I am unfortunate enough to have a thermo class right now. My approach to
effiency would be to consider the engine a compressor any time other than
the power stroke (since energy FROM the power stroke is used for
intake/exhaust). If you think about it, these are two total different
processes.

Efficency of the power stroke could be calculated from the max temp in the
combustion chamber (intial temp) and the exhaust temp and however much Q
wound up in the cooling system....efficency of the intake would need to be
seperate since the engine is acting like a compressor.

Could be wrong, but it does make a little sense. Maybe what Ian is thinking
of is the situation of a high temp gas coming in (such as a steam turbine?)
and lower temp gas and work coming out.

Thoughts?

Tim


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If you look at Otto cycle efficiency (the equation Jordan posted), the
temperature ratios you are looking for are either combustion temperature
divided by exhaust gas temperature or compression temperature (temperature
of the charge at the end of compression with no ignition) divided by the
inlet temperature. Relations can be made between all of these temperatures,
but for a real internal combustion engine, they aren't really relevant. As
mentioned before, Otto cycle efficiency is much better than the efficiency
of a real internal combustion engine.

Colin

I had a similar idea....(yeah, I know, they're all coming out now!) but I'm
unfamiliar and never seen a crank from horizontally opposed engine a la BMW
boxer. I'm guessing they must  have two crankpins 180 deg apart, if so what
is between them, a flywheel, a bearing??.

Don





From: ian <iwd@...> on 07/03/2001 00:43

Please respond to mc-engine@yahoogroups.com

To:   mc-engine@yahoogroups.com
cc:
Subject:  Re: Balance of Single


> I like the idea of balancing behind the Ducati
> Supermono.
> My question is would there be beter balance using a
> horizontaly opposed balance weight rather than the
> half of a 'V' in the ducati.
> If you use a twin crank and use the second journal for
> the balance weight?........maybe

Damn - you've pinched my idea.

Yes it will work - you just get a rocking couple ( no
primary or secondary vibes ) as opposed to the S.Mono
which ha s areduced secondary vibe only.   ( No
primary vibe and the tiniest of rocking couples )

Too easy.

Cheers   IAN

--
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AUSTRALIA
Ph :+613 9562 4260
Fax:+613 9546 8938
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Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

ian wrote:
.
>
> Thermodynamics isn't my strong suite Hoyt but without
> dragging out my thermo books I am sure my statement
> is correct.    The higher the temperature differential
> between the intake and exhaust gases - then the higher
> the efficency of the engine.   ( I agree that it seems
> counter-intuitive as the exhaust is waste gas )
>

I don't think that this is correct, think of a turbo, It reduces the
exhaust temp in exchange for work.  It has increased the efficiency of
the engine while lowering the ratio between the intake/exhaust temps.

You have 4 terms that balance in the energy equation


T1 inlet temp,T2 temp after compression, T3 temp after combustion, T4
exhaust temp.

work in = Cp(T2-T1)
combustion energy = Cp(T3-T2)
work out = Cp(T3-T4)
wasted energy = Cp(T4-T1)

Efficiency is defined as (work out-work in) / combustion energy
To have maximum efficiency you want T4, or the exhaust temp to be as low
as can be.

Just my thoughts.  (P.S, I don't have my thermo book either since I have
switched to studying incompressible fluids at my work, someone must
though)
Matt

At 12:39 AM 3/7/01 +1000, you wrote:
>Thermodynamics isn't my strong suite Hoyt but without
>dragging out my thermo books I am sure my statement
>is correct.

Better get the books out, big guy.

Regards,

Hoyt

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   I've seen fossils but I've never seen angels

At 01:51 PM 3/6/01 -0000, you wrote:
>Am I right in thinking that an Intercooler is there to reduce the Intake
>charge temperature after a turbo compressor in order to increase the
>volumetric efficiency of the charge (ie its oxygen content per unit
>volume) or for another thermodynamic reason??

It improves charge density and power at expense of overall efficiency. You
get more in there to burn, but you toss away the heat used to drive the
compressor instead of cycling it thru motor where it can be expanded and
show up at crank.

