Engine swapping question.

[Losi-HPI]

Hey everyone, I went to my LHS on Sunday afternoon and I saw something pretty interesting there, it was one of those four stroke RC engines. It seemed to be about the size of a .15 nitro though, so, I was wondering, would it be possible for me to swap my .15 mach engine on my XXX-NT for one of those little four strokers? I would like the additional realism and torque that four stroke provides and it looked about the same size. Thanks for any comments of wisdom/interest here, peace.

 

[tbsleeper]

couldnt have been a lot of cc's and probably would be less powerfull then the engine u got now

 

[Losi-HPI]

Really, you think it'd be less powerful? :dumb:

 

[olds97_lss]

Considering the displacment of it, probably. A 4 cycle is bigger in outer dimensions vs a 2 cycle. Also, from what I've noticed, 4 cycles are considerably lower in the RPM department as well.

 

[Waste Land]

YEah the 4cycles are mostlt used on Planes if I'm not mistaken.

 

[tbsleeper]

yea its def not worth the time because nitro methanol is the most powerful gas out there. i mean i would die to run nitro in my quad!! but like you said four-strokes have a lot of low end torque but lake top end.:shhh: :x

 

[olds97_lss]

If I'm not mistaken, the 4 cycle rc engines are still nitro meth engines. They just run differently. I think the only non-nitro meth engines for rc are like the zenoah engines which are for 1/5 scale. They run on gas/oil mix which would still make them a 2 cycle engine.

 

[Losi-HPI]

Hmm, interesting. You say it still runs off of nitro fuel eh? I can't see it. As far as the torque and rpms go I already knew that and I like the idea of additional low end torque, I am not too interested in high end power. What would you all say then?

 

[olds97_lss]

I just don't think they are designed for on-ground use. They have small cooling heads or none at all which allow them to cook themselves. They are basically made for planes only.

 

[Losi-HPI]

But do you think a plane could run off of an engine of such small size, would that really be possible, I mean, that's why I considered it because of it's size, I couldn't see it for any other application. I have seen the big mothers and understand their purpose but this seems to small to propel a plane.

 

[PhillyB]

there are some on the maxxtraxx forums that are running 4 strokes, but i would rather just do a .21. go there if you are really interested.

4stroke advantage

tons of torque
high gas mileage
cleaner burning
easier to tune i believe or less sensitive to tuning changes

but

low RPM - in planes you need massive amounts of torque to turn the larger propellers at speed, but they only run like 9-10K rpms or so @
meant for planes in most cases so the cooling system is mostly the air rushing by the motor (engine sticks out the side of the plane)


it can be done, and might be cool - 4 strokes have a different sound I'm told. but it would be real expensive and not as fast as a healthy .21-.28. 4 strokes are just not designed to run on the ground. also use a different mix of nitro.

 

[bill61]

Four-stroke engines are less horse power, but more torque when comparied to the same size two-stroke engine. Also less rpm's. People are putting them in monster trucks for the realistic sound and low end torque. They run on the same fuel as we use in our two stroke engines. olds97_lss is right in that they have smaller heads and so cooling is a consideration.

 

[SkyMaxx]

If all you are interested in is torque, then go for it. You will lose about 20mph off the top speed, but gain a beefy rock crawler.

 

[4u2nv]

Theres alot less resistance to turn a prop that to turn tires. I think a 4 stroke would be really gutless in a car or truck, I would think at least. I would think itd be no torque but high speeds in the long run. But I think itd have to have less resistance to go fast. And a long straight away. Like on dirtbikes. 2 strokes are Really Snappy and have mad power (Plus louder) than a 4 stroke that has less torque and less nuts off the line, but would outrun a 2 stroke in a great lengthd race.

 

[SkyMaxx]

Was trying not to respond to the last post, but....

Most four stroke RC engines have a peak rpm of below 15,000rpms. They are strong engines and built for torque. Even in a long race with the best gearing you could fit on a T-Maxx or other RC, you would lose the race. Not enough rpms to generate any kind of serious speed.

 

[Losi-HPI]

Thanks SkyMaxx, you had great points that were "to the point" and made me think about it and you're right, I will lose speed but will have some mad torque. I am not into racing or anything, for what I do more torque would be a lot more appropriate. I think I will switch. :hammer:

 

[bill61]

SkyMaxx is right, you will lose top end, but have a great rock crawler. But your XXX-NT is only two wheel drive, right? So rock crawling isn't really a choice for you. If you just want the sound and torque you could try to gear for more top speed. It will take some trial and error but you might be able to do it.

 

[Losi-HPI]

No not necessarily rock climbing, even just for more tractional output in other areas, more power and strength on more challenging terrain where mine doesn't shine too well now. Do you see what I'm saying?

 

[4u2nv]

Originally posted by SkyMaxx
Was trying not to respond to the last post, but....

Most four stroke RC engines have a peak rpm of below 15,000rpms. They are strong engines and built for torque. Even in a long race with the best gearing you could fit on a T-Maxx or other RC, you would lose the race. Not enough rpms to generate any kind of serious speed.

Lower Rpm's mean less torque though most the time doesn't it?

 

[tbsleeper]

no way :n00bie: