millerhill

My Feedback: (19)

I'd like to get more power out of my OS .10. I've seen video on YouTube of "turbo plugs" and increasing the bore. Can anyone give me some pointers on how to get more RPM out of my little engine? I'm running it on a Herr Li'l Extra.

Steve

icerinkdad

Power is a function of how much air and fuel you can get through an engine in a given time. Often using more nitro (15 or even 25%) and a smaller prop will give you more power but it may not be something that gives you vertical performance. What prop are you currently using? A lower pitch prop will slow the plane but improve vertical because more thrust will be generated at lower speeds (kinda like low gear in a car with a manual transmission). If you are looking for all out speed a smaller diameter may be what you need. So lets start with what fuel you are using and what prop?

soarrich

My Feedback: (98)

Get a .15, save the .10 for something it works on. Other than switching to 15%, and playing with prop selection I wouldn't do anything to the motor.

millerhill

My Feedback: (19)

I'm running a 7x4 prop and 15% nitro. I had a mousse can muffler on it that gave me a pretty decent improvement in RPM, but I found that it created a hydraulic lock problem that I couldn't resolve. I don't want to go nuts here...just optimize the engine. I'm going to try different props and see what I like best. I do have a .15 that I can put in the plane, so I guess that would be the next step.

The plane's getting pretty beat so I also have in the back of my mind building an 1/2A extra over the winter to put the .10 in so I'm looking ahead a bit in terms of optimal power for this engine.

combatpigg

My Feedback: (3)

I agree, for the couple ozs difference between a .10 and a .15, that's where the biggest gain is to be had.
A .10 will turn a 7x3 the best for all around sport performance and pulling power. Going to 30% heli fuel drives the cost of flying up, but you will see some gain. It's nice to have an extra head gasket on hand when experimenting with higher nitro. The prop load effects the optimum compression setting. The rest of the mods are simple, but not worth typing unless you are willing to sacrifice or give up throttlability.
The most basic speed secret of all is to make sure the crank fit is free, but not sloppy. Polishing a relief in the main journal between the ends reduces friction. Removing material from the inside of the piston and oval shaping the rod will improve the unloaded rpm.
The hydraulic lock tells me that you need to shim the head, then your pipe set up might work better.

Yuu

soarrich is probably right, considering ALL the threads written on the lil Extra with a .15 engine. But... you could search for thread 5789602 for 'tricks' for the OS .10

Mr Cox

Which OS10 is it, the LA? Plain bearing and ABN is not so good for high power...

Andy has worked on the FP I think(?)
If I remember correctly there was not such a big gain using a turbo plug, but some gain was found by increasing the compression ratio. In the end I think he kept the case and stuffed something else in there in the usual manner.
Should be several movies on the youtube from that tinkering.

If you are going for a .15 you might as well go for an Enya .19, about the same weight as a Magnum/ASP .15

longdan

There was a thread a couple of years ago about hotting up a FP .10.
A couple of things I recall that made small gains were:
1. Putting a fillet of JB Weld into the crankshaft opening to smooth the 90 degree turn that the air has to make after coming through the carb.
2. Grinding a relief into the crank where the air exits the crank centre and enters the case, but it has to be at the correct angle relative to the pin to be effective.

Also, position the NVA so the end is only just protruding into the carb throat, as its a pretty small hole and the end of the NV jet can take up quite a bit of this small area.

All of these things plus those already mentioned only give incremental gains, but put together, may add up to a noticeable increase.

I'd be keen to hear if they all work. Keep us updated if you decide to hot up your .10.

millerhill

My Feedback: (19)

The engine is an FP and pretty long in the tooth (I got it with a Baby Bee that was built in the 50's!). I think I'll try a .15 for now and see how that goes because most of those physical mods are beyond my experience.

I still haven't figured out exactly what a turbo plug is. I did follow a reference to an OS plug used for nitro cars. The YouTube video shows a 5K increase in RPM which would be substantial. What's the deal with that?

