Norvel 061 Big Mig vs. COX Tee Dee 051

balogh wrote:

Surfer_kris wrote:From my own experience, the Norvels are superior to cox engines. It sounds like there is something wrong with your Norvel engine, could you post some rpm numbers?

Will tach both of them tomorrow.

been following this thread.....the symptoms are all but mind boggling, but until the engines are run, speculation can drive one nuts.

have you run them yet?

i run engines that are much bigger than these that have shown same signs of quality issues...........rpm's were much better than expected while the overall compression feel was lower than expected.........then again, the worst thing that some do to their engines is to pull the prop thru slowly..........brisk flipping of the prop thru compression is a must for those setup with pinch at the top.
by pulling thru slowly you are allowing the natural pinch to actually force the oil out of the fit and cause galling which worsens the fit.
on the other hand, my best engines have been the ones that seem extremly loose.

MikeM wrote:

balogh wrote:

Surfer_kris wrote:From my own experience, the Norvels are superior to cox engines. It sounds like there is something wrong with your Norvel engine, could you post some rpm numbers?

Will tach both of them tomorrow.

been following this thread.....the symptoms are all but mind boggling, but until the engines are run, speculation can drive one nuts.

have you run them yet?

i run engines that are much bigger than these that have shown same signs of quality issues...........rpm's were much better than expected while the overall compression feel was lower than expected.........then again, the worst thing that some do to their engines is to pull the prop thru slowly..........brisk flipping of the prop thru compression is a must for those setup with pinch at the top.
by pulling thru slowly you are allowing the natural pinch to actually force the oil out of the fit and cause galling which worsens the fit.
on the other hand, my best engines have been the ones that seem extremly loose.

If you read the first message of this thread you will see there is no speculation here...the performance compariosn of the NV and COX engines was based on flight experience

balogh wrote:

MikeM wrote:

balogh wrote:

Surfer_kris wrote:From my own experience, the Norvels are superior to cox engines. It sounds like there is something wrong with your Norvel engine, could you post some rpm numbers?

Will tach both of them tomorrow.

been following this thread.....the symptoms are all but mind boggling, but until the engines are run, speculation can drive one nuts.

have you run them yet?

i run engines that are much bigger than these that have shown same signs of quality issues...........rpm's were much better than expected while the overall compression feel was lower than expected.........then again, the worst thing that some do to their engines is to pull the prop thru slowly..........brisk flipping of the prop thru compression is a must for those setup with pinch at the top.
by pulling thru slowly you are allowing the natural pinch to actually force the oil out of the fit and cause galling which worsens the fit.
on the other hand, my best engines have been the ones that seem extremly loose.

If you read the first message of this thread you will see there is no speculation here...the performance compariosn of the NV and COX engines was based on flight experience

OH......i thought i read where you said you were going to post some tach readings..........

i seriously doubt you have the Norvel propped properly, along with head clearance setting.................is the NV peaky when trying to lean?.........or does it fall off into a rich setting easily?

for the record, i run TeeDees only and never venture out to what seems to be better as the Cox's have always proven reliable and more than enough power for their intended aircraft size.

I've been tinkering with my three Big Migs this afternoon. I have one that I received as a new engine and ran it in myself. I did follow the NV instructions at first, but by the time I finally cranked it, I knew not to run it sloppy rich, thanks to Andrew, Kris, Fit90-Bob and Ken, all of whom jumped in to help my incompetent ass get it cranked. At the time, I was new at flip starting too, and didn't know there were springs to be had. I think it's a Russian engine because it has a shiny silver prop driver.

This new one has SPI but neither of the two old ones do. All are revlite and all appear to be Russian. One looks cruddier than the rest but has more pinch and as good or better compression than my newest. The middle one has no pinch but it still clicks at the top, which might be the con rod like in the Coxes. I can't see any 10W oil blowing out when compressed on any of them. I put too much in one and couldn't turn it through TDC at all. I watched while I was compressing the oil and none bubbled out of any of them after it was past 1/3 of the way up. I can hear it sucking through the venturi, but I hear nothing from the exhaust while turning through TDC. My hearing isn't super any more, but not awful either.

