Engine running in reverse..

[Roadkill]

Went into a little spin last weekend, halfway through the spin, the engine stalls and gets bump started into running in reverse. I had my helmet on and didn't realize at the time what had happened. The car was in 1st, and when i would let out on the clutch, the car would start moving backwards. Took a little bit to get it started again (flooded cylinders??) but no adverse effects that i have noted. Checked everything out and all appears fine. Am i the first to have a Viper engine running backwards? Good thing i caught it on tape.. otherwise i think a lot of people would be saying B.S.
The Video

 

[VIPER52USA]

BULLSHI.... Wait, you have video? Let's take a look.

 

[VIPER52USA]

It isnt the most clear video, but what I heard is that you stalled, or did you cut the engine off? Maybe you were just rolling backwards. Was the car on when you were rolling backwards at idel or were you pressing the gas in 1st? Very odd.

 

[Roadkill]

the car stalled AFTER running in reverse. if you notice, i start backing up a little, stop, (this is when i took the car out of gear, then put it back into first just to make sure)and then it continues to back up while in 1st until it stalls. I was not just rolling backwards.. it was in 1st gear when you see it going backwards

 

[VIPER52USA]

I see it rolling, no doubt. That is very weird, I have never seen anything like this before.

 

[JDR]

Happens occasionally to my RC plane, but then it's a 2 stroke and doesn't have a cam (nor reeds, like on a motorcycle) controlling which direction the air flows...

A (non-broken) CARBERATED 4-stroke could never do this... however a DIRECT PORT FUEL INJECTED... that's another story.

My guess is a 50+ psi direct port fuel injector will overcome the (idle) exhaust coming in to the intake manifold - just enough wet the piston head so there's fuel for the reversed exhaust stroke (now intake). Then the power stroke becomes compression, and the compression becomes power. Would I be reaching that timing would cause the sparkplug to fire ATDC rather than BTDC, enabling such a poor A/F ratio be enough for a small reverse idle?

I can't imagine it would ever rev-up that way.. but a slow idle, sure.

I REALLY liked the way you got the engine to reverse direction with a spinout to force it to turn backwards.

Very cool video - a definite keeper.

 

[ROCKET62]

Pretty Weird! Roadkill, what exhaust/mods do you have on your Viper?

 

[Cop Magnet]

Don't know exactly how it could happen--I've certainly heard about the two stroke bikes doing this (can seem perfectly tuned, too, but run backwards). For lack of better technical knowledge, I'll buy JDR's theory. I do believe it, however, based especially on the abnormal idle quality on the video while you were backing up. Definitely wasn't running right.

 

[AviP]

Looks like an extreme case of engine braking.

Normally engine braking causes the engine to rev down to idle/positive revs (clutch disconnected) or stall/0 revs (clutch connected). Your wheels (which were obviously moving in reverse at some point during the spin) seemed to have cranked the engine past stall/0 into reverse/negative revs. The firing sequence is not suitable for an engine running in reverse and it eventually stalled.

So there was a period of time during this spin when your engine was moving forward while your wheels were moving backward. During this period, your clutch was the loser. Depending on how long this period was, the damage to your clutch could be bad. Theoretically this period could also be 0. But keep an eye on your clutch though.

This situation can be replicated by pushing a car in reverse and clutch-starting it. The engine will need to be warmed up prior to this because I think it will never work otherwise.

 

[Travis]

Gas pedals fall off, balancers fall off, engines run backwards, whats next?

 

[Eddie N]

Gas pedals fall off, balancers fall off, engines run backwards, whats next?

Power steering cap failure?

Eddie

 

[99GTSACR]

Broken lower Steering coupling.

 

[Cop Magnet]

I am not sure by definition the engine and wheels HAD to be going in two different directions. The transition from forward to reverse would actually be at a pretty slow crank speed in a spin. Even if they did, the stress would likely not be any more than dumping the clutch at 3 or 4 K RPM at a complete standstill.

By the way, no one brought up the old track adage "In a spin, both feet in".

 

[JDR]

What's the oil pump doing when the engine is running backwards?
(Sucking oil from the bearings, down to the oil pan?)

 

[ViperJoe]

So is it intaking through the exhaust and exhausting through the intake??

 

[ViperRay]