Naff Landrovers

"beamendsltd" <[email protected]> wrote in message
news:f4567d814d%[email protected]...
> In message <[email protected]>
> Austin Shackles <[email protected]> wrote:
>
>> On or around Sat, 25 Jun 2005 08:25:11 +0000 (UTC), beamendsltd
>> <[email protected]> enlightened us thusly:
>>
>> >In message <[email protected]>
>> > Austin Shackles <[email protected]> wrote:
>> >
>> >> I spose I should say that the original idea was 2 reliant 850cc
>> >> engines put
>> >> together to make a 1700cc 8...
>> >>
>> >
>> >The major problem would be to get the two engines running the
>> >characteristic, i.e. not fighting each other. I guess (from
>> >railway locomitives) that you'd be lucky to get 150% more
>> >power than a single engine. Somewhere on the web is a discourse
>> >by someone who put 2 (proper) Mini engines together, complete
>> >with the maths on why the power output isn't simply x2
>> >
>> >Richard
>>
>> I dunno how as they'd fight, as such, if bolted rigidly together.
>> They're
>> both turning the same way, after all, and every power stroke adds to the
>> torque. I daresay you don't actually get 2x the power of one, but
>> equally I
>> don't really see where you lose that much either. I don't, in fact, know
>> what angles your typical straight-8 crankshaft uses, but it ought to be
>> 90
>> degrees, in order to get even firing sequences.
>
> Every engine has its own charecteristics, and unless they are a prefect
> match one or the other will be trying to driver the other, acting as
> a brake. If you had an arragement to detect this, the slower engine
> would have to speed up to match its partner. In doing so it would
> likely become the master, and force the other to speed up too, leading
> to runaway. The converse would be true if the tactic was to lower the
> speed of the master engine. Unless the control was renarkably accurate,
> and could react predictively, the engines would end up fighing each
> other. An ECU could probably do this, but it would most likely be
> far more cost effective (in terms of design, maintainance and fuel
> costs) simply to fit a more appropiate engine.
>
> A single engine, but with more cylinders, would not suffer from the
> above as it would only have one control system operating on one
> crank, i.e. a closed system.

But 2 V8's (for arguments sake) running EFI with a single throttle each and
commoned together as a V16 would be no different to balancing twin carbs on
a single V16, or to a similar extent a single V8. Just because the cylinders
are located within another block casting, but mechanically linked, it
doesn't cause any real issues at all. You could argue that a twin carb
engine will have lagging and leading cylinders depending on how the carbs
were balanced, in fact this is done deliberately on some engines (Jag XK 4.2
and RoverV8) to provide for a smooth acceleration at low rpm's, the
imbalance becoming an acceptable factor in the interests of driveability,
the effect reducing to virtually nothing as full throttle is reached.
Badger.

In message <[email protected]>
"Badger" <[email protected]> wrote:

>
> "beamendsltd" <[email protected]> wrote in message
> news:f4567d814d%[email protected]...
> > In message <[email protected]>
> > Austin Shackles <[email protected]> wrote:
> >
> >> On or around Sat, 25 Jun 2005 08:25:11 +0000 (UTC), beamendsltd
> >> <[email protected]> enlightened us thusly:
> >>
> >> >In message <[email protected]>
> >> > Austin Shackles <[email protected]> wrote:
> >> >
> >> >> I spose I should say that the original idea was 2 reliant 850cc
> >> >> engines put
> >> >> together to make a 1700cc 8...
> >> >>
> >> >
> >> >The major problem would be to get the two engines running the
> >> >characteristic, i.e. not fighting each other. I guess (from
> >> >railway locomitives) that you'd be lucky to get 150% more
> >> >power than a single engine. Somewhere on the web is a discourse
> >> >by someone who put 2 (proper) Mini engines together, complete
> >> >with the maths on why the power output isn't simply x2
> >> >
> >> >Richard
> >>
> >> I dunno how as they'd fight, as such, if bolted rigidly together.
> >> They're
> >> both turning the same way, after all, and every power stroke adds to the
> >> torque. I daresay you don't actually get 2x the power of one, but
> >> equally I
> >> don't really see where you lose that much either. I don't, in fact, know
> >> what angles your typical straight-8 crankshaft uses, but it ought to be
> >> 90
> >> degrees, in order to get even firing sequences.
> >
> > Every engine has its own charecteristics, and unless they are a prefect
> > match one or the other will be trying to driver the other, acting as
> > a brake. If you had an arragement to detect this, the slower engine
> > would have to speed up to match its partner. In doing so it would
> > likely become the master, and force the other to speed up too, leading
> > to runaway. The converse would be true if the tactic was to lower the
> > speed of the master engine. Unless the control was renarkably accurate,
> > and could react predictively, the engines would end up fighing each
> > other. An ECU could probably do this, but it would most likely be
> > far more cost effective (in terms of design, maintainance and fuel
> > costs) simply to fit a more appropiate engine.
> >
> > A single engine, but with more cylinders, would not suffer from the
> > above as it would only have one control system operating on one
> > crank, i.e. a closed system.
>
> But 2 V8's (for arguments sake) running EFI with a single throttle each and
> commoned together as a V16 would be no different to balancing twin carbs on
> a single V16, or to a similar extent a single V8. Just because the cylinders
> are located within another block casting, but mechanically linked, it
> doesn't cause any real issues at all. You could argue that a twin carb
> engine will have lagging and leading cylinders depending on how the carbs
> were balanced, in fact this is done deliberately on some engines (Jag XK 4.2
> and RoverV8) to provide for a smooth acceleration at low rpm's, the
> imbalance becoming an acceptable factor in the interests of driveability,
> the effect reducing to virtually nothing as full throttle is reached.
> Badger.
>
>