Regards,

Hoyt

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   I've seen fossils but I've never seen angels

> The higher the temperature differential
> between the intake and exhaust gases - then the higher
> the efficency of the engine.   ( I agree that it seems
> counter-intuitive as the exhaust is waste gas )
>

Indeed. Think of the Diesel - huge compression, low exhaust gas
temperature, high efficiency ??? Intake temp is surely not a major
factor?


Mike Kilty

> I like the idea of balancing behind the Ducati
> Supermono.
> My question is would there be beter balance using a
> horizontaly opposed balance weight rather than the
> half of a 'V' in the ducati.
> If you use a twin crank and use the second journal for
> the balance weight?........maybe

Damn - you've pinched my idea.

Yes it will work - you just get a rocking couple ( no
primary or secondary vibes ) as opposed to the S.Mono
which ha s areduced secondary vibe only.   ( No
primary vibe and the tiniest of rocking couples )

Too easy.

Cheers   IAN

--
DRYSDALE MOTORCYCLE CO.
AUSTRALIA
Ph :+613 9562 4260
Fax:+613 9546 8938
990-V8 Grand Prix Racebike project on:
http://www.22000rpm.com
750-V8, 1000-V8, 2X2X2 & Racecar on:
http://home.mira.net/~iwd

> >differential
> >between the intake and the exhaust gases.
>
> Source vs sink, yes? Ex gases are sink, but source isn't intake temp.
> If it
> were, engines would have negative power, as do compressers. It's
> instead
> peak temp at max pressure, somewhere in vicinity of the burn's last
> stage.

Thermodynamics isn't my strong suite Hoyt but without
dragging out my thermo books I am sure my statement
is correct.    The higher the temperature differential
between the intake and exhaust gases - then the higher
the efficency of the engine.   ( I agree that it seems
counter-intuitive as the exhaust is waste gas )

I see your point with compressors but the situation is
different in that there no heat producing ( exothermic )
chemical reaction between the inlet and outlet.


Cheers   IAN



--
DRYSDALE MOTORCYCLE CO.
AUSTRALIA
Ph :+613 9562 4260
Fax:+613 9546 8938
990-V8 Grand Prix Racebike project on:
http://www.22000rpm.com
750-V8, 1000-V8, 2X2X2 & Racecar on:
http://home.mira.net/~iwd

> Is there a good web site where we can keep up with all the latest in
> F1
> engine developments?

I found one discussion list once - it had an odd format
and I couldn't log on at one stage and just lost interest.
If anyone knows of this discussion group I would be
interested in getting back on it - wasn't overly technical
but it was worth aread.

There are F1 discussion lists but they are more about
driver gossip than technical stuff - I mean 99.9% cr*p.


Cheers   IAN


--
DRYSDALE MOTORCYCLE CO.
AUSTRALIA
Ph :+613 9562 4260
Fax:+613 9546 8938
990-V8 Grand Prix Racebike project on:
http://www.22000rpm.com
750-V8, 1000-V8, 2X2X2 & Racecar on:
http://home.mira.net/~iwd

> Source vs sink, yes? Ex gases are sink, but source isn't
> intake temp. If it
> were, engines would have negative power, as do compressers.
> It's instead
> peak temp at max pressure, somewhere in vicinity of the
> burn's last stage.

That is how I understood this too - differential between combustion and
exhaust

Am I right in thinking that an Intercooler is there to reduce the Intake
charge temperature after a turbo compressor in order to increase the
volumetric efficiency of the charge (ie its oxygen content per unit
volume) or for another thermodynamic reason?? Obviously there is heating
from the compression of the turbine - maybe cooling the compressed side
increases the compressor efficiency?


Mike Kilty

At 09:29 AM 3/6/01 +1000, you wrote:
>differential
>between the intake and the exhaust gases.

Source vs sink, yes? Ex gases are sink, but source isn't intake temp. If it
were, engines would have negative power, as do compressers. It's instead
peak temp at max pressure, somewhere in vicinity of the burn's last stage.

Patrick,

This info is very useful. I have a set of Keihin CR33's when time permitts I
will be fitting to a Yamaha SRX600. The carbs dont seem to have any form of
emulsion tube, would this go some way to explaining the large changes
required in the air jet to change the fuel curve, or does this comment only
apply to the FCR's.

