- 9 months ago
We're taking a flyer on this one but we couldn't resist talking about AIR! True to form, Technical Editor Kevin Cameron starts talking about us breathing and how gravity holds air on the earth ("Which is really good for us.") and we take it from there. Poppet valves, pressure waves, exhaust and intake tuning, and so much more. Ever heard of an Aspin valve? Rotary valve? Sleeve valve? You can say yes to all those if you just have a listen to this week's Cycle World podcast. Join us in the air!
Subscribe to Cycle World Youtube: http://www.youtube.com/c/cycleworld?sub_confirmation=1
Listen on Spotify: https://open.spotify.com/show/6CLI74xvMBFLDOC1tQaCOQ
Read more from Cycle World: https://www.cycleworld.com/
Buy Cycle World Merch: https://teespring.com/stores/cycleworld
Subscribe to Cycle World Youtube: http://www.youtube.com/c/cycleworld?sub_confirmation=1
Listen on Spotify: https://open.spotify.com/show/6CLI74xvMBFLDOC1tQaCOQ
Read more from Cycle World: https://www.cycleworld.com/
Buy Cycle World Merch: https://teespring.com/stores/cycleworld
Category
🥇
SportsTranscript
00:00Welcome to the Cycle World Podcast. I'm Mark Hoyer, Editor-in-Chief. I'm with Kevin Cameron, our Technical Editor.
00:06This week we're going to talk about air.
00:09Air. All that we take for granted. The qualities of air.
00:14That, you know, that would be a...
00:16It is a broad topic, but we're going to kind of concentrate on the management of air
00:19really going into the engine.
00:22Qualities of air.
00:23And some things about air that we don't immediately think of.
00:27And what do you think of all that, Kevin?
00:32Well, I think first of all, here we are breathing 17 times a minute
00:38to take in the atmosphere for its oxygen.
00:45Because like an internal combustion engine,
00:47our bodily economy depends upon oxidizing our fuel with oxygen.
00:56And that gives us vitality.
01:02And we...
01:03I must need to breathe more. I need some more vitality.
01:06I guess that's exercise.
01:08The air that we breathe is held on the Earth by the Earth's gravity,
01:15which is really good for us.
01:17And it's roughly 78% nitrogen, which for most purposes is inert.
01:25It does combine to a very minor degree with oxygen at very high temperature.
01:31Ooh, nitric oxides, NOX.
01:33Nitric oxides, yes, sir.
01:35We've got to keep that out of the tailpipe if we can.
01:38And when all those nuclear scientists were waiting for the Trinity test,
01:43the first atomic bomb, there were some people who were a little nervous.
01:48Because what if the intense heat of the bomb ignited the atmosphere?
01:53Fortunately for us, it didn't.
01:57So nitrogen is...
01:59Nitrogen kind of keeps to itself, so we don't have to consider it.
02:04And then trace elements are carbon dioxide.
02:07Everyone's worrying because there's 417 parts per million now.
02:12But it's essential for plant life.
02:15So what we're interested in, the engine business,
02:18is the roughly 20% of the atmosphere that is oxygen.
02:22And although we have all these expressions like give it the gas or gas it up,
02:31when you operate the throttle, you are controlling only airflow.
02:37Either the butterflies of fuel injection throttle bodies
02:44or the slide of a carburetor, you're controlling the air.
02:50And the carburetor or the computer-controlled digital fuel injection
02:57adds to that mass of air the right amount to combine with all of the oxygen,
03:05leaving no unburned fuel, no unreacted oxygen.
03:09And that state is called correct combustion
03:13and occurs at about a weight ratio of 14.7 parts air to one part of fuel.
03:19And that can readily be ignited by a spark.
03:25But mixtures that are 20% have 20% more fuel
03:29or 20% less fuel than that ratio,
03:34the engine starts to misfire.
03:36And it may quit altogether because the spark can't ignite those far-out mixtures.
03:42So the old idea that some people have that,
03:44well, the more fuel you can push through the engine,
03:46the more power you'll make.
03:48It's not true.
03:50What we're trying to push through the engine is air.
03:53Because if we can fill the cylinder,
03:55and it is being done by very well-designed engines
04:00to 125% of full,
04:05we can make a lot of power.
04:08And so one of the measures of
04:13how well-designed an engine is,
04:17is how well it fills its cylinders.
04:20As cylinder filling goes up,
04:25torque rises with it.
04:27As cylinder filling becomes poorer,
04:30torque falls with it.
04:31Because the degree of cylinder filling
04:34determines how much mixture of fuel and air
04:38we can burn in that cycle.
04:44And so we're all looking to fill our engines
04:48as well as possible.
04:50The measure of how well the cylinders are filled
04:55is called volumetric efficiency, or VE.
04:59And you probably at least vaguely remember
05:01reading about volumetric efficiency
05:03in somebody's article somewhere.
05:06But 100% means that you've filled the cylinder
05:10to its displacement.
05:12You do your high school geometry
05:15and you find the area of the bore,
05:19pi r squared, r being the radius of the bore,
05:22times the stroke length.
05:24And that gives you the volume.
05:27So this is why a larger engine
05:31takes in more oxygen,
05:34therefore can make more fuel.
05:36or an engine that is supercharged,
05:38that has a pump to force air into the cylinder,
05:42can make more power.
05:44And also an engine that revs very high,
05:50that is filling the cylinder many more times per second,
05:53also makes more power.
05:56So anything that allows us to burn
06:00a larger mass of fuel-air mixture
06:03is going to make more power,
06:05other things being equal.
06:06I mean, if we've got a completely incompetent design,
06:09it's not going to do well anyway.
06:12But these are the basics.
06:16And when you turn the throttle towards closed,
06:21the piston pulls a partial vacuum.
06:25And at idle,
06:26it may be 25, 26 inches of mercury.
06:31That's why we call it a throttle.
06:33Yes, because it...
06:34It's going to throttle you, right?
06:36Yes.
06:36The engine wants to run until it explodes.
06:39Like the engine's preference
06:40would really just like let me go.
06:42Yes.
06:42And that's where we hold it back.
06:44Because we have respect for our connecting rods
06:47and piston cracking
06:49and all those tiresome subjects.
06:52No matter what.
06:52Yep, go ahead.
06:53Yep.
06:54Well, I was going to ask what,
06:55you know,
06:56forced induction supercharger, turbocharger
07:00is essentially increasing the displacement.
07:03It is.
07:03It's pushing a bigger engine's air
07:06through a smaller engine.
07:08Yeah.
07:09But what allows us...
07:12Well, what are the qualities of air
07:13that allow...
07:14us to fill a cylinder 225%
07:18without stuffing it in using a pump?
07:22Well, air has mass,
07:24which is why the Earth is able to attract
07:26and hold it
07:28so we can breathe it.
07:31And that mass...
07:33Well, here's an example.
07:34I visited General Motors at one point
07:40and I saw a little piece of data sheet
07:46on the window of one of the dyno rooms
07:49and they had dynoed a 400 Yamaha.
07:53And what they were doing
07:55is measuring the pressure inside the cylinder
07:59with a little microphone.
08:01And this high RPM engine,
08:04fairly high RPM,
08:06basically,
08:09the air in the intake pipe
08:11was not moving
08:12during the first half of the piston stroke.
08:15The reason being
08:16that the air has mass
08:18and it therefore has inertia.
08:20If we're all standing around in the room
08:23and somebody yells fire,
08:25it's going to take us a while
08:27to accelerate toward the exit.
08:29And what happens is
08:32that the piston
08:33pulls a partial vacuum
08:35for about half of the stroke
08:38in a high RPM case
08:40and the air is
08:41starting to move
08:43and then in the second half
08:45of the piston's downstroke,
08:47intake stroke,
08:48the air accelerates
08:50until it's moving
08:52at several hundred feet per second.
08:54And it's just
08:56roaring in there.
08:58And this is why
09:00when the piston reaches
09:02bottom center
09:02at the end of the intake
09:04or suction stroke,
09:06we leave the intake valve
09:08or valves
09:09open for some time
09:11after bottom dead center
09:13because
09:13we've got a fortune
09:15in kinetic energy,
09:16air rushing.
