engine running in reverse ??!!

[ty901]

I've run searches and either get a zillion hits or come up empty. the car is not mine and I have yet to see it in person. my buddy is a good wrench, has been working on cars (hobbyist) for a long time and is quite familiar with air cooled VWs. this is his first air cooled 6. in 40+ years as a hobbyist w/ air cooled Porsches I've never even heard of such a thing.

the engine runs backwards.

some things to check before I go have a look are appreciated.
TIA

[stownsen914]

That doesn't make much sense. How well is it running in reverse? How would it even get spinning in the reverse direction in the first place?

That is, unless someone went to the trouble to properly time the ignition and camshaft to piston events to support it, install a reverse rotation starter, etc. Theoretically possible, but why?

Not to doubt your friend's wrenching abilities, but did someone install a trans with a flipped ring and pinion, giving the car 5 reverse gears and misleading people into thinking the engine is running backwards?

[john walker's workshop]

Serious pre-ignition will do that, for a short time, when the ignition is shut off.

[porschedude996]

Runs or runs well?

The cams would need to be ground for that direction, and the starter motor would need to spin the opposite of stock. I’ve seen people ise a standard starter motor on a reverse direction engine (twin engine boat). They never start.

I’ve personally experienced a condition where the engine ran fairly well. I was a small motorcycle (175cc) that was a 2 stroke with a rotary valve. You can cut the opening (pie shape) wider and it increases the intake duration. The engine kicked back and actually ran backwards. The guy who owned the bike I was experimenting on had a 5 speed reverse. Ok, I was 15 years old…

['78 SC]

I doubt it would run that way for long, since the oil pump is turning in reverse and the cam tensioners would be on wrong side of the chain (not the slack side).

What direction does he think it should run?

[stownsen914]

Good point on the oil pump, that wouldn’t work out for long …

[Dpmulvan]

I’d check THC levels first.

[cgarr]

Is it one of the old Mooney aircraft engines?

[jac1976]

Does your friend have the car in his possession or are y’all both looking at video from the owner? There are obvious reference points that would alert both you and your friend that the video is reversed, but maybe it is or the guy is filming over his shoulder in selfie mode? Again, would be evident in juxtaposition to the injection system, oil filter, fuse panel, etc.

[dannobee]

I ain't buying the reverse rotation Porsche engine.

The Mooney thing (PFM 3200) rotated the same direction as the car engines. It had 3 gears in the gearbox so that the propeller turned the same direction as a standard engine (two gears would obviously turn the prop backward, or the engine would need to turn backward).

FWIW, aircraft engines use the flywheel side to drive the propeller, so that in effect, the engine is in there backward to its car counterpart. If you look at the crankshaft turning while running, on the drive belt/fan side, the pulley will rotate clockwise, while the flywheel side will rotate counter clockwise.

Of course someone will mention british engines or hondas, where some rotate backward, but those aren't germane to this conversation.

For reasons mentioned in prior posts, it's not possible for the engine to rotate backward for very long. As John mentioned, "dieseling" engines rotate backward, but not usually for very long, and the exhaust comes back up through the intake. And if by "backward," the OP suggests it has 4 or 5 reverse gears and only 1 forward gear, either the ring gear is installed on the wrong side OR the transmission is installed upside down. And remember on a Porsche (and air cooled VW for that matter) the fan would be rotating backward, too. Most people would notice that huge volume of air going the wrong direction.

[porschedude996]

Haha, I recall the guy next door in my childhood house that repaired his VW Bus and had a 1 Speed Forward and a 4 speed Reverse. At the time I wasn’t schooled in VW and I don’t even know if it’s possible to install the ring gear on the wrong side. This is just a jarred memory from 60 years ago.

Thanks, I enjoy the conversations.

Originally Posted by dannobee

either the ring gear is installed on the wrong side OR the transmission is installed upside down.

[Mike Billings]

I heard this happens when you interchange the cams. Left cam on right side, right cam on left side.

[Mike Billings]

[dannobee]

How do the cams dictate the rotation of the starter motor?

Installing the cams on the wrong side results in bent valves, not a reverse rotation engine.

[Mike Billings]

[QUOTE=dannobee;12123311]How do the cams dictate the rotation of the starter motor?

I'm not getting paid enough to figure that one out.

I'm just impressed I remembered reading this in Bruce Anderson's book 27 years ago!

[Neil Harvey]

""Could this be a hemisphere thing like the toilet water phenom""?

[porschedude996]

Wow, didn’t see that, my pages must be stuck together.

[pocv0]

Not a big deal, you just need to drive in Reverse.

[dannobee]

I just dummied up a set of heads and cam housing to see what would happen. Because, you know, inquisitive and too much time on my hands. It'll bend the valves. The exhaust valve is way up on the flank of the lobe when the piston is approaching TDC. Mind you, I just tried one side with the wrong cam, but I would imagine the other side would have similar results.

[stownsen914]

I like Neil’s suggestion. Perhaps a gray market car from from Asia that wasn’t properly converted, still runs backwards lol