Four stroke nitros?

[The_Thubbed_One]

I once saw a story in RCCA about a fourstroke R/C car engine. with pushrods, valvetrain and everything. I was just wondering if this ever made any headway. I want to say it was a .26 back in the heyday of the .12 and before NiMh batteries. And what advantages, if any did they posess?

[SixVi6-Camaro]

Torque.. 4 strokes have crazy amounts of torque but little top end RPM. They never really went anywhere after the mild 4 stroke craze in the last 90's.

There were some crazy projects with 4 strokes though. The Mother Thumper was always my favorite..
http://www.rcalloys.com/our_trucks/fourstroke.html

[Traxxas_Junkee]

thats kinda cool, not much room left on the chassis though, now all they need to do is find out how to make a 2 or 4 stroke gas motor that is as small and has enough power as the nitro, that way we all can save some money.

[The_Thubbed_One]

It'd never have the same power if it was gas. not as much energy in gas as hi-test nitro fuel. That project is pretty sweet. I'm kind of wondering if a fourstroke would be a better engine for bashing. mostly idle speculation. don't mind me.

[Tex]

my 2 stroke idles all day, you don't need a four stroke to have a reliable good idling motor

[thenewguy821]

my 2 stroke idles all day, you don't need a four stroke to have a reliable good idling motor

+1

A well tuned engine will idle fine. Some of the HIGH oil fuels (such as Trinity Monster Brew--18-20% oil) have a problem with loading up, but an occasional blip of the throttle helps keep that under control.

[kevinF]

my 2 stroke idles all day, you don't need a four stroke to have a reliable good idling motor

yea my t-maxx in the 23 degree weather can idle forever also.

+1

A well tuned engine will idle fine. Some of the HIGH oil fuels (such as Trinity Monster Brew--18-20% oil) have a problem with loading up, but an occasional blip of the throttle helps keep that under control.

I run 20% and I dont have too much of a problem with it loading up.

[Tex]

So your 2.5 runs ok now trxthrasher? that's cool.

Yeah I wouldn't do a 4 stroke because of the powerband (no tops). With a nice 2 stroke you can have stupid torque and gobs of top so I'd just stay with those.

[kevinF]

So your 2.5 runs ok now trxthrasher? that's cool.

Yeah I wouldn't do a 4 stroke because of the powerband (no tops). With a nice 2 stroke you can have stupid torque and gobs of top so I'd just stay with those.

yes it does thanks for asking.
one day I took it out and it was of course revving up like normal when I flipped and my pipe flew off. so I decide to take it in and end the day, when I noticed that my motor and shocks where drenchen in fuel. so I figured well thats odd, so I looked at that blue coupler for a air leak and of course there it was. the only place I didnt look and there it was. the rip was half way around it :eek: so yeah that was a big air leak. but its all fixed now thanks for asking. :p:

and by the way your money order will be going out today or tommorow.

[SixVi6-Camaro]

4 strokes don't make all that great of bashers either. They require more maintence (valves, springs, pushrods ect) and because of the very low RPM when you put a 4 stroke in an RC made for a 2 stroke you have to completely change the gearing and on some RC's there just isn't enough gearing options to give the 4 stroke decent top end. a small block 2 stroke will see 35,000rpm pretty easily on a high speed run.. a 4 stroke will be lucky to see over 15,000 rpm so top speed if you didn't change the gearing would effectivly be cut in half.

OS is/was making a 4 stroke engine for 1/10 touring cars. I think its called the FS26C or SC or somehitng like that. I remember reading aobut it a while back but they only recomend it for very small track and on road Rc's that have very wide gearing options to cope with the limited RPM of the 4 stroke.

[thenewguy821]

I run 20% and I dont have too much of a problem with it loading up.

20% Nitro, or 20% oil?

[kevinF]

I use 20% traxxas top fuel.
so yes 20% nitro (correct me if im wrong)

[thenewguy821]

Yeah, that's 20% Nitro. The oil content in Top Fuel is 14% (I think). If you go much higher than that in oil content, it actually makes the engine harder to tune properly. When the truck idles, the fuel isn't pushed through the engine fast enough, and the extra oil sits in the engine. That's what causes it to load up.

Also, I agree with Six on the maintanence also. When a 2-stroke isn't running right, it's a little easier to narrow down the cause. On a 4-stroke, there are TOO many different things that can go wrong, making diagnosing the problem much harder.