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Old 08-26-2004, 02:24 AM   #31
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Default Profoxcg,

Profoxcg,
Unfortunately right now OS has stopped selling the FS-26S-C engine, and is very hard to find. The good news is they have a new version coming out soon. Hopefully, anyway! I have not confirmed if they will be selling them in the US yet. The new engine is called the OS FS-26S-C VerII, original huh?
Anyways, I have made huge improvements to the FS-26S-C over the past few weeks, see my post on this forum 'OS FS-26S-C development project'. I show my dyno graphs detailing my improvements! As far as what you would need to stick one in your mugen, I'm not sure yet. I hope to offer a conversion kit for all popular models of 'competitive' car kits in the near future.

Check back soon to see my latest results in development!

BK
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Old 08-26-2004, 05:16 AM   #32
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Default great info thanks !

Thanks,

I love those original names lol
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Old 12-22-2005, 11:52 AM   #33
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Default Two-Stroke VS. Four-Stroke Test Vehicles.

These two HPI MT conversions were of mine were featured In RC Nitro magazine December 2002.

I have not fully tested them head to head. I think it could answer a lot of questions.

Who would like to pilot the Two-stroke and where should we do it? I think it's time to get them dirty.

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Old 12-23-2005, 04:24 AM   #34
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Quote:
Originally Posted by RebelRacer
let me tell ya somthing

torque=power
You might claim to know a lot, but you've just said something that, in terms of physics, is plain, no-question-about-it, simply WRONG.

Torque, or, to use the scientific term, turning moment = force x distance from fulcrum. (Fulcrum means the point about which a turning object - in this case a drive shaft - pivots.)

Power is the amount of kinetic energy produced by the engine, therefore the amount of kinetic energy wich the car has.

Basically, to use equations:

Torque:

M = F x D.

Power:

KE = 1/2 x M x Vsquared.

Incidentally, concerning these two equations, the upshot of the first one is that the greater distance from the fulcrum, the more the torque applied to the ground by your car, so technically, by fitting bigger wheels, you will give your car more torque, but this doesn't improve acceleration, because bigger wheels are heavier. However, this is partly why big wheels are good for rock crawlers, which need loads of torque but not much acceleration. The upshot of the second equation partly explains why 4-stroke engines produce more low-end power, but 2-stroke engines produce more high-end power: as you can see from the equation, where M means Mass, the more rotating mass there is the more power there is. This partly explains the low-end power of 4-strokes; they have a heavier rotating mass, because of all he valves and springs and pushrods that they have. 2-strokes are better at the high revs for the same reason: they don't have any valves, or anything like that, so they have a much smaller rotating mass, so because of momentum (which is another story altogether which i won't go into here) they can rev higher, and becaue the equation tellls us that the more V (Velocity) there is, the more power there is.
This isn't actually the full story, but it is the basic reasons why 2-strokes and 4-strokes are different. The part that I havn't gone into is the chemistry of fuel consumption, and efficient burning of fuel. You probably don't want me to go on about Hydrocarbons for dozens of lines, so let's just leave it at that, eh?

So, there you have it, the PROPER explanation of just what's going on with engines.


Last edited by Azonixmaestro; 12-23-2005 at 04:52 AM.
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Old 12-25-2005, 02:03 AM   #35
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Quote:
Originally Posted by Azonixmaestro
You might claim to know a lot, but you've just said something that, in terms of physics, is plain, no-question-about-it, simply WRONG.

Torque, or, to use the scientific term, turning moment = force x distance from fulcrum. (Fulcrum means the point about which a turning object - in this case a drive shaft - pivots.)

Power is the amount of kinetic energy produced by the engine, therefore the amount of kinetic energy wich the car has.

Basically, to use equations:

Torque:

M = F x D.

Power:

KE = 1/2 x M x Vsquared.

Incidentally, concerning these two equations, the upshot of the first one is that the greater distance from the fulcrum, the more the torque applied to the ground by your car, so technically, by fitting bigger wheels, you will give your car more torque, but this doesn't improve acceleration, because bigger wheels are heavier. However, this is partly why big wheels are good for rock crawlers, which need loads of torque but not much acceleration. The upshot of the second equation partly explains why 4-stroke engines produce more low-end power, but 2-stroke engines produce more high-end power: as you can see from the equation, where M means Mass, the more rotating mass there is the more power there is. This partly explains the low-end power of 4-strokes; they have a heavier rotating mass, because of all he valves and springs and pushrods that they have. 2-strokes are better at the high revs for the same reason: they don't have any valves, or anything like that, so they have a much smaller rotating mass, so because of momentum (which is another story altogether which i won't go into here) they can rev higher, and becaue the equation tellls us that the more V (Velocity) there is, the more power there is.
This isn't actually the full story, but it is the basic reasons why 2-strokes and 4-strokes are different. The part that I havn't gone into is the chemistry of fuel consumption, and efficient burning of fuel. You probably don't want me to go on about Hydrocarbons for dozens of lines, so let's just leave it at that, eh?