It would be different - each engine would react differently since
each engine has it's own unique charteristics - a change in throttle
position for one engine (even if the carbs/ECU were sapped over)
would have a different effect on that engine to another one.
As you observe, twin carbs are a compromise that is regarded
as being acceptable. If the carbs are not balanced, even by a bit,
then the compromise fails. The ideal solution would be to have
one carb, which doubltless could be done but is not (finacially and
probably functionally) viable. In other words, exactly the same
debate, only with twin carbs the compromise is acceptable
(functionally) whereas with twin engines the "imporovement" can be
exceded at lower cost by choosing a more approtiate engine.

Richard
--
www.beamends-lrspares.co.uk [email protected]
Running a business in a Microsoft free environment - it can be done
Powered by Risc-OS - you won't get a virus from us!!
Helping keep Land Rovers on and off the road to annoy the Lib Dems

beamendsltd wrote:

> Every engine has its own charecteristics, and unless they are a prefect
> match one or the other will be trying to driver the other, acting as
> a brake. If you had an arragement to detect this, the slower engine
> would have to speed up to match its partner. In doing so it would
> likely become the master, and force the other to speed up too, leading
> to runaway.

What would it take to consider the unit as a single engine, in the
diesel case. ONE injection pump, with 8 ports, ONE turbocharger ?

Steve

"beamendsltd" <[email protected]> wrote in message
news:9caf85814d%[email protected]...
> In message <[email protected]>
> "Badger" <[email protected]> wrote:
>
>>
>> "beamendsltd" <[email protected]> wrote in message
>> news:f4567d814d%[email protected]...
>> > In message <[email protected]>
>> > Austin Shackles <[email protected]> wrote:
>> >
>> >> On or around Sat, 25 Jun 2005 08:25:11 +0000 (UTC), beamendsltd
>> >> <[email protected]> enlightened us thusly:
>> >>
>> >> >In message <[email protected]>
>> >> > Austin Shackles <[email protected]> wrote:
>> >> >
>> >> >> I spose I should say that the original idea was 2 reliant 850cc
>> >> >> engines put
>> >> >> together to make a 1700cc 8...
>> >> >>
>> >> >
>> >> >The major problem would be to get the two engines running the
>> >> >characteristic, i.e. not fighting each other. I guess (from
>> >> >railway locomitives) that you'd be lucky to get 150% more
>> >> >power than a single engine. Somewhere on the web is a discourse
>> >> >by someone who put 2 (proper) Mini engines together, complete
>> >> >with the maths on why the power output isn't simply x2
>> >> >
>> >> >Richard
>> >>
>> >> I dunno how as they'd fight, as such, if bolted rigidly together.
>> >> They're
>> >> both turning the same way, after all, and every power stroke adds to
>> >> the
>> >> torque. I daresay you don't actually get 2x the power of one, but
>> >> equally I
>> >> don't really see where you lose that much either. I don't, in fact,
>> >> know
>> >> what angles your typical straight-8 crankshaft uses, but it ought to
>> >> be
>> >> 90
>> >> degrees, in order to get even firing sequences.
>> >
>> > Every engine has its own charecteristics, and unless they are a prefect
>> > match one or the other will be trying to driver the other, acting as
>> > a brake. If you had an arragement to detect this, the slower engine
>> > would have to speed up to match its partner. In doing so it would
>> > likely become the master, and force the other to speed up too, leading
>> > to runaway. The converse would be true if the tactic was to lower the
>> > speed of the master engine. Unless the control was renarkably accurate,
>> > and could react predictively, the engines would end up fighing each
>> > other. An ECU could probably do this, but it would most likely be
>> > far more cost effective (in terms of design, maintainance and fuel
>> > costs) simply to fit a more appropiate engine.
>> >
>> > A single engine, but with more cylinders, would not suffer from the
>> > above as it would only have one control system operating on one
>> > crank, i.e. a closed system.
>>
>> But 2 V8's (for arguments sake) running EFI with a single throttle each
>> and
>> commoned together as a V16 would be no different to balancing twin carbs
>> on
>> a single V16, or to a similar extent a single V8. Just because the
>> cylinders
>> are located within another block casting, but mechanically linked, it
>> doesn't cause any real issues at all. You could argue that a twin carb
>> engine will have lagging and leading cylinders depending on how the carbs
>> were balanced, in fact this is done deliberately on some engines (Jag XK
>> 4.2
>> and RoverV8) to provide for a smooth acceleration at low rpm's, the
>> imbalance becoming an acceptable factor in the interests of driveability,
>> the effect reducing to virtually nothing as full throttle is reached.
>> Badger.
>>
>>
>
> It would be different - each engine would react differently since
> each engine has it's own unique charteristics - a change in throttle
> position for one engine (even if the carbs/ECU were sapped over)
> would have a different effect on that engine to another one.

