HS 142-F reverse engine and SBP freewheel brainstorming...

[KCvale]

Turn the seat around and steer from behind.

Thats the only way that will work as you simply can't make a 4-stroke engine run backwards starting from the very basics, how you gonna start it?
Not with the pull start, it goes the other way.

You can however make a transfer case to give you the gear reduction you need AND reverse the direction of travel with 2 meshed gears but I find the whole thing a little silly when there are well designed kits to build a shifter.

 

[gary55]

It's done on marine engines. boats with twin engines have one modified to use reverse rotation. I think on these little engines you need to do it with a external mechanisms. Cam, ignition timing, and starting issues could be overcome, but I think as Steve said the top end oiling would be the problem. I think the oil channel would need to be at the front to work in reverse.

 

[Frankenstein]

It's done on marine engines. boats with twin engines have one modified to use reverse rotation. I think on these little engines you need to do it with a external mechanisms. Cam, ignition timing, and starting issues could be overcome, but I think as Steve said the top end oiling would be the problem. I think the oil channel would need to be at the front to work in reverse.

I don't think the word 'modified' is exactly appropriate.. More like designed, and often with a transmission and not the engine itself. Some with a jet/impeller like a ski doo just use a big curved thing that pops out over the out jet and as a result turns the water pressure around to the front. I don't honestly think I've even heard of an engine that physically reversed its rotation especially when a boat gear is way easier to implement, even in a duel in board engine/prop set up.

Pretty sure even outboards use a reverse gear in the clutch, I've only been around a couple mercury outboards while opened and they all had physical gears to handle forward and reverse...

Maybe whoever described boats to you forgot to mention that only one transmission on a duel board vessel needs to have a reverse, you'd never have to go faster than docking speeds in reverse so 2 props pulling the boat would be kinda redundant...

 

[Frankenstein]

The spark timing, cam lob order/timing and any oil pumps or directionally oriented oil dippers/slingers/scrapers/baffles need to be changed. Timing is typically easy with a new flywheel keyway. The cam needs to be cut and rewelded (typically drilled for an alignment shaft) to reverse the order of the lobes and then retimed. Splash lubricated engines may need some thought where direction often determines top end lubrication, but most just rely on splash and mist so you may be OK.

That sounds like it's more trouble than it's worth, and the oil distribution seems like it can be the biggest killer, you'd need to have a specific engine that by luck was capable of being reversed safely in splash models, generally anything else with an actual pump you'd be better off just turning the seat around like mentioned earlier.

I'm pretty sure the engine is beefed up in a way to handle the rotational stresses in one direction but not the other. You'll probably see failures at multiple points. Think about how many nuts/bolts are threaded so they tighten with regular usage but unscrew themselves if reversed. You'll have to reverse thread many things.

Yes, one of the big reasons why standard driving vehicles have such heavy transmissions is the bevel gearing that makes them so quiet, the problem is that bevel gears push along that rotating axis and so the transmission has to be built heavier, if you reversed the gears they'd push the wrong way and if the wall isn't properly reinforced it will push right out the side. In racing vehicles they use the plain straight tooth gears since that reduces the reinforcement needed, and thus the weight, which is ideal in something to want to go fast...

Depending on just how the engine is designed and what types of gear are in it, reversal could lead to the death of the motor, again requiring more insight to the design of a motor before it can be given the go to be reversed.

I think the best option is to jackshaft whatever it is that needs to be driven, once you start to see all the problems involved it just makes sense to keep it freaking simple...

 

[gary55]

Actually the basic engine "designs" are identical. Modifications to cam shafts and gearing for distributors and oil pumps are changed to allow a reverse, or I should say opposite rotation as the forward or rearward forces are not the desired effect. These will still be achieved in the same manor as you have described weather it be jet or prop driven. The object is in to cancel the torque effects in twin engines applications by having the engines spin away from one another. Impellers and props are designed accordingly. Not a sound means for motorized bike use, But big dollar boats generally don't mind expensive setups to enhance performance and comfort.