I've gotten the two older ones mixed up, but one of them turned 28.8k on the tach with an APC prop and the others have test run in the mid 20s, both over 25K. Oddly the old one with the best pinch and compression has a blued piston top. The cylinder walls look fine and like I said, it has the best pinch of all.

I wanted to get a better look at the rods on the two older non-spi engines, and find out if the loosest one really had no pinch, but I could not turn the hex bolts in either engines' cylinders. I'm pretty sure I had one of them apart before because it was stiff when it was given to me. I might have just had cheap wrench problems today. The closest fit was a 2.5mm allen key. If anyone knows the right size please tell me so I can get a quality new hard metal key. As I recall, my New engine has regular slotted screws in it. When I get the hex screws out I need to put some longer ones in like the CEF Norvel experts do. That way, you can grab them at the bottom with pliers.

Hope this helps,
Rusty

RknRusty wrote:I've been tinkering with my three Big Migs this afternoon. I have one that I received as a new engine and ran it in myself. I did follow the NV instructions at first, but by the time I finally cranked it, I knew not to run it sloppy rich, thanks to Andrew, Kris, Fit90-Bob and Ken, all of whom jumped in to help my incompetent ass get it cranked. At the time, I was new at flip starting too, and didn't know there were springs to be had. I think it's a Russian engine because it has a shiny silver prop driver.

This new one has SPI but neither of the two old ones do. All are revlite and all appear to be Russian. One looks cruddier than the rest but has more pinch and as good or better compression than my newest. The middle one has no pinch but it still clicks at the top, which might be the con rod like in the Coxes. I can't see any 10W oil blowing out when compressed on any of them. I put too much in one and couldn't turn it through TDC at all. I watched while I was compressing the oil and none bubbled out of any of them after it was past 1/3 of the way up. I can hear it sucking through the venturi, but I hear nothing from the exhaust while turning through TDC. My hearing isn't super any more, but not awful either.

I've gotten the two older ones mixed up, but one of them turned 28.8k on the tach with an APC prop and the others have test run in the mid 20s, both over 25K. Oddly the old one with the best pinch and compression has a blued piston top. The cylinder walls look fine and like I said, it has the best pinch of all.

I wanted to get a better look at the rods on the two older non-spi engines, and find out if the loosest one really had no pinch, but I could not turn the hex bolts in either engines' cylinders. I'm pretty sure I had one of them apart before because it was stiff when it was given to me. I might have just had cheap wrench problems today. The closest fit was a 2.5mm allen key. If anyone knows the right size please tell me so I can get a quality new hard metal key. As I recall, my New engine has regular slotted screws in it. When I get the hex screws out I need to put some longer ones in like the CEF Norvel experts do. That way, you can grab them at the bottom with pliers.

Hope this helps,
Rusty

Thanks Rusty you have hit the nail on its head. The name of the game is compression that your engines apparently have, but mine, though young and almost virgin (if "almost virgin" makes any sense at all) has a poor compression and tight pinch...two conditions that I as a humble combustion engineer find reason enough to explain the experience I put down at the beginning of the thread. Politically incorrect, though, but having grown up behind the Iron Curtain and gained sufficient experience with Russian technology, I am not surprised at all.

I have nothing more to add here, only to confirm that COX (that I have known/used since the mid-70-s) is unbeatable in manufacturing precision.

[/quote]
Thanks Rusty you have hit the nail on its head. The name of the game is compression that your engines apparently have, but mine, though young and almost virgin (if "almost virgin" makes any sense at all) has a poor compression and tight pinch...two conditions that I as a humble combustion engineer find reason enough to explain the experience I put down at the beginning of the thread. Politically incorrect, though, but having grown up behind the Iron Curtain and gained sufficient experience with Russian technology, I am not surprised at all.

