[FullyFamous]

I've had R/C cars for many years, and had a airplane too in the past. R/C airplanes have had 4-stroke nitro engines for a long time. Why no 4-stroke nitros in cars?

[seanmanibog]

I suppose you could, there was a project truck on this site once that he put 2 4 stroke airplane engines in, I just think its too much power?? Im really not sure.

[Eli the rc guy]

I think its way too much power. The motors we are using right now some of them are already way over kill. You cant do much with the power because of the friction. Its different for air plains cause it is spinning a propeller, but we are spinning wheels here. Too much dam power.

[josh222]

There just to underpowered as of now, OS makes a .26 4 stroker with a pullstart but it only makes .5hp and like 15000rpms.

[seanmanibog]

Yeah. I guess you could try no gears and a really long crankshaft with a dogbone at the end, mount the engine in the center and have only front wheels drive, but it would just eat the diff im guessing

[apollo]

because the power is way too low, the hpi 15fe (crappiest, oldest hpi engine to date) makes the equilvalent horsepower as the os .26 4 stroke does, the 4 stroke is moer efficient but it has about 1/3 the hp and about 1/2 (thats being generous) the rpm, the 2 good things about hem are efficiency and torque, but to use the torque you would have to find a custom, super high ratio

[balang_479]

a guy put a .46 OS in a Revo (its actually about the same size of a .28) and it went extremely well. He raced it and it looked awesome, did well with it too and then sound was amazing, just like a huge Quad, i wish all my RC cars made that sound.

Also Mika put a OS 4S in a MP777 buggy.

[julian]

Mainly 4 stroke do not produce enough power and not close to enough rpm

[badd_maxx.25]

they put out low hp but more torqe

[balang_479]

im sure with the technology of today we would be able to use that power and torque more effectively... all you have to do is gear it down.

[seanmanibog]

balang do a project cuz we all are too lazy. lol.

[c2s]

I always wondered why they don't use rings.

[zakerid]

http://osengines.com/engines/osmg2091.html
and he put a .52 4st in a revo...
http://www.rcccs.com/index.php?showtopic=683

[balang_479]

Originally Posted by seanmanibog

balang do a project cuz we all are too lazy. lol.

i wish, if i had the money i would do it straight away

[josh222]

I have the perfect chassis for that OS .26 4 stroke Pirate 10. its got the room and the throttle servo linkage is already setup to work with the way the 4 stroke carbs are mounted maybe make it a summer project. If anyone know where to get those kyosho 4 stroke flywheel and clutch parts let me know

[jato-racer33]

not enough power or rpm...lots of torque though

[cucan]

OS was producing the OS .26 4 strokes for the cars and i believe they still do.Not enough power though...

[badd_maxx.25]

they had a .40 about 3-4 years ago but stop importing it

[joshy1991]

because a 4stroke plane engine is meant to be going full speed most of the time so the rpm is at a low rpm . whereas a cars engine is supposed to go quick off the line so the rpm is different and this is some what 36,000 rpm which a plane cant take. it could probably be done but the car will go slower

[awnelson]

Everyone that really doesn't know why four strokes aren't used should probably stop guessing. I have a .40 in a T-Maxx and it barely has 1.4 hp. But, to start the big debate, torque is about double any motor producing that kind of hp. The difference is where that torque is available at. It takes somewhere north of 10,000 rpm before the clutch on a two stroke can engage without bogging or killing the engine. It then has approximately 20,000 rpm to accelerate the vehicle to maximum velocity. With a four stroke, it starts out at a much lower rpm and tops out at 14,000 rpm. In order to use that torque, clutch engagement needs to be positive and at a very low rpm, preferably just off idle. The motor will pull hard until about 10,000 rpm and then taper off. It is doable, has been done in the past, but people who don't know how to do stuff on their own because it doesn't say RTR will most likely never see one run, much less own one. They don't have the same cooling heads because they were meant for use behind a very large prop moving lots of air so in a vehicle they heat up rather quickly. Anyone can use one if they have a little determination.

[Adanmtxt1]

Well, to answer the question at hand here, the reason there is not exactly a proliferance of 4-stroke engines in the car and truck scene is three-fold. First, it is safe to say that manufacturers have not devoted their R&D dollars and valuable time to developing a 4-stroker. It all begins with consumer demand, and to tell the truth, they have only seen a demand for more power for monster trucks, as well as top-end for touring cars. As it stands, there is no real reason for engine manufacturers to throw together a brand new engine design with a different set of guidelines.

Second, although there are convertible engines such as the OS .26 and .40 which have found their way into touring cars and monster trucks, for the most part the conversion is a fully custom installation requiring modifiied (if not custom fabricated) engine mounds, exhaust headers, and clutches. Additionally, because these engines have larger crankcases (.12 versus .26), there is a shortage of chassis space available. The Nitro TC3 is one chassis that can accomodate the .26 (was a project car in RC Nitro).

Finally, the general powerband of a 2-stroke is remarkably different from that of a 4-stroke. In a 2-stroker, you have the engine producing power on every reciprocation of the crankshaft, compared with the every-other in the 4-stroker. Additionally, there are several other differences; with some of which I am familiar, and others I am not. Regardless, the 2-stroke will produce (theoretically) twice as much overall power as a similarly-sized and designed 4-stroke. However, the 4-stroke will tend to produce a noticeably greater amount of torque, and will rev lower than the similar 2-stroke. What does this add up to? The necessity of vastly different gear ratios. The Nitro TC3 powered by an OS .26 required a very large set of clutch bell gears. Even when so equipped, although the car displayed fantastic acceleration, it had a low top speed.

You can liken the 4-stroke in a 2-stroke-developed car to putting a diesel in. The Audi R10, winner of the last 24 Hours of LeMans in France, produced 'acceptable' overall power, but had an abundanceof torque that required a special transmission and clutch. Also, it revved to only about 5000 RPM versus 8000 - 12000 in more typical 4-stroke racecars. The special transmission was the reason the car was fast: it took advantage of the available (and plentiful) torque.