09:18Leave the door open.
09:20A lot of molecules
09:21are going to rush in.
09:23And as the piston
09:24starts to rise,
09:26it starts to raise
09:27the pressure
09:27inside the cylinder.
09:28That pressure
09:29is opposed
09:30by the inertia
09:31of the inrushing air.
09:33And at some point,
09:35it's advisable
09:36to close the intake valves
09:37and trap all that
09:39lovely stuff in there.
09:40Well,
09:41it's one of those
09:42great observations.
09:45Who is that?
09:46The flow bench guy.
09:48The engine only makes power
09:49when the valves are closed.
09:51It's important to remember
09:52the engine only makes power
09:53when the valves are closed.
09:54The late Kenny Augustine.
09:56Kenny Augustine,
09:57yep.
09:57Who was a wonderfully
09:59bright guy
10:00who spent his life
10:02with air flow
10:03and then got interested
10:04in constitutional law
10:06rather late.
10:07so there is a science
10:17to this valve timing business.
10:20I'll just explain
10:22why we leave
10:23the intake valves open
10:24for a time
10:25after bottom dead center
10:26because once the air
10:28is accelerated,
10:29rushing into the cylinder,
10:31it makes sense
10:31to let it rush in
10:33until no more
10:34can rush in
10:35just as the valve
10:36is closing.
10:38So let's talk about,
10:39well,
10:40do you have something
10:41you want to finish?
10:42Well,
10:42I wanted to say
10:43that there is no valve timing
10:45that is ideal
10:46for all speeds.
10:48So,
10:49for example,
10:50if we had an old style
10:51Harley Davidson
10:53two valve engine,
10:55they leave
10:57the intake valve open
10:58for not very long
10:59after bottom center.
11:00and the reason
11:02for that is
11:03that
11:04one of the most
11:05valued things
11:06in a large
11:07touring motorcycle
11:08is the ability
11:10to heave that
11:11800-pound
11:12lump
11:13into motion
11:14and that means
11:16these people
11:17aren't going to want
11:18to slip the clutch
11:19at 7,000 RPM
11:20to get going.
11:21They want the thing
11:22to start going
11:24right away.
11:25So,
11:25this is why
11:27touring engines
11:28have
11:28big bottom end
11:30torque
11:31and they
11:32don't leave
11:33the valve
11:33open very long
11:34after bottom center
11:35intake valves
11:36because they don't
11:37want the rising piston
11:38to push it back out
11:40because at lower speed,
11:43lower RPM,
11:44the intake velocity
11:46is less
11:46because the piston
11:47is moving more slowly
11:49and it can't
11:51it can't crowd
11:52into the cylinder
11:52the way it can
11:53when it's moving
11:55at say
11:55500 feet a second.
11:57So,
11:59if we're going
12:01to go for a record
12:03at Bonneville,
12:04we want to leave
12:05the intake valves open
12:06as long as there's
12:08airflow on top end
12:09and we may have
12:11some really ridiculous
12:12cam timing cards.
12:15Collect them,
12:15trade them with
12:16your friends.
12:17Well,
12:17I had an MG
12:18Magnet
12:19with a 1500
12:20inline-4,
12:21you know,
12:21it's a British
12:22saloon
12:22sedan,
12:241958,
12:25and the intake valves,
12:27the valve timing
12:28was opening
12:29at top dead center.
12:31Yes.
12:33And it surely
12:34did idle beautifully.
12:36It would.
12:37And the EPA
12:37would strongly
12:39approve of it
12:39because
12:40if the valves
12:42are not,
12:44there's a situation
12:46that can occur
12:46at top center
12:47at the end
12:47of the exhaust stroke
12:48which is called
12:49overlap.
12:50The intake valves
12:51are already opening
12:52before top dead
12:54center
12:54because we want
12:55them open
12:56sooner in the
12:57suction stroke.
12:58And the exhaust
12:59valves,
13:00we want the
13:01exhaust process
13:02to be as
13:03complete as
13:04possible so
13:05we don't close
13:06the exhaust valves
13:07until some
13:07distance after
13:08top dead center.
13:10So the two
13:11valves are open
13:12for a little
13:12while together.
13:14And that means
13:15fresh charge
13:16from the inlet
13:16can sail out
13:18the exhaust
13:18and the EPA
13:19is right there.
13:20and they
13:22say
13:23unburned
13:24hydrocarbons
13:24you will have
13:25to pay a large
13:26fine.
13:27Indeed.
13:28To the
13:28manufacturer.
13:29So
13:29onward.
13:32Well I would
13:33like to
13:33talk about
13:35the suction
13:37signal,
13:38the intake.
13:39So
13:39the piston
13:40starts to go
13:41down in the
13:42cylinder,
13:43the intake
13:43valves are open,
13:45the creation
13:46of vacuum
13:47negative pressure
13:48is occurring
13:50in the
13:53cylinder really.
13:54It's happening
13:54at the top
13:55of the piston.
13:56Yes.
13:56So that's
13:57where the
13:58inertia is
14:00beginning.
14:00That's where
14:01the signal
14:02of negativity
14:03is then
14:05creating a
14:06wave,
14:07correct?
14:07Which travels
14:08at the speed
14:09of sound,
14:09local speed
14:10of sound,
14:11up the
14:11intake.
14:12So it
14:12takes a
14:13while for
14:13it to
14:14spread the
14:16message like
14:17Paul Revere
14:18all the
14:21way along
14:21the intake
14:22pipe so
14:22that the
14:23molecules there
14:24start to
14:25we're wanted
14:27over here.
14:28So come on
14:29guys.
14:30And they
14:31start to
14:31rush in.
14:32And at
14:37low RPM
14:37it's a
14:38fairly
14:40simple
14:40process,
14:41kind of
14:41like pumping
14:42up a
14:43bicycle tire
14:43with a
14:44manual pump.
14:45But at
14:46higher and
14:47higher speeds,
14:48as Rob
14:49Muzzy once
14:49said,
14:50the harder
14:51you tune
14:51on a
14:52four-stroke,
14:53the more
14:53it begins
14:54to act
14:54like a
14:55two-stroke.
14:56Tune on
14:57a four-stroke,
14:57it begins
14:58to act
14:58like a
14:58four-stroke.
14:59You get
15:02the idea,
15:02I hope.
15:03Anyway,
15:04the thing
15:04is that
15:06four-stroke
15:06engines have
15:07a great
15:08appeal for
15:10their utility
15:11in society
15:11because they
15:12are more
15:14like linear
15:14devices than
15:16any other
15:16combustion
15:16engine.
15:18But if
15:18you begin
15:19to increase
15:20the overlap
15:21and rely
15:22on exhaust
15:23pipe waves
15:24and intake
15:26waves and
15:27all these
15:27inertial
15:28effects,
15:28which are
15:29what make
15:30two-strokes
15:31powerful,
15:32then a
15:33four-stroke
15:33begins to
15:34act more
15:35like a
15:35two-stroke.
15:37It has
15:38a narrow
15:38power band
15:39and it
15:39has a
15:41strange
15:41dependency
15:42on intake
15:44and exhaust
15:44lengths.
15:46Which is
15:47true of
15:48four-strokes
15:49or we're
15:49utilizing
15:50those pulses
15:51quite a
15:52bit,
15:53even in
15:54street bikes
15:54with air
15:56boxes and
15:57varying
15:57lengths.
15:58of intake
15:59trumpets
16:00inside the
16:00air box.
16:02There's the
16:02fabled
16:03Helmholtz
16:03resonator that
16:04was popular
16:06for Buells
16:08to kind of
16:09stuff it in
16:10in the
16:10mid-range
16:11and keep it
16:11quiet at the
16:12same time.
16:14Can you give
16:15us kind of a
16:16tour of,
16:17I mean,
16:18you know,
16:19you're making
16:19the wave and
16:20it's traveling
16:21sonically
16:23upstream.
16:26And so it's
16:26sending the
16:27signal into
16:28an air
16:29box.
16:30The tube's a
16:30certain length
16:31and we're
16:33waiting for
16:34the wave
16:34to come
16:34back.
16:35Yes?
16:36Sure.
