Running an engine in opposite direction

[JonD]

I am working on my thesis at university, I need to be able to run an engine in the opposite direction.

Would it be possible to get the engine to run in the oppposite direction if I were to reverse the pull starter? Would it create the same amount of power?

From what I have seen of the engines they seem pretty symmetrical, I just dont know how the valves would work. You nitro gurus have any thoughts on this.

 

[newnitrofan]

Turn around the one way bearing and it will run backwards but only for a little bit. Since it is meant to run back wards it will eventually spit out fuel from the carb area and soak the fuel filter and not run anymore. There are no moving valves that I can think of on any of my nitro motors. Can't think of anything else to include.

 

[JonD]

So there is no way to run it backwards with the same power?

btw its an HPI 15FE engine off an RS4 2

 

[Error401]

No, it's about port timing. The only engines I know of that can be made to run backwards (clockwise from the front) are K&B engines, and this is only by replacing the crank with one that is ported to run that way.

If I can ask, what's the application you're trying to get at? It might be easier to put a reversing gear somewhere in the drive train than to try to get the engine to run backwards.

 

[JonD]

I'm designing a cvt transmission for it.

Theres no space to put a set of gears in, I think I may have to turn the engine around and mount it differently

 

[Error401]

That would probably be the best thing to do. Best of luck with it, and keep us posted.

 

[kwong2001]

Well I can tell you, i've ran my novarossi backwards, but that was just because my starter box's polarities were set backwards. It ran like poop that way.

And to answer your question JonD, get a starter box and reverse polarity and it'll run it backwards.

 

[JonD]

I need it to run with the same power and performance as going the proper direction

 

[Error401]

Originally posted by JonD
So there is no way to run it backwards with the same power?

Originally posted by kwong2001
It ran like poop that way.

Uh, right.

 

[Krusty]

A piston port intake two-stroke will run in either direction, as the timing is exactly the same for either rotation of the crankshaft. A rotary valve intake engine will only run (correctly) in its designed direction as the timing of the rotary intake (crank) valve is timed to run efficiently in one, but not both directions. Unfortunatly, for your backward experiment, the engines we use are rotary valve intake engines which are much more efficient than the piston port intake equivalent. To get a rotary valve intake engine to run "backwards" you will have to replace the original rotary valve with one that is timed for reverse rotation. In a typical model engine, this will require a reversed timed crankshaft.

 

[wdavidhicks]

Well-stated Krusty.

I know those old Cox engines could easily change from an airplane motor (suck) to a swamp boat motor (blow).

 

[Krusty]

Those Cox thimble-drone engines were / are reed valve intake. A reed valve engine will run efficiently in either direction, as stated, just by starting it in the direction you want it to run.

 

[FlyinRazorback]

My Nova Medial Pro M2K started up running backwards this past weekend. Don't know why. I shut it down and started it back up and it was running the right way.

 

[junglboy_152000]

in my hyper 7 i started it up at the race track and dropped it down and it went backwards due to the motor running the wrong way. it stalled within a 60 seconds and i started it back up and it was fine. u cannot run the motor backwards while its on the truck or buggy or car. if its a straight drive it will just go backwards, and if it has a transmission like most MT's it will just rev as if its in neutral.

 

[dgrobe2112]

yeah.. i have started my 8 port motor backwards. once.. and it sat there and idled backwards.. but as soon as i blipped the throttle it died..

i started the motor backwards.. and once.. on accident.. blipped the thottle with the ignitor on the truck still.. and it actually started itself the other direction.. weird.. i know this because.. when i went back to start the truck again.. someone told me that my polarities were backwards on the truck. .and i swithed the wires.. and it started right up.. and ran fine..

 

[mickmack]

will a nitro motor run backwards just as well! yes but with twice the fuelconsumption

4 years post reply.

The tmaxx 3.3 I have which had been converted to pull start seems to run in reverse.

It runs forward through the use of the reverse gears! I had removed the two reverse gears and the truck will only run in reverse direction off the gears that are meant for forward movement!

It also uses a lot of fuel, but it seems to run fine apart from this!

Having not corrected it or having any experience with normal operation it is hard to comment, however it seems to run Okay in reverse!

 

[Scrogg]

Well I can tell you, i've ran my novarossi backwards, but that was just because my starter box's polarities were set backwards. It ran like poop that way.

And to answer your question JonD, get a starter box and reverse polarity and it'll run it backwards.

He's right, many of us have done that. It will never run good backwards though, forget that.

 

[newnitrofan]

Man did I hear a coffin open? It's cute look at my noob ass way back than sayin it'll run backwards. lol

 

[beason]

you probably have the diffs in upsidedown on your 3.3. if they are in wrong it will drive backward.

 

[Scrogg]

Man did I hear a coffin open? It's cute look at my noob ass way back than sayin it'll run backwards. lol

Didn't notice the date, you def. heard a coffin open.:\

Mickmack, I have to agree, the diffs are probably installed wrong. Also another common mistake. Done it myself ....once!