I think you might just be missing the point here, the different cylinders
within a single engine can in practice operate at differing efficiency
levels to their adjacent cylinders, due mainly to inlet and exhaust
breathing capabilities. This is very obvious on a carb rover V8, where the
outer 4 cylinders (1,2,7&8) do not get the same inlet charge volume as the
other 4, mainly down to the design of the inlet manifold. If you were to
bolt two theoretically identical 4-cyl engines together, then at worst you'd
be no worse off charge efficiency wise than a std V8. It's been done for
years in tractor-pulling circles, using nose-to-tail, chain, belt, and
collector gearbox types of systems, all with reasonable success. They even
join the outputs from Isotov gas turbine engines, one machine having 3 of
the damn things feeding into a collector gearbox!

> As you observe, twin carbs are a compromise that is regarded
> as being acceptable. If the carbs are not balanced, even by a bit,
> then the compromise fails.

Re-read my last posting, some engines are indeed set up with a deliberate
carb imbalance. RV8 and XK4.2 being 2 that I can quote off the top of my
head, where one carb opens prior to the other. In fact, jaguar even quote
differing carb lead values for auto and manual versions of the same engine
with the same carbs!

> The ideal solution would be to have
> one carb, which doubltless could be done but is not (finacially and
> probably functionally) viable. In other words, exactly the same
> debate, only with twin carbs the compromise is acceptable
> (functionally) whereas with twin engines the "imporovement" can be
> exceded at lower cost by choosing a more approtiate engine.

Multi-carbs were traditionally used so that individual port runner gas
velocity could be maintained as high as possible in the interests of
mid-range torque, in addition to the engineering problems encountered when
trying to make one carb feed a largeish engine from idle to max. The port
runner issue still stands today, look at the length of the runners including
the trumpets feeding a v8, and consider why the outer 4 are a different
length to the others, in respect to my first para of this post.
Badger.

In message <[email protected]>
"Badger" <[email protected]> wrote:

>
> "beamendsltd" <[email protected]> wrote in message
> news:9caf85814d%[email protected]...
> > In message <[email protected]>
> > "Badger" <[email protected]> wrote:
> >
> >>
> >> "beamendsltd" <[email protected]> wrote in message
> >> news:f4567d814d%[email protected]...
> >> > In message <[email protected]>
> >> > Austin Shackles <[email protected]> wrote:
> >> >
> >> >> On or around Sat, 25 Jun 2005 08:25:11 +0000 (UTC), beamendsltd
> >> >> <[email protected]> enlightened us thusly:
> >> >>
> >> >> >In message <[email protected]>
> >> >> > Austin Shackles <[email protected]> wrote:
> >> >> >
> >> >> >> I spose I should say that the original idea was 2 reliant 850cc
> >> >> >> engines put
> >> >> >> together to make a 1700cc 8...
> >> >> >>
> >> >> >
> >> >> >The major problem would be to get the two engines running the
> >> >> >characteristic, i.e. not fighting each other. I guess (from
> >> >> >railway locomitives) that you'd be lucky to get 150% more
> >> >> >power than a single engine. Somewhere on the web is a discourse
> >> >> >by someone who put 2 (proper) Mini engines together, complete
> >> >> >with the maths on why the power output isn't simply x2
> >> >> >
> >> >> >Richard
> >> >>
> >> >> I dunno how as they'd fight, as such, if bolted rigidly together.
> >> >> They're
> >> >> both turning the same way, after all, and every power stroke adds to
> >> >> the
> >> >> torque. I daresay you don't actually get 2x the power of one, but
> >> >> equally I
> >> >> don't really see where you lose that much either. I don't, in fact,
> >> >> know
> >> >> what angles your typical straight-8 crankshaft uses, but it ought to
> >> >> be
> >> >> 90
> >> >> degrees, in order to get even firing sequences.
> >> >
> >> > Every engine has its own charecteristics, and unless they are a prefect
> >> > match one or the other will be trying to driver the other, acting as
> >> > a brake. If you had an arragement to detect this, the slower engine
> >> > would have to speed up to match its partner. In doing so it would
> >> > likely become the master, and force the other to speed up too, leading
> >> > to runaway. The converse would be true if the tactic was to lower the
> >> > speed of the master engine. Unless the control was renarkably accurate,
> >> > and could react predictively, the engines would end up fighing each
> >> > other. An ECU could probably do this, but it would most likely be
> >> > far more cost effective (in terms of design, maintainance and fuel
> >> > costs) simply to fit a more appropiate engine.
> >> >
> >> > A single engine, but with more cylinders, would not suffer from the
> >> > above as it would only have one control system operating on one
> >> > crank, i.e. a closed system.
> >>
> >> But 2 V8's (for arguments sake) running EFI with a single throttle each
> >> and
> >> commoned together as a V16 would be no different to balancing twin carbs
> >> on
> >> a single V16, or to a similar extent a single V8. Just because the
> >> cylinders
> >> are located within another block casting, but mechanically linked, it
> >> doesn't cause any real issues at all. You could argue that a twin carb
> >> engine will have lagging and leading cylinders depending on how the carbs
> >> were balanced, in fact this is done deliberately on some engines (Jag XK
> >> 4.2
> >> and RoverV8) to provide for a smooth acceleration at low rpm's, the
> >> imbalance becoming an acceptable factor in the interests of driveability,
> >> the effect reducing to virtually nothing as full throttle is reached.
> >> Badger.
> >>
> >>
> >
> > It would be different - each engine would react differently since
> > each engine has it's own unique charteristics - a change in throttle
> > position for one engine (even if the carbs/ECU were sapped over)
> > would have a different effect on that engine to another one.
>
> I think you might just be missing the point here, the different cylinders
> within a single engine can in practice operate at differing efficiency
> levels to their adjacent cylinders, due mainly to inlet and exhaust
> breathing capabilities. This is very obvious on a carb rover V8, where the
> outer 4 cylinders (1,2,7&8) do not get the same inlet charge volume as the
> other 4, mainly down to the design of the inlet manifold. If you were to
> bolt two theoretically identical 4-cyl engines together, then at worst you'd
> be no worse off charge efficiency wise than a std V8.