16:37And this
16:37is so
16:39much of
16:39this material
16:41was discovered
16:42early in the
16:4320th century
16:43by practical
16:44people.
16:46For example,
16:47working at
16:47the Great
16:48Brooklyn
16:48Speedway
16:49in England,
16:50which was
16:51built 1907
16:53or thereabouts,
16:54and they
16:56found that
16:57intake length
16:58made a
16:59difference.
17:01And, of
17:01course,
17:01what's going
17:02on is the
17:03piston produces
17:05a suction
17:05pulse that
17:06travels up
17:07the intake
17:07pipe,
17:08is reflected
17:09at the
17:10open end
17:10as an
17:12opposite wave,
17:14a positive
17:14wave,
17:15and it
17:16may bounce
17:17back and
17:17forth several
17:18times while
17:18the whole
17:19engine cycle
17:20is going
17:21on.
17:21But what
17:21we want
17:22is for
17:24a positive
17:25wave to
17:26arrive at
17:26the intake
17:27valve just
17:28as it's
17:28opening.
17:30And in
17:31that way,
17:32you can
17:34gain a
17:36maybe 10
17:38or even
17:39more percent
17:40of torque
17:41over a
17:42certain RPM
17:43range.
17:43at other
17:45ranges,
17:46the sound
17:47waves either
17:48don't help
17:48you or
17:49they may
17:50work against
17:50you,
17:51which is
17:51why if
17:54we have a
17:55lot of
17:55overlap,
17:56which means
17:57those two
17:57valves,
17:58the valves
17:58are open
17:59together for
18:00a longer
18:00period of
18:01time,
18:01there is a
18:02longer period
18:03for exhaust
18:05waves to
18:06reach the
18:07cylinder and
18:09affect the
18:10intake,
18:10which works
18:13as follows.
18:15We have
18:16the engine
18:18fires,
18:19power stroke
18:19takes place
18:20as the
18:22piston nears
18:22bottom center
18:23of the
18:23exhaust valves
18:24begin to
18:25open and
18:25they release
18:26a high
18:27velocity
18:27exhaust
18:30outflow
18:31into the
18:32pipe.
18:33And that
18:33thing rushes
18:34down to
18:35the end
18:35of the
18:36pipe and
18:36is reflected
18:37as a
18:38negative
18:38wave.
18:39When you
18:40go to
18:41the end,
18:43an opening
18:44at the
18:45end of a
18:45pipe,
18:45it reverses
18:46the signal.
18:48So the
18:50positive wave
18:50comes back
18:51towards the
18:52engine,
18:53negative wave
18:55comes back
18:55towards the
18:56engine,
18:56and it
18:58can propagate
18:59into the
19:00cylinder
19:01through the
19:03exhaust port,
19:05and then
19:07into the
19:07intake
19:08through the
19:09opening
19:09intake
19:10valves,
19:10and it
19:11can play
19:13come hither
19:13with the
19:14intake
19:15flow,
19:16even though
19:17the piston
19:18is essentially
19:19stopped at
19:20top dead
19:20center.
19:21The piston
19:21is not
19:22pumping,
19:23it's waiting
19:24there,
19:25slowly reversing
19:26its direction.
19:27So we've
19:28created a
19:29wave in the
19:29exhaust,
19:30we've made
19:30the exhaust
19:31a certain
19:31length so
19:32that at
19:33the RPM
19:33we're interested
19:34in,
19:34this negative
19:36wave comes
19:37back and
19:38causes intake
19:39flow to
19:39begin to
19:40enter the
19:41cylinder.
19:42This is
19:42desirable
19:43because at
19:45top dead
19:46center, at
19:47the end of
19:47the exhaust
19:48stroke,
19:48there is a
19:49volume above
19:50the piston,
19:50that's the
19:51combustion
19:51chamber itself,
19:52that's filled
19:53with exhaust
19:53gas.
19:55That's going
19:55to dilute
19:56the next
19:57intake charge
19:58if we don't
19:59blow it
19:59away.
20:00And that
20:01negative wave
20:02from the
20:03exhaust,
20:03aspirates
20:05that nasty
20:06exhaust gas
20:07into the
20:08pipe and
20:08begins the
20:09intake process.
20:10So it
20:11basically,
20:12the combination
20:14of the
20:14exhaust length
20:15and the
20:17valve overlap
20:19gives the
20:21intake process
20:22a head
20:23start.
20:23so that's
20:27another way
20:28in which
20:28the length
20:30of a
20:32input-output
20:35device
20:35affects
20:37torque.
20:39And so
20:39we're
20:40manipulating
20:40that now
20:41on street
20:41bikes.
20:42We're
20:42manipulating
20:42the volume.
20:43There's
20:44sometimes
20:44multiple
20:45volume
20:45airboxes
20:46that help
20:49fill in.
20:50You know,
20:50if you get
20:51your resonance
20:52at peak
20:53power is
20:5410,000 and
20:55you're really
20:55ripping at
20:5610,000,
20:57you're going
20:57to have
20:57the,
20:58you know,
20:59the fabled
20:59dip in
21:00the torque
21:01curve.
21:01Yes.
21:02And they're
21:02filling that
21:03in by
21:04getting
21:04multiple
21:07resonance
21:08out of
21:09intake and
21:09exhaust systems.
21:10And so
21:11we get the
21:12best of both
21:12worlds.
21:13Plus,
21:14we can now
21:14add variable
21:15valve timing
21:16and we can
21:17get that
21:17overlap.
21:19Overlap.
21:20You can
21:20either have
21:20the timing
21:21like this,
21:22this being
21:22the overlap
21:23here.
21:24This is
21:24Kevin crossing
21:25his fingers
21:26again for
21:26you on
21:27Spotify.
21:28He's
21:28overlapping
21:28the valves
21:29and he's
21:29showing them
21:30open at
21:30the same
21:30time.
21:32Yep.
21:33But that
21:35is what
21:35variable valve
21:36timing does.
21:37And if you
21:37open the
21:38hood on a
21:39lot of
21:39modern cars
21:40and look
21:41at the
21:41cam covers,
21:42you'll see
21:42these big
21:43lumps on
21:45the drive-in
21:45and that's
21:46where the
21:47cam phasers
21:47are located.
21:48And some
21:48of them
21:49are hydraulic
21:49and some
21:50of them
21:50are,
21:51I think
21:51some of
21:52them are
21:52electric
21:52even.
21:53But their
21:54job is
21:55to change
21:56cam phase
21:57according to
21:59a schedule
22:01that has
22:01been determined
22:02on a
22:02dynamometer.
22:04Say,
22:04okay,
22:05well,
22:06that's good.
22:07Hold that.
22:07Write that
22:08one down.
22:09Yeah.
22:09Now,
22:10even without
22:10VVT on
22:13motorcycles,
22:14I've looked
22:15at thousands
22:15of dyno
22:16charts over
22:16the years.
22:17Sure.
22:17And in
22:18this discussion,
22:19I want to
22:19give a
22:20shout out
22:20to Honda
22:21because
22:22Honda torque
22:25curves and
22:26power curves
22:27in general
22:28are very
22:31refined.
22:33Like if you,
22:34I mean,
22:34from like
22:35250,
22:35300cc
22:36dual sport
22:37bikes to
22:371000cc
22:38sport bikes,
22:39they really
22:41have done
22:41consistently a
22:43very good job
22:44of refining
22:45the torque
22:45curve.
22:46it's pretty
22:48artful.
22:48I've seen
22:49it with
22:49other
22:50manufacturers.
22:51It doesn't
22:51have horrible
22:52dips in
22:52it.
22:53No dips.
22:54We set
22:55our smoothing
22:55and we
22:56have our
22:56SAE
22:57correction
22:57factors and
22:58all that
22:58stuff.
22:58But in
22:59general,
23:00hundreds of
23:02motorcycles,
23:03more than
23:04a thousand.
23:04I mean,
23:05I can't even
23:05imagine how
23:06many dyno
23:06sheets I've
23:07looked at
23:07because we've
23:08been running
23:08the dyno
23:09at Cycle
23:09World since
23:10sort of
23:13mid-90s.
23:14And we
23:15have all
23:15those charts.