I have nothing more to add here, only to confirm that COX (that I have known/used since the mid-70-s) is unbeatable in manufacturing precision.[/quote]

so your analysis is based on what you feel compression wise...........no tach readings as you posted............glad i haven't wasted money on these engines then.

"combustion engineer".......

Balogh, I'm really disappointed to hear that about your new engines. Nobody deserves to get crap in exchange for money. I hope you will follow up and get the situation remedied. If you could somehow get a set of Norvels built like they are supposed to be I think you'd eventually be glad you did.

Proper running .061s are so powerful that you have to tame them with props to fly different weight planes at a comfortable speed. Many makes of 6" props, like my favorite, Master Airscrew, are too much load for flying hardcore stunts, but you can use combinations of different pitches and lengths to keep the revs up in the 20s in the air and they are just remarkable performers, never slowing in the pullups. I had to learn more than I ever knew about props after I started flying with a Norvel up front.

MikeM wrote:

Thanks Rusty you have hit the nail on its head. The name of the game is compression that your engines apparently have, but mine, though young and almost virgin (if "almost virgin" makes any sense at all) has a poor compression and tight pinch...two conditions that I as a humble combustion engineer find reason enough to explain the experience I put down at the beginning of the thread. Politically incorrect, though, but having grown up behind the Iron Curtain and gained sufficient experience with Russian technology, I am not surprised at all.

I have nothing more to add here, only to confirm that COX (that I have known/used since the mid-70-s) is unbeatable in manufacturing precision.[/quote]

so your analysis is based on what you feel compression wise...........no tach readings as you posted............glad i haven't wasted money on these engines then.

"combustion engineer"....... [/quote]

Instead of spending time/fuel on tachning, I went out to the field to fly my R/C plane with NV this afternoon. The NV engine run so poor that I have almost crashed my plane...will reinstall my COX tomorrow...the compression in the NV is getting poorer the more I run it (25% castor!!! ) Good luck to all NV owners I have no doubt that yours are fine..I may have picked one from a poor production run. (What do you mean by LoL combustion engineer??? I have decades of experience in engine technology) To Rusty: I ran the NV on a 6x3 COX prop that no doubt is found to be a good fit by many of you.

MikeM wrote:...glad i haven't wasted money on these engines then.

"combustion engineer".......

Not to be a smartass, but I'm glad I haven't wasted any money on them either.(I know, they were gifts, but I'd still say that if I had paid for them)

RknRusty wrote:

MikeM wrote:...glad i haven't wasted money on these engines then.

"combustion engineer".......

Not to be a smartass, but I'm glad I haven't wasted any money on them either.(I know, they were gifts, but I'd still say that if I had paid for them)

So what is YOUR conclusion....good or bad?

First of all, keep in mind I'm a CL flyer, a freestyle stunter which is extremely demanding of constant power with no bogging in hard pullouts and loops. I'm estimating the 70mph range is my fun comfort zone on 45' of line, which is about 3 second flat laps.

My conclusion is that up until you bought yours, the Norvel is far superior to any engine in the class for the money. To get a better off-the-shelf performer you'd have to get a Norvel AME(pressure feed only), or spend a lot of money on a Cyclon or one of those exotics. But I bet they don't last as long.

Next in line for me is the Tee Dee .049/.051, which I love. There is not an easier engine to crank, needle and run. But if my planes were any heavier, they wouldn't perform as well with the TD, where a Norvel would still have plenty of reserve. I'm already close to the minimum prop at 5-1/4x3 for the Tee Dee .051 on my heaviest Baby Streak(minimum being 5"). The Streak with the Norvel is 7.2oz, but the one with the tee Dee is around 9oz. Any heavier and I would have to use a 5x3, and any smaller than that will wear a Tee Dee out fast. If Tee Dees were still a dime a dozen, I wouldn't worry, but I want to preserve it as long as I can.

