Twin engined Fitipaldi
- Max Welton
- Posts: 3023
- Joined: Mon Jun 03, 2002 12:01 am
Twin engined Fitipaldi
http://jalopnik.com/5799726/emerson-fit ... gen-beetle
This car was just shown on the Car Crazy TV show. The above article says the car was dismantled and lost, but it is still around and was shown on the show.
Other info found by google:
http://www.dlg.speedfreaks.org/archive/ ... 0/3200.php
Max
This car was just shown on the Car Crazy TV show. The above article says the car was dismantled and lost, but it is still around and was shown on the show.
Other info found by google:
http://www.dlg.speedfreaks.org/archive/ ... 0/3200.php
Max
- FJCamper
- Moderator
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- Joined: Wed Nov 14, 2007 2:19 pm
Re: Twin engined Fitipaldi
A swing axle like the original BiMotor is show above, but the car may actually use a 914 rear suspension. And carbs are shown above, but a twin turbo system is slated as the actual induction system.
The X-CAR PROJECT
Hi Max,
As interesting as the Bimotor is, it gets very little attention within the VW community. And here at Cold Source/RetroRacing, we intend to change that. We are in process of building an updated version of this historical twin-engine Bug.
This is not a homage showcar copy of Emerson Fittapaldi's original "Fuscha," but an actual road racer with twin 914 engines, and a technical solution to the BiMotor's weakness, the elastomeric coupling that joined the engines. We have an input shaft welded as an extension of the crank on the trailing engine that engages the pinned clutch assembly on the leading engine.
There are lots of technical hurdles we're solving in this project, most in the almost total new fabrication body shell, and keeping the weight down.
We are withholding an official announcement on the project until we can show more of the chassis and body work, so just consider this a leak. I will answer what questions I can, however.
FJC
- Piledriver
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Re: Twin engined Fitipaldi
Too bad AWD twin engine and transmission isn't practical...
Solves many complex issues. (while creating a few of it's own, but comparatively minor)
Would make for a fun rally car
Solves many complex issues. (while creating a few of it's own, but comparatively minor)
Would make for a fun rally car
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
-
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- Joined: Wed Apr 13, 2011 1:01 pm
Re: Twin engined Fitipaldi
almost easier to weld together two cases and make a boxer 8..... never as simple as it seems lol
cool project though!
cool project though!
- Max Welton
- Posts: 3023
- Joined: Mon Jun 03, 2002 12:01 am
Re: Twin engined Fitipaldi
Makes me think of the time a friend broke the crankshaft in his 1776. Because of the way it broke, the engine still ran. It was essentially two loosely connected crankshafts at that point.
Connecting two crankshafts such that are still separate but act as one sounds hard. Welding them together (and mating their respective cases) means you have together everything perfectly (and I mean perfectly) straight? Not trivial.
But a flat eight would be awesome.
Max
Connecting two crankshafts such that are still separate but act as one sounds hard. Welding them together (and mating their respective cases) means you have together everything perfectly (and I mean perfectly) straight? Not trivial.
But a flat eight would be awesome.
Max
- Fiatdude
- Posts: 971
- Joined: Mon Oct 12, 2009 6:58 pm
Re: Twin engined Fitipaldi
Where's those pictures of those 8 and 12 cylinder cranks that somebody developed
- FJCamper
- Moderator
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- Joined: Wed Nov 14, 2007 2:19 pm
Re: Twin engined Fitipaldi
Hi Max,
Fittipaldi's original twin-engines were connected by a big rubber donut, the cranks phased 90 degrees from each other. The car was brutally fast, but the donut usually failed.
There has to be some "slack" between the two cranks, but not much. Being two separate engines, they will never run exactly in synch. What we've done, after much experimentation, is let the spring center clutch disk of the leading (most forward in chassis) act to give us some play. The outer edge of the disk is pinned to the flywheel so that the disk center can rotate around its axis a little, and be self-correcting, cushioning the shock of the trailing engine as it engages its working clutch.
Obviously, we want both engines operating as much as one as possible, meaning a unified induction system. This seems to be best achieved with a turbo. This can theoretically be done with one large turbo, but two small units pressuring a common plenum feed might be better for overall drivability.
Do any of you remember Bruce McDowell's tandem-engine "Double Trouble" VW drag car from 1976? The car was a National Record Holder. Hot VW's Oct 1980, pg 34.
His engines were joined by a splined coupler. The front of the crank from the trailing engine was cut off at the #1 bearing, and a splined steel extension was welded on. Bolted to it was a coupler that mated the spline on the flywheel of the leading engine. The coupler was machined to allow about one degree of flex. We achieve the flex with our spring clutch hub.
FJC
Fittipaldi's original twin-engines were connected by a big rubber donut, the cranks phased 90 degrees from each other. The car was brutally fast, but the donut usually failed.
There has to be some "slack" between the two cranks, but not much. Being two separate engines, they will never run exactly in synch. What we've done, after much experimentation, is let the spring center clutch disk of the leading (most forward in chassis) act to give us some play. The outer edge of the disk is pinned to the flywheel so that the disk center can rotate around its axis a little, and be self-correcting, cushioning the shock of the trailing engine as it engages its working clutch.
Obviously, we want both engines operating as much as one as possible, meaning a unified induction system. This seems to be best achieved with a turbo. This can theoretically be done with one large turbo, but two small units pressuring a common plenum feed might be better for overall drivability.
Do any of you remember Bruce McDowell's tandem-engine "Double Trouble" VW drag car from 1976? The car was a National Record Holder. Hot VW's Oct 1980, pg 34.