I don't beleive I am missing the point at all - the V8 is a closed system,
i.e. inouts to one or more cylinders have a direct efffect on the
total output of the system. Bolting 2 4-cylinder eninges together
is trying to run two independent closed systems together, not
the same thing at all.

> It's been done for
> years in tractor-pulling circles, using nose-to-tail, chain, belt, and
> collector gearbox types of systems, all with reasonable success. They even
> join the outputs from Isotov gas turbine engines, one machine having 3 of
> the damn things feeding into a collector gearbox!

And how long do they last?

It's been done for years on railways too, with great success, BUT,
two locomotives (of the same class) working in tandem (2 drivers,
one in each) only gives a 133% power increase, and in multiple
(one driver, using remote controls to the second engine) only gives
a 150% increase - an exact anology to our two 4-cylinder engines
bolted together.

>
> > As you observe, twin carbs are a compromise that is regarded
> > as being acceptable. If the carbs are not balanced, even by a bit,
> > then the compromise fails.
>
> Re-read my last posting, some engines are indeed set up with a deliberate
> carb imbalance. RV8 and XK4.2 being 2 that I can quote off the top of my
> head, where one carb opens prior to the other. In fact, jaguar even quote
> differing carb lead values for auto and manual versions of the same engine
> with the same carbs!
>
> > The ideal solution would be to have
> > one carb, which doubltless could be done but is not (finacially and
> > probably functionally) viable. In other words, exactly the same
> > debate, only with twin carbs the compromise is acceptable
> > (functionally) whereas with twin engines the "imporovement" can be
> > exceded at lower cost by choosing a more approtiate engine.
>
> Multi-carbs were traditionally used so that individual port runner gas
> velocity could be maintained as high as possible in the interests of
> mid-range torque, in addition to the engineering problems encountered when
> trying to make one carb feed a largeish engine from idle to max. The port
> runner issue still stands today, look at the length of the runners including
> the trumpets feeding a v8, and consider why the outer 4 are a different
> length to the others, in respect to my first para of this post.

To make the compromise work.

> Badger.

Richard
>
>

--
www.beamends-lrspares.co.uk [email protected]
Running a business in a Microsoft free environment - it can be done
Powered by Risc-OS - you won't get a virus from us!!
Helping keep Land Rovers on and off the road to annoy the Lib Dems

On or around Mon, 27 Jun 2005 07:24:38 +0000 (UTC), beamendsltd
<[email protected]> enlightened us thusly:

>Every engine has its own charecteristics, and unless they are a prefect
>match one or the other will be trying to driver the other, acting as
>a brake. If you had an arragement to detect this, the slower engine
>would have to speed up to match its partner. In doing so it would
>likely become the master, and force the other to speed up too, leading
>to runaway. The converse would be true if the tactic was to lower the
>speed of the master engine. Unless the control was renarkably accurate,
>and could react predictively, the engines would end up fighing each
>other. An ECU could probably do this, but it would most likely be
>far more cost effective (in terms of design, maintainance and fuel
>costs) simply to fit a more appropiate engine.