Steve

longdan

A turbo plug, as commonly used in RC car engines is one that; instead of using a copper gasket at the top of the thread to seal, it has a short taper at the bottom and the head is specially machined to accept it. The seal is made at the bottom of the threads and does away with the compression losses caused by the piston trying to compress mixture up into the threads of the glowplug and this compression then trying to expand out of the thread clearances.
I probably haven't explained it very well, but if you saw one, it would be immediately obvious.
Nothing wrong with an FP engine. Even if its old it is still pretty much the same, if not better than the LA engines that replaced it and are still being sold today.

combatpigg

My Feedback: (3)

A 5000 rpm improvement from doing a plug change......... I suppose you could replace a faulty plug of any brand with a new plug and see dramatic improvement. Especially in a racing engine that has been optimised to run just a certain way with no exceptions. Some dramatic improvements [1000-1500] have been seen in the 1/2A engines with plug design.

Mr Cox

There was not a gain of 5000rpm from merely a plug change! Of that I am absolutely sure, I think I would have remembered that one... [X(]

The consensus was that the plug change added much less (for a large prop) than the typical 1500 rpm as seen in 1/2a engine. For the OS 10 is was more like 200 rpm as seen here: [link=http://www.youtube.com/watch?v=26aG0d89KRg]10 FP modified[/link]

The full story should be in here: [link=http://www.rcuniverse.com/forum/m_5789602/anchors_5794931/mpage_1/key_/anchor/tm.htm#5794931]OS .10 tricked out[/link]

mtntopgeo

My Feedback: (12)

Got to go along with soarrich on this one. For the 'Lil Extra, if you want more power, & performance, get a .15 & save the .10 for something it's more suited to. ............... Yes, a guy with a lot of talent (& skill), who has all the right "toys" (machine shop), & who enjoys tinkering with these little noise (music) makers, can get some very measurable increases in performance. I've only had one (new) la .10. After playing with it for awhile I made a very easy mod for more performance. Swapped it out for an Enya .09, & never looked back. sold the OS, & since, have bought several more of the Enyas. ........................ George K.

combatpigg

My Feedback: (3)

If I had a OS .10 that I wanted to use for general sport flying with the best climb, usable throttle response, reasonable glow plug life........

I'd use a 7x3 prop. MAS has a very good one.
30% helicopter fuel. Powermaster is good.
Experiment with that MCP...I've never tried one on a .10, but they are fantastic on .25-.40s.
Have a few head shims and a liner shim handy to dial in the MCP. If all else fails the stock muffler with the baffle removed helps. A full tuned pipe set a little bit long works in sport applications, too.
Finally, taking a fine carbide rotary file and elongating the throttle bore will improve the top end. The throttle will still function, just not as well.
Keep the all up weight of the plane to 24 ozs or less using "HD 1/2A" gear.

Mr Cox

ASP .12 are not too bad either, a bit heavier than the OS, but they are true ABC, twin ballbearing and twin needle.
10% nitro seems quite enough and they will spin an apc 7x4 for sport use and excellent idle (down to 2500 rpm) or the APC 6.3x4 for a little more scream to it.

Andrew

Here are some pics to accompany longdan's explanation. Notice how the plug sits flush with the bottom of the head.

longdan

I can vouch for the ASP .12. It honks compared to the OS10. And it's a drop-in replacement - mounting holes are the same. A bit heavier due to twin BB and twin needle carb, but the extra power more than makes up for its extra weight.

chevy43

Dieselize it! My OS.10 FP swings a 9x4 MAS at 10,300 rpm. I have a Davis head on it.

Mr Cox

If Diesel is an option, then a PAW 09RC will swing a MAS9x4 at about 10600 rpm and it weights about 1oz less than the OS10...

ndb8fxe

My Feedback: (1)

I had the same outfit : Herr Lil extra with a os .10 however mine was a LA. I ended up dropping a .15 in it and it flies much better.

wolfy888

Much in agreement.... add nitro, remove weight from the airframe....you get the picture.

Mr Cox

The muffler might be a good place to start. A folded pipe design might give an extra 1000rpm at the top and the stock mufflers are heavy. The noise level will increase too though.

iskandar taib

My Feedback: (5)

Send it off to this guy for rework and a Nelson plug conversion.

http://www.flyfreeflight.com/Site/Ve...son_Heads.html

But then.. it'd be like putting lipstick on a pig (Henry Nelson's description of something similar).

Iskandar