His engines were joined by a splined coupler. The front of the crank from the trailing engine was cut off at the #1 bearing, and a splined steel extension was welded on. Bolted to it was a coupler that mated the spline on the flywheel of the leading engine. The coupler was machined to allow about one degree of flex. We achieve the flex with our spring clutch hub.
FJC
- Max Welton
- Posts: 3023
- Joined: Mon Jun 03, 2002 12:01 am
Re: Twin engined Fitipaldi
It might actually be easier to just cast a new case and crank for the flat-8.
Max
Max
- yodogg
- Posts: 143
- Joined: Tue Sep 14, 2010 1:26 pm
Re: Twin engined Fitipaldi
I don't know. Unless I misunderstood your comment, I have a hard time believing it would be easier (certainly not cheaper) to have both a flat-8 crank and case custom cast. Plus I think I would rather take my chances with two forged cranks mated together, than a single extra long cast crank.Max Welton wrote:It might actually be easier to just cast a new case and crank for the flat-8.
Hawkeye
- Max Welton
- Posts: 3023
- Joined: Mon Jun 03, 2002 12:01 am
Re: Twin engined Fitipaldi
I'm just thinking about the problem of either joining two cases so that the crankshafts remain exactly in line with each other, or a crank coupling device that allows for a small amount of dynamic alignment error during operation. I would imagine the Fitipaldi's 'big rubber donut' failed due to heat and fatique. It wouldn't take much movement at crankshaft speeds and loads.
FJC's solution sounds like a torque-spring a little like some motorcycle drive-shafts use to absorb shock loads. I wonder what sort of interesting harmonics it will generate.
Max
FJC's solution sounds like a torque-spring a little like some motorcycle drive-shafts use to absorb shock loads. I wonder what sort of interesting harmonics it will generate.
Max
- yodogg
- Posts: 143
- Joined: Tue Sep 14, 2010 1:26 pm
Re: Twin engined Fitipaldi
Hi Max,
Sorry, I understand now. Still giubo style linkages between drive shafts and transmissions are quite common, so it should be possible to link engines by this method. If I remember correctly (from the accounts that I have read), the rubber linkage only failed on one or two occasions (once during testing and once during a race) while it was the transaxle that failed during the second race. The main issue seemed to be that neither the transmission or their version of a giubo were really strong enough to deal with all the torque they were able to develop (400+ lb-ft!).
That said, I like the current proposal for linkage of the two crank shafts as there are plenty of components available that are strong enough to handle 400 lb-ft of torque. It will just come down to the welding and modifications being up to snuff. I would think so long as each rotating assembly is well balanced and the clutch components are properly mounted and in spec that harmonic vibration should not be too bad of an issue. At least not so long as the engines are on throttle/under load. I do worry a little bit about what will happen during braking or with slow downshifts, when the rotating mass will be "spinning free". Hopefully these will be so brief that it won't matter. We'll see though.
Hawkeye
Sorry, I understand now. Still giubo style linkages between drive shafts and transmissions are quite common, so it should be possible to link engines by this method. If I remember correctly (from the accounts that I have read), the rubber linkage only failed on one or two occasions (once during testing and once during a race) while it was the transaxle that failed during the second race. The main issue seemed to be that neither the transmission or their version of a giubo were really strong enough to deal with all the torque they were able to develop (400+ lb-ft!).
That said, I like the current proposal for linkage of the two crank shafts as there are plenty of components available that are strong enough to handle 400 lb-ft of torque. It will just come down to the welding and modifications being up to snuff. I would think so long as each rotating assembly is well balanced and the clutch components are properly mounted and in spec that harmonic vibration should not be too bad of an issue. At least not so long as the engines are on throttle/under load. I do worry a little bit about what will happen during braking or with slow downshifts, when the rotating mass will be "spinning free". Hopefully these will be so brief that it won't matter. We'll see though.
Hawkeye
- raul arrese
- Posts: 58
- Joined: Thu Jan 26, 2012 2:51 am
Re: Twin engined Fitipaldi
back in the old days , they used two sprockets and a fat chain to connect 2 motors , it worked for them ??? i made a coupler for myself once with some gears mark williams sells to couple a rear end and a tranny in a dragster , ?? they slide together , inner and outer ...
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Re: Twin engined Fitipaldi
A flat 8 block should be easy to machine and the crank is doable so why not.
http://www.youtube.com/watch?v=GU32Q6QXtWQ
http://en.wikipedia.org/wiki/W16_engine
Notice the name VW…
http://auto.howstuffworks.com/bugatti1.htm
http://www.youtube.com/watch?v=GU32Q6QXtWQ
http://en.wikipedia.org/wiki/W16_engine
Notice the name VW…
http://auto.howstuffworks.com/bugatti1.htm
- yodogg
- Posts: 143
- Joined: Tue Sep 14, 2010 1:26 pm
Re: Twin engined Fitipaldi
Cool video! But unless you have a CNC machine and are planning to mass produce, I don't see it as a practical option.
Welding 2 flat-4 cases together was a real consideration, but there was still the issue of fusing two cranks and then ensuring that the union would be strong enough. Not to mention finding a shop to dynamically balance it. Conversely having a custom crank built would have been cost prohibitive and dynamic balancing (locally at least) would still be an issue.
Welding 2 flat-4 cases together was a real consideration, but there was still the issue of fusing two cranks and then ensuring that the union would be strong enough. Not to mention finding a shop to dynamically balance it. Conversely having a custom crank built would have been cost prohibitive and dynamic balancing (locally at least) would still be an issue.