So, there you have it, the PROPER explanation of just what's going on with engines.

Torque = rotational force (for example one lb/ft is equal to the force of one pound applied one foot from the axis of rotation)

Power = the rate at which work is done (work is the ability to move an object that has mass)

What are your qualifications? I'm no expert, but I've never seen the equation Mass = Force x Distance. Maybe you are reffering to Work = Mass x Distance or maybe Force = Mass x Acceleration.


The reason why a car with smaller wheels accelerates faster has nothing to do with weight, but because the final drive ratio is higher. For each complete cycle of the engine, you have to move the car a shorter distance (the circumference of the tire) with the smaller wheels.

Your argument about applying more torque with the bigger wheels is flawed because you're looking at the system backwards. Try turning a nut with a longer wrench, and it will be much easier to turn. But in the case of a wheel, the force isnt being applied TO the fulcrum (the nut in my example), it is comming FROM it. Think of it like this: you're standing in place holding a pole, on the end of that pole is a 10kg weight. Will it be easier for you to pivot about your position with a shorter pole or a longer one? The length of the pole represents the radius of a tire.

Also while the weight of engine components do play a role in power output, it is not a significant factor in the different power characteristics of two-stroke and four-stroke engines. If this was the case, simply increasing the weight of a flywheel on a two-stroke engine would give it the characteristics of four-stroke. This concept also means that the entire valvetrain in a four-stroke engine is nothing more than a means to increase the rotating mass inside the engine. This is certainly not the case. Though the extra mass and friction in a four-stroke are definately what help reduce its maximum RPM, they are not what give it its advantages.
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Old 01-05-2006, 10:00 AM   #36
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Wow, this is an old thread...

I've raced 2 types of 4 stroke powered cars against 2 strokes. One was at club level races at my home track, and the other was all over the Pacific Northwest in a series that averages about 200 entries per round. I run a Perry VP-30 fuel pump and WildCat HeliMix 30% fuel in both.

Car 1 is a Kyosho Ultima ST type R (2WD gas truck) with a heavily modified FS26-C. I've never raced it in a series for 2 reasons: 1, it's not legal. 2, it falls apart every gallon or so.
The reason it falls apart is because I moved the intake port from the back of the head to the side, and the intake manifold is held in place with JB-Weld. The alcohal in glow fuel attacks epoxy-based glues, so after about a gallon, it simply falls apart.
This truck is VERY competitive running 30% full-synthetic heli fuel, an OS 2 needle slide carb and bored out FS-52 muffler. Of course, it's geared to the moon, and as such will keep pace with a P-5 powered 1/8th scale buggy on the long backstrait.

Car 2 is a Traxxas Revo, which I race in the Unlimited MT class in the Northwest Championship Tour. It is powered by a modified OS FS52. Mods are:
FS40-C cam, valve springs, and spring seats
3 needle slide valve .21 2 stroke buggy engine carburetor
Surpass 90 muffler with bored-out stinger
Competition in this class is pretty tough, with most guys opting to run a TM18. There are some who run big block 2 strokes in their Revos, and a few LST drivers running the Collari .32! So far, I've not found myself wanting more power, and at most tracks I don't need more speed. I eat up the 2 strokes exiting corners, so of course I do better on tighter/loamier tracks.
This truck is very much in the prototype stage, and it's made 3 A-mains at 2-day races this year. Results of those races were 6th, 8th, and 4th. At the 8th place race, I set fast lap in qualifying and felt like I could have won, right up to the 11:30 mark when the transmission let go. I was in 2nd at the time and the guy in 1st ended up breaking. I'll get 'em this year!

The FS26C compared to the NovaRossi .12 I used to run has faster throttle response, more controllable power, and has this wicked little kick right when you think the engine's going to sign-off in over-rev land. You can see this on MXWrench's dyno charts of the modified 4 stroke on his website. In Dyno-land, it's a nice little peak. On the track, it's a power-lift at the end of a medium size strait. The 4 stroke also gets better fuel economy.

The FS52 compared to the 2 strokes I race against has more bottom-end accelleration, instant throttle response, but runs out of gear on a bigger track. It just can't breath as well as the FS26C, so there's not as much power on top. I've got taller gears on order for next season. 15/38 is stock. I was running 19/36. I will be running 20/35 next season. It has worse fuel economy than the TM18s, and about the same as the .28 - .32 big blocks.
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