OS FS26S-C 4-stroke development
 

Hi all, I don't know how many of you are following the 4stroke thread, but I thought I would start my own thread regarding the development of the tiny OS .26 4stroke engine.

So far I have only scratched the surface of what I think this little engine is capable of.

Let me know what you think of the idea and any suggestions are always welcome.

I will keep posting results as testing progresses.

So far I have only tested the engine for base tests and compared it to a .15 thundertiger sport engine (std).

This dyno comparison is on the '2stroke vs. 4stroke' thread.

I designed my first attempt at creating a new header and silencer for this engine and will post dyno runs below.

the green run is the std OS .26 4stroke straight out of the box, broken in, and tested with a available short header and std silencer.

the blue run is the same OS .26 4stroke, with bushings replaced with bearings for camshaft support, and my header and silencer added.

I was very suprised with the results that the header and silencer made.
peak rpm was increased from 18,500 to 24,500
peak hp was increased from .38 to .54
peak tq showed no increase but tq range broadened substancially.

Much more to come...

BK

Awesome work, Keep it coming:D

Wow that's lot of jump from the stock HP.
is it the pipe or the bearing?
Can this engine fit in 1/10?

The change was definitely the pipe. The bearings for the cam only eliminate parasitic losses from bushing drag. The bearings might increase revs slightly but I didn't show an increase when I tested the bearing change by itself.

The difference with the pipe change was incredible. Really increased response also.

I have a few more pipe ideas to try before I settle on one.

BK

how about a picture of the stock pipe vs your new pipe and do you have any results of checking of just running a straight header.

More progress!!!
 

For those interested,

I have made a bit of progress today on the OS FS-26S-C development project. I made a new intake manifold and fitted a 2 needle carb from a 2 stroke engine I had lying around. The new carb has a bore 1mm larger than the std os carb.

The gains were substantial;
peak hp .54-->.64
peak tq .16-->.18
peak rpm 24,800-->26,500

Granted we lost a little bit of power on the front side, but I think with a better quality carb that has more precise metering we can get that back easily.

Dyno run explaination:
Light blue run is std OS FS-26S-C
Green run is the run from my previous post.(New pipe and silencer)
Dark Blue run is the latest run.(New pipe and silencer, and new manifold and carb)

I havn't even started messing with the compression or the ports yet!!

Looks like we might have a winner here after all!!

I'll post more on this project as I have time to mess with it. I gotta get some real work done!!

BK

Good stuff. Can't wait to see how much more power you can squeeze out of the engine. Looks like I might be putting my OS .26 back in my FW04 soon.

OS FS-26S-C VerII
 

hello all,
I just wanted to see if anybody has heard any news if OS will release there OS FS-26S-C VerII in the states. They have them showing on their Japanese website but not on their English website. Maybe someone from OS, or a hobbyshop with some inside info can help us out! I really hope to see these engines in the US soon!

Check back soon to see dyno graphs of my latest improvements!

BK

How about some pictures of the motor, pipe and carburator. instead of these graphs.

Pictures...
 

I will show pictures of all modified components when development is finished and the parts are ready for sale. In the mean time I will try and post a few seek peeks of the engine on the dyno in the next few days.

BK

I'd like to see a picture of the Dyno.

Where did you get it? What do they cost? How realistic are their readings?

But interested in pics of the engine, too.

Dyno answers
 

Red,
If you would like information on the dyno please visit my web site. http://www.nitrodynesystems.com . I originally designed the dyno to test some exhaust systems I am working on. I had so much interest I decided to manufacture them for sale. The price for a complete dyno is $4995.00. I realize that is not cheap but the cost of components and labor involved in machining dictates such a price. (this price does NOT include laptop computer).

As far as accuracy and repeatability is concerned, I believe this dyno to be VERY accurate, but more importantly is is extremly repeatable. I can repeat runs within .01 hp. It also has real time weatherstation capabilities, for correction factors.

One thing I have found is that most manufacturers that publish hp figures are full of c*&p. The best .12 engine I have tested so far is .78 hp. Which in my opinion makes sense, 1.6 hp from .12ci simply is not possible!! If you compared these claims to a top fuel dragster making 5000 hp, they make 10 hp per cubic inch. If you were to compare the claims of manufacturers, they claim 13.3 hp per cubic inch. Does that make sense?

BK

I was lucky to be invited by Brian to test couple of engines. I can tell you that device is realy cool tool.
We were running my engine on it and we did repeated runs many times and it has never fail-always, if I don't change setting on engine, was mshowing the same numbers in HP, torq and RPM.
Great tool for anybody who is looking for max power from engines. Specialy good for modifiers who is doing their work from the sky, so they can check how one or other type of modding affecting performance.
I hope I will be able to run my P/S sets on it to compare to original. I know how it is better on track, but will be very interesting to see in #s
Edward

Hey, BK

Can you tell me what engine it is that makes .78 HP?
You can PM me if you can't tell...
I won't tell anyone....

OS FS-26S-C VerII availability...
 

I spoke to OS today and I was informed that OS US was not planning to import the OS FS-26S-C Ver II to the states. The reason was that due to lack of sales of the previous version they don't feel they could sell enough units to warrant stocking the engine.

I discussed what I was working on and that I feel that the engine may be competitive with some more development, we just need to get race organizers to allow the engine to race with the .12 two strokes.

Let me know what you guys think. If the OS FS-26S-C Ver II was competitive with the two strokes but got way better fuel mileage, and had way more torque on bottom would you consider racing it? What would you be willing to spend to make it competitive? I realize that competitive .12 two strokes can range between $350-$650. What would be the limit you were willing to spend to race the four stroke?

Please give me some input on what route to take, should I push to get this engine in the us or should I scrap the four stroke project?