CraigJ
|
| posted on 27/6/09 at 01:39 PM |
|
|
YEH BABY THEY FIT
This car is going to kill me lol
Aiming for 500kgs or under as well.
|
|
|
|
|
Mark Allanson
|
| posted on 27/6/09 at 01:41 PM |
|
|
One for each rear wheel!
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
|
|
|
locoboy
|
| posted on 27/6/09 at 02:01 PM |
|
|
How are you planning on combining their oomph and getting the to run in union so to speak?
Looks crazy  
ATB
Locoboy
|
|
|
CraigJ
|
| posted on 27/6/09 at 02:03 PM |
|
|
like this
http://www.mkengineering.co.uk/apps/photos/photo?photoid=10993799
|
|
|
locoboy
|
| posted on 27/6/09 at 02:59 PM |
|
|
i see how it works now but is there a diff in any of that?
Also how can you get the engines to run at exactly that same rate so that one is not carying the other if you know what i mean?
ATB
Locoboy
|
|
|
M$RK_VXRD
|
| posted on 27/6/09 at 03:12 PM |
|
|
the stronger engine will pull the other along i asked martin the same question when i seen the twin engined kitty
|
|
|
stevebubs
|
| posted on 27/6/09 at 04:04 PM |
|
|
quote:
Originally posted by locoboy
i see how it works now but is there a diff in any of that?
Also how can you get the engines to run at exactly that same rate so that one is not carying the other if you know what i mean?
Yep - diff is in a carrier below the shaft driven directly by the engines..the 3rd chain (middle one) puts the power from the engines through the
diff.
[Edited on 27/6/09 by stevebubs]
|
|
|
Guinness
|
| posted on 27/6/09 at 04:18 PM |
|
|
Nice one! Straight eight!
Same technique as Russ used on the Furore? His seemed to go well!
Mike
|
|
|
speedyxjs
|
| posted on 27/6/09 at 04:32 PM |
|
|
Nice one
How long can i resist the temptation to drop a V8 in?
|
|
|
CraigJ
|
| posted on 27/6/09 at 05:00 PM |
|
|
Cheers for the comments guys.
It will take time to get it all running together but i have no deadline so i will just keep at it till it goes right.
|
|
|
locoboy
|
| posted on 27/6/09 at 05:31 PM |
|
|
Surely there should be some kind of diff bit in the shaft connected directly to the engines to allow the engines to work at different speeds. They
are not going to be exactly in tune so you will not be maximising your output from both engines as one will inevitably be dragging the other alone and
wasting BHP in doing so................
Or have i still not got it!
ATB
Locoboy
|
|
|
suparuss
|
| posted on 27/6/09 at 06:08 PM |
|
|
quote:
Originally posted by locoboy
Surely there should be some kind of diff bit in the shaft connected directly to the engines to allow the engines to work at different speeds. They
are not going to be exactly in tune so you will not be maximising your output from both engines as one will inevitably be dragging the other alone and
wasting BHP in doing so................
Or have i still not got it!
thats initialy what i thought but when i thought about it- what you are saying is correct if it was just a matter of engine speed, as in one engine
keeping up with the other. but i think it is all to do with torque rather that speed. like a beefcake and a skinny guy both pushing the same car, the
little guy will be helping a bit even if hes half as strong.
very nice project by the way. being nuts is what we like on here!
|
|
|
locoboy
|
| posted on 27/6/09 at 07:22 PM |
|
|
Yes but if you have 2 beefcakes, one who cant be arsed and the other one is in the zone.
Whilst the one who cant really be arsed will be helping a bit he is not working to his full potential so you dont gain double the output.
Or a better example is Sir Chris Hoy and me on a tandem, i would help a bit but it wouldnt be the same as haveing 2 x Chris Hoy's pedaling in
unison would it.
I know it will be like poo off astick with 2 engines in it but i cant help thinking there is going to be a lot of lost power.
What would be the outcome if one of the engines went down or began struggling could the other one damage it by 'forcing' it along?
ATB
Locoboy
|
|
|
JoelP
|
| posted on 27/6/09 at 07:34 PM |
|
|
I think its not an issue myself. One engine, when revving under load, will raise its revs (ie accelerate the car) at a certain rate. The other engine
will definately assist even if it was underpowered, because to actually be a hinderance it would have to raise its own revs slower than the engine
that is pulling hard. This is never going to happen because in this situation the engine is doing no work so the revs would rise at the same rate as
it would if it were in neutral - ie fast.
Or another way, it will always be able to add something even if completely strangled.