Steve

> -----Original Message-----
> From: Patrick Burns [mailto:patrick@...]
> Sent: 04 March 2001 17:26
> To: mc-engine@yahoogroups.com
> Subject: Re: MC Engine: Carb Jetting On Dynojet Dynos
>
>
> Don DRI05 Ricciardiello wrote:
> >
> > Every bike I've ever seen put through it's paces on a
> Dynojet dyno (roller
> > type) followed the same procedure where the bike is put
> into 4th gear and
> > the throttle pinned wide open. The reports from the runs
> I've seen have the
> > power/torque graphs and also a air/fuel ratio trace along
> the rpm axis
> > however this is at WOT. If you had to calibrate your
> midrange jetting (i.e
> > needle jet) how would you do it on a dyno as described
> above? I imagine
> > you'd want to use part throttle settings/acceleration etc
> but is this
> > possible?
>
> http://www.lifenet.com/patrick/dyno.txt
>
>
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
>

I had a thought the other day.
I like the idea of balancing behind the Ducati
Supermono.
My question is would there be beter balance using a
horizontaly opposed balance weight rather than the
half of a 'V' in the ducati.
If you use a twin crank and use the second journal for
the balance weight?........maybe

Regards

=====
Damian Searles
damo_4701@...
Brisbane, Australia

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I put the question to a chemical engineer chum who also likes to play
with motorcycle engines. His reply:

The more you compress gas the hotter it gets
by winding up the compression ratio you are compressing it more
so the the compression pressure goes up along with the temperature
When you fire the compressed mixture this compounds the
temperature rise and the peak firing pressure and temperture increase
even more then the increase in the compression pressure. This creates
more pressure on the piston ie more work into the crankshaft but the
proportion of the fuels energy that ends up in the cooling system and
the exhaust gases actually goes down. In fact the exhaust temperature
actually falls a bit as you wind up the compression
T o put numbers to it
If you increase the compression ratio, from say 6 to 12 you would
expect the compession pressure to rise from 150 psig to 450 psig
but the peak firing pressure to rise from 550 psig to1100 psig
It is all about improving thermal efficiency and the proportion of the
heat in the fuel that is  turned into shaft work as compared to that
which is wasted in the cooling system and down the exhaust
Theoretically  E = 1- (1/C.R.)^(n-1) were E is the thermal efficiency
and n is the ratio of specific heats of the gases in the cylinder( say
1.21)

In practice the internal combustion engine is something of a paradox
because at high compression ratios good thermodynamics has to be
tempered with a dollop of strenght of materials technology otherwise
everything would melt. It is illogical to cool the cylinders of  ICEs
because this takes temperature and pressure out of the bang but
it has to be done to stop the engine collapsing in a heap
This limitation set a lid on compression ratio. Another limitation is
the antiknock properties of the fuel. As you increase the temperature
of compression the fuel tends to go off by itself rather than waiting
for
the spark. It detonated or explodes rather than burns. Water injection
here we come

Power requirements:

There are 2 ways to calculate the power.
The first one is the energy of the system at full speed divided by the time
taken to get there.

In your case:
450 pounds = 204kg.

energy in joules =  ½M*V² that is half of M * V squared where M is mass in
kg and V is velocity in m per second.
V = 100mph = 180km/h = 180000m/h = 50m/sec

Total energy of 450 pound bike travelling at 100mph = 255000 joules.
Power in watts = joules/time.
so you will need 255000/10 = 25500 watts = 25.5 kw = 33.8 hp.

Now this does not take into account wind resistance or any other type of
friction loss and it also assumes that the power will be constant for the 10
seconds. That would require a variable ratio gear box.

A more realistic approach is as follows.
For a real 4 stroke engine lets say that the torque remains constant (to
make calculations easier)
what you would do is calculate what gear would give you 100mph when the
engine is at maximum power.
Then work out what torque you would get at the wheel which you can then turn
into a forward force. From that you can work out acceleration which should
remain more or less constant (remember that we are assuming that the motor
will have a constant torque output thru the rpm range). With this you can
then calculate what torque you will need to make the mass accelerate form 0
to 50m/sec in 10 sec.
Roughly

the acceleration will have to be 50m/s / 10 sec = 5 m per sec squared.
force(in newtons) = mass time acceleration = 204*5 = 1020 newtons.
Power = force * velocity which gives us that just before the bike reaches
max velocity it will be
1020 newtons * 50m/s = 51000 watts = 51kw = 67.7 hp.
This is assuming that the engine does it with out changing gears. If you use
a gear box it will get there quicker or need less power. Also I am assuming
that there is no friction or wind resistance.