Yours are not right. I hope it's only a glitch, but in the mean time, I think you qualify for a refund or an exchange for some engines that they test and confirm to be top quality before shipping them to you.

balogh wrote: The blow-by was there right when I took it out from the box...then I added COX after run oil into the cylinder and carb....the blowby was still there...I followed the Norvel break-in instructions....poured some oil into the cylinder and carb then turned the engine without the head on it with an electric starter for some time...then started up and let it run rich for many minutes...then let it peak out....the pinch is still there when cold, as is the blowby...I can only hope the castor shellac will deposit in the micro scratches of the cylinder and piston thus improving the compression over time.

I don't understand why they tell you to run it rich. My understanding is that you should get it up to peak ASAP and let it settle in there. Steady running is what wears-in the parts here. The hard-anodized cylinder is much harder than the high silicon aluminum piston so the piston will wear much faster.
Castor varnish does not imbed well in the surfaces of the aluminum oxide nor on the aluminum piston. That characteristic is more or less reserved for porous iron (mehanite) pistons.
I would not expect the fits to improve. If it runs well, great. If it does not, change them. Do not go just by what you see, the bottom line is how it runs. Good luck.

George

I guess the only option would be to talk to NV directly, one shouldn't accept any problems with a brand new engine. If they screwed up one batch of their engines (or piston/cylinder sets), they should also take their responsibility and replace or refund those who have been affected.

Surfer_kris wrote:I guess the only option would be to talk to NV directly, one shouldn't accept any problems with a brand new engine. If they screwed up one batch of their engines (or piston/cylinder sets), they should also take their responsibility and replace or refund those who have been affected.

It would be unjust not to tell you about my experience in the field today: I left only 1 shim under the head and tried again. The engine revved up and screamed at a so far unheard frequency...the R/C plane was a ball to fly.

Unfortunately my basic observation on the poor compression remain valid, but at least the power has returned into the NV.

Thanks for the contribution from you all. My conclusion:

1. Once I replace the present set, I will preheat the spare cylinder/piston combo before breaking in
2. I will leave only use shim under the head.
3. I will call NV and tell them about my experience. I do not think, though, that they will ship me a new cylinder/piston combo free-of-charge...they are not a charity organization and it is hard to proof I used the engine as per the instructions i.e. the warranty is still valid. You will believe me I have been in the modelling business since the mid-70's and I know how to handle engines.


Thanks again. maybe I will later continue this thread with my experience with NV as a model engine vendor...

I think this thread was worth it...but I still remain an adamant COX worshipper.

Okey, that's good news then.
Next step is to run a smaller prop, the cox 6x3 has rather wide blades and will not let the engine rev as it should. Try an APC 5.7x3 for instance, or a 5x3 prop. Cox also made a narrow blade 5x4 that works well.

Surfer_kris wrote:Okey, that's good news then.
Next step is to run a smaller prop, the cox 6x3 has rather wide blades and will not let the engine rev as it should. Try an APC 5.7x3 for instance, or a 5x3 prop. Cox also made a narrow blade 5x4 that works well.

Thanks,

how about a 3-bladed 6x3 Master Airscrew? It has narrower blades, albeit 3 of them, than the black COX 6x3, and thus seems to be a bit large.

A 3-bladed prop would give an even higher load on the engine. If you have a 2-bladed 6x3 MAS it can quite easily be cut down to e.g. 5.5x3.

That GF series MA 6x3 is my main prop. I cut them to all different sizes.
Speaking of MA, I bought some larger props for my Shoestring, and the new ones are slimmer than the older ones. I haven't tried one yet, but I expect thrust will be reduced.

The newer MA props work well, just deburr the trailing edge before using them. I've had a 9x4 that cut straight trough a leather glow while flipping a PAW diesel...