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Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

os 55, webra 50gt, or rossi 45

Old 02-01-2010, 10:00 AM
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taildragger21
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Default os 55, webra 50gt, or rossi 45

Ok guys.. Mind me but I have been to the "dark side" of 100-150cc aerobatic gassers and havent ran the 40 size in a while.. Myself and 4 others got the need for speed and bought great planes vipers.. I just maidened mine yesterday with an old os 46ax and macs tuned exaust. I was spinning an apc 9x6 at 16000 rpm. Noticed before the engine was installed it had a bad "gald on the piston".. the engine had been on a GP learjet and ragged out for 5 years doing speed runs, so I am not suprised. On my first flight of the viper it was spinning 16k and ripping through the air. Second flight the engine ran rough and lost the perfect needle setting I had. I think its about gone. SO....... sorry for the long story.. I am about to buy a new engine and am looking for anyone with experience with these types.. I have never had a bad os.. The 46 I have has been most reliable and had a hard life. Thats why I was thinking of the 55. I know they are pointed more towards torque.Can I get the rpm out of the os 55?? . I know my 46ax turned up. The rest of the guys are running JETS, and ROSSI'S on their vipers. never had a webra and only one rossi.. I am thinking the os because my macs pipe will fit right on.. What do you guys think??
Old 02-01-2010, 10:14 AM
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Default RE: os 55, webra 50gt, or rossi 45

The Webra is the strongest of the three but a bit heavy. Maybe finding a MVVS, Jett, or Nelson?
Old 02-01-2010, 11:24 AM
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Default RE: os 55, webra 50gt, or rossi 45

go with the 55. run a 9x9 prop on it.
Old 02-01-2010, 01:46 PM
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Default RE: os 55, webra 50gt, or rossi 45

Webra is the lightest of the three but I don't know if they still make the .50. The webra (and probably rossi) will rev and unload better than the new OS's. OS exhaust spacing doesn't fit webra though. None of them will compete with Jett.
Old 02-01-2010, 02:53 PM
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Default RE: os 55, webra 50gt, or rossi 45

with some work you can get any of those enegine to out turn the jett. now i am not knocking jett at all as own several. now what you do get with the jett engine is quality and those engines will make that same power six or seasons of heavy flying. the other engines even including the OS dont last to long making great power.

our engine guy in the club gets most all 47-55 size engine to turn around 18,000 -19,200 on apc 9x8 props on 5% the magnums and super tigers seem to turn the most rpm out of all the normal engines.


what ever engine you get put the Jett stream red muffler on it. you will love that muffler.
Old 02-01-2010, 03:03 PM
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Default RE: os 55, webra 50gt, or rossi 45

if you are buying new, then a jett or a rossi 45 with the 10mm carb, its about the long term running costs, and dead nuts stability day in day out
Old 02-02-2010, 06:04 PM
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Default RE: os 55, webra 50gt, or rossi 45


ORIGINAL: evan-RCU

The Webra is the strongest of the three but a bit heavy. Maybe finding a MVVS, Jett, or Nelson?
I bet you were talking about the heavy Rossis... Webras are lighter than their os equivalent (like the .32 for example ).
Old 02-02-2010, 08:58 PM
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Default RE: os 55, webra 50gt, or rossi 45

There's a guy running a OS 55AX with a Jett tuned muffler on a Viper and it flat out hauls. The engine is running a 10X10 apc around 14K and before someone mentions it, yes he tried a 10X9 and it was slower on this plane. The engine never really screams but pulls like mad. The 55AX is not a high RPM engine, piped or not. Great flight time

If you can find a discontinued Webra 55 (black head!) it will turn a 9X10 at 16k with a red Jett muffler. The problem is, most used Webra 55s have been damaged from use of over 10% nitro. The rod ends get hammered and that shortens the stroke so it finally stops popping plugs, but the high potential performance is gone. Webra 55/50 and Jetts are the lightest of the engines. You can’t loose with a fast and durable Jett 46, or 50 but I find them thirsty.