23:17But it's
23:17really something
23:18and it
23:18takes a lot
23:19of effort
23:20to make
23:21that happen.
23:23Well,
23:24Dynojet
23:26came out
23:27with their
23:28low-cost
23:29dynamometer
23:30that came
23:31with software
23:31that enabled
23:33a shop
23:35owner or
23:36an individual
23:38investigator
23:39to do
23:39fairly
23:40sophisticated
23:41dyno work
23:41at an
23:44affordable
23:44cost.
23:45And they
23:45sold thousands
23:46of those
23:47dynos.
23:48And one
23:49of the
23:49first things
23:49that happened
23:50when the
23:51dynos went
23:51on the
23:51market was
23:52Mark
23:53Dobeck
23:54began to
23:55get these
23:55nasty phone
23:56calls.
23:57And people
23:57are saying,
23:58your goddamn
24:00dyno is
24:01given me
24:02a flat
24:03spot and
24:03I can't
24:04tune my
24:05way out
24:05of it.
24:07And what's
24:08happening there
24:09is that
24:10at some
24:11RPM other
24:12than the
24:13one at
24:13which the
24:14pipe length
24:14is correct,
24:17some lower
24:18RPM,
24:19instead of a
24:20negative wave
24:21coming back
24:22to the
24:22cylinder and
24:23starting the
24:24intake process
24:25early,
24:26it's a
24:28positive wave
24:29and it
24:30blows exhaust
24:30gas into
24:32the cylinder
24:32and out
24:34the intake
24:35valves and
24:36fills the
24:37intake port
24:38and even
24:38blows back
24:39into the
24:39airbox so
24:41that when
24:41the piston
24:42finally says,
24:43okay, I'm
24:44going to do
24:44it now and
24:45it starts
24:45down on the
24:46suction stroke,
24:48the first
24:4830% of the
24:50cylinder fills
24:51with exhaust
24:51gas.
24:52So naturally
24:53you've got this
24:53lovely power
24:54peak up here
24:55from the
24:56correct length
24:57of the
24:57exhaust pipe
24:58at that
24:58RPM and
24:59then it
25:00drops into
25:01this deep
25:02hole and
25:04the wider
25:04you make
25:05the overlap
25:06timing,
25:07the deeper
25:09the hole
25:09and the
25:10taller the
25:11peak.
25:13And as a
25:14result, the
25:15curve that
25:16joins the
25:17two from
25:18way down
25:19there to
25:20way up
25:20here is
25:21so steep
25:22that no one
25:23can ride that
25:24motorcycle off
25:25a corner
25:25at anywhere
25:27near the
25:28traction limit.
25:29So racers
25:30were really
25:32upset about
25:33that flat
25:33spot and
25:34people would
25:36tune and
25:37tune and
25:37tune.
25:38They said,
25:39yeah, we
25:40leaned it
25:40way out and
25:41it seemed to
25:42help, but it
25:43killed the
25:43power everywhere
25:44else.
25:45Well, no
25:46surprise because
25:48what's happening
25:48is first
25:51exhaust gas
25:54blowing out
25:55the intake
25:56valve goes
25:57through the
25:57carburetor
25:58backwards.
25:59It picks up
25:59fuel.
26:00Carburetor
26:01doesn't care
26:01which way
26:02the air is
26:02going.
26:03And then it
26:03sucks it back
26:04in and it
26:04picks up
26:05fuel the
26:06second time.
26:07So it's
26:08double rich
26:09and it
26:10won't run.
26:12It stutters.
26:13It misfires.
26:14It gobbles.
26:15Yeah.
26:15But it
26:16doesn't make
26:17dark.
26:17I mean, the
26:18first time I
26:19ever saw
26:19standoff when
26:20I saw a
26:21mixture, a
26:22cloud.
26:23Oh, yeah.
26:24A cloud of
26:25fuel on
26:26the outside
26:27of the
26:27carburetor
26:28intake.
26:29Anybody got
26:30a lighter?
26:31I was just
26:32blown away
26:33that that
26:33could happen.
26:34I always
26:36struggled with
26:37envisioning this
26:40stuff without it
26:41sort of being
26:42instantaneous and
26:43it's none of
26:44it is
26:44instantaneous.
26:45We cannot
26:45instantly open
26:46a poppet
26:47valve.
26:48It takes
26:49time.
26:50It takes
26:51time.
26:51It takes
26:52time for the
26:52signal to run
26:53from the
26:54dome up
26:55to the
26:55intake to
26:56make suction
26:58happen.
26:59It's got to
26:59travel down
27:00the pipe.
27:01I think the
27:02magic of
27:03tuning is
27:04someone who's
27:04able to
27:05visualize
27:06visualize those
27:10timings and
27:12manipulate them
27:13and learn
27:13to speak.
27:15They become
27:15familiar through
27:16experience with
27:17the kind of
27:18thing.
27:18Oh, this
27:19reminds me of
27:20something that
27:20happened at
27:21this point.
27:22Or this is the
27:23way a lot of
27:23people talk about
27:24it because these
27:26learning experiences
27:27are intense.
27:28when you
27:30begin to
27:30pick out a
27:32simple tune
27:32on the
27:33keyboard,
27:33it's a
27:34thrill.
27:35And the
27:37first time
27:38that I was
27:39able to
27:39make a
27:39fast
27:40250
27:41two-stroke,
27:42I just
27:42felt a
27:43tremendous
27:44elation that
27:45made me
27:45cheerful the
27:46whole rest
27:47of the
27:47day.
27:48And so
27:49the
27:51practitioners
27:51of these
27:52dark
27:53arts
27:53remember
27:56these
27:56learning
27:56experiences
27:57very fondly
27:58and
27:59nothing is
28:01remembered
28:01like stuff
28:02you've taught
28:03yourself.
28:05Now,
28:05some of
28:06these people
28:07are quite
28:08unsophisticated
28:09in terms of
28:10engineering
28:11or physical
28:12science,
28:12but they
28:13know what
28:13they're doing.
28:14They can
28:15get results
28:16because they
28:17have the
28:17experience to
28:18be able to
28:18say,
28:19hmm,
28:21this is
28:21looking pretty
28:22mysterious,
28:23but let's
28:23try this.
28:24Oh,
28:24that's a
28:24little bit
28:25better.
28:25Well,
28:26now we're
28:27on our
28:27way,
28:28aren't
28:28we?
28:29And so
28:31I think
28:32that that
28:33kind of
28:34experiential
28:35knowledge is
28:36admirable.
28:42So
28:43you can,
28:45of course,
28:46lose yourself
28:47in all
28:49the variables.
28:50Well,
28:50the cam
28:50timing,
28:51the compression
28:51ratio,
28:52the amount
28:53of overlap,
28:55the intake
28:56and exhaust
28:56lengths,
28:57but people
28:59just get
29:00through it.
29:02And
29:02sometimes,
29:04here's another
29:06one of those
29:06old saws,
29:07they say,
29:08never change
29:09more than
29:10one thing
29:11at a time
29:11because that
29:13way you know
29:14what's causing
29:15the change.
29:16Well,
29:17that makes
29:18sense.
29:18Let's do it
29:19that way.
29:20One
29:20wealthy
29:22California
29:23race sponsor
29:24said to
29:25his man,
29:26I want
29:27you to
29:27buy 40
29:28TZ250
29:29cylinders and
29:30we'll have
29:30them modified
29:31each in a
29:32different way
29:33and then
29:33we'll test
29:34them.
29:34And then
29:35we'll know
29:35they were
29:37all worse
29:37than stock.
29:38All of
29:39them,
29:39worse than
29:40stock.
29:40so I
29:44thought,
29:45who am
29:47I to
29:47go against
29:49this wonderful
29:51truth?
29:53But what I
29:53found was
29:54that if I
29:55raise the
29:58exhaust port
29:58one millimeter
29:59and widen it
30:00a millimeter
30:00on either
30:01side,
30:02raise the
30:04compression
30:05by milling
30:05twenty-five
30:06thousandths
30:07off the
30:07head and
30:07recutting the
30:08water seal
30:09groove,
30:09and
30:11shortening
30:13the exhaust
30:14pipe header
30:15twenty
30:15millimeters,
30:17I had a
30:20really fast
30:21bike.
