.S car engines where just O.S CV11 pylon specials with a big finned head and rc carb.

I have an aftermarket true hard chrome P/C set that came from tower for $! (edit: i won`t say how much.. the price went up...) and it is has excellent fits and roundness... and it is for the 15 [8D], though if you want to you can get the one with a smaller hole down the middle too for the 12....

Here is the link:
http://www3.towerhobbies.com/cgi-bin...?&I=LXGYC5&P=7



J.M

mtntopgeo

My Feedback: (12)

CP, thanks for the input. I lean towards the wing-build on the 1/16th sheet. I had/have a beautiful piece of 1/4 balsa sheet (6x36) & even got as far as layng a full length 1/4 " spruce spar into it. Since then (2 years ago) I've even managed to sit down a couple of times, with razor plane in hand, & just looked at that board; knowing full well that I'm gonna screw up, on trying to shape that fine looking piece of lumber. Appears that the only way I'm gonna have a slab wing is to start with the SIG airfoiled plank, (as I have done in the past,) & they don't offer that in 3/8 th ".


Stefan, I followed the link that you posted. Great price, but Tower was outta stock. (This seems to be happening more often, not only with Tower) So, I followed Towers link to the mfg., Dura Trax) They list that piston/sleeve assembly for several OS engines, but then made a specific statement that it won't work in the CVR. No explanation, too bad. Sooner or later, a cheap 15 is bound to show up on the auction site. ................ George K.

Mr Cox

That's certainly a good rpm number. How much does it weight?

Japanman

I just did a search on tower for the CVR p/l set.
It looks to me like the porting and construction are really good: the other CV engines seem to be ABN but the CVR is ABC. more importantly, the porting looks a little more modern: a lot like the picco porting, which is really good IMO.

I think for $20 you got a steal.

S

mtntopgeo

My Feedback: (12)

Pretty heavy, 'bout 7 & 3/8 OZs. However, over 1 & 3/4 OZs of that total are in that huge car head. I should be able to get rid of at least 1 OZ, maybe more. ............................ George K.

skaliwag

My Feedback: (1)

Got this at the Flea Market. Thread at the business end seem to have been cut off. Needs a piece of aluminum sclupted for the front. Compression feels good. Any interest.

proptop

My Feedback: (8)

When it came to racing, the .12 CVR was never competitive...IMO anyway... and has been "obsolete" for a long time. It has a decent torque curve (for a sport .12 ) and good fuel "mileage" (talking about car useage here ) but is heavy, and a Picco would/will slaughter it when it comes to power.

skaliwag..that crank is cut like that for use with a pilot shaft style clutch nut.

I have several CVR .12's and .15's (most have been retired ) and they make for a relatively mild / torquey car engine...might make for an OK airplane engine?

Isn't the .15 airplane version still available?

Japanman

I am beginning to remember looking into the 15 and 18CVR engines. For a time the 18CVR was cheap and it looks really good: I considered the possibility of building a long stroke or near square 15 with the CVR 18 crank and the duratrax P/L set (and re-working the ports.) In the end I did not, but I remember thinking about just buying a CVR15, untill I realised it had the same small crank as the CV/ CZ engines, while the 18 has a bigger crank. At the time i was pretty sure the small crank was a major limitation to power. After running the Picco P-0 I am not so sure that it is, for general prop piston speeds. But in a car and with the airflows increased by using a pipe, I suspect it may be one of the limitations of the CVR VS a picco or other engine with a larger crank rotary valve/ tunnel. Plus of course I bet the picco comes with several mods standard that the O.S would need done to it by hand.
Did you ever run the CVR18?

J.M

proptop

My Feedback: (8)

Yeah, I think the small intake passage in the crank is a limiting factor with the .12 and .15 (at least in car useage )
The .15CV airplane engine seems to be a decent performer.
Might make a fun project converting the car engine to airplane use?


I've never seen the insides of the 18 though...don't have any experience w/ those.

Mr Cox

It is a pity that all the effort seems to be in the car department at the moment, why aren't they using lipos like the rest of the world seems to do?

At my local fields I haven't seen anyone else using a glow engine below .15 for several years...

Back on topic, for about the same weight (appr. 7 oz) HPI are making something with ABC technology, except that the C stands for "Carbide". Looks about ready for an airplane once the head is chopped a little. The price is a wopping $200, but if it works then why not, it is rated for 35000 rpm...



More info here: [link=http://www.hpiracing.com/optionparts/stat-ns12rss.htm#stats]HPI .12[/link]

mtntopgeo

My Feedback: (12)

[quote]ORIGINAL: Mr Cox


At my local fields I haven't seen anyone else using a glow engine below .15 for several years...

Back on topic, for about the same weight (appr. 7 oz) HPI are making something with ABC technology, except that the C stands for "Carbide". Looks about ready for an airplane once the head is chopped a little. The price is a wopping $200, but if it works then why not, it is rated for 35000 rpm...



[More info here: [link=http://www.hpiracing.com/optionparts/stat-ns12rss.htm#stats]HPI .12[/link]



I can relate to the absence of small powerplants. I've been a member of our club for 1 & 1/2 years, & rarely see any powerplants even in the .15 size. My usual engines are .061 & .074 Norvels, .09 & .11 Enyas, & sometimes a .15 XLS, & a .30 Saito.

Yep, the car engines do seem to get a lot of attention/effort from the mfgs.. Other than the price, (I'm a titewad) & availability, what got me interested in the CVR were some of the reports that I read. Seeing that this engine appears to be totally obsoleted by progress & the competition, & was said to have a nice torque band, (as reported by some of the car guys), I thought that it had a chance of turning a decent size prop. At 21K with the APC pylon 6.5x5, things look promising. The HPI rocketship would very likely greatly overshadow the CVR in a car, but this here cheap-skate is quite reluctant to spend a couple of hundred bucks to see how it can spin a prop. Besides, getting a $20 engine to "do well" is part of the fun.!!!!!!! Got a stupid question here. (Please don't laugh too hard) I know that there are gear drives on some highly tuned engines, but, would one of those car type "clutches" work on these smaller engines? Just wondering that if the engine could get into it's horsepower producing RPM range, before engaging power to the prop, it might be able to spin said prop. ????????? OK, I'll shut up now, & let you guys point me in the right direction. .... George K.

combatpigg

My Feedback: (3)

George, I'm with you on this. Anything you get out of $20 plus your time making the prop drive is gravy. If you want to run it without a muffler, GreatPlanes has a brass 6-32 pressure fitting that you could install in place of one of the backplate bolts. I just did so on a K&B .15 and it works good.

mtntopgeo

My Feedback: (12)

Yep. I'm with you there. However, all I could find laying around was a Fox with 4-40 threads. Plenty of meat in the center of the cc cover for the small thread size. Between cold weather & some med. issues, haven't had the time to try it out yet. May have to give the house a castor oil fogging, & test out the smoke alarms.!!! ........... George K

combatpigg

My Feedback: (3)

Well, you're 1 step ahead of me! I'm surprised a modern engine comes with that option. Those car engines must need the extra strength there.