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'[EE]: VW engine RPM question'
2011\03\07@121431 by

Hi to all,

There is some  thing I do not clearly understand about VW battle engine. the rotor has 4 magnets on it and the board has
1 hall effect sensor with none latch version so each magnet will control each cylinder.  lets say 8000 engine RPM
I divide by 60 to get the frequency 8000/60=133.33 since 4 pulses is one revolution x4 I get 533.33. I have been told 133.33 is my frequency but the way I calculate 133.33 is each cylinder not looking at the hall sensor.
it sounds like 133.33x4 should be 533.33 not 133.33 since 1 revolution is 4 pulses? my question is witch one is correct 133.33 or 533.33
my understanding is it should be 533.33

thanks

Andre

On Mon, 07 Mar 2011 09:14 -0800, "Andre Abelian" wrote:
> Hi to all,
>
> There is some  thing I do not clearly understand about VW battle engine.
> the
> rotor has 4 magnets on it and the board has
> 1 hall effect sensor with none latch version so each magnet will control
> each
> cylinder.  lets say 8000 engine RPM
> I divide by 60 to get the frequency 8000/60=133.33 since 4 pulses is one
> revolution x4 I get 533.33.
> I have been told 133.33 is my frequency but the way I calculate 133.33 is
> each
> cylinder not looking at the hall sensor.
> it sounds like 133.33x4 should be 533.33 not 133.33 since 1 revolution is
> 4
> pulses?
> my question is witch one is correct 133.33 or 533.33
> my understanding is it should be 533.33

Hi Andre,

Neither is correct.

The rotor spins at half the engine speed, at 8000 rpm the rotor is
spinning 4000 rpm. With four lobes that is 16000 sparks per minute or
266.66 Hz.

Cheerful regards,

Bob

-- http://www.fastmail.fm - Or how I learned to stop worrying and
love email again
Hi Andre -

"VW Battle engine"  = "VW Beetle engine?"...

If it's a 4-cycle engine, and the rotor you refer to
is the distributor rotor, it turns at 1/2 crank speed.

Jac
Jack,

sorry yes I mean beetle.
this means 8000rpm/60 =133hz/2 = 66.6 this is what I should see per cylinder right?
and by looking at main sensor side (or coil side) I should see 66.6*4=266..4hz now I am totally lost... are you sure it divided by 2?

thanks

AA

________________________________
From: John Gardner <goflo3gmail.com>
To: Microcontroller discussion list - Public. <piclistMIT.EDU>
Sent: Mon, March 7, 2011 9:39:08 AM
Subject: Re: [EE]: VW engine RPM question

Hi Andre -

"VW Battle engine"  = "VW Beetle engine?"...

If it's a 4-cycle engine, and the rotor you refer to
is the distributor rotor, it turns at 1/2 crank speed.

Jac
Bob,

thanks now I understand. I was right about x4 deal but since I didn't know it was divided by 2 so my info was wrong too.

thanks

Andre

________________________________
From: Bob Blick <bobblickftml.net>
To: Microcontroller discussion list - Public. <piclistmit.edu>
Sent: Mon, March 7, 2011 9:38:10 AM
Subject: Re: [EE]: VW engine RPM question

On Mon, 07 Mar 2011 09:14 -0800, "Andre Abelian" wrote:
{Quote hidden}

Hi Andre,

Neither is correct.

The rotor spins at half the engine speed, at 8000 rpm the rotor is
spinning 4000 rpm. With four lobes that is 16000 sparks per minute or
266.66 Hz.

Cheerful regards,

Bob

-- http://www.fastmail.fm - Or how I learned to stop worrying and
love email again
Let's pick an RPM which is user-friendly.

If engine speed is 6000 rpm, the crank is making a complete
revolution every 10 milliseconds. Since the engine is a 4-cycle,
a complete Intake, Compression, Power, & Exhaust cycle
takes 2 crank revolutions - So the camshaft & distributor turn
at half the crank speed, or 3000 rpm.

Since its a 4-cylinder engine, an ignition event comes along every
90 degrees of distributor rotation, so...

3000 rpm is 1 rev every 20 milliseconds, so you'll have an ignition
event every 5 ms, a frequency of 200 Hz.

In practice, you'll see some phase jitter because of gear backlash,
contact bounce if you're using (gasp!) points, and the "advance" &
"retard" built into most mechanical distributors.