30:22Who knew
30:22it was a
30:22system?
30:24Yes,
30:25it's a
30:25system.
30:26So,
30:27when you
30:28raise the
30:29compression,
30:31you lower
30:32the exhaust
30:32temperature
30:33because raising
30:34the compression
30:35takes more
30:36energy out
30:37to drive
30:37the piston,
30:38leaving less
30:40to go out
30:41into the
30:42exhaust pipe.
30:43So,
30:44colder gas
30:45is going
30:45into the
30:45exhaust pipe,
30:46so now
30:46the engine
30:47is running,
30:50it's lost
30:50500 or
30:51750 revs.
30:53Well,
30:54we want
30:55those revs
30:55back,
30:55so now we
30:56shorten the
30:56exhaust pipe.
30:57and if
31:00the engine
31:00is going
31:01to run
31:01at a
31:01higher
31:01speed,
31:02it needs
31:02more
31:03exhaust
31:05area
31:05exposed
31:06just before
31:08the piston
31:09begins to
31:10open the
31:10transfer ports
31:11to let
31:11fresh mixture
31:12into the
31:13cylinder.
31:14so it
31:16is a
31:16system,
31:17but people
31:18get a
31:18feel for
31:19it.
31:20And I
31:21think Rob
31:22Muzzy is
31:23a favorite
31:25example because
31:26he found
31:28out from
31:28running and
31:29running and
31:30running on
31:31the dyno,
31:31he said,
31:32don't imagine
31:33that you're
31:33going to learn
31:34something on
31:35the dyno and
31:35then generalize
31:36it to your
31:37race bike,
31:38which is over
31:39there in the
31:39truck somewhere.
31:40He said,
31:41test what
31:42you race.
31:44Because so
31:44often you
31:46think you've
31:47done something,
31:48but what
31:49you've actually
31:50done is a
31:50little different
31:51from what
31:51you think.
31:53So this
31:54makes skeptics
31:56out of
31:56people.
31:58And there
31:58are so
31:59many sectarian
32:01views of
32:02how to use
32:03a dynamometer.
32:04Oh no,
32:04you have to
32:05step test,
32:06hold it at
32:07a constant
32:07RPM for so
32:08many seconds
32:09to stabilize.
32:11Well,
32:11that's going
32:11to wear my
32:13engine out.
32:13I can't
32:14afford that.
32:16And those
32:17people,
32:17those step
32:18test people
32:19just didn't
32:20like the
32:20new dyno
32:21jet dynos,
32:22which just
32:22go burp,
32:25and that's
32:25a test.
32:27Yeah.
32:27You've run
32:28across this
32:29RPM range,
32:29you've got a
32:30torque for
32:30each RPM,
32:31it's all in
32:32the computer.
32:33Yes.
32:34What's not
32:35to like?
32:37I think
32:38we've seen
32:39learnings here
32:41of doing
32:42that at
32:42half throttle
32:42as well.
32:44Yeah.
32:45Because the
32:45behavior is
32:46different.
32:46Sure it is.
32:47And so
32:48if you're,
32:48you know,
32:48as a general
32:49rule,
32:49we're testing,
32:51you know,
32:51we're clicking
32:52into usually
32:53fourth gear
32:53because it's
32:54the closest
32:54to direct
32:55and,
32:56you know,
32:58hitting it
32:58as wide,
32:59you know,
32:59wide open
33:00as at a
33:01low an
33:01RPM as it
33:02will take,
33:03which is
33:03pretty darn
33:04low with
33:04most of
33:05these fuel
33:05injected engines
33:06that aren't
33:06relying on
33:07signal alone.
33:08that means
33:10the air
33:10is flowing
33:11and we're
33:11squirting in
33:12the fuel.
33:12We're not
33:13waiting for
33:13the air
33:14to draw
33:15the fuel
33:15through an
33:16orifice like
33:16in a
33:16carburetor.
33:17So you can
33:18just let
33:18it rip.
33:19so the
33:22inertia
33:22dyno,
33:23I mean,
33:23it's been
33:24fabulous.
33:27It's a great
33:27jetting tool
33:28too,
33:28what I found.
33:30You know,
33:31you can set
33:31up your
33:32lean,
33:32your mixtures
33:34at cruise.
33:36You can say
33:36like,
33:37oh,
33:37let's do
33:383,000 RPM
33:39in top gear
33:39and see what
33:41happens when
33:41the throttle's
33:42cracked,
33:43you know,
33:43just barely
33:44and see how
33:45it runs
33:45and then
33:45transition
33:46without being
33:47out on the
33:48road.
33:48And I'm
33:51not even
33:51relying on
33:52a chart
33:52to get
33:53this
33:53information.
33:54I'm just
33:54doing that
33:55so that I
33:58can concentrate
33:59on what's
34:00going on
34:00without running
34:01into the
34:02back of a
34:02Ford Explorer
34:03and watching
34:03Little Mermaid
34:04with a kid.
34:05You know,
34:05it's like
34:05we can do
34:07this in a
34:08controlled
34:08environment.
34:12But getting
34:12the dyno
34:13into a lot
34:14of people's
34:15hands gave
34:15us,
34:16you know,
34:16it was
34:18a kind
34:18of
34:18democracy
34:19in the
34:19sense
34:20that you
34:20could then
34:20find your
34:23flat spot
34:23and kind
34:25of tune
34:25for that
34:26area under
34:26the torque
34:27curve,
34:27which is
34:27really
34:28your
34:29successful
34:30acceleration.
34:31And then
34:33there came
34:33that fateful
34:34day at
34:35Daytona
34:35when
34:36four-into-one
34:37exhaust pipes
34:38on four-cylinder
34:39engines just
34:40disappeared.
34:42Not a one
34:43could I find
34:44in all the
34:45garages.
34:46And what
34:46had happened
34:47was
34:47somebody had
34:50decided not
34:51to put up
34:51with that
34:52flat spot
34:53any longer.
34:55And what
34:55they did
34:56was they
34:57joined the
35:00header pipes
35:01in pairs
35:02so it
35:03became
35:03four
35:04into two
35:05the joint
35:07into one.
35:10And by
35:10having
35:11a second
35:12enlargement
35:14where the
35:14two individual
35:16pipes joined
35:17a larger
35:18pipe,
35:18that acts
35:19like a pipe
35:20end because
35:21it allows
35:21the gas
35:22to expand.
35:24And it
35:24expands in
35:25all directions
35:26when it's
35:27allowed to
35:28including
35:29back up
35:29the pipe
35:30to the
35:31exhaust valve.
35:33So
35:33by putting
35:34a second
35:35enlargement
35:36in the
35:37middle of
35:37that
35:38four-into-one
35:41pipe
35:41turning it
35:43into a
35:44four-two-one
35:45they were
35:46putting a
35:48negative wave
35:50on top
35:50of the
35:51positive wave
35:53and canceling
35:54it out.
35:55So now
35:55the torque
35:57curve was
35:57no longer
35:58and it
36:01became much
36:01more rideable
36:02and everybody
36:03went quicker.
36:05And we'll
36:06call it
36:07progress.
36:10In certain
36:10areas humans
36:11haven't made a
36:12lot of progress
36:13but there's
36:14one and
36:14let's cling
36:15to it.
36:16so now I
36:19want to
36:20talk about
36:20our
36:22adherence
36:24to the
36:25poppet
36:25valve.
