Some more twin engine questions

I've been looking at the twin engine threads, and I have a couple of questions because I'm not too bright.

1.) When there was talk of "keying" the front of the crank shaft on a north and south engine alignment, what does that mean?

2.) If you go with an east and west engine alignment there was talk of reversing rotation on one of the engines. How is this done?

3.) In the east/west configuration is there any way to center up the transmission.

I know there are many guys on here that will think these questions are obvious, but I have no idea so please help me out.

 

1. a piece is made to bolt the flange from one and be splined to the snout of the other, crank must be machined as well

2. just like in boats, reverse ground cam and gears.

3. Hurst had a trans dyno with a pair of engines, 440s IIRC so they could really put some torque through it, bas ically some gears attached to both flywheels that coupled to a central "bellhousing"

 

I think I understand the reverse ground cam, but could you explain the reverse gears please?

 

There are only a couple of gearsets in an engine---camshaft to distributor and starter to flywheel. The starter to flywheel are square cut spur gears, so they would run in either direction with no trouble. the camshaft to destributor are helical cut 90 degree gears, but they should run in either direction. I think perhaps all you would need to do is reverse grind the camshaft and wire the starter to turn in reverse----

 

That was my thinking, too, but like I said I'm not too bright so I thought I'd ask.

 

Some boat motors were designed to run in reverse rotation, different cam and distributer drive but also the knurling on the back of the crank at the seal area is reverse to turn the oil back into the engine and help the lip seal work.

 

Do you think if I had a cam Custom gound they could do that sort of thing as well, at the same time?

 

If you want to use a reversed engine, talk to a marine engine dealer and use something that's available. Ford 302 V-8s and Chevy small and big blocks are popular, parts should be easy. If it has "boat" or "marine" attached to the name, the price is like attaching "Mustang" or "Corvette" to it -- more expensive even if common. So stick to the stuff you have to have only.

There are some side by side twin engine cars running two transmissions and two differentials on the same axle. Can't recall the name, but there's one rather famous custom that does this with two Jaguar diffs. Standard engine, auto trans, and diff (open diff -- might not work with a limited slip -- what if one locked and the other didn't??). The two diffs had a straight shaft connecting them in the center. That's easy with a Jag axle. For a standard live axle you'd need an axle shaft custom made and splined to fit in the side gears, then use a straight tube in the center, short axles on each side.

The auto trannys make up any slight difference in engine performance, though of course everything should be matched as closely as possible. An in-line arrangement would be a bit harder. The two engines must be timed to fire exactly the same. Even being slightly off would affect the way it runs drastically (mainly in vibration). If one distributor got out of adjustment in the in-line arrangement you'd know right away, on the side by side with two trannys you may never know unless it's bad off.

 

I was thinking more along the lines of a linked gearbox that I would make myself. With the help of a machinist.

 

I'm pretty sure that I read about one of the old twin engine dragsters that used 2 engines side by side , but each engine was tipped on enough of an angle that they mated the flywheel teeth. The gearbox ran off a normal tranny clutch and bellhousing on one of the engines, but the pumpkin in the rearend had to be offset quite dramatically to one side of the dragster center to line up with the tranny output shaft of the one engine.

 

I'm curious why you think they need to be timed together. The gopher twin car my club ran back in the 70s had two completely different motors in an inline configuration. The front 392 ran right into the crank of the donovan with a coupler and it was never a problem.

 

i think there are also some tractors that had gearboxes made for two engines maybe i just dreamed that up but i think they use them on competition pulling tractors

 

I checked into this, and $8,000.00 for a gearbox is too much for me.

 

Are flywheel teeth strong enough for this? It seems like I'd be losing teeth after I drove it enough.

 

If the two engines were hooked end to end, with the proper rotational offset in degrees between the two crankshafts, using a coupling with keyways or splines, could that work?

 

The most logical method is inline motors and as four-thirteen said oddball combinations have been run in the past, the only problem with that is that it puts a much greater load on the coupling because of different torque ratings. one old trick was to use sprockets to join them with a double row chain, but the horse power on those was a lot less than modern tech puts out now

 

The more I think about this, the more I see this being the far easier option. I was just looking to have the "LOOK" of the two engines sitting side by side. Also, I thought it would help to keep the wheel base manageable.