Still not clear? Tell me what you don't understand...

Jac

> -----Original Message-----
> From: piclist-bouncesmit.edu [piclist-bouncesmit.edu] On
Behalf
{Quote hidden}

If the rotor you are looking it is part of the distributor then it
*absolutely, definitely* will be turning at 1/2 crankshaft speed.  A 4
cylinder, 4-stroke engine requires a spark every 180 degrees of the
crankshaft (hence every 90 degrees of the camshaft and distributor).
The total spark frequency is therefore (8000/60) * 2 = 266.7Hz.  Each
cylinder has an ignition event every two turns of the crank, so spark
frequency at a given spark plug will be (8000/60)/2 = 66.7Hz.

This assumes your Beetle engine will hang together for more than one
spark period at 8000RPM...

Mike

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Andre,

For *each* cylinder, you will get one pulse every two crankshaft  rotations.  So at 8000 rpm, you will get 8000/2 = 4000 pulses per  minute, or 66.67 pulses per second (Hz).  For four cylinders you will  get 266.67 Hz at 8000 rpm.

Cheers,
-Neil.

Quoting Andre Abelian <abelian.andreyahoo.com>:

{Quote hidden}

>
....This assumes your Beetle engine will hang together for more than one
spark period at 8000RPM...

Yes, there is that :)

IIRC Type 1 1600 rev limit is 5700 rpm according to VW, and that's a bit
ambitious in my opinion - The stock crank is not balanced across adjacent
throws, & will beat out the main bearing bores fairly quickly if you insist on
buzzing the engine. It's pointless, anyway, in a stock engine - Peak torque
is ~3700 rpm, and the fan... Well, see "Fan Law".

All addressable, of course, but it's not very "stock" w2hen you get done.

Jac
On 07/03/2011 18:58, Michael Rigby-Jones wrote:
> This assumes your Beetle engine will hang together for more than one
> spark period at 8000RPM...
>
red line at 5,000 rpm?
my VW van did 55mph

it was revised flatter flat air cooled twin done after Beetle ceased production.  Eventually the covers over the push rods started to leak :(

It had electronic Ignition. When I was very small my Grandfather had a Beetle with 6V electrics.

Most 1960s to 1980s cars I worked on  12V and  ignition coil + "points" and distributor cap with 4 sparks in turn per revolution, 4 cam bumps  on shaft opening the "points" to interrupt current to ground through ignition coil.

Four stroke is 1 spark every two revolution. So distributor shaft is at engine RPM x2 since it does 1/4 revolution for distributor each piston stroke
On 07/03/2011 19:14, PICdude wrote:
> For four cylinders you will
> get 266.67 Hz at 8000 rpm.
or a more believable 26.7 Hz at 800rpm
....So distributor shaft is at
engine RPM x2 since it does 1/4 revolution for distributor each piston
stroke?

Nope. Distributor turns at 1/2 crank speed - One ignition event every
180 degrees. Remember; it's a 4-cycle, so it takes two complete
engine revolutions for all four cylinders to fire.

Mike's numbers & mine look different because he's looking at individual
ignition events, & I'm looking at the low-voltage side of the ignition coil..
Adjusted for RPM, it's the same deal.

Jac
On 8 March 2011 08:28, Michael Watterson <mikeradioway.org> wrote:
> On 07/03/2011 19:14, PICdude wrote:
>> For four cylinders you will
>> get 266.67 Hz at 8000 rpm.
> or a more believable 26.7 Hz at 800rpm.
> --

8000 rpm on a VW engine is believable?? Maybe possible, but not for long.

R
....red line at 5,000 rpm? my VW van did 55mph

My 1970 Westphalia was turning 3000 rpm at 50 mph also.
It was relatively stock, other than some longevity mods.

It's predecessor, a '71 9-passenger, was not stock, and just
roared up hills - lots of fun passing tired old Datsuns on grades :)

No matter the puissance of your motor though; at 70 mph Buses
are getting light in the front end - Not the ideal vehicle to do a snap
roll in...  Side winds can blow you off the road, too.

Jac
Richard,

thats what I am trying to find out? what's the maximum RPM on VW engine?

