NikolayTT

Hi Fellows,

Is there any one who has some experience with the old Webra Speed .91,
I do not mean the most recent one which is Speed-P5. I am interested in
any details about that old engine from basic parameters and into user comments.
On RCUniverse seems there isn't any evaluation report, same is on Google.
Is this a kind of misterious engine which nobody has or kept after buying ?

Best Regards,
Nikolay

Dr1Driver

Hi Nikolay,

I had one and loved it! It's a beautifully cast and machined engine. and moderately user friendly. It likes to rev and breathe. It likes nitro. It occassionally kicks back when starting, due to the high compression. It's easy to tune and reliable, especially with the TN carb.

Mine ran great! It's moderate weight and better-than-average power. I don't remember specific RPM figures, but I seem to remember it has no problems with a 14" prop.

Dr.1

djlyon

I have one and flew it for years on a Sukoi. Mine had a dynamix carb. Made me fall in love with Dynamix carbs.. The engine runs great and turns a 14/6 about 10000 rpm peak.

Denis

NikolayTT

Thank you for the replies - it is really great on RC Universe this way !!!

Lets go a bit further if you do not mind:
It seems by the rpm posted Webra turns almost like OS.91 FX, does it ?
Is it in fact better in general than OS .91 FX, comparing it in the way you
feel about those engines, what do you think ?

Also, if possible, please comment on the relations between the used
type of a mufler or Tuned pipe vs. the Carburator.

Frankly, on any engine it seems we loose 1000 rpm from open exhaust operation
for making it more quiet, or we add about 1000 rpm to make it lot more loud
with the tuned pipe for example. It seems cheaper to forget about all tuned pipes
and that would not cause too much losses of power to some engines, mostly the
general use ones. How about Webra, is it Resonance "hungry" or it doens't
care much about any pipe; that is surely influenced by the carburator a bit.
What do you think ?

How about I just run it without any pipe and any pump and get the pressure from the
crankshaft case like in the good old times most of the Italian SuperTigers were build
for. Lot of saved money and maybe (?) not so much lost power especially at the
remote airfields where nobody cares about noise. Is that good idea for Webra too '
or I would degrade the power well due to the partial expansion of the volume
under the piston with the pipe for tank pressure ?

Thanks for reading and hopefully not getting upset with my anti-mufler ideas,
but that is reasonable somehow, please comment how much is or isn't ?

Best Regards,
Nikolay

Dr1Driver

Thanks for reading and hopefully not getting upset with my anti-mufler ideas,
but that is reasonable somehow, please comment how much is or isn't ?

Not upset here. If it's allowed in Finland, go for it! Caution: Most glow engines need some type of back pressure to idle and transition properly, and to not run lean on uplines and tight maneuvers. The Webra is no exception. Your Webra will love a flow thru-type of muffler, or a tuned pipe. You will gain significant power using either the flow-thru or a pipe. If you can find a Macs Flow-thru muffler or a mini tuned pipe, you're all set! I remember using crankcase pressure on control line planes where the engine was constantly at full throttle. I haven't used it on any R/C engines, but I've heard of transition problems with it. Seems it produces too much pressure at idle, causing the pilot to set the idle needle leaner, which causes the problems.

Webras unload a lot in the air, so don't set it too lean on the ground, or you will have mysterious sagging problems. I'd pick the Webra over the OS for the unloading characteristic. They may turn the same RPM on the ground, but the Webra will eat it for breakfast in the air. I gotta admit, I'm a Webra lover from my teen years, and I'd pick one over just about any other engine for a specific application.

Dr.1

djlyon

I have a 91 FX also, 2 of them actually. In practice the OS 91FX is more powerful. It will turn the 14/6 500+ rpm more than the Webra but it is not as durable. The OS well burn up in a heart beat if set to lean and will give you fits quitting if set to rich. The Webra is much more tolerant of not being set perfect. I use a Slimline Pitts style muffler on mine. I had to partially block one pipe to get enough pressure for the engine. I don't believe crankcase pressure will work if you intend to use the carburetor. The carburetors are not designed to meter fuel properly with so much pressure and will go very rich at low throttle settings no matter what you do. In addition crankcase pressure will give you no more power unless you increase the venturi size a lot. However if you intend to only run wide open with an enlarged venturi it will work fine. I've never run my Webra on a tuned exhaust but I imagine it would respond very well. You might ask that question on one of the German forums. If you don't speak German just ask the question in English. They rely on tuned exhaust much more than we do because of their tough noise restrictions.