All the engines mentioned can be fast, it's a matter of how well you matched up engine, prop and exhaust type.
I cant say whats the fastest, so have a look:

http://www.youtube.com/watch?v=zdf1EU5cEc0

P.S. I don't know if the one in the video has a stock or Jett muffler.
Old 02-02-2010, 10:35 PM
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Default RE: os 55, webra 50gt, or rossi 45

Thanks guys.. Actually I ordered a magnum 52.. I kinda cheaped out but I hear they love rpm. Should go great with my macs exaust I already have from the os.. The magnums are cheap enough that if I burn the 52 up after a season then I could just buy another one...LOL
Old 02-03-2010, 03:26 AM
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Default RE: os 55, webra 50gt, or rossi 45

ORIGINAL: taildragger21

Thanks guys.. Actually I ordered a magnum 52.. I kinda cheaped out but I hear they love rpm. Should go great with my macs exaust I already have from the os.. The magnums are cheap enough that if I burn the 52 up after a season then I could just buy another one...LOL
I had one with a Jett "in-cowl"(Turbo Jett) tuned muffler, and it ran like a scalded ape. The early ones had carb mid range and crankshaft breakage issues, both of which I had. After about 4 gallons of use (abuse[sm=lol.gif]) the crank snapped at the port. I hear they are much improved.

If your Macs exhaust is "the black pipe", the performance is close to stock since that is not a tuned muffler or pipe, but a light weight, rugged replacement for stock mufflers that shake apart.

The Macs tuned pipe or muffled pipe for the ultimate power or Jett tuned RED muffler(highly recommended) for simple compact boost.
Old 02-03-2010, 05:31 PM
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Default RE: os 55, webra 50gt, or rossi 45

i have the magnum 52 with a nelson ultra thrust, on a black-horse twister 36, at 4 pounds 8 ounces, goes like hell, vertical out of sight at half throttle, my next mod will be some heli bearings with the plastic cage on the rear bearing, as one of our local guys had his cage come apart, he runs 10x7s and winds it up on a stock exhaust less baffle......
Old 02-03-2010, 05:45 PM
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Default RE: os 55, webra 50gt, or rossi 45

Yeah, after I done some reading here I have found out the magnum 52 is actually a hot rpm turner.. Should be insane on the 3.5 lb. viper!![8D].. Gonna hold it straight down from a mile up and do a full throw 180 degree pylon turn when it levels on the deck and see if she holds up...[&:]
Old 02-03-2010, 07:21 PM
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Default RE: os 55, webra 50gt, or rossi 45

i am using a 4d carb from a os engine, and the stock magnum carb needs some tlc, i take them a part, then clean, then reassemble with blue loctite thread locker, i have found the fuel inlet nipple is frequently loose... so dry and clean the use blue loctite, my needle valve was incomplete in its taper, so i removed the mushroom shape on the end of the needle the, then polished the taper with 1000 grit wet or dry paper till it shone, now it is very stable, set the needle and forget about it.
Old 02-07-2010, 11:30 AM
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Default RE: os 55, webra 50gt, or rossi 45

ORIGINAL: RVman

Webra is the lightest of the three but I don't know if they still make the .50. The webra (and probably rossi) will rev and unload better than the new OS's. OS exhaust spacing doesn't fit webra though. None of them will compete with Jett.
The Webra .50 GT is still around. Swaynehouse ($162) and Hobby Club ($169.95) sell them on-line. You can also get the Speed 55 GT for $175-$225, but it doesn't come with a muffler. It is definitely a speed demon and Webra will be selling it for quite some time to come. Both engines are newer technology builds, too, with 5 ports, instead of 3.

Run a WEBRA on 0-10% NITRO and do not put anything higher in it without shimming the head, or you will ruin the engine as stated above by "freakingfast".
Old 02-07-2010, 02:17 PM
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Default RE: os 55, webra 50gt, or rossi 45

Hopefully they still have the older Webra "Speed" 55's in stock at Swanyshouse http://www.swanyshouse.com/engines/engines.aspx




http://www.webra-austria.at/motor.ph...der=AERO〈=EN (discontinued "speed" black head, known for speed & power.)

http://www.webra-austria.at/motor.ph...der=AERO〈=EN ( new 5 port "P5", natural colored square head, feed back seems to indicate it's a lower RPM working range engine.)
Old 02-16-2010, 06:01 PM
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Default RE: os 55, webra 50gt, or rossi 45

Just for an update.... I have ran the magnum 52 on the test stand for 5 tanks on a 10x7.. Switched to a 9x8 and the macs muffler from my os46 VERY slightly rich and got 15500 RPM. Just mounted the magnum on the plane. Engine starts and runs well.. I am impressed. All the guys in the club with their rossi/jet powered vipers were getting scared![8D]

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