Granting these things, how does this differ from a single mutli-cylinder
engine with separate carbs, such as bike engine? If I have a 2-cylinder
engine with 2 carbs, and they're not balanced, one pot fires less strongly
than the other, which leads to less power and possibly more vibration.
Similarly only moreso for a 4-cylinder with 4 carbs.

My proposed 2xTDi would have the cranks rigidly fixed together, at least as
regards the rotation of same - there might be a problem the blocks bolted
together true enough to actually run a rigid crank connection, although it
could probably be done. But suppose some suitable coupling which allows
slight lateral misalignment but not rotational play between the 2 sides.
The crankshaft is then effectively one piece. The cylinders will be
supplied with fuel by 2 fuel pumps, which would have to be adjusted so as to
provide the same fuel to each bank of 4 clylinders. Once having done that,
I don't see that the losses should be much.

I grant that synchronising the fuel pumps absolutely would be difficult or
impossible, but then by the same token it's also difficult or impossible to
synchronise multiple carbs absolutely.


Finally, as to the "fit a more appropriate engine", where's the fun in that?
But seriously, there's a lot to be said for a double-TDi compared wit some
other type of 5-litre diesel - parts are easily available and cheap, for
example.


Father's just pointed out - put 'em back-to-back and take the drive from the
middle. They will counter-rotate, so they can be geared together by a brace
of big sod-off gears (instead of flywheels), and the drive taken from the
back of the front engine by a shaft alongside the rear one; or possibly,
moutnt the rear one alongside the gearbox with a modified bellhousing to
allow the gears to mesh.

--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Quos deus vult perdere, prius dementat" Euripedes, quoted in
Boswell's "Johnson".

On or around Mon, 27 Jun 2005 08:22:43 +0000 (UTC), "Badger"
<[email protected]> enlightened us thusly:

[words of wisdom]

more succinct than mine. well done.

--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Quos deus vult perdere, prius dementat" Euripedes, quoted in
Boswell's "Johnson".

beamendsltd wrote:

> It's been done for years on railways too, with great success, BUT,
> two locomotives (of the same class) working in tandem (2 drivers,
> one in each) only gives a 133% power increase, and in multiple
> (one driver, using remote controls to the second engine) only gives
> a 150% increase - an exact anology to our two 4-cylinder engines
> bolted together.

Hang on, thats MORE than double ?

Anyway, the man Shackles wants to use diesels, and I want to watch him
do it too.

Now, where do we get an 8 port pump.....


Steve

beamendsltd wrote:

> The major problem would be to get the two engines running the
> characteristic, i.e. not fighting each other. I guess (from
> railway locomitives) that you'd be lucky to get 150% more
> power than a single engine. Somewhere on the web is a discourse
> by someone who put 2 (proper) Mini engines together, complete
> with the maths on why the power output isn't simply x2

Any details on this because as a simple minded physicist
I'm pushed to see how an engine at a set revs with the
pedal down does not deliver its rated torque regardless
what the load looks like.

I just can't see power vanishing. Conservation of energy
is a pretty basic law of the universe.

nigelH

"beamendsltd" <[email protected]> wrote in message
news:78459a814d%[email protected]...
<<big snip!>>
>> I think you might just be missing the point here, the different cylinders
>> within a single engine can in practice operate at differing efficiency
>> levels to their adjacent cylinders, due mainly to inlet and exhaust
>> breathing capabilities. This is very obvious on a carb rover V8, where
>> the
>> outer 4 cylinders (1,2,7&8) do not get the same inlet charge volume as
>> the
>> other 4, mainly down to the design of the inlet manifold. If you were to
>> bolt two theoretically identical 4-cyl engines together, then at worst
>> you'd
>> be no worse off charge efficiency wise than a std V8.
>
> I don't beleive I am missing the point at all - the V8 is a closed system,
> i.e. inouts to one or more cylinders have a direct efffect on the
> total output of the system. Bolting 2 4-cylinder eninges together
> is trying to run two independent closed systems together, not
> the same thing at all.

Ok then, take an I4 engine with a single SU carb, bolt another identical I4
engine to it to make it a twin carb I8. Now, apart from the fact that the
resultant engine is 2 blocks bolted together and a joining sleeve/spline on
the now 2-piece crank(s), why is that suddenly so different from an I8
engine with a single block casting and 2 carbs and a dual-point dizzy, where
each set of points feeds 4 cylinders (preventing points bounce at higher
rpm's)?? Answer, it isn't!

>> It's been done for
>> years in tractor-pulling circles, using nose-to-tail, chain, belt, and
>> collector gearbox types of systems, all with reasonable success. They
>> even
>> join the outputs from Isotov gas turbine engines, one machine having 3 of
>> the damn things feeding into a collector gearbox!
>
> And how long do they last?