Denis

NikolayTT

Thanks, that is well encouraging and also nicely refering to a type of "oscilations" I had on my control line
Super Tiger G46 on which I placed a carb from OS .46. Yes, exactly as you wrote, there is instability with
the idle if there isn't a mufler. That effect I managed to minimise by using on the pressure line to the
fuel tank one directional filter, i.e. clamp filter, in which I have changed the spring with stronger one
till achieving good enough my style of flying mostly in high-rpm. Surely for 3D one needs more
sophisticated solutions than mine; Perry pump etc.

I will look for those muflers from Macs - that is nice direction to follow and not to offend too much
the hearing system of the people with the open exhaust anyway. Otherwise in Finland is even too
quiet and even the electric planes have problems - they offend badly the hearing system of the
horses and there are many horse farmers arround ... including very active Green Peace people;
thus less noise is a very good idea anyway.

Best Regards,
Nikolay

NikolayTT

Thanks Denis !

I was just typing my previous reply while your comments came. Yes, I will take a good look at the
muflers for Webra. Also, I did not try yet to write in English on the German forums. Yes they have
very strict noise control and should be also well populated with all kind of Webra from Austria.

What was written also by Dr1Driver and you on the comparisson between OS.91 and Webra is also
well supported by the prices in Europe. Webra is lot more expensive. You can see if interested the
prices at
www.lindinger.at
which is one of the most popular and sensible shops in Europe; it has English text as well.
Surely I am looking continuosly at
www.towerhobbies.com
but Webra is not offered there.

Is there in USA any major shop which offers Webra ?

Nikolay

djlyon

Right here Nikolay. Good prices also.

www.horizonhobby.com

Hobbsy

My Feedback: (102)

Nik, I have 3 of the .91s, two are ringed engines and 1 is of ABN construction, in my opinion they hate nitro, 5% or 0% will make it a much friendlier engine. I use a Fox .74 muffler and/or a SuperTigre Swing muffler on mine, mine was not drilled and tapped for a muffler so I drilled it for the Fox. Mine have 3 different style carbs with 1 being the DynaMix, as mentioned, it is a great carb.
Here is a picture of the newest one with the ST muffler. As you can see I did a little machine work on the ST header.

NikolayTT

Thanks, I will check Horizon Hobby - it might prove cheaper at the end to pay the postage and the 22%
VAT in order to get Webra cheaper from Austria via USA ... In fact that might be even released from
those 22% VAT because is made in EU.

Oops, NOW I HAVE SOMETHING INEXPECTED IN HAND (maybe) - the catch is maybe possible;
the First Thing Tomorrow is to call the Customs here and find out what is the case !
Thanks a lot to Denis for the Hint !!!

Thanks for the reply from Hobbsy ! I like the modification very much - machining looks very nice !
But then now I have more questions:
- How to recognise which Webra is with Ring or ABN only on the photos;
- Maybe it is possible to get somewhere on the web the manuals for those
old Webra; Do you know some links ? I tried Google and also Horizon
Hobby but could not find for .91 anything; there are many things for
the .61 and for the helli-versions.
- Could you please tell at least the rpm difference on the same propeller
between the Ring and ABN versions, or what is in their data-books as
bhp at what rpm ?

Regards,
Nikolay

djlyon

I agree they don't like nitro. Don't use more than 5%. I used a strap-on muffler. worked fine, looked ugly, but was hidden under a cowl.

Denis

djlyon

Dr1
I'm surprised yours liked nitro. I tried 15% and it detonated like crazy. The engine did come with a bag of head shims though and I obviously could have reduced the compression but it ran so well on 5% that I left as it was.

Denis

Hobbsy

My Feedback: (102)

NIK, the ABN version will not have a bar in the center of the exhaust port, it will be wide open.

Dr1Driver

Oh, I forgot, I DID use head shims, and made sure to not run it too lean. However, I've had .32s and .40s. The .32s love up to 25% and the .40 likes 15%. You're right, though, for normal sport flying, 5% - 10% is plenty.

