I finally found an FS-26S-C at a decent price. I was almost positive I read about someone using it (the car version) in an airplane, here on RCU. Anyone have a link? Search didn't turn up anything. This four stroke will wind up to 16-18k in stock form and over 20k modified.

Thanks,

gkamysz,
That is really high rpm for a 4 stroke. Dose it use an overhead cam or pushrod valve train? You may have to use a smaller prop then usual for this size engine, because of the advanced timing. Can you upload a picture?

Dave

I have a FS26 airplane engine. Its rather mild and easy going. I use a 10-5 APC on it. It runs in the low 9's

It starts and run easily and doesn't quit

You will need to change the crankshaft ($32.95) to the longer airplane model of the airplane 26. Also, you will need the prop drive washer, retaining washer for holding the prop.
http://www2.towerhobbies.com/cgi-bin...=++&search3=Go


Fuel draw will be a factor because the carb is mounted so far away from the center line. Will need some way to pressurize the tank or pump fuel to the carb yet regulate the fuel flow to prevent too much fuel getting to the carb in some situations. The added weight of the complexity may overshadow and advantages in power?

I plan to change the carb to an aircraft version, or make a manifold. But a horizontal or inverted installation would allow the supplied manifold. This is a "just to be different" project. A four stroke speed plane. The modified engines have been dynoed at over .6HP at 20kRPM. As shipped, the engine has no crankcase breather. I don't know how they get away with that. I can use the stock crank with a special prop nut. The small prop is a must to allow that RPM. I thought the thread I'm looking for said an 8x6 at 16-18kRPM, stock.

This engine has a different cam and heavy valve springs to prevent float. It takes some effort to turn over, without a plug in it.

A horizontal carburator will allow higher gas velocity direct into in the cylinder to give better cylinder filling without hit to much corner inside the canal between carb. and cylinder head. Interest to see what happen if use aircraft carburator without loose power and rpm.

Jens Eirik

The pressure goes through the rear bearing. Pull off the pushrod tubes and you'll see how crankcase pressure is allowed to vent alongside the cam follower and up the pushrod tube. Theoretically?

pssst... don't tell anyone, but while you are ordering a fs-30 crank and drive washer, you can also get a piston/pin/ring/cylinder for the .30 and drop that in. Voila, you'll definitely have the strongest .26 at the field! I won't tell anyone!

I can see the small canal in holes for valvelifter, it allow oil to pass from crankcase to the valves at the cylinder head therefore it give enough lube for the valvelifter and the valves since the engine are running hi revolution. Smart solution!!!

Jens Eirik

That's interesting about the lifter bore, I haven't take mine apart enough to see that. Maybe I'll put a nipple in the rocker cover to let it breathe. Without some way for the gasses to get out, I have doubts about how much oil circulates. The manual is explicit in saying not to run it slobbering rich during breakin, otherwise damage will result. I would expect very rich with an unseated ring would result in a lot of accumulated fuel in the crankcase, and with not much of a way to get out it would lead to problems.

It still surprises me everytime I look inside a new OS FS, that it has little to no lube in it. This one had no oil at all on the cylinder, or rod ends, the cam and lifter box was lubed with grease in this one, something I haven't seen before. The cranks rubs the backplate, but it might not be fully seated in the bearing, I haven't checked yet. I did read that the FS-30 liner is a drop in. I have a several FS-26 I may borrow a crank to make life easier.

For those interested I found this thread.

http://www.rctech.net/forum/showthread.php?p=1202390

This project is a couple months out, but I'll update when I have it.

Don't tell anyone . . . but for $61 plus shipping . . . I can make a 30 out of my 26?

I made a "52" out of my "48" but I didn't consider it cost effective after I got done. The engine runs nice though.

I notice the regular 26 and 30 heads and head gaskets are the same part number

I have a stroked FS-20. I remember reading about the mod in MAN, 15 years ago. I picked up a FS-20 on the auction site and when I got it I tought it looked odd. A teardown revealed the mod which uses an FS-26 crank and some home made parts, like pushrods and a cylinder spacer. It displaces .25ci now.

The 40SC cam fits right in the 48's and 52's. I have two 52's with the 40 SC cam. They seem to run just fine.

The only difference between a 48 and a 52 head is that on the 52 the glow plug is dropped down into the combustion chamber about 1/8". It's worth about 300 rpm try one head and then the other. You can see this from the outside when the heads are side by side.

What are you using the FS-52 with the 40C cam for?

Actually the total lift and duration appear to be the same between the two cams. But the profile is a little broader on the S-C cam. Using the same prop, there doesn't appear any definitely measurable increase in power. It probably would open up a little better than the stock cam using a 10-6 prop rather than a 12-6? But I'm getting along just fine the way the engine runs with a APC 12-6. Right now the engine is on a Slow Poke so it is pointless right now.

I discovered that there wasn't any difference in the valve springs after you get bigger than the 26/30 engine. They all have the same free height and OD.

A few years back I read a magazine article about Saito 30 engine designed for RC cars. It had a strengthened valve train to allow the engine to rev beyond 20,000 RPM. Will endeavor to find the magazine article & report back [8D]

The 40S-C spring is larger in diameter and has a thicker wire. It will have a higher rate than the stock FS-52 spring.

I have an O.S. FS-26S-C that I want to run in an Associated Nitro Factory Team TC-3 but can't find clutch parts or engine mounts to work. Any Suggestions? I have a K-factory racing push type clutch for the TC-3 that might be nice to use because it's got adjustable engagement, but the motor shaft of the O.S. engine seems to be 8mm instead of 7mm like the majority of the small block engines. I don't race - this is just a project for fun in my driveway.

Sounds like fun, I don't run cars enough to know what clutch nut you need etc.

I'm weird... I put a fs-30 crank in my 26SC and look for a plane to put it in.

I haven't done any more with my FS26S-C. I did acquire a FS-40S-C and bench ran it on a 7x6 prop at 18,000. That's well below rated power. Pull starting was pretty cool.

I have no idea about clutch parts. Check in the car section, there must be a few four stroke fanatics. Otherwise, if possible modify the clutch you have on a lathe.