Some test results that have me puzzled.  It appears that these engines should be producing more horse power than what they produced on the ground.  Here are some results.  Standard fuel and the tach was checked prior to the testing.

1. Super Tigre .49 cl. 10-6 @10.660 rpm. .493 hp., 11-6 @68940 rpm .426 hp.

2.  HP Silver Star with Byron Gardner p&c 10-6 @13130 rpm. .922 hp., 11-6 @10750 rpm .741 hp.

3.  OS .35 Stunt 10-6 @9400 rpm. .338 hp.

4.  HP Gold Cup .40 with .281" venturi and ST CL nva. 11-6 @ 10180 rpm .430 hp.

5.  HP .40 Gold Cup Blue printed by an "expert" .281 venturi and ST nva 11-6 @10200 .633 hp.

6.  HP .40 Gold Cup with HP factory nva 11-6 @ 11080 rpm .811 hp.

7.  OS LA .46 cl. 11-5 @ 8400 rpm just breaking into a 2 cycle,  factory venturi and ST nva.  .294 hp,  air speed  40 mph static thrust 45 oz.  No wonder that it will not my 58 oz. and 676 sq." stunt plane!  I have been told that this engine should be turning 10,300-10,500 rpm. with an 11-5" prop at launch!  I am about 2000 rpm. short of that figure. I can see nothing amiss with these engines and the fuel and the props used were the same.

     I went through this with four OS SF .46 engines and their clones so this may be indictive that the problem may be me.  I doubt it as thee engines doe not fly the planes well with the exception of the HP BG engine.  It is a powerhouse! The other engines stagger through the air providing very little line tension.  These engines are very easy to start and run very well but are lacking in power.   My figures are much inferior to the numbers printed in engine reviews.  For example, I was getting Fox .35 Stunt performance from an OS SF 46 engine???

    Suggestions/Comments? 

                                                                                                             Be well,

                                                                                                              Frank McCune

                         

     


Ps. Has anybody else had this problem with under performing engines? 

I have a Top Flite Score that I have not built due to not having an engine with enough power to fly it! I have an ASP .61 20 oz. that may have enough power to pull a stunt plane.

      I am at my wits end attempting to derive enough power to enjoy UC flying.
.

  Frank,
   I found the OS SF 46 to be a very good runner & lots of power using the stock muffler / APC 11-4 or 11-5 10,100 RPM near 30 years ago cant remember I think it was the 11-5.
           John L.

      One common denominator that all of my underperforming engine have is that they preowned or modified by an expert.

I have a bunch of used engines that I've run.  Most have only been modified to the extent that an RC engine has been converted to CL with a venturi and needle valve.  One of those has an ST-style needle valve -- in a venturi that is properly oversized compared to one of the stock OS venturis (there are at least two for the 46LA, so saying "stock venturi" doesn't tell the whole story).

All of them work great, except for the one 40LA that was modified by an "expert".  That one runs just like Brett complains about.  It's actually not bad compared to the one Fox 35 that I've run, but it's not at all great compared to my stock used 46LAs, my stock used Magnum 36, my stock used Tower 40 -- are you seeing a trend here?

I would suggest that if these "expertly modified" engines have been modified by someone trying to make them run like a Fox 35, that you either just run them like they're Fox 35's -- i.e. 2-4 breaks, high-pitch props, and super-light planes to go with the fact that they've been made into wimpy engines.

Alternately, follow these simple steps:

• S**t-can them all, or sell them honestly as "modified for 2-4 run" engines
• Buy a few new 46LA engines, or buy used 46LA engines from RC guys, with the carburetor still on.  That way you know they haven't been "improved".  Buy venturis and needles as necessary from Tower or Randy
• Buy just 46LA engines (or just Tower 40's, or just Magnum 36 XLS, or just OS 40FPs)).
• Run them all the same, only change the prop to match the airframe

That's it.  I see you endlessly screwing around with engine after engine, and I question whether you actually get any chances to fly a decently performing airplane.  If you want to endlessly screw with engines -- well, you can endlessly screw around with any one engine type, and the advantage is that everything you learn can be applied to all your other engines.  You simply cannot do that with a huge bucket of mismatched, modified, and god-knows-what-else engines.

      One common denominator that all of my underperforming engine have is that they preowned or modified by an expert.

      Two engines come to mind.  One is a modified .40 that has less performance than a stock OS .35 Stunt.  The other came back with the compression so low that it was the same with or without the plug in place!  Lol.

  "Expert"? If your modified 40LA or similar is weaker than a OS35S, that is the sort of expertise you could well do without, I think. Your story is very familiar, I see it *all the time*, this is why I go on rants about the Head Gasket Patrol.

