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Dual engine coupling

29K views 29 replies 16 participants last post by  26richardson-norrd 
#1 ·
I've been researching dual engine setups and haven't had luck with very much info online and was curious if anyone on the forum could give me any info. So I've been looking at engine couplers that mounts the damper on the front of one motor that connects to the back of the front motor. So once the two cranks are joined in a union wouldn't the 2 cranks rotate at the same speed and how does that affect the power to the wheels. How does this work exactly and how is it setup with the theory behind it. The other setups I've seen are parallel motors with a gear box that hooks to both flywheels connecting the cranks with a roller chain and I've seen 2 motors in a car one in the trunk powering the rear wheels and one under the hood powering the front wheels essentially all wheel drive.

Maybe sombody can help me understand how this works and give me some useful information.
--thanks
 
#2 ·
wow i was wondering the same thing ill be waiting for follow ups.... barris did the Raiders coach with a side by side mount using the inside motor mount only and joining the 2 with a bracket.and a brace at the rear on the trans and driven together by a chain Assembly..
i would like to try building twin engine car sometime.....tvtommy had the 4 engine dragster.... its on you tube with info on how he made that work .... phew right over my head.thee was one on ebay last yr that was made to look like a 60's type and he used some type of setup like you mentioned..
 
#3 ·
See pics. They usually use a chain coupling for in line coupling except a bigger version than the pic. Some custom machining is required. The trike you see has two 502 Chevy V8's joined in line with 550 HP each. Add them up and you get 1100 HP and basically a V16. The 4 engine dragster has 2 engines coupled in line to the front differential and 2 engines coupled in line to the rear differential. That's Tommy Ivo's dragster from the 1960's. Cool stuff but heavy.
 

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#4 ·
2 independent engines is easier.
end for end coupling changes the crank shafts harmonics
side by side engines that are linked with a chain will cause heavy side loading on the rear bearings. side by side engines going into a 2 into drive system is easier on side joined engines
separate engine, IE; one drives front wheels the other the rear wheels do not have to operate at the same rpm.
The other styles have no choice
 
#5 ·
With one 4 stroke V8, you get ignition once every 90 degrees of crank rotation. When coupling 2 V8's, rotate one of the cranks 45 degrees ahead of the other. That way you would get ignition once every 45 degrees of the coupled crank rotation. That would help greatly with crank harmonics and the package would run as smooth as a V16 engine.
 
#6 · (Edited)
Although I have been on this planet for quite some time and have seen a lot of things and done a lot of things, I have never set up a multi-engined car. It has rattled around in my brain for 60-odd years though and perhaps before I am recalled by my Maker, I will have the opportunity to jump in on such a project.

As a techinspector at the drag races, I have seen my share of dual-engined cars and have talked with the owners/builders. One of the main things that crops up is how are we going to phase the motors to each other.

A 4-cycle motor goes through 4 different cycles to make one power pulse........ intake, compression, power and exhaust. Each of these cycles are 180 degrees in length, so 4 of them add up to 720 degrees (two complete turns of the crankshaft) to make one power pulse to the tires. If we connect the motors both at 0, then both of them will be in unison and will double the forces that they exert on components. The first problem will be starting them. With two cylinders on each motor firing at the same time, that will be a tremendous load on the starter motor of whichever motor you hang the starter on (probably the rear motor would be the one with a starter ring on the flexplate or flywheel), so it makes sense to me to phase the second motor a ways off from the first motor, like maybe halfway between the front motor #1 and #8 cylinders. Tied together and firing number one on the front motor and number one on the rear motor at the same time, for instance on a 350 Chevy, you would have this.....11-88-44-33-66-55-77-22. If you phased the firing so that the rear motor fired halfway between 1 and 8, you would have this......1-1-8-8-4-4-3-3-6-6-5-5-7-7-2-2. You can see how the power would be spread out over the two crankshafts, so that instead of having a power pulse every 90 degrees, you would have a power pulse every 45 degrees. This is how a factory would do a V-16, a power pulse every 45 degrees. It would not only be easier to start, but the flow of power would be more gentle on the parts that come after the motors (clutch, transmission, driveline, differential).

This might be a good place to enter the sound of a Harley-Davidson 45 degree motor. Here'why they sound like they do....
The Harley Sound
So, a dual-engined setup with odd timing might sound almost as strange if you were to time them, for instance, 10 or 20 or 30 degrees apart instead of 45.

Here is a detailed thread from the H.A.M.B. that may offer some enlightenment. If not, come back and let's talk more. Use all the links that are provided in the discussion on the H.A.M.B., because some of it applies to coupling systems too.
Twin Engine Coupling (How Do You Get Two V8's In-Line?) | The H.A.M.B.

P.S. When I began typing, nobody had answered yet, then when I posted, I was amazed to see all the fellows who had posted while I was typing. This thread has struck a nerve.....:eek:
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#7 · (Edited)
Back in the hay days of Top Gas Dragster there were many twins. All that I saw and ran against were in line. There were only a couple that used the chain coupling shown. These were fabricated from industrial parts. I'm not sure of the chain size. 60 or 80 I think. I wouldn't use this as the strength is not there for today's motor.s.