"Corskie Supertramp", over 12 years that I know of and still pulling strong
with a multiple (6) rover V8 setup. I once remember it throwing a rod out
the side of a block, but that was due to it being run at too high an rpm,
nothing else.
One (forget its name, might be Midnight Express?) with 4 (or6) jag XK 4.2's
and a V12 on top!! (Drive belt issues, but engines all ok after a good few
years)
Now, that's just 2 for starters that are based in the North of Scotland that
I know of, there are many, many more up and down the country and on the
continent, and if banking engines up together, either in series through a
common crank output or in parallel via chains, belts etc didn't work or was
seriously problematic, they wouldn't do it!

> It's been done for years on railways too, with great success, BUT,
> two locomotives (of the same class) working in tandem (2 drivers,
> one in each) only gives a 133% power increase, and in multiple
> (one driver, using remote controls to the second engine) only gives
> a 150% increase - an exact anology to our two 4-cylinder engines
> bolted together.

Sorry, I can't see the logic in that at all. If I have 2 loco's each having
an individual, separate, tractive effort of say 10, then I have a total
combined tractive effort of 20. There is no extra work lost to friction etc
by either engine as it is still pulling its own weight along, so neither
robs any tractive effort from the other! If I have 2 engines, each of
200bhp, then I have 400bhp in total if they are utilised correctly. Either
engine's power output doesn't simply drop off just because it is now working
alongside another! The laws of physics couldn't be true otherwise.
It's fair to say, however, that adding 2 2litre 200bhp engines together to
make a new single engine of 4 litres will not automatically give 400bhp,
this is due to pumping losses and friction.

<< another big snip >>

>> Multi-carbs were traditionally used so that individual port runner gas
>> velocity could be maintained as high as possible in the interests of
>> mid-range torque, in addition to the engineering problems encountered
>> when
>> trying to make one carb feed a largeish engine from idle to max. The port
>> runner issue still stands today, look at the length of the runners
>> including
>> the trumpets feeding a v8, and consider why the outer 4 are a different
>> length to the others, in respect to my first para of this post.
>
> To make the compromise work.

No, it was done as a deliberate compromise to the engine's power delivery
characteristics, not as a compromise to make something work in the first
place! If both carbs were opened simultaneously, the sudden torque rush was
too severe when coupled with either 1. an auto when pulling away from rest
or 2. when trundling along in heavy traffic and feathering the throttle at
very low rpm without using (slipping) the clutch.
In both cases the designers introduced an efficiency (cylinder power
balance) compromise in the interests of user-friendliness and driveability,
Proving that at lower power and rpm settings you really don't need to have
all cylinders perfectly matched. The important things are 1. that all idle
stops/mixture screws are in balance and 2. all reach full throttle at the
same time.
Badger.

"Nigel Hewitt" <[email protected]> wrote in message
news:1119881986.86567d2901a61f18113cfa24bd5ba594@teranews...
> beamendsltd wrote:
>
>> The major problem would be to get the two engines running the
>> characteristic, i.e. not fighting each other. I guess (from
>> railway locomitives) that you'd be lucky to get 150% more
>> power than a single engine. Somewhere on the web is a discourse
>> by someone who put 2 (proper) Mini engines together, complete
>> with the maths on why the power output isn't simply x2

I suggest he buys a new calculator, then. Acceleration time won't half by
doubling the power, because you've added weight. It can be easily worked out
by the following equation, though.
Force (F) = Mass (Kg) x Acceleration (m/s2)

> Any details on this because as a simple minded physicist
> I'm pushed to see how an engine at a set revs with the
> pedal down does not deliver its rated torque regardless
> what the load looks like.
>
> I just can't see power vanishing. Conservation of energy
> is a pretty basic law of the universe.

Indeed. Well said that man.
Badger.

>>>>> "Austin" == Austin Shackles <[email protected]> writes:

Austin> Father's just pointed out - put 'em back-to-back and take
Austin> the drive from the middle. They will counter-rotate, so
Austin> they can be geared together by a brace of big sod-off

Can you put one at each end driving each axle independently?



--
Andy Cunningham -- www.vehicle-diagnostics.co.uk
2*3*3*37: The Prime Factorization of The Beast

> Father's just pointed out - put 'em back-to-back and take the drive from the
> middle. They will counter-rotate, so they can be geared together by a brace
> of big sod-off gears (instead of flywheels), and the drive taken from the
> back of the front engine by a shaft alongside the rear one; or possibly,
> moutnt the rear one alongside the gearbox with a modified bellhousing to
> allow the gears to mesh.
>
> --
> Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that

This is how the tractor pulling boys do it
http://www.tractorpulling.freeserve.co.uk/howit.htm


--
Andy

SWB Series 2a ( dressed as a 3) "Bruce"
It's big, it's mean it's really, really green