Dr.1

jaka

Hi!
Nicolai! There is a Webra dealer in Sweden (Elltech) ...far closer to you than the US.

http://www.elltech.o.se

NikolayTT

Hi Jan,

Thanks. I immediately checked and I found the images of the engines, but no prices.
There are prices for Moki but not for Webra. Do you know what would cost for example
such .91 Webra any model in Sweden; of course if you have had come accross of such
information, or shall I call those guys and ask them to make an offer ? Usually in
Finland the things are lot more expensive than Austria, for example see www.lindinger.at,
including the shipment too, but for example the best OS max deals I get from USA anyway
inclusing shipment and + 22% VAT. I wander how is in Sweden.
Thanks,
Nikolay

Hobbsy

My Feedback: (102)

Niko, there is no difference in power between the ABN and the ringed version.

NikolayTT

Hi Hobbsy,

Thanks, that is good news. Do you have some numbers from some data sheet
or by testing ?

Buy the way is that bar on the exhaust window only on the slave, or it is
also on the crankshaft case too ?

Nikolay

Dr1Driver

Nikolay,

The bar is only on the sleeve. The ringed version should use fuel with a pure synthetic mix, like Morgan's Cool Power. The ABC/N version should use fuel with a castor/synthetic mix, like Morgan's Omega. The engines are comparable in power, and pretty much interchangeable.

Dr.1

PS I don't know if this would work, but you might consider someone in the states buying it for you here and mailing it to Finland.

Hobbsy

My Feedback: (102)

APC 14x6 10,000, the synthetic lube would not be a good idea for either engine, it leaves the cylinder dry when you run all the fuel out of it and the ring rusts to the cylinder.

NikolayTT

Hi Fellows,

Thanks ! Well, I am in fact still too "emotional" although I should be more cooled down when it comes
to engines. I still wander what is the best to continue with, after I have already several (4-5) OS.91FX
some of which well used to the let say 50% of their resourses (good question is maybe how we could
define what is 50 % exhausted engine) and then shall I continue with OS or gradually switch to Webra
starting from the old models avaialble from eBay and going into the new ones. Ebay works so far
nicely to me thus I feel more confortable that I do not have to load anyone of the friends to buy
and send me an engine or parts.

Maybe in this Webra .91 discussion we can still try to reorder in sense of .91, the OS.91FX, the Webra.91RC,
and the ST.90 in the following manner (i.e. please put your vote for some of the choices, "Yes", "0", "No",
please delete what is not OK with you):

1. Keep all OS and buy only spare parts. "Yes" "0" "No".
2. Sale the OS on eBay and move to Webra. "Yes" "0" "No".
3. Buy ST and use the OS carburators. "Yes" "0" "No".
4. Your approach would be: ......(please advice) ...

Well, since it is a very serious decision for me I will appreciate very much your advices.

Thank you !
Nikolay

Hobbsy

My Feedback: (102)

Niko, just keep them all, you can never have enough engines.

jaka

Hi!
Of corse you can run all engines on just syntetic oil. 15 % seems to be the norm over here.
All my engines just loves it. Have been using it for 6 years now. Was a very lojal advocate of Castor oil before as I'm a pylonracer, ands as such "knows" there are no oil that can stand heat as effectively as Castor oil can...but ...still syntetics seems to work and work better than Castor oil...strange!!
Prices is for a Webra is around the same as for an OS, but call Elltech and hear fisrt hand.

How about a MVVS 15cc engine? Cheaper than both Webra and OS and equally good running!

Dr1Driver

Hobbsy, I've never had that problem. Of course, I keep all my stuff in an enviromentally-controlled space.

1. Keep all OS and buy only spare parts. "Yes" "0" "No".
Depends. When the cost of replacement parts approaches half that of a new engine, or it ceases to be reliable, I sell the engine.

2. Sale the OS on eBay and move to Webra. "Yes" "0" "No".
Despite people saying otherwise, eBay has done right by me on many occassions.

3. Buy ST and use the OS carburators. "Yes" "0" "No".
Swapping parts is a royal pain in the rump. Nothing wrong with ST carbs, if you know how to adjust them.

4. Your approach would be: ......(please advice) ...
If the OS engines fall under #1 condition, keep them. Go ahead and buy the Webra. You'll be happy with both. As Hobbsy said, you can never have too many engines. Fill'em with oil and put them on the shelf. They won't go bad.

All this is worthless advice if you want to have all the same engines and you want to switch to Webra exclusively. In that case, sell the OS engines on eBay, and buy Webras.

Dr.1