To calculate wind resistance you can do it by getting up to speed on a flat
bit of road and then checking how fast you slow down in a given time.
If you then use the equation above (for energy) you can then calculate how
much energy you have stored at say 100mph then at 80mph and then work out
the difference and divide it by the time it took or alternatively see how
far you slow down in say 2 seconds. This will give you how many watts it
takes to keep the bike running at that speed (approximately). The power drop
that you get will be what the wind and friction is using up.
To get an accurate value you should do the test in both directions to
average out any effect of slope on the road and head or tail wind.
Then to calculate the total power needed you just add the wind resistance to
the power that we calculated above.
I did this before because I was working on an hybrid electric car think
project and needed to work out how big an electric motor and battery
capacity was needed to take a 1500kg car from 0 to 100 km/h in 6 seconds and
also how big a generator I would need to ensure that the batteries would not
run flat.
The results were some where along the lines of (not very accurate) 10kw to
keep it going at 100km/h and about 60kw for acceleration.
My original design was aiming at having 4 50kw electric motors (one for each
wheel) with electronic gearing (electric motor directly driving the wheels
thru a cv joint) As for battery size a 50Amphr battery like the one on most
cars stores enough energy to accelerate the car from 0 to 100 km/h 5 times.
That is without regenerative braking.
The numbers are very optimistic and do not take account of things like
losses in the system and the fact that you can not run the battery
completely flat and that a normal car battery would not be able to generate
the power that I needed (due to the internal resistance which is to do with
the way they are constructed).
But it goes to show that an electric car with a small very efficient
constant speed petrol engine could be made to be faster and definitely more
fuel efficient than a car with a big engine.
BTW I worked out that with 200 kw of electric motors the car would
accelerate from 0 to 100km/h (60mph) in about 2 sec. This is because the
electric motors produce constant torque from no revs to max revs and can be
electronically geared so they can run very close to max power all the time.
It would be a good demo if a car like that would run with a 300 cc petrol
engine.

Francisco

Ian wrote:

>Hence the need for intercoolers on turbo engines and
>why F1 cars are now running very high engine
>temperatures via high pressure cooling systems.


Is there a good web site where we can keep up with all the latest in F1
engine developments?

Don



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Paul Friday wrote:
> <francisco@...> wrote:
> >One quick question for all those engine experts.
> >I have heard that higher compression leads to an engine running hotter.
> >Is this true and if it is why?
> >Thanks for the replies.
>
> One quick answer:
> Yes.
> Adiabatic compression.
>
> Think of a diesel engine. It ignites its fuel by heating the air taken
> into the engine by compressing it very hard.

Well, yeah, but then it expands again, and intake closing and exhaust opening
are generally about the same amount away from TDC, so compression and expansion
are about the same, so heating and cooling due to adiabatic compression and
expansion are about the same, so _that_ theory's shot. ;)

As someone already pointed out, they probably run cooler per unit power, but the
whole point is to go faster, so you're going to be pushing it to its potential
no matter what, and it'll run hotter, because it's making more power and
probably has the same cooling system it had before. :)

> >One quick question for all those engine experts.
> >I have heard that higher compression leads to an engine running
> hotter.
> >Is this true and if it is why?



In thermodynamics another way to measure engine
efficency is to compare the temperature differential
between the intake and the exhaust gases.

Hence the need for intercoolers on turbo engines and
why F1 cars are now running very high engine
temperatures via high pressure cooling systems.


Cheers   IAN

--
DRYSDALE MOTORCYCLE CO.
AUSTRALIA
Ph :+613 9562 4260
Fax:+613 9546 8938
990-V8 Grand Prix Racebike project on:
http://www.22000rpm.com
750-V8, 1000-V8, 2X2X2 & Racecar on:
http://home.mira.net/~iwd

In message <005f01c0a50a$1d626ea0$1300a8c0@wrks3>, bec
<francisco@...> wrote:
>One quick question for all those engine experts.
>I have heard that higher compression leads to an engine running hotter.
>Is this true and if it is why?
>Thanks for the replies.