 

[Frankenstein]

Actually the basic engine "designs" are identical. Modifications to cam shafts and gearing for distributors and oil pumps are changed to allow a reverse, or I should say opposite rotation as the forward or rearward forces are not the desired effect. These will still be achieved in the same manor as you have described weather it be jet or prop driven. The object is in to cancel the torque effects in twin engines applications by having the engines spin away from one another. Impellers and props are designed accordingly.

That still doesn't have anything to do with a boat gear, the actual physical reversal of a prop is not the engine going a different direction, it's just a lever switching the gear driving the prop to a different gear.

Actually both motors in the haul can spin the same direction, mostly because of those torque effects you are mentioning don't make any sense until you are in the water at the prop itself, and even then the bearings supporting the shafts shouldn't be putting that much stress on the haul that you'd have a structural problem... Did we forget to mention a boat with 2 engines tends to be very heavy, so the spinning of the motor or props probably isn't going to do diddly squat to how the boat handles... Spinning props in 2 directions helps center the force of the props and keeps the wake pushing down into the water while reducing turbulence and torque on the prop tips.

 

[gary55]

Two motors anywhere can spin in the same direction. That does not make it the optimum setup. In a twin engine boat it is not. We are not talking about gears, we are not talking about direction of travel, we are talking about engine rotation. You really should look into this a bit farther before continuing to dig as my rope ladder is only so long, and I'm not sure how much deeper you can go before my throwing it in will be of no use. Chevy, Chrysler, and Ford all make reverse rotation marine engines.

 

[Steve Best]

True story Gary, especially big powerful engines in light fast boats.
Aircraft too. Some twin engine jobs like the P-38 Lightning did it with a gearbox but the Germans used some with paired engines in WWII.

Most 2 stroke snowmobiles and some boat engines are using engine reversal instead of a gearbox for reverse. Awesome to watch. Push a button, the engine comes to a stop and immediately goes in reverse. This system has been used in this area for 100 years with "Make'n Break" boat engines. It was also used on 1960s Mercury snowmobiles with 2 coils, one for forward, one for reverse, although you had to shut the engine off and restart it in reverse.

 

[gary55]

True story Gary, especially big powerful engines in light fast boats.
Aircraft too. Some twin engine jobs like the P-38 Lightning did it with a gearbox but the Germans used some with paired engines in WWII.

Most 2 stroke snowmobiles and some boat engines are using engine reversal instead of a gearbox for reverse. Awesome to watch. Push a button, the engine comes to a stop and immediately goes in reverse. This system has been used in this area for 100 years with "Make'n Break" boat engines. It was also used on 1960s Mercury snowmobiles with 2 coils, one for forward, one for reverse, although you had to shut the engine off and restart it in reverse.

I can see how this would be much easier with 2 strokes. I'm guessing they use 2 electronic sensors powering to one or the other to control spark timing on the new ones. Also guessing maybe a rotating stator on the 60's model?

 

[Street Ryderz]

That still doesn't have anything to do with a boat gear, the actual physical reversal of a prop is not the engine going a different direction, it's just a lever switching the gear driving the prop to a different gear.

Actually both motors in the haul can spin the same direction, mostly because of those torque effects you are mentioning don't make any sense until you are in the water at the prop itself, and even then the bearings supporting the shafts shouldn't be putting that much stress on the haul that you'd have a structural problem... Did we forget to mention a boat with 2 engines tends to be very heavy, so the spinning of the motor or props probably isn't going to do diddly squat to how the boat handles... Spinning props in 2 directions helps center the force of the props and keeps the wake pushing down into the water while reducing turbulence and torque on the prop tips.

As Gary stated all the big three make reversed marine engine as do many of the outboard companys! when I was really young and didnt all ways think things thru I put twin outboards on a home built hull wanting to go faster than my buddys big block inboard well let me tell you first hand it does make a big difference, First is the right turn same direction as prop rotation the hulls rear end lifts and abruptly does a 180 spin!Not fun when doing a good speed,then you wash out the feed to the left side prop and that engine see's less load also not good at speed,lastly there is a list to the left that tries to push the hulls bow to the right.