However, I also probably need to think about how much more the car would be balanced and handle with either engine configuration.
Side by side would take a lot of weight off the center line of the car.

 

I would also like to ask about something that is probably way out there but here is goes,

Would it be possible or adventageous at all to make the engines fire in a way that was almost like they were one 12 cylinder engine? Maybe this is what you are talking about with the timing, but I'm meaning they would actually use one distributor with 12 firing spots on it. Probably dumb, just wondering.

 

The flywheels that were used were specially made ones with specialy teeth that were designed to mesh together. The stock teeth on a regualr flywheel just destroyed themselves. The special flywheels were designed with wider teeth and special cut. One major problem with locking the engines together with gears or metal type coupling was when one broke the good one beat the living shit out of the broken one......but that is just a minor issue right!!?!

 

What motors are you planning on using?

 

Engines with the same number of cylinders would be the easiest to time, minimizing vibration and harmonics. As long as they were timed to fire at the same time or with the firing orders spilt evenly, mismatched ancestry shouldn't be a major issue, although I would think the closer one could get them (one plus it's clone, for instance), the smoother they would be in a street car. Rigidly connecting the cylinder blocks and suspending them on the motor mounts as one engine couldn't hurt either. Coupled properly with the firing impulses spilt, two sixes timed to run as a 12 for example, you should end up with a far smoother running powerplant overall than either one of the individual engines could be by itself.

 

Intersting thread. There is a guy in Menomonee Falls WI who built a number of two engine drag cars.

I was fortunate enough to meet him and talk shit for 4 hours a year or two back.

He said the end to end configuration was the best way to go. He used two heavy sprockets and a triple wide chain to couple the two sprockets together.

My main question was how do you synchronize thw two engines? His answer was it does not matter. One motor will pull the weaker motor along. His cars were well known in the local drag arenas.

Good Luck on this project.

kermit

 

I will probably end up using 2 crate motors because I can buy 2 identical & save my self a lot of head aches. I was going to try to use 2 / V-6 engines. Does anyone know where to buy V-6 engines. I've only ever seen 350 and bigger V-8s. This project is down the road, but as I've found out from my current build, I will plan everything down to the smallest detail before I do any building next time.

 

I think this is a good idea. If I used the holes in the blocks it would also assure the cranks were lined up correctly. Then if one motor did have a problem the other (I would think) would would continue to turn in over smoothly. Is this kind of what you were thinking?

 

Wasn't Eddie Hill's twin engined rail built like this?? I seem to remember reading about ti, or maybe it ran a hefty chain to couple both motors to a single cox box?
Either way, Eddie's rail ran hard for its time he even had to add a thick lump of plate steel to the front to keep the wheels on the ground some of the time.
Doc.

 

I know this is probably a great way to do it, but I'm uncomfortable trying to get anything to link up with chain. I just don't have any experience with chain at all.

 

Fair call, I always wondered about the safety of using a chain in a high HP setup, in the drive line it would have to be the weak point.
Doc.

 

I've often thought of using two V8 sides by side with an ally plate/adaptor across the rear ends, and gears connecting the two motors, with a single conventional tranny mounted central to that, or even straight behind one motor. It saves the hassle of two rear diffs or trying to synchronise two shift points.
Here's a couple of pics of various setups:

 

I guess my next obvious question is, if I couple them togeather front to back what kind of horse power will I end up getting? Double? If both engines put out 300 HP and 300 ft/lb of torque will I get 600 HP and 600 ft/lb of torque?

 

You might even get a tad more than double as you're giving a far smoother firing pulse though out the process.

If you mount them in line you can use a flexi type coupling, like they us on big powerboats to align propshafts to motors, They allow a little flex and misalignment, take a little vibration out of the equation.

Remember though, all the power of that front motor is going through the rear motors crankshaft and drive flange/flywheel/flexplate whatever, doubling up the destruction capability. Best make sure it is up to it.