Please say if that doesnt make sense because i know another way to explain it.
|
|
|
JoelP
|
| posted on 27/6/09 at 07:35 PM |
|
|
more simply maybe, if you engaged both engines and accelerated, dipping the clutch on just one would cause the revs in that engine to shoot up faster
than the engine that is under load - proving that it was producing more power than it was using in being turned.
|
|
|
zilspeed
|
| posted on 27/6/09 at 08:31 PM |
|
|
quote:
Originally posted by Guinness
Nice one! Straight eight!
Same technique as Russ used on the Furore? His seemed to go well!
Mike
As I understand it, it's not the same technique.
The picture shown is how I would do it myself - summing the drives via a jackshaft.
But I believe that the furore has an engine driving each wheel which I must say I'm not quite so sure about.
|
|
|
Sven
|
| posted on 28/6/09 at 12:18 AM |
|
|
isn't it about load? Meaning, if one engine is putting out more power then there's less load on the other and the latter can spin up
quicker until it puts it's power to the jack shaft?
The ideal would be two perfectly matched engines, but I would assume that's almost impossible. This, at least, gives the combined power of both
even if one is slightly down on the other?
"Lightheadedness through quickness"
|
|
|
Alan B
|
| posted on 28/6/09 at 03:32 AM |
|
|
Why is this problem fundamentally any different to tuning just one engine?...all the pistons are connected by the crank and have to run together at
the same speed but some will be driving the crank with more force than others?...effectively this just makes a kind of straight 8 engine (as somebody
said earlier)
Alan
|
|
|
zilspeed
|
| posted on 28/6/09 at 06:30 AM |
|
|
quote:
Originally posted by Alan B
Why is this problem fundamentally any different to tuning just one engine?...all the pistons are connected by the crank and have to run together at
the same speed but some will be driving the crank with more force than others?...effectively this just makes a kind of straight 8 engine (as somebody
said earlier)
Alan
Totally agree.
Do a compression test and you'll find a variance across the cylinders.
The crankshaft doesn't twist like a barley sugar, it just gets on with it.
As long as you don't exceed the safe rev limits, it's possible to run the two engines / one jackshaft setup in different gears and it
still works.
I'm not recommending it, but it still works.
It's like a tug of war onto the jackshaft, some of the guys pulling the rope are different strength, but as long as they're all pulling
the rope the efforts are summed at the end of the rope.
I understand that grasstrackers have been doing it for years.
(Jackshafts, not tug of war.)
|
|
|
Tralfaz
|
| posted on 28/6/09 at 12:48 PM |
|
|
What happens in the event of some sort of shift failure on only one engine?
|
|
|
CraigJ
|
| posted on 28/6/09 at 02:21 PM |
|
|
quote:
Originally posted by Tralfaz
What happens in the event of some sort of shift failure on only one engine?
Swap the engine for another.
|
|
|
Tralfaz
|
| posted on 28/6/09 at 04:46 PM |
|
|
quote:
Originally posted by CraigJ
quote:
Originally posted by Tralfaz
What happens in the event of some sort of shift failure on only one engine?
Swap the engine for another.
Ok.
Perhaps I was unclear?
What would the implication/result be of an upshift failure on only one engine while accelerating full out?
One engine shifts to fourth, the other misses, ends up in neutral or stays in third. Say to a linkage problem, or other.
Disaster?
Honestly just curious of the possible result.
T
|
|
|
JoelP
|
| posted on 28/6/09 at 06:34 PM |
|
|
quote:
Originally posted by Tralfaz
quote:
Originally posted by CraigJ
quote:
Originally posted by Tralfaz
What happens in the event of some sort of shift failure on only one engine?
Swap the engine for another.
Ok.
Perhaps I was unclear?
What would the implication/result be of an upshift failure on only one engine while accelerating full out?
One engine shifts to fourth, the other misses, ends up in neutral or stays in third. Say to a linkage problem, or other.
Disaster?
Honestly just curious of the possible result.
T
I think craig jumped a step in the logic, rather than missing what you meant. The engine would get lunched through over-revving, and then it would get
swapped for another. I believe he is using very cheap old engines. 
|
|
|
andyd
|
| posted on 29/6/09 at 09:33 AM |
|
|
That's how Tiff Needel lunched the 0-60 record holder car isn't it? Was it a Tiger or something?
It has (had?) two gear shifters side by side and he missed one of them... result was one shifted up and the other over revved and went pop. Rod
through the block if I recall. 
Oops. 
Andy
|
|
|
iank
|
| posted on 29/6/09 at 09:49 AM |
|
|
quote:
Originally posted by andyd
That's how Tiff Needel lunched the 0-60 record holder car isn't it? Was it a Tiger or something?
It has (had?) two gear shifters side by side and he missed one of them... result was one shifted up and the other over revved and went pop. Rod
through the block if I recall.
Oops.
Why wouldn't you lock the shifters together to avoid that. Wouldn't help if a control cable snapped on one engine, but would prevent
human error.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
|
|
|