One quick answer:
Yes.
Adiabatic compression.

Think of a diesel engine. It ignites its fuel by heating the air taken
into the engine by compressing it very hard.

----------------------------
Paul Friday

At 10:20 AM 3/5/01 +1000, you wrote:
>One quick question for all those engine experts.
>I have heard that higher compression leads to an engine running hotter.
>Is this true and if it is why?

Properly tuned motors will run cooler per Hp produced, with higher
compression. That's because compression ratio is expansion ratio, and
expansion ratio is efficiency.

Regards,

Hoyt

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    May the farce be with you

Don DRI05 Ricciardiello wrote:
>
> Every bike I've ever seen put through it's paces on a Dynojet dyno (roller
> type) followed the same procedure where the bike is put into 4th gear and
> the throttle pinned wide open. The reports from the runs I've seen have the
> power/torque graphs and also a air/fuel ratio trace along the rpm axis
> however this is at WOT. If you had to calibrate your midrange jetting (i.e
> needle jet) how would you do it on a dyno as described above? I imagine
> you'd want to use part throttle settings/acceleration etc but is this
> possible?

http://www.lifenet.com/patrick/dyno.txt

Temperature does increase as you increase a gas'
pressure. Since a higher compression engine exerts
greater pressure on the gas mixture, an increase in
temperature occurs, and can get high enough to cause
predetonation. The relationship between pressure and
temperature of a gas is given in the Gas Law where
P*V=m*R*T.

--- bec <francisco@...> wrote:
> One quick question for all those engine experts.
> I have heard that higher compression leads to an
> engine running hotter.
> Is this true and if it is why?
> Thanks for the replies.
>
>
> Francisco
>
>


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One quick question for all those engine experts.
I have heard that higher compression leads to an engine running hotter.
Is this true and if it is why?
Thanks for the replies.


Francisco

Every bike I've ever seen put through it's paces on a Dynojet dyno (roller
type) followed the same procedure where the bike is put into 4th gear and
the throttle pinned wide open. The reports from the runs I've seen have the
power/torque graphs and also a air/fuel ratio trace along the rpm axis
however this is at WOT. If you had to calibrate your midrange jetting (i.e
needle jet) how would you do it on a dyno as described above? I imagine
you'd want to use part throttle settings/acceleration etc but is this
possible?

Don

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Does anyone have any experience with forged piston kits that increase
displacement and compression ratio?

Specifically, I'm currently reassembling an engine for a 1988 CBR1000F.  It
had been run without oil, and I'm replacing the crank, rods and bearings.
I'm trying to decide whether or not to install Wiseco's 1050 kit that would
increase my compression ratio to 12:1

I'm trying to find out the following from anyone who has experience with
this type of thing.  Is a 12:1 compression ratio going to cause me trouble
with my starter or ignition being too weak, or detonation trouble on 93
octane?  Has anyone had trouble with the general tendency of forged pistons
to be heavier than cast, as far as rod failure or engine balance?

Can anyone provide any seat of the pants data on performance?

Thanks,
Dave

The old MC-Engine mailing list is dead, long live the new MC-Engine
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                       > Temporarily Out Of Order <

Saw a new magazine advertised in a Classic mag called Moto Technica, which
deals more with the technical side of motorcycles than " we went for a ride
& had a beer at this pub snooze snooze snooze" & never tells you anything
about the bike itself. It said that you could subscribe at NPM Publishing.
Is this mag available in North America? Anybody read it & can confirm if it
is of any interest?

John "Player" Martin

I'm looking for a camshaft for my 500cc Norton Domiracer project I'm
building. To me it looks like all the camshafts out there, Norvil, Mick
Hemmings etc are Commando profiles S4, S7, PW3 etc on a Dominator length
shaft. Because the shorter stroke & valve size Domie will rev higher, I
would have thought that the profile should be different than a Commando. Is
there anybody out there who makes one specifically for this model or am I
going to have to get the text books out & get somebody to make me one?

John "Player" Martin