36:27So we
36:28have
36:28you know
36:29we
36:29every
36:30engine
36:31out there
36:32we had
36:33a Mazda
36:34flirted with
36:34the rotary
36:35which had
36:36its own
36:36unique
36:38qualities
36:38but
36:40you know
36:41the poppet
36:41valve is
36:42in every
36:43four-stroke
36:43pretty much
36:44and almost
36:45invariably
36:47it's
36:48overhead
36:48cam
36:49you know
36:50we have
36:50a few
36:50deviants
36:51out there
36:51still with
36:52push rods
36:52but
36:53poppet
36:54valves
36:55why do we
36:56like them
36:57so much
36:57because there
36:57have been
36:58rotary
36:58valves
36:59cone
37:01valves
37:01sleeve
37:02valves
37:02there's
37:03all these
37:03different
37:05ways of
37:06controlling
37:06and we
37:07could
37:07certainly
37:08get into
37:08two-strokes
37:09but I'm
37:09you know
37:09because four-strokes
37:10have basically
37:12won the
37:12battle
37:13all the ways
37:15of controlling
37:16air getting
37:16into a four-stroke
37:17we have our
37:18limitations with
37:18poppet valves
37:19which will
37:20float and get
37:21thrown off their
37:22cam shafts
37:22if you spin
37:23them too fast
37:24and how
37:25stiff can we
37:26make the
37:26springs
37:27nope too
37:27stiff
37:28the cam's
37:28going away
37:29or whatever
37:29it is
37:30but why not
37:31just make
37:32a
37:32I know
37:33it's a
37:33podcast
37:34we got
37:34to talk
37:34and there's
37:35people on
37:35spotify
37:36are going
37:36to be like
37:36what's a
37:37sleeve valve
37:37but maybe
37:38help us
37:39help us
37:40visualize
37:40if you
37:41might
37:41well
37:42the one
37:44thing that
37:45has kept
37:46the poppet
37:46valve
37:47where it
37:48is in
37:49all the
37:49engines of
37:50the world
37:50is that
37:51nothing is
37:52moving when
37:53it is
37:53closed
37:54there's no
37:56rubbing
37:56there's no
37:58sliding
37:59it's like a
38:01manhole
38:01cover in
38:02the street
38:02with rush
38:04hour traffic
38:05rolling over
38:06it
38:06it doesn't
38:10require a
38:10lot of
38:11fussy
38:12business
38:12now in
38:13those huge
38:14aircraft
38:15engines
38:15the poppet
38:18valves were
38:19like two
38:20and a half
38:21three inches
38:21in diameter
38:22tremendous
38:22great big
38:23thing
38:23so they
38:24got the
38:25exhaust valves
38:25got very
38:26hot because
38:27they're being
38:28heated on both
38:29sides the
38:29side that
38:30faces a
38:30combustion
38:30chamber
38:31and when
38:32the valve
38:32lifts and
38:33the exhaust
38:33gas rushes
38:34out heats
38:35the back
38:35of the valve
38:36so they
38:37decided to
38:38deal with
38:38that by
38:39half filling
38:40the hollow
38:41valve with
38:42liquid sodium
38:43and that
38:47worked well
38:48it helped
38:49so the
38:51sodium's
38:51ricocheting
38:52around in
38:52its little
38:53chamber
38:53and carrying
38:54the heat
38:55up the
38:55stem
38:56yes
38:56yes
38:56most of
38:59the heat
38:59of the
39:00valve
39:00travels
39:01out of
39:01the valve
39:02through its
39:02sealing
39:02surface
39:03into the
39:04valve seat
39:05ring which
39:05is a part
39:06of the
39:06cylinder head
39:07which is
39:08either water
39:09cooled or
39:09it's covered
39:10with fins
39:11no wonder we
39:12wreck those
39:12things so
39:13much
39:13yeah
39:14so
39:15uh
39:17the hot
39:19exhaust valve
39:20acted as an
39:21ignition source
39:21or it caused
39:23the engine to
39:24detonate which
39:25is an abnormal
39:25form of
39:26combustion in
39:27which little
39:28pockets of
39:29the very last
39:30part of the
39:31mixture to
39:31burn just go
39:32pop all by
39:33themselves and
39:34burn at the
39:35speed of the
39:35sound a speed
39:36of sound and
39:37they make an
39:38awful slap when
39:39they hit the
39:39inside of the
39:40combustion chamber
39:41and we call it
39:41tinkle or
39:42knock or what
39:44have you so
39:45one group of
39:46engine manufacturers
39:48decided to do
39:49without the
39:49popping valve
39:50and what
39:51they came up
39:52with
39:52was a
39:57sleeve valve
39:57this is worth
39:58seeing on
39:59youtube folks
40:00yeah
40:00so it's a
40:01sleeve valve
40:02it's um
40:03on this end
40:05yeah
40:05there was a
40:07peg
40:08and a ball
40:09on it
40:10and here
40:12was a crank
40:13going round
40:14and round
40:14that clenched
40:16that ball
40:17so that
40:17this thing
40:19made this
40:20motion
40:20and these
40:27ports
40:27some of them
40:29functioned
40:30as intake
40:30ports only
40:31some as
40:31exhaust only
40:32and some
40:33were shared
40:34but the way
40:35this motion
40:36causes them
40:37to open
40:38these make
40:39a very
40:40efficient
40:40kind of
40:41port
40:42and the
40:43sleeve is
40:43constantly
40:44moving
40:45which means
40:45that the
40:46oil film
40:47between it
40:48and the
40:48outer cylinder
40:49is maintained
40:51by the
40:52motion
40:52and
40:54transmits
40:55heat quite
40:56well
40:56so the
40:58sleeve did
40:58not overheat
40:59and burn
41:00up immediately
41:01and many
41:03thousands of
41:04aircraft engines
41:05like using
41:06sleeve valves
41:07like this
41:07were built
41:08in Britain
41:08by Bristol
41:10and by
41:11Napier
41:12and
41:15today
41:16they're
41:17they're
41:17a curiosity
41:18because we
41:18don't use
41:19exhaust valves
41:20that big
41:20anymore
41:21for any
41:22purpose
41:22and
41:24usually we
41:25don't have
41:25to fill
41:26exhaust valves
41:27with sodium
41:27because the
41:28valves are
41:28small enough
41:29that their
41:30heat can
41:31be transmitted
41:32to the
41:33valve seat
41:33but on the
41:35other hand
41:36this is why
41:36we don't
41:37make valve
41:38seats as
41:38narrow exhaust
41:39valve seats
41:40as narrow
41:41as we do
41:41intake valve
41:42seats
41:43on the
41:44intake valve
41:44we're mostly
41:45interested in
41:46making the
41:46seat as
41:47smooth as
41:47possible
41:48to invite
41:49the air
41:49into the
41:50cylinder
41:50smoothness
41:52but for
41:54the exhaust
41:54valve the
41:55seat has
41:56to be wide
41:56enough for
41:57the heat
41:58in the
41:59valve to
42:00be transmitted
42:00to the
42:01valve seat
42:02ring and
42:03into the
42:04cylinder head
42:04now I know
42:05we were
42:05moving on
42:06from poppet
42:06valves but
42:07it brings up
42:07a point what
42:08you're describing
42:09also
42:09that intake
42:11valves are
42:12larger than
42:13exhaust valves
42:14and that
42:14would be
42:14basically due
42:15to the
42:15density of
42:16the charge
42:17correct and
42:18that we're
42:18trying to
42:19and heat
42:21the temperature
42:21originally they
42:22made the
42:22exhaust valves
42:23larger and
42:25then people
42:26tried it all
42:27different ways and
42:28they decided that
42:29it worked best
42:29with a larger
42:31intake valve
42:32well all we
42:34have to fill the
42:35cylinder on
42:35intake in
42:37most engines
42:37is the
42:38atmospheric
42:38pressure of
42:3914.7
42:40pounds per
42:41square inch
42:41whereas at
42:43the bottom
42:43nearing the
42:44bottom of
42:44the stroke
42:45the exhaust
42:45residual gas
42:47as the
42:48exhaust valve
42:49opens is
42:50of the order
42:51of 100
42:51psi so
42:53with that
42:55much pressure
42:56it doesn't
42:56take that
42:57much valve
42:57once you
42:58get out
42:58and in
42:59fact our
43:01favorite wise
43:02guy Jim