     I have seen multiple copies of 46LAs that were incapable of getting a Pathfinder up to an acceptable flying speed, just level flight - with as much as a *10-7* prop. The mods were cleanly done with good workmanship, but you might as well just go get a Fox 35 to improve the performance.   Congratulations, it's 1965 all over again. *This was their intent*, I have talked to a few of these guys, their goal is to make it so putting a 46LA in a Nobler makes sense. It flies better with a stock engine half the size.

   The last thing in the world you, and most other people in your boat (which includes almost everyone that routinely reads this board), need, is a *modified engine*, particularly when the "modifications" are like these. Slight changes to the venturi size (not factors of two, like the other thread) can adjust it a little, and might be beneficial, but gross changes like "block the boost port, drop the liner, raise the intake, and add 10 head gaskets" are never necessary, and serve only to reduce the performance. When you hear "experts" gas on about that, " I dropped the liner, raise the intake, so I could reduce the blowdown" or similar, you can just hear it in their voice, that is a RED FLAG that they are using "jargon" that makes them seem cool and savvy, but probably (not always) have no idea what they are talking about.

    Many times, these guys come on like real experts, and they, in many cases, are firmly convinced that they have learned the "secret", and passing on their hard-won expertise to the lesser lights. They aren't (for the most part) scam artists, the really believe what they are saying and what they are doing, and they think it is a service. But that doesn't change the fact that the results are, as you and many others have found, disastrous. Many times, the clients will adopt the same idea - they might not know any better-  "this is great, I have this Modified Joe Blow 46LA, it pulls my Nobler just great, it just growls, like a Real Stunt Motor. It must be right because it's a Joe Blow motor."  You would note that you don't see Joe Blow's name on that list of winners.

   A real stunt motor is a 40VF, it sounds for all the world like a gas turbine (to the point contests in the mid-90s got really annoying)and runs in a two-stroke all the time.  Compare that to the threads on this board - there isn't a thread in the first 20 pages that deals with or asks about a genuinely competitive system, except for when Randy or I do it for sake of comparison. 

    Brett

p.s. I have been doing some engine testing on "real" stunt engines (RO-Jett 61 BSE "mistake* version), and my latest experiment was to *raise* the liner with a shim (.002"), and then removed the last head .003" head gasket. It ran the break point out another 200-300 RPM an made it match my other engine. A piece of printer paper is about .002-.003. That's a small but distinct change - not .020 and "grind the intake with a Dremel tool". And I emphasize again - I am no "engine expert". I *do* know how it has to run to be competitive.

 

   

I can understand your frustration, but you keep comparing "modified" engines so you have no baseline for performance. It's too dark for me right to use a tach, tomorrow afternoon I will take a brand new 46LA-RN out of the box, put it on a test stand, and see what it does.

  OK, here we go:


Prop                    original         rpm (4-2 point)        rpm (peak)
Top Flite 11-5.3    (from 11-6)           9600                    10400
APC 11.5-4          (95 NATs)            10000                    11400
Bolly 11.5-4         (from 12-6)         10000                    11200
Bolly 12-4.5         (from 12-6)          9600                    11000
   


    This is with a bone stock, completely new ,straight out of the box 45 minutes ago, OS-46LAS-RN engine with no break-in and now has a total of about 2 minutes. Plug is whatever came with it.  Fuel was Powermaster 10% "Air", unmodified, air temp 76 degrees, altitude = 15 feet ASL, pressure alt 100 feet, humidity 33%. Not "disassembled-cleaned-lubed", head screws per factory, backplate per factory, no idea what head shims (factory). Venturi is STOCK 7.2 mm (~.283xx), spraybar is STOCK 3.5mm OS nozzle, needle is STOCK backplate remote needle,

    Engine was *extremely tight* throughout, and clearly getting better with each run. It did the typical thing, it was *boiling hot*, particularly the front end. That is the normal reaction to it still being tight. It would pick up maybe 4-500 RPM at the 4-2 break point, and at least that much on the top end, when fully broken in. The only issue I had with it was my fuel line splitting at the tank, which caused me momentary confusion about where all that air in the line was coming from.

   The prop selection is as close as I had to your test prop, and then 3 props that I would consider running on a regular 650-square inch airplane.
 The 11-5.3 is actually a cleaned-up Top Flight 11-6 Super-M that I last ran on a Fox 35 at about 2000 less ground RPM (in *1979*), 5.3 is the measured pitch.
The APC 11.5-4 is the original 11.5-4 "narrow" that Billy asked APC to make for the OPS-40, and that I ran and qualified at the 94 NATS on my 40VF.
The Bolly 11.5-4 is made from a Bolly 12-6, this is also a 40VF prop, maybe I ran this prop at the 98 NATs.
The Bolly 12-4.5 is an old fiberglass 12-6,  depitched, which I definitely ran at the 96 Golden State contest, which I won, and *may* have been the prop Ted used on the 46VF on the original Trivial Pursuit. This is clearly too much for the 46LA with no break-in, *maybe* it would be OK with it broken in, I would start with it at 5" for most applications, which would be a lot easier on the engine (because the in-flight RPM would be 4-500 RPM lower).