On Monday, in article
<[email protected]>
[email protected] "Badger" wrote:

> "beamendsltd" <[email protected]> wrote in message
> news:f4567d814d%[email protected]...
> > In message <[email protected]>
> > Austin Shackles <[email protected]> wrote:
> >
> >> On or around Sat, 25 Jun 2005 08:25:11 +0000 (UTC), beamendsltd
> >> <[email protected]> enlightened us thusly:
> >>
> >> >In message <[email protected]>
> >> > Austin Shackles <[email protected]> wrote:
> >> >
> >> >> I spose I should say that the original idea was 2 reliant 850cc
> >> >> engines put
> >> >> together to make a 1700cc 8...
> >> >>
> >> >
> >> >The major problem would be to get the two engines running the
> >> >characteristic, i.e. not fighting each other. I guess (from
> >> >railway locomitives) that you'd be lucky to get 150% more
> >> >power than a single engine. Somewhere on the web is a discourse
> >> >by someone who put 2 (proper) Mini engines together, complete
> >> >with the maths on why the power output isn't simply x2
> >> >
> >> >Richard
> >>
> >> I dunno how as they'd fight, as such, if bolted rigidly together.
> >> They're
> >> both turning the same way, after all, and every power stroke adds to the
> >> torque. I daresay you don't actually get 2x the power of one, but
> >> equally I
> >> don't really see where you lose that much either. I don't, in fact, know
> >> what angles your typical straight-8 crankshaft uses, but it ought to be
> >> 90
> >> degrees, in order to get even firing sequences.
> >
> > Every engine has its own charecteristics, and unless they are a prefect
> > match one or the other will be trying to driver the other, acting as
> > a brake. If you had an arragement to detect this, the slower engine
> > would have to speed up to match its partner. In doing so it would
> > likely become the master, and force the other to speed up too, leading
> > to runaway. The converse would be true if the tactic was to lower the
> > speed of the master engine. Unless the control was renarkably accurate,
> > and could react predictively, the engines would end up fighing each
> > other. An ECU could probably do this, but it would most likely be
> > far more cost effective (in terms of design, maintainance and fuel
> > costs) simply to fit a more appropiate engine.
> >
> > A single engine, but with more cylinders, would not suffer from the
> > above as it would only have one control system operating on one
> > crank, i.e. a closed system.
>
> But 2 V8's (for arguments sake) running EFI with a single throttle each and
> commoned together as a V16 would be no different to balancing twin carbs on
> a single V16, or to a similar extent a single V8. Just because the cylinders
> are located within another block casting, but mechanically linked, it
> doesn't cause any real issues at all. You could argue that a twin carb
> engine will have lagging and leading cylinders depending on how the carbs
> were balanced, in fact this is done deliberately on some engines (Jag XK 4.2
> and RoverV8) to provide for a smooth acceleration at low rpm's, the
> imbalance becoming an acceptable factor in the interests of driveability,
> the effect reducing to virtually nothing as full throttle is reached.

Some Cold War Russian military vehicles used a pair of engines, I think
based on the diesel (originally pre-WW2 French) which powered the T34
tank. I don't think there was anything fancy in the control system, and
I've a vague recollection of it involving engine/clutch/gearbox units
running in parallel.

Also, at least one WW2 version of the Sherman tank used an engine made
up from multiple car-engines, but integrated into one unit.

--
David G. Bell -- SF Fan, Filker, and Punslinger.

"I am Number Two," said Penfold. "You are Number Six."

On Mon, 27 Jun 2005 14:49:22 +0100, Austin Shackles
<[email protected]> wrote:


>
>Finally, as to the "fit a more appropriate engine", where's the fun in that?
>But seriously, there's a lot to be said for a double-TDi compared wit some
>other type of 5-litre diesel - parts are easily available and cheap, for
>example.
>
>
This man knows about joining engines together.

http://uk.zn1300.com/
http://www.saltmine.org.uk/kgb/mechshow.html

--
ColonelTupperware,
spouting bollocks on Usenet since 1997
Usenet FAQ at
http://www.its.caltech.edu/its/services/internetapps/news/news2.shtml
UPCE FAQ at http://upce.org.uk/ UKRM FAQ at http://www.ukrm.net/faq/

On or around Mon, 27 Jun 2005 12:52:49 +0000 (UTC), beamendsltd
<[email protected]> enlightened us thusly:

>It's been done for years on railways too, with great success, BUT,
>two locomotives (of the same class) working in tandem (2 drivers,
>one in each) only gives a 133% power increase, and in multiple
>(one driver, using remote controls to the second engine) only gives
>a 150% increase - an exact anology to our two 4-cylinder engines
>bolted together.

not quite. There's no solid link between the 2 engines - in the railway
engine case, depending on transmissions, it would be possible for one engine
to be pulling faster than the other one was running. However, if they're
both running at a power output and transmission setting suitable to run at
e.g. 60 mph, then they should both contribute more-or-less equally.