AA

________________________________
From: Richard Prosser <rhprossergmail.com>
To: Microcontroller discussion list - Public. <piclistmit.edu>
Sent: Mon, March 7, 2011 11:34:40 AM
Subject: Re: [EE]: VW engine RPM question

On 8 March 2011 08:28, Michael Watterson <mikeradioway.org> wrote:
> On 07/03/2011 19:14, PICdude wrote:
>> For four cylinders you will
>> get 266.67 Hz at 8000 rpm.
> or a more believable 26.7 Hz at 800rpm.
> --

8000 rpm on a VW engine is believable?? Maybe possible, but not for long.

R
A VW bug (horizontal opposed 4 cyl.) probably 5000 rpm, but modified, might be 7000 rpm maximum. That's unless racing, and even then, probably the 7000 is tops.

On 3/7/2011 2:55 PM, Andre Abelian wrote:
{Quote hidden}

>
On 8 March 2011 08:55, Andre Abelian <abelian.andreyahoo.com> wrote:
> Richard,
>
> thats what I am trying to find out? what's the maximum RPM on VW engine?
>
> AA
>
>
>

One spec sheet I found for the 1600 engine quoted 63hp at 4000rpm.
<http://www.carfolio.com/specifications/models/car/?car=78320>

R
For which engine do you want the data?

I have OEM data back through the 36 Hp.

Jac
Michael,

I know one thing for sure that the rotor has 4 magnets and 1 turn of rotor will fire 4 cylinder.
I just do not understand what does "Four stroke is 1 spark every two revolution" means?
can you give and example?

thanks

AA

________________________________
To: Microcontroller discussion list - Public. <piclistmit.edu>
Sent: Mon, March 7, 2011 11:25:56 AM
Subject: Re: [EE]: VW engine RPM question

On 07/03/2011 18:58, Michael Rigby-Jones wrote:
> This assumes your Beetle engine will hang together for more than one
> spark period at 8000RPM...
>
red line at 5,000 rpm?
my VW van did 55mph

it was revised flatter flat air cooled twin done after Beetle ceased production.  Eventually the covers over the push rods started to leak :(

It had electronic Ignition. When I was very small my Grandfather had a Beetle with 6V electrics.

Most 1960s to 1980s cars I worked on  12V and  ignition coil + "points" and distributor cap with 4 sparks in turn per revolution, 4 cam bumps  on shaft opening the "points" to interrupt current to ground through ignition coil.

Four stroke is 1 spark every two revolution. So distributor shaft is at engine RPM x2 since it does 1/4 revolution for distributor each piston stroke
On 07/03/2011 21:40, Andre Abelian wrote:
> Michael,
>
> I know one thing for sure that the rotor has 4 magnets and 1 turn of rotor will
> fire 4 cylinder.
> I just do not understand what does "Four stroke is 1 spark every two revolution"
> means?
> can you give and example?
>
> thanks
>
> AA
The four strokes
Revolution 1
INTAKE stroke  Piston descends and sucks in air and fuel (inlet valve open)
Compression Stroke,Piston rises (all valves closed)  Piston rises and just before top dead centre, spark is applied
Revolution 2
Piston descends due to ignition of fuel/air mixture gas pressure
Exhaust stroke (exit valve open), piston rises and pushes out waste exhaust gases.

So each cylinder gets a spark once every two revolutions.
With four cylinders, each compresses and gets a spark in turn, so 4 sparks every 2 revolutions. Cam has 4 bumps for "points" or 4 magnets and distributor cap on same shaft, four contacts.
*

Andre Abelian wrote:
> I just do not understand what does "Four stroke is 1 spark every two
> revolution" means?

This is from the basics of how four stroke engines work.  The piston goes up
and down twice (and the crankshaft therefore around twice) for each complete
cycle of what happens in the cylinder.  The cycles are intake, compression,
power, and exhaust.  Whatever performs the timing related to this full cycle
has to do it at half the engine speed.  This includes the cam shaft and the
distributor rotor.  The cam shaft manipulates the valves to let gasses into
and out of the cylinders at appropriate times, and the distributor rotor
switches one of the sparkplugs into the spark circuit each spark.  It
usually also controls the spark timing.

So if a 4-cylinder 4-stroke engine is spinning at 10Hz (600 RPM), then the
cam shaft and the distributor rotor are spinning at 5Hz, sparks happen at a
20Hz rate, but each cylinder is sparked at 5Hz.
Just to clarify, it's possible the VW engine has a waste spark during
the exhaust cycle, this is not all that uncommon with lawnmower
engines.

