"Jobjoris" (Jobjoris)
12/11/2015 at 05:19 • Filed to: None
2
23|
"Jobjoris" (Jobjoris)
12/11/2015 at 05:19 • Filed to: None | 2
| 23 |
!!!error: Indecipherable SUB-paragraph formatting!!! to get this amazing piece of history. I’m all out of cash at the moment so I’m skipping this one. Two engines! FWD, RWD or AWD!
TheAnswerIsAlwaysCitroën
> Jobjoris
12/11/2015 at 05:43 |
|
There’s no way I can afford it either. Let’s join ranks, buy it, then take it for a round-the-world trip! It’s probably the only way it’ll ever see off-road use again, instead of languishing in some private collection.
Who’s with me?
KatzManDu
> Jobjoris
12/11/2015 at 05:47 |
|
That looks like an insane amount of fun.
|
Jobjoris
> TheAnswerIsAlwaysCitroën
12/11/2015 at 06:06 |
|
I’m with you, just afraid the little time that’s left will kill our opportunity.
Not sure if it will survive a world trip either, it’s a Citroën ;-)
|
Jobjoris
> KatzManDu
12/11/2015 at 06:08 |
|
The two gas tanks are mounted under the front seats. Better try avoid crashing it. It’s amazing how (if they actually did) Citroën could synchronize those two running engines!
Probenja
> Jobjoris
12/11/2015 at 06:10 |
|
It’s not a Citroën in the same way a DS is, the 2cv is extremely reliable and simple, you still see them arround here in Latin America as farmers cars.
|
Jobjoris
> Probenja
12/11/2015 at 06:31 |
|
Believe me: I know. But this is a Sahara. With two engines. Running synchronous. You bet stuff will fall of/break down.
We had a 2cv6 in the family for over 10 years, I know they’re quite reliable.
|
Probenja
> Jobjoris
12/11/2015 at 06:58 |
|
We had one in the family too! But i wasn’t born yet... Yeah I thought your comment was reffering to Citroën’s in general, I guess a Sahara wouldn’t be the most reliable thing in the world. I’m guessing some people have taken these things rallying so there must be reports on how reliable they are.
|
TheAnswerIsAlwaysCitroën
> Jobjoris
12/11/2015 at 07:07 |
|
Why would the engines be more unreliable just because there are two of them? Yes, there are twice as many parts to break, but on a 2CV that’s still significantly less than on most cars. I don’t see why they should be under more stress than in a normal 2CV - quite the opposite, in fact! And if one of them breaks, you still have the other to get you to the nearest garage.
|
TheAnswerIsAlwaysCitroën
> Jobjoris
12/11/2015 at 07:09 |
|
Why would they need to synchronize them? They drive separate wheels through separate transmissions - no hocus pocus. You just couple the throttle cables so they share the load about equally, make a linkage so you don’t have two clutch pedals and two gear levers, and you’re pretty much good to go.
|
Jobjoris
> TheAnswerIsAlwaysCitroën
12/11/2015 at 07:15 |
|
Because this was a time prior to electronic control. How would you get these engines/transmissions (two as well!) to work synchronously in a correct way? I can imagine the “workload” being unbalanced all the time so more stress than a normal 2cv only seems to be natural. To me that is. And to a lot of people probably as Citroen sold only about 600 of these. And got a different system for the Méhari 4x4 for a reason.
But using one to get to the nearest garage is an awesome feature of course...
shop-teacher
> Jobjoris
12/11/2015 at 07:17 |
|
Pretty cool! That’s one expensive 2CV!!!
I wrote my French Friday post last night, but my pictures came out terrible. I need to do a reshoot before I post it.
|
TheAnswerIsAlwaysCitroën
> Jobjoris
12/11/2015 at 07:21 |
|
See my other reply further down - you don’t need to synchronize anything, other than by coupling the throttles so they are both at about the same position.
Each engine just feels a lighter load - to them, it’s as if you are constantly driving downhill. Whether the additional “push” comes from gravity or from a second engine doesn’t really matter.
If you have made the linkage so the front engine always gets a bit more throttle than the rear, then that engine might take 60% of the load, with the rear engine taking 40%. No big deal, it’s still less stress than if you only had one engine (apart from the bit of additional weight, of course).
The only problem I could see was if the linkage was so far off that one engine was actually engine braking instead of driving. Then you would put more load on the other engine. That shouldn’t be too hard to avoid, though.
|
Jobjoris
> TheAnswerIsAlwaysCitroën
12/11/2015 at 07:27 |
|
Because without decent synchronization I can imagine the two sets of wheels to be rotating at different speeds? Can’t be good if you ask me. Again: Citroën ditched the solution of two engines for a reason.
|
TheAnswerIsAlwaysCitroën
> Jobjoris
12/11/2015 at 07:40 |
|
I don’t know why they ditched the solution. Maybe it didn’t fit into the Mehari very well, maybe it was too expensive, or maybe people were afraid of it because they didn’t understand it. Anyway, as a physicist I think your fears are unfounded.