Going back to the 2 engines, again. Suppose I run one engine at idel and
the pother at full chat, obviously, the one at idle is doing nothing and is
in fact absorbing power. But suppose one is running at 3000 rpm and the
other, on the same setting, would in normal circumstances be running at
2900, the one running at 3000 will still be doing more of the work, but the
second one will be contributing something significant, albeit not full
power. Now suppose that I set the thing up on a dyno, open the throttle to
an appropriate setting (say 2500 rpm for a TDi) I can then tweak one of the
pumps/linkages 'til I get maximum output. If they run through 2 separate
exhausts (which would make sense) I can also assess the smoke from each
separately.

I don't doubt that it's impossible, practically and maybe theoretically, to
get twice the output, but by careful setting up I reckon you should get
enough to make it worth while.

--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Quos deus vult perdere, prius dementat" Euripedes, quoted in
Boswell's "Johnson".

On or around Mon, 27 Jun 2005 13:11:01 +0100, Steve Taylor
<[email protected]> enlightened us thusly:

>beamendsltd wrote:
>
>> Every engine has its own charecteristics, and unless they are a prefect
>> match one or the other will be trying to driver the other, acting as
>> a brake. If you had an arragement to detect this, the slower engine
>> would have to speed up to match its partner. In doing so it would
>> likely become the master, and force the other to speed up too, leading
>> to runaway.
>
>What would it take to consider the unit as a single engine, in the
>diesel case. ONE injection pump, with 8 ports, ONE turbocharger ?

nah, you can have twin turbos. Mostly on V engines. The mack V8 which they
use (with one turbo) in the reanult magnum trucks puts out about 500 BHP or
a bit more. The same basic engine, with 4 turbos, produces 1000BHP.
Probably not for so long, though.

--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Quos deus vult perdere, prius dementat" Euripedes, quoted in
Boswell's "Johnson".

On or around Mon, 27 Jun 2005 16:06:36 +0100, AndyC the WB
<[email protected]> enlightened us thusly:

>>>>>> "Austin" == Austin Shackles <[email protected]> writes:
>
> Austin> Father's just pointed out - put 'em back-to-back and take
> Austin> the drive from the middle. They will counter-rotate, so
> Austin> they can be geared together by a brace of big sod-off
>
>Can you put one at each end driving each axle independently?

now yer back to the 4CV sahara. There's something to be said for that
arrnegment, too - given the proper amount of practice, you could, by having
twin throttle pedals side-by-side, by rocking your foot left or right bias
the power to the front or rear.

The 4CV had the 2 engine slinked to one set f controls, however, AFAIK, and
also had the ability to run on one engine (by putting the other in neutral)
on tarmac.

VW did a twin-engine 4x4 sirocco a bit back, too - very successful in
initial tests but I think it fell foul of the demise of the group B rally
class.

--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Quos deus vult perdere, prius dementat" Euripedes, quoted in
Boswell's "Johnson".

On Mon, 27 Jun 2005 19:09:27 +0100, Austin Shackles
<[email protected]> wrote:

>On or around Mon, 27 Jun 2005 16:06:36 +0100, AndyC the WB
><[email protected]> enlightened us thusly:
>
>>>>>>> "Austin" == Austin Shackles <[email protected]> writes:
>>
>> Austin> Father's just pointed out - put 'em back-to-back and take
>> Austin> the drive from the middle. They will counter-rotate, so
>> Austin> they can be geared together by a brace of big sod-off
>>
>>Can you put one at each end driving each axle independently?
>
>now yer back to the 4CV sahara. There's something to be said for that
>arrnegment, too - given the proper amount of practice, you could, by having
>twin throttle pedals side-by-side, by rocking your foot left or right bias
>the power to the front or rear.
>

You also get the benefit of 'limp home' mode should one engine fail
and could run 2wd when you didn't need the power / traction / fuel
bills of running both engines.

Didn't someone do an Audi TT with two engines driving one end each?


--

Tim Hobbs

'58 Series 2 88" aka "Stig"
'77 101FC Ambulance aka "Burrt"
'03 Volvo V70

On or around Mon, 27 Jun 2005 18:51:47 +0100, Colonel Tupperware
<[email protected]> enlightened us thusly:

>On Mon, 27 Jun 2005 14:49:22 +0100, Austin Shackles
><[email protected]> wrote:
>
>
>>
>>Finally, as to the "fit a more appropriate engine", where's the fun in that?
>>But seriously, there's a lot to be said for a double-TDi compared wit some
>>other type of 5-litre diesel - parts are easily available and cheap, for
>>example.
>>
>>
>This man knows about joining engines together.
>
>http://uk.zn1300.com/
>http://www.saltmine.org.uk/kgb/mechshow.html

feckin' amazing.


--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Quos deus vult perdere, prius dementat" Euripedes, quoted in
Boswell's "Johnson".