Even the best 392's of the early 70's only made about 800 hp. Supercharged on pump gas. Today nobody I know of makes a production coupler for coupling motors. Mark Williams Ent., Strange Eng. and several others could easily make one as they make the best couplers for coupling trans to rear ends. These are totally bullet proof. It's what we used on all our dragsters and funny cars. They were custom made back then too.

As for phasing two motors, it's trial and error. Both motors need to be well tuned and very close to the same power to work really well. Yes there were a couple of Chev / Chrysler combinations but they were not very successful. Some ran straight up, some ran 45 deg off. Some ran odd offsets. The Chrysler and BBC had big snouts so easily connected. The SBC has a small snout and by itself is easily broken. The fix was a billet crank with a BBC size snout. " The Freight train" was the best known SBC twin.

Some guys tried different timing settings to load one motor or to offset harmonics.

The bottom line was the twins were feared when all was running well but easy prey when things fell apart. We never beat a good running twin as a single, they simply out ran us no matter how hard we ran.

Twin engine gas dragster class was hugely popular in its day. NHRA killed it overnight banning twins and delegating top gas dragsters to comp eliminator. Many very good racers simply walked away from drag racing altogether as a result.

I'll try and find a coupler and edit this shortly.

http://www.kenlowe.com.au/driveshafts_couplers_and_covers.htm

You can page down here and see the male and female parts of the coupler. It would have to be custom made to fit the cranks however.

As for starting, back then we push started the dragsters or they were started on rollers. The big removable starters of today were not invented yet. However these new starters would have no trouble turning two big hemis over.

If you want to see the history of twins here is the ultimate site

http://twotogo.homestead.com/

Byron
 
#13 ·
Back in the hay days of Top Gas Dragster there were many twins. All that I saw and ran against were in line. There were only a couple that used the chain coupling shown. These were fabricated from industrial parts. I'm not sure of the chain size. 60 or 80 I think. I wouldn't use this as the strength is not there for today's motor.s.
Those chain couplings are used extensively on drilling equipment to couple the right angle drive to the kelly bar (~4.5" o.d. coupler). Typical torque output varies from 8,000 to 16,000 lb-ft, and I've never seen (or heard of) one break(ing) - been drilling since 1989.
I don't think I would worry much about the strength of the coupler....
 
#8 ·
Thanks for the imput so far people. I wasn't expecting so many quick responses :)
I've seen some of the dragsters online that were referred to but haven't read up on them. The part I have yet to fully understand from what I've gathered is how this affects all the other parts does this kind of setup (2 inline coupled motors) just send more power to the wheels general if it was configured to fire and run in the most efficient way and what would need to be added/altered to make this efficent. I've been looking into some airplane engines with the same setup aswell. Very interesting.
 
#11 · (Edited)
In 1962, Eddie Hill from Witchita Falls Texas, in his "Double Dragon" dragster with a pair of side by side blown Pontiac engines, dual drag slicks on each side, dual clutches, two differentials with the ring gear bolted to welded flanges on oil field drill stem for an axle. The Double Dragon was the first dragster to exceed 200 MPH. He set that record with the Double Dragon at the Hobbs New Mexico Dragstrip and did 203 MPH with a 8.0 second ET.

NHRA limited multi-engine dragsters to pump gas, no nitromethane, then later they were banned from completion completely, except for exhibition racing. That was when the Double Dragon was retired from competition. Later after Eddie Hill retired from Top Fuel drag boats, he set the record for Top Fuel dragster at Dallas International dragstrip on opening day!

The dragstrip at Hobbs NM was at that time an abandoned concrete airstrip, with lotsa bite. It had the longest shut down area of all sanctioned dragstrips. Hill removed his two ribbon chutes and saved 100 lbs. and hand braked the Double Dragon to a stop.

Sometimes he used two 421 Pontiac engines and sometimes a combination of 370, 389 or 421 Pontiac engines. He said there was no different in power output!

Eddie Hill built our first short wheel base C/Gas dragster in 1964. In 1967, we had a chromoly, long wheel base, front engine frame built by Woody Gilmore , especially for NHRA Junior Fuel racing, using a bored and stroked 327 Chevrolet engine for 355 CI with Enderle fuel injection. The late Henry "Hank the Crank" Bechiloff at CSC, prepared the crank, rods and Pistons.
 
#22 ·
In 1961 at the Nationals in Indianapolis Eddie dug two ruts in the starting line with that car. Things were shut down until they coptered in some repair material from Indianapolis. His et's were lousy but I seem to remember he set top speed, either him or the green monster, I don't remember which. Sixteen days later I left for boot camp at MCRD San Diego.
 
#12 ·
How do the multi engine tractor-pullers do it? I remember all kinds of weird stuff back in the 80s. A couple guys ran mixed engine combos, some ran sidewinders; and most were staggered in mounting height. REALLY wild stuff. I often wondered if some of the twin engine gas digger guys ended up there some 20-odd years later.

