Regards to superten require a fan for 4stroke. The 4stroke engine was originally designed for airplane. As you see all airplane engine doesn't require huge fins or heatsink head to do the cooling due to the propeller is driving air flow over the engine. OS modified the .26 or .40 4stroke to fit on a car without altering the external casting. Secondly, the 4 stroke doesn't have huge heatsink head like our 2stroke due to the over head valves. It's main cooling are from the small fins around the cylinder wall.

The main advantage of 4 stroke engine is fuel efficency and huge torque produce on low rpm. Hence it can geared to very low gear ratio to make up lack of RPM comparing to 2stroke engine. A properly geared car for 4 stroke engine will be just as fast as properly geard car for 2 stroke entry level, 1HP rated, engine. But for each tank a 4 stroke might last 2x than 2 stroke engine so 4 Stroke engine is good for multiple hours endurance races.

From what I understand, the Japanese kinda have a cult following for the 4 stroke sedan class, It's not the fastest but it is becoming very popular.

Yes, testing engines is alot of fun, but sorry I can't say what were testing

I agree that 4 stroke engines have a huge advantage in the fuel consumption dept.

I will get ahold of a .26 surpass 4stroke engine and test it against a .12 sport engine, and post my findings.

Should be interesting to see exactly what the differences will be.

BK
http://www.nitrodynesystems.com

until the neighbors complain.

do you know what kind of fuel the 4 stroke runs ?

looking forward to it and nice work on the dyno.

There is a speical blend of fuel for 4 stroke engine but that's for planes. If anyone here have ran 4stroke version of kyosho superten fw04 or any contact with OS can share some light on this.

The RC car 4 strokes run on standard car fuel. I think that they recommend lower nitro content though.

It would be interesting to see just how much power the OS 4 stroke could make with a lighter valvetrain.

Comparing an OS .21 VZ-R Turbo 2 to an OS FS 26 SC...

The .21 VZ-R:

Displacement: 0.211 cu in (3.5cc)
Bore: 0.654 in (16.6mm)
Stroke: 0.630 in (16.0mm)
Practical rpm: 3000-42,000
Output: 2.5 ps @ 34,000 rpm
Weight: 11.1 oz (315.5g)


The 4 stroke:

Displacement: 0.269 cu in (4.4 cc)
Bore: 0.728 in (18.5 mm)
Stroke: 0.648 in (16.4 mm)
Practical rpm: 2000-22,000
Output: 0.5 ps @ 17,000 rpm
Power Output: 0.5 bhp (ps) @ 17,000 rpm
Weight (FS-26S-C): 8.56 oz (243 g)


As you can see the .21 puts out 5 times the power at twice the RPM.....

Bear in mind, all the research and development going into 2 strokes has yielded these power figures.

I'm sure with development we will see power increases in 4 strokes, and i think 4 strokes should run superchargers of some sort to increase output.

Perhaps dual overhead cams and 4 valve engines to increase power?? 4 stroke tuned exhausts, larger heatsink head etc.etc.
Just needs time and development, but 2 strokes will probably always have more power.

I heard a rumour that honda has designed a revolutionary 2 stroke that uses no oil, and is more economical than a 4 stroke.....


The fact that 2 stroke nitro engines have like 3 moving parts wins me over.....simple yet extremely effective...

Wow? That much Difference? :eek

OK, I have a OS FS-26S-C Four stroke car engine on the way! I will dyno it when it gets here and post the results. I will also compare to a TOP .12 rear exhaust engine and post those results also.

My plan is to test the mini 4 stroke in stock form, then rip into it and see what kinda changes we can make.

First I plan to redesign the head with much larger cooling capacity, and a higher compression head with better port design, via CNC.

Second, redesign piston and rod for more compression and lighter weight.

Third maybe regrind the cam with more lift.

Definately a tuned pipe with a nice megaphone.

Maybe change the rocker ratios to gain more lift.

Maybe larger valves.

Maybe Supercharger similar to YS 63 airplane engine.


Not like I don't have enough projects going on right now but this thread got those wheels turnin' in my head, and I think it should be interesting to see what we can come up with!

Wouldn't it be cool to see a 4 stroke car engine that could outrun a 2 stroke on the track!!

Sounds like a tall order but who knows? 6 years ago who would have thought that a 250cc four stroke could EVER out power a 125cc 2 stroke! Now they have 5 hp on the little MX bikes!

Can't wait to get started!!!

BK

I just can't wait to see it.
Maybe you can make your own brand of Engine and sell it.
Keep us updated.

Sorry having trouble posting image...

Here are the results of the 2 stroke vs. 4 stroke dyno tests.
The blue lines are the OS FS26S-C 4 stroke and the green lines are the AE ThunderTiger .15 sport engine. Both are completly std. No modifications.

Note: The four stroke came with no exhaust so currently I am using a short headpipe and FS26 silencer I picked up today.

Results clearly show the 4strokes superior torque in lower rpm's.
Almost 50% more than the .15 2 stroke. However the 4stroke is definitely limited in the rpm dept. Powerband is very narrow compared to the 2 stroke.

Later I will show more tests as I make progress in testing.

BK

I've got a 4 stroke Kyosho FW04. Haven't tried 4 stroke fuel yet but I've heard it improves power. Not sure how valid this info is but I just run what the other 4 stroke guys are running at my track. 20% with high castor oil content.

mxwrench is pretty much right too about the 4 strokes info.

I'm very interested in the development of this "modified" 4 stroke. I'd like to see stronger pushrods paired up with stiffer valve springs. That would certainly give it a little more RPM. And with a new profile cam with bigger valves that you're making, I'm sure it will be a beast in the top end. But definitely keep us updated. I love running my thumper but just wished it had more power!

I am wondering where to get this 4 cycle engine and what else do i need to put it in my car,, or do i need a whole new car. i have an MTX3

To answer your original question. 200mm cars were originally designed to run on smaller twisty tracks which they do in most parts of the world. For this type of track the 4-stroke would be a huge benefit due to its awesome low end torque for brilliant acceleration.