43:03fueling and
43:04I'm very
43:05sorry to
43:06bring up
43:06his name
43:06for those
43:07people who
43:07didn't get
43:08on with
43:09him but
43:09we all
43:12agree that
43:12he is a
43:13very clever
43:13man and
43:14he sold
43:15Detroit on
43:17the idea
43:18of solving
43:19their cylinder
43:20head heat
43:20problems by
43:21making the
43:22exhaust valve
43:22and the
43:23exhaust port
43:24smaller and
43:27it worked
43:28because there's
43:30all this
43:31pressure to
43:32push the
43:32exhaust out
43:33and the
43:35smaller the
43:36port and
43:36the shorter
43:37you can make
43:38it in the
43:39cylinder head
43:39the less
43:40exhaust heat
43:41enters the
43:43cylinder head
43:43where it has
43:44to be trucked
43:46away by the
43:47cooling system
43:47so it's a
43:49it's a big
43:49gain to
43:50to sort of
43:51make the
43:53exhaust system
43:53disappear
43:54as short as
43:56possible as
43:57small as
43:58power will
43:58permit
43:59they made a
44:01lot he made
44:01a lot of
44:02money that
44:02way
44:03yeah
44:03he had a
44:04collection of
44:05tanks
44:05he did
44:07yeah and
44:07he had
44:07engines in
44:08a can
44:09he had
44:09great big
44:104360s and
44:12engines and
44:14cans at
44:14his shop
44:15I rode the
44:16W3 and I
44:17went up there
44:17and interviewed
44:17him and we
44:18talked about
44:18little kernel
44:20shaped combustion
44:21chambers that he
44:22was making for
44:22two strokes so
44:23he was taking
44:23the chamber
44:24and basically
44:26making nearly
44:28the entire
44:28diameter squish
44:29yeah and
44:31then putting a
44:31tiny little
44:32rocket rocket
44:33shaped outlet
44:35with a spark
44:36plug and a
44:37tiny little
44:37kernel in the
44:38middle of it so
44:39it just got
44:39smashed up in
44:41there and
44:42then blasted
44:42out of that
44:43little hole and
44:44and he was
44:45making some
44:45power there
44:46were guys in
44:47European GP
44:49racing back in
44:50the two-stroke
44:51era who were
44:51firing their
44:53two-stroke
44:53ignitions at
44:5510 10
44:56degrees before
44:57top center
44:58so that
45:01was probably
45:02pretty rough
45:03steep pressure
45:05rise
45:05yeah but
45:06back to
45:07sleeve valves
45:07so and
45:08other other
45:09types because
45:09there was a
45:10rotary valve I
45:11think that was
45:11a Roland
45:12cross
45:13design
45:15the cross
45:17valve was a
45:18cylinder that
45:19rotated and
45:21the exhaust pipe
45:22was connected
45:23to one end
45:24and the
45:25carburetor to
45:26the other
45:27and in the
45:27middle of this
45:28cylinder was a
45:29diagonal
45:29septum and
45:33there was a
45:33port in the
45:34head that was
45:35roughly rectangular
45:37so that as
45:38the cylinder
45:39rotated it
45:40would expose
45:41intake as
45:42the piston
45:43descended on
45:44its intake
45:44stroke and
45:46then it
45:47would close
45:48and the
45:48piston would
45:49rise on
45:50compression
45:50and power
45:51and then at
45:52the end of
45:52the power
45:52stroke the
45:54exhaust port
45:55inside the
45:56cylinder would
45:57line up with
45:58the rectangular
45:58port in the
45:59head and
46:00what the
46:01Germans so
46:03delightfully
46:03call
46:04auspuff
46:05exhaust would
46:07occur
46:07auspuff
46:08auspuff is
46:09nice
46:10yep
46:10yeah so
46:13it's a it
46:14would generally
46:14run in
46:15parallel with
46:16crank
46:17yes
46:18and it
46:18would rotate
46:19and as you
46:21say that the
46:22cylinder the
46:22pipe the
46:24pipe has a
46:25septum a
46:26barrier and
46:27on one side
46:28the carburetor
46:29is on one
46:29side and it
46:30would go in
46:30that tube and
46:32kind of ricochet
46:3390 degrees
46:34into the
46:34cylinder
46:34thing keeps
46:37turning closes
46:38the chamber
46:38bang does
46:39its thing and
46:39then when it
46:40rolls over it
46:42goes out the
46:43other end
46:43that's pretty
46:44the cylinder has
46:46two ports in
46:46it of course
46:47an intake and
46:47exhaust port
46:48so Norton
46:51got interested
46:51in this
46:52toward the
46:53end of
46:53their
46:54period of
46:56admirably
46:59intensive
46:59development and
47:00they built
47:01a cross
47:01rotary
47:02single
47:03and they
47:05were able to
47:06get up to
47:06the same
47:07power that
47:07they were
47:08getting from
47:08their factory
47:09poppet valve
47:10road race
47:12max engines
47:12but because
47:15it took quite
47:16a bit of
47:16oil to
47:16lubricate this
47:17valve
47:18it was
47:22hard for
47:22the engine
47:23to pick
47:23up when
47:24the rider
47:24wanted to
47:25feed power
47:26to accelerate
47:26out of a
47:27corner
47:27because
47:28I would
47:29imagine
47:29sealing that
47:30also would
47:31be a
47:31challenge
47:31sealing that
47:32big long
47:33cylinder
47:34you know
47:34today they
47:35would surround
47:36the port
47:37with something
47:39very much
47:39like a
47:40vonkel tip
47:41seal
47:42and it
47:43would be
47:44like a
47:45piston ring
47:46made
47:47in any
47:48arbitrary
47:48shape
47:49just like
47:49honda's
47:50nr500
47:51they said
47:51why can't
47:52we make
47:52an oval
47:52cylinder
47:53well it
47:54turned out
47:54they could
47:55and so
47:57and the
47:58vonkels
47:58they have
47:59seals of
48:00all different
48:01weird shapes
48:02wonderful stuff
48:03that they did
48:04unfortunately
48:05the tapering
48:09tips of the
48:11combustion
48:11space
48:12were
48:13quench
48:14areas
48:15the cold
48:15metal
48:16had that
48:17part of the
48:17charge
48:18surrounded
48:18and it
48:19said
48:19yeah I
48:20was really
48:21hot
48:21to burn
48:22but now
48:23I give
48:23up
48:24and so
48:26you'd get
48:26unburned
48:27hydrocarbons
48:28out the
48:31exhaust
48:31so all
48:33these things
48:33have
48:33some
48:36people will
48:37sort of
48:37tell you
48:38almost any
48:38idea can
48:39be made
48:39to work
48:40but can
48:41we afford
48:41to make
48:42it work
48:43can we
48:44tool this
48:45thing for
48:46economical
48:46production
48:47and whenever
48:49I see
48:49world beating
48:51new engine
48:52designs I
48:53think who's
48:53going to
48:54throw away
48:55their round
48:57cylinder
48:57poppet valve
48:58production line
48:59and give
49:00this a try
49:01someone's
49:03going to
49:03have to
49:03have some
49:04money
49:04pretty serious
49:06money that
49:06they can
49:06afford to
49:07kiss
49:08goodbye
49:09if it
49:10should turn
49:11out that
49:11way
49:11yeah
49:12well there
49:14was also
49:14the aspen
49:15valve
49:15which was
49:16a cone
49:17yeah
49:17and how
49:18was the
49:19the cone
49:20as I
49:20understand it
49:21was the
49:22was the
49:22chamber
49:23yeah
49:24and it
49:25it rotated
49:26essentially the
49:26top of the
49:27chamber
49:27rotated
49:28yes
49:29it did
49:30frank
49:30frank aspen
49:31lined up
49:32with ports
49:33that were
49:33provided for
49:35that and
49:36velicet
49:37invested
49:38quite a bit
49:39of money
49:40in in
49:41this thing
49:41and
49:42harold
49:43willis
49:44was their
49:45competitions
49:47director and
49:48a very
49:49bright man
49:50and a
49:50word lover
49:50i'm sure he
49:52eventually had
49:52some delightful
49:53things to say
49:54about the
49:54aspen valve
49:55but they
49:56were never
49:57able to
49:57bring it
49:58to workable
50:00excellence