Eddie Hill was not only an innovator, fabricator and one HELL of a driver; he was also one of the luckiest people on earth to survive the dragboat wars, twin engine diggers and top fuel dragster for as long as he was competing.
 
#14 ·
About 25-30 years ago I remember reading a car magazine article where they put two complete drivetrains into a Ford Festiva. They used an automatic transaxle and somehow mounted the 2nd engine in the back so that it drove the rear wheels (it was a FWD car). It used a complete engine and automatic transaxle to drive each end of the car.

The Festiva was a cheap economy/rental car, but for some reason people were attracted to modifying it. There was also a V-6 conversion called the Shogun, where they used the Yamaha 3.0 DOHC engine from a Taurus SHO to drive a Festiva.

Bruce
 
#15 ·
I do remember there was one set up where as the two side by side engines were directly geared together via special "Flywheels". They were basically two special cut gears intermeshing together. One engine was cammed to run in the opposite direction. I was thinking it was a Mickey Thompson car (he was always thinking out of the box) but all I could find was his four wheel drive twin. That car was the precursor to his four engined Challenger.

I used to work with Don "Red" Fogelman, driver of Ken Fullers "The Odd Couple".
Chevy up front, Chrysler behind. We used to go to lunch together ending up shooting pool in a beer bar. Don gave me the nickname"Quarters".

I found it! It was Ivo who had te geared together set up. Dual ring gears one each flywheel.Each engine running in opposite directions.

BB :thumbup::thumbup:
 

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#21 ·
http://www.hotrodders.com/forum/attachment.php?attachmentid=353233&stc=1&thumb=1&d=1491492232
This picture of side by side engines is not from Ivo's car...ivo's deal was two Buick 322 Naihead engines coupled by flywheels equipped with two ring gears on each flywheel to get the strength needed.
The picture shows two Pre-'68 SB Chevys, one forward and one backward, so that a reverse rotation for one engine isn't needed.

Ivo's car did run one of the Nailheads as reverse rotation.
 
#19 ·
Here's some pictures of a dual engine coupler I found in a video for anyone who's interested. It connects 2 motors inline. The video just shows the guy putting the 2 peices together and shows how it goes on the damper
There it is the quibo thing i was talking
about looks just like the merc one i linked too. That may hold some power and reduce shock loads.

But what is the purpose of the project let us in on the details. Is this for power or show???
I'm not planning on making a dual engine setup right now I'm just curious to how it works and I want to better understand it and know a little more about the diffrent fabrication and ideas people have made over the ages. It's interesting to me and even if I never actually make one I just love the idea and pretty much cars in general
 
#18 ·
Having two engines inline simply gives you twice the power... then the rest of the driveline and suspension has to be for an engine twice as powerful... and there is more weight... a problem is the rear of the crank of the second engine is getting twice the torque it was designed for... and all the throws of the rear crank have a lot of extra torque on them...

The Invader custom car had dual drivetrains... dual GTO Pontiac 400 engines... and independent rear suspension which wasn't strong enough for the power making it a 'widowmaker' to drive... the rear tires towed in and the rear of the car tended to dive off for the left or right under power...


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#24 · (Edited)
Eddie Hill had dual slicks for serious competition. He would remove a slick from each side for a smoke show. The twin blown Pontiacs would smoke the single pair of slicks half way through the quarter.

I talked to Eddie Hill again at the Houston Dragstrip (Royal Purple Raceway) in Baytown Texas in 2000. He remembered our C/Gas dragster he built for us in 1964. He said, "Oh yeah, you were the guys from west Texas"

We raced that old dragster until 1967 when we had Woody Gilmore build us a long (170") wheel base Junior Fuel front engine dragster chassis. It was state of the art in 1967. In 1969, we had the late Ed Mabry modify the chassis to a flex-frame design in order to prevent damaging wheelies. Junior Fuel class soon became dominated by front engine, fuel injected, early Dodge and Chrysler Hemi 354 CI engines.
 
#26 · (Edited)
Well, you've managed to get my juices flowing. My 9 yr old grandson wants a rat rod and I have been chosen the builder. I'm thinking of using an S10 single cab with the roof cut off and Mickeys on the rear, right up against the cab with no bed......much like a Lakes Modified that I have wanted to build for decades. Motive power will be TWO LR4's side by side, carbureted with crank-turned HEI's. Sprockets bolted to the rear ends of the cranks will drive chains that will turn a single steel bar that will drive a flywheel and clutch setup in a scattershield for a 6-speed manual trans. I have the whole mess sketched out on paper, so I know it will work. It's just a matter of designing and fabricating the correct support pieces. With a couple of custom cams, I should be able to net about 700 hp with the two motors. Watching what I do and drilling everything full of holes, I should be able to put it on the road at less than 2300 lbs.

I hope I live long enough, it sure sounds like fun. :eek:
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