On Mon, Mar 7, 2011 at 4:59 PM, Michael Watterson <mikeradioway.org> wrote:
{Quote hidden}

>
.... it's possible the VW engine has a waste spark ...

Air-cooled through 1976, no. At least not US models
> The four strokes
> Revolution 1

The other Beatles (Fab four strokes) have Revolution
The original VW bug engines with breaker point/capacitor ignition has 4 cam lobes on the distributor shaft which turns at 1/2 crankshaft speed. Therefore there would not be a wasted spark.

On 3/7/2011 4:59 PM, Michael Watterson wrote:
{Quote hidden}

>
Em 7/3/2011 19:12, AK escreveu:
> Just to clarify, it's possible the VW engine has a waste spark during
> the exhaust cycle, this is not all that uncommon with lawnmower
> engines.

I have seen some engines with this "waste" spark. I think it simplifies
the design.
The manufacturer says it helps to burn some fuel that may have remained
unburned. To me they are just trying to "fancy" the facts.

I have also seen at least one engine that produces sparks at the end of
each stroke, even at the end of the intake stroke. It seems that the
uncompressed mixture doesn't detonate even with the spark.
This engine doesn't need a distribution system, each cylinder has a
spark at each half-turn of the crank-shaft.

Isaac
distributor lobes (below the ignition lobes, which triggered the
injectors twice per cylinder cycle...  :)

Jac
What year were those "D-jets" made. I was talking of the original beetle, 4 cyl. horizontal opposed, and not the front engine/drive vehicles. I had 1958, 1961, and 1970? Vw's, and 1958 and 1964 Porsches 356A and 356C. They all had 4 lobes for ignition on the distributor shaft.

On 3/7/2011 5:57 PM, John Gardner wrote:
> distributor lobes (below the ignition lobes, which triggered the
> injectors twice per cylinder cycle...  :)
>
>   Jack
>
Yes, of course. D-Jetronic fuel injection was introduced in the
1968 Type 3 - The little station wagons. The injector trigger
assembly was inside the body of the distributor drive housing,
with a wire run up through the body of the distributor and out the
side with a separate connector. The trigger switch assembly
could be accessed by prying off the cover on the drive housing.

D-Jet had excellent power - The early Type 3s were spec'ed at 65
BHP, & got terrific fuel economy if you kept your foot out of it.

Biggest drawback was too many places for the owner to put a
screwdriver - Not the last VW to suffer from this malady...

Jac

All,

My 2 cents worth of knowledge to this conversation. This is my
experience.  YMMV.

The only time I have seen an engine have a "waste spark" is in 6 and 8
cylinder automotive engines with
electronic ignition and coil packs.  These engines are typically fuel
injected.  The way this works is
there are two cylinders that are connected in series through the coil
pack. These two cylinders are 180
degreess out of phase with each other.  When one is on the compression
stroke, the other is on the exhaust
stroke.  The one under compression has a higher resistance than the one
on the exhaust stroke, therefore
the one under compression receives the greater amount of voltage, which
fires the fuel-air charge.  The one
on the exhaust stroke has much less resistance, so therefore receives
very little voltage.  On the next
turn of the crank, the roles reverse.  The relative resistances of the
contents of the cylinders, in
conjunction with the coil pack, is just your basic resistive voltage
divider.  Very simple in concept.

The lawn mowers I have worked on throughout the years get ignition from
a magneto. They also have points
that close just before the magnet get near the core, and then open at
the correct time to interrupt the
current in the primary from the magnet passing the core as it nears
it's peak. This causes the primary
field to collapse, thereby generating a higher voltage in the
secondary.  When the magnet passes the core
when the points aren't operated, the secondary will have a high voltage
induced into it, but it is much
lower and rather slow in rise and fall, therefore the voltages induced
is much lower.  So much lower, that
it may or amy not jump the spark plug gap.  Either way, it isn't a
problem.

Regards,

Jim

> ---{Original Message removed}
haha :)

On Mon, Mar 7, 2011 at 5:29 PM, IVP <joecolquittclear.net.nz> wrote:
>> The four strokes
>> Revolution 1
>
> The other Beatles (Fab four strokes) have Revolution 9
>
very well said, very concise. finally could visualise your explanation.

so does this mean that there will be 4 sparks in 1 complete rev just because 20ms/5ms?

thanks.

________________________