IF a throttle pedal controlled the exact speed of an engine, THEN the problem you describe would arise. You would need to set the throttle positions so they matched exactly, taking into account slight diameter differences of the tires. That is the case for traditional 4x4 systems without a centre differential: The front and rear axles are forced to rotate at the exact same speed, and if e.g. the tyres on one axle are slighly more worn than those on the other (or if you go round a corner), you’d have a problem - potentially breaking the axles or transfer case. That is why you should only engage 4x4-mode on slippery ground.
IN ACTUALITY, a throttle controls the power or the torque that the engine outputs. It’s not a perfect, linear control, and the power also depends on the speed of the engine, but the important thing is that at a given throttle position the engine will continue to push even if the engine speed changes.
Think about it: Imagine you are driving along, throttle pedal halfway down on horizontal ground, speed is stable at 100 km/h. Then you reach a downward slope, and the car accelerates to 120 km/h. Does the engine suddenly go from pushing the car forwards to violently engine braking, because the throttle position no longer matches the speed? No, of course it doesn’t! The car accelerates because it is now powered not only by the engine, but also by gravity. The engine speed rises slightly, but it continues to put down about the same amount of power.
It’s basically the same case with the 2CV Sahara, except it’s not gravity but a second engine that gives you a helping push.
|
Jobjoris
> TheAnswerIsAlwaysCitroën
12/11/2015 at 07:57 |
|
Thanks for the explanation as a physicist, quite interesting and enlightening. The costs sure were a problem for these as the price of the Sahara was twice the one of a normal 2cv if I remember correct. Nowadays it’s even worse: did you see the estimate on this one?
|
TheAnswerIsAlwaysCitroën
> Jobjoris
12/11/2015 at 08:11 |
|
No problem, I like being able to explain things without boring people to death for once :)
Yes, even normal 2CV’s have gotten a bit pricey, but these things are just insane - I wish they hadn’t been so rare, then maybe they would be somewhat approachable.
I’ve toyed with the idea of making a ghetto-Sahara from a normal 2CV, fueled by an article by the late Jeroen Cats: http://www.cats-citroen.net/citroen_atypes…
but a) I don’t think I have the skills, and b) I’d probably never get it through the Danish inspections. It’d have to be a trailer queen taken out for special occasions to play in the mud, and that’s not really what I want.
I just really like the principle of that type of 4WD - simple and elegant in its own way. Come to think of it, it’s basically what Tesla has done with the P85D...
kanadanmajava1
> Jobjoris
12/11/2015 at 08:29 |
|
If I remember correctly some auxiliary device isn’t present in both engines and the front one has to be running to keep the car operating. Maybe it was the alternator?
|
Jobjoris
> TheAnswerIsAlwaysCitroën
12/11/2015 at 08:33 |
|
Ah, Jeroen’s amazing vault of information for my French Friday posts on LaLD when it comes to Citroën. Seems to be doable. Not sure if I’ve got the skills either although I’m in the process of getting my ‘73 2002 Touring up to tii specification. That will go through Dutch inspections, hopefully march/april 2016. And then of to a new project, probably French.
My Volvo V60D6 has the same principle as well I suppose: FWD diesel, RWD electro, AWD combined ;-)
|
Jobjoris
> kanadanmajava1
12/11/2015 at 08:42 |
|
Could be. There’s a separate lever next to the gear-change lever to select which engines to use. Reading more here does make me think there was either front- or AWD.
|
TheAnswerIsAlwaysCitroën
> Jobjoris
12/11/2015 at 09:03 |
|
Oooh, nice! I’m not on LaLD so much, but I think I should be.
I think modifying a 2002 (cool car by the way!) to tii specs would be allowable even in Denmark.
Moving the fuel tank(s), putting another engine in the boot, adding drive shafts to previously undriven wheels, replacing the rear suspension arms with front arms with the steering locked off and, perhaps worst of all, moving the brakes inboard to act through the new drive shafts, though... I don’t think they’d like that!
|
Jobjoris
> TheAnswerIsAlwaysCitroën
12/11/2015 at 09:26 |
|
Watch out, it’s a dangerous place. You’ll be spending a lot of money on stuff you don’t really need. I shifted slowly from Oppo to mainly LaLD the last year. Haven’t updated my Touring project a lot lately but that has to do with moving house/rebuilding lately as well.
It’s probably not as bad as the Sahara no. But it’s not just adding the Kügelfischer either. Fuel retour line to the fuel tank, different struts in front, bigger brakes all around, different fuel pump, I’m adding a Getrag 245 5-speed in the process, I’m sure I’m forgetting stuff.
Jonee
> Jobjoris
12/11/2015 at 13:00 |
|
Wow, it looks beautiful. I wish I hadn’t bought the C30 now. I should have held out for the Safari. Oh, well. Maybe the next one that comes up.
|
Jobjoris
> Jonee
12/11/2015 at 15:53 |
|
Maybe if you let one of your neighbors crash into the NX? Even more insurance money!!!
The next one that comes up will be even more expensive. I remember one could get one of these for barely 10k!