50:02it was like
50:04yeah we
50:05proved that
50:06you can make
50:06an engine
50:07run this
50:07way but
50:09not as well
50:09as the engine
50:10that we
50:10already have
50:11particularly
50:13the excellent
50:14ktt
50:16350
50:17yeah aspen
50:18aspen had
50:21a 250
50:22that he
50:22was spinning
50:23in
50:231937
50:251940
50:26they were
50:26spinning
50:27to 14,000
50:28rpm
50:28sure
50:29because
50:29no valve
50:30springs
50:30no valve
50:31springs
50:31and so
50:32you're
50:32balancing
50:33advantages
50:35and
50:35obviously
50:38whatever it
50:40was
50:40ceiling
50:41surface
50:42too much
50:43oil
50:43all the
50:44things that
50:45made that
50:45work were
50:45not enough
50:46of an
50:46advantage
50:47people have
50:48tried to
50:50make rotating
50:51valves that
50:52have the
50:53same that
50:53are sitting
50:54still during
50:55the high
50:56pressure phase
50:57just like a
50:58poppet valve
50:58and they're
50:59driven by
51:00something like
51:00a
51:02all those
51:04those Geneva
51:05stars that
51:06drive camera
51:08shutters
51:08movie camera
51:09shutters
51:10of the
51:11as the
51:13star
51:14rotates
51:15it is
51:17driven by
51:17a pin
51:18on a
51:19wheel that
51:20goes into
51:20a space
51:21and
51:21and then
51:23it sits
51:24still until
51:24the pin
51:25comes around
51:26again
51:26so it's
51:29it should
51:31have worked
51:32but
51:33when you
51:35have going
51:36to have it
51:36sitting still
51:37and then
51:38accelerating
51:38violently
51:39you're going
51:40to have
51:40the same
51:40problems
51:42of durability
51:42that you
51:43have with
51:43a poppet
51:43valve
51:44so
51:45where's
51:46the
51:46advantage
51:47but
51:48there are
51:49people who
51:49who want
51:50to know
51:50and so
51:51they keep
51:51on dragging
51:53out these
51:53old ideas
51:54adding some
51:55modern materials
51:56or a
51:56modern lubricant
51:57or a
51:57modern sealing
51:59system
51:59and they
52:00show this
52:02to the
52:02potential
52:02investors
52:03and they
52:03all go
52:04oh
52:04that's
52:05that's
52:05very
52:06interesting
52:06Phil Vincent
52:08he worked
52:08on a
52:09one of
52:09the many
52:10barrel
52:11engines
52:11that has
52:12a series
52:13of pistons
52:14with a
52:14swashplate
52:15between them
52:16so that the
52:17pistons are
52:17all moving
52:18in a
52:20in a
52:21sort of
52:21sine wave
52:23fashion
52:23and
52:24AC compressors
52:25are like that
52:26yeah
52:26very compact
52:28yeah
52:29they're
52:29some of them
52:30they're
52:30they say
52:31they're 10
52:32cylinder
52:32but really
52:33it's five
52:34and they're
52:34but they're
52:34working on
52:35either end
52:35yeah
52:36and they
52:37just
52:37they swash
52:38they have
52:38a plate
52:38and it
52:39moves them
52:39back and
52:39forth
52:40and that
52:40gives you
52:40your
52:40you're
52:42constantly
52:42cycling
52:43pressure
52:44build
52:44and
52:44throwing
52:45it
52:45through
52:45your
52:45check
52:46bowels
52:46and
52:46watching
52:47snowflakes
52:48come out
52:48of your
52:48air conditioning
52:49ducts
52:49and your
52:5089 Ford
52:51F-250
52:51good one
52:53well we've
52:58yeah
52:58yeah
52:59you know
52:59I was just
53:00going to say
53:00we've got
53:0053 minutes
53:02of air
53:02yes
53:03a lot of
53:06air coming
53:07in and out
53:07yep
53:0917 times
53:10a minute
53:10well
53:12as the
53:14late
53:15Kenny
53:15Augustine
53:16did
53:17there have
53:18been a
53:18great many
53:19people who've
53:19devoted their
53:20lives
53:20to getting
53:23more air
53:23into engines
53:24and
53:26Harry
53:28Westlake
53:29an Englishman
53:29in 1926
53:31bought
53:31three
53:32Sunbeam
53:35500cc
53:36race engines
53:37and one
53:38of them
53:38made
53:3826
53:39horsepower
53:40one
53:40made
53:4125
53:42horsepower
53:42and one
53:43of them
53:43made
53:4329
53:44and he
53:45wanted to
53:45know why
53:46and he
53:47thought that
53:48it must
53:48have to do
53:49with their
53:50pumping
53:50ability
53:50they were
53:52all had
53:52the same
53:52bore and
53:53stroke
53:53they all
53:54had the
53:54same
53:54intake
53:55dimensions
53:56but when
53:56he looked
53:57into it
53:57he found
53:58that lots
53:59of small
54:00details
54:00in the
54:01shape
54:01of the
54:02intake
54:02port
54:02and the
54:03way the
54:04valve
54:04seat is
54:04cut
54:05and the
54:06way the
54:06valve
54:06seat blends
54:07into the
54:08cylinder head
54:08on the
54:09inside
54:09of the
54:10combustion
54:10chamber
54:10can exert
54:12a large
54:13influence
54:14on how
54:14much air
54:15enters the
54:16cylinder
54:17and is
54:17trapped
54:17there
54:18so this
54:19is why
54:20people go
54:20to the
54:21airflow
54:24it used
54:24to be
54:25of course
54:25you had
54:25to take
54:26your
54:26heads
54:26and they
54:27would
54:27grind
54:28every
54:29port
54:29nowadays
54:31the
54:31wizard
54:32does
54:32one
54:32port
54:33and
54:34then
54:35they
54:35digitize
54:36that
54:36and
54:373D
54:39machine
54:40does
54:41all the
54:41grinding
54:42it turns
54:44the nasty
54:44parts of
54:45the port
54:45into
54:46powder
54:46yeah
54:49it's
54:50those
54:50CNC
54:51porting
54:52machines
54:52are
54:53spectacular
54:53to watch
54:54and it
54:54just
54:55takes
54:55the tedium
54:56right out
54:56of it
54:57yes
54:57indeed
54:58you do
54:58it the
54:59one time
54:59you make
54:59your art
55:00and then
55:00the machine
55:01replicates
55:01that for
55:02you and
55:02away you
55:03go
55:04that means
55:05that you
55:05can then
55:05go down
55:06on the
55:06boulevard
55:06order a
55:07very dark
55:08coffee
55:09adjust the
55:10angle of
55:10your beret
55:11and be an
55:11artist
55:12well air
55:16has mass
55:16it doesn't
55:17like to
55:17turn corners
55:18ports
55:19need to
55:20be smooth
55:20we need
55:21to take
55:21get rid
55:22of usually
55:22the sharp
55:23edges
55:23you gotta
55:24pay attention
55:25to so
55:25much
55:26because
55:26air
55:26air is
55:29invisible
55:29but it's
55:31very clearly
55:31there
55:32yes
55:32and it
55:34has an
55:34opinion
55:34it does
55:36thanks for
55:37listening
55:37everybody
55:38get down
55:40in the
55:40comments
55:40we're still
55:41enjoying
55:41those
55:42we have
55:42more
55:43ideas
55:43coming
55:44out of
55:44those
55:44for
55:45future
55:45programs
55:46I was
55:48going to
55:48say the
55:48Yamaha
55:49R7
55:50not the
55:51current
55:52twin cylinder
55:52R7
55:53but the
55:53homologation
55:54special
55:54of
55:551999
55:56ish
55:57this is
55:59something
55:59perhaps for
56:00a future
56:00podcast
56:01Kevin
56:01but why
56:02did that
56:02motorcycle
56:02sound
56:03so good
56:04what was
56:05it about
56:06its
56:06intake
56:07valve
56:07timing
56:08the length
56:09of its
56:09trumpets
56:10the size
56:11of its
56:11airbox
56:12I've
56:12ridden
56:13a lot
56:13of
56:13motorcycles
56:13and it's
56:15a quality
56:16of air
56:16it's
56:17why the
56:18trombone
56:19can sound
56:19good
56:19and it
56:21was amazing
56:22so maybe
56:23next time
56:24we can
56:25think about
56:27the sounds
56:27of engines
56:28and
56:28oh the
56:30sounds of
56:30engines
56:31is a
56:31wonderful
56:31topic
56:32thanks for
56:35listening
56:35thanks for
56:36listening
56:36everybody
56:37we'll
56:37catch you
56:38next time
56:39take care
Comments