   If I was going to fly an airplane your size with this engine, I would probably start with the 11.5-4 Bolly, adjust the pitch up if it was too "flat" and down if it was too responsive in the maneuvers.

    I suppose the point is taken - this BOX_STOCK engine, not broken in and, honestly, sounding distressed because it is still so tight, greatly outperforms your "expertly modified" version, and most of the ancient former hot-rods, and a few hundred RPM off the best one you have, and will certainly get much better with break-in.

   Of course, this is just ground testing, but stock 46LAs are know to be exceptional at flying stunt planes, power notwithstanding, much better than any HP 40 Gold Cup I ever saw - all of which I routinely beat with my weak ST46, back when they were both viable competition engines.

    Brett

     Hello Brett:

     A big thank you for taking the time and effort to test your new OS .46 LA  engine. Your results give me reference point to enable me to judge my engine.  I am going flying today and will have an opportunity to test my engine.

     As shucks, I just remembered that I another “new” plane equipped with a “new” OS .46 LA engine in the attic.  This will provide me with a chance to do an A-B comparison.

      Yes,  I realize that I am behind the times for getting involved with HP .40 engines, but it very similar to getting involved with an older lady. Lol  Some of the members may have had that experience.  Again lol!

                                                                                        Stay safe,

                                                                                         Frank McCune

                             

     Hi Brett:

      Dunning Kruger? I was introduced to it a couple of weeks ago. Talk about a small world!

      One of the people with whom I fly with, is a practicing psychiatrist.  At times, I have an opportunity to breach matters of the mind.  What a field!  However, we have agreed not to discuss politics or religion.  Only model airplanes.  I am fearful of attracting attention to myself! Lol He might ask me to lie down.

     I flew the OS LA .46 in question today and it peaked out @ 9000 rpm on a 9-5 wooden prop.  When launched at @ 8600 rpm., I got a nice 2 cycle run All day.  I am using 55’ lines to keep the lines tight in the overhead manouvers.  I guess  that is as good as it is going to get with that engine.  I will fly it and enjoy it for what it is.


                                                                               Be well,

                                                                                Frank McCune

...    Yes, the backplate is OK as is (until you crash and break off the corner)  ...

Or until you "fix" the "loose screws" holding it on.  Those plastic backplates work just great -- until you overtorque the screws (by, for instance, taking the engine apart to change out the perfectly good screws for a different, also perfectly good, set of screws).

      Hi Brett:

       After reading your reply, I noticed a glaring typo, mistake, in my post yesterday.  The prop that I used was an 11-5 and NOT a 9-5 as I wrote. This is a major error!  I proofed the reply but did not see the error.  In the future, I am going to proof my proofs! Perhaps, it may be wise if I wait until the next day, after a good night’s rest before I attempt to use a keyboard.

        Thank you again fo all of the aid that you have provided over the years.  As previously stated, Old Age is terrible!

                                                                                     Be well,

                                                                                      Frank McCune

Hello
Back in April when locked down at home (Kakanui north Island of New Zealand) I did a few engine tests and my stock near new LA46 with RC carb and muffler did 12000 on an APC 11.5x4 which was considerably better then a lot of other similar engines I tested. The obvious thing was a lot second hand engines when tested proved to be worn out or 'damaged' .

Sort of remind me of the old saying when trying to find a good deal at a swap meet or online auction "buy a fresh crash engine" as it will hopefully be a low hour unmolested engine out of someones shinny new plane that came to a sudden end.

 Same applied when buying US import V8 engines as a youngster to put in little old English or Australian  4 or 6 cylinder cars "find a fresh crash engine"  especially a good stock engine from the late 1960's cars that looked clean with no hot rod bits added indicating it had a hard life. I latter learnt to avoid cold state engines with freeze cracking and to steer well clear from truck (huge mileage) or boat engines (cracks and corrosion) which are a bit like RC car engines!.  If you had a sound engine to start with you may get many miles out of it as a stock engine or hop ups and rebuilds were much easier on the wallet. Our cheap fun ended when our road safety guys figured we needed well engineered modifications and it all got very expensive to achieve 'certification' of modifications.
Regards Gerald

HI Frank.

One thing you for got to tell people that you only use wood props. A wood prop 12x5 cut down to an 11.25 or 11.50 anod start out at 9500 to 9800 should be fine. AND check you fule. Sig 10% 50-50 or sim. is a starting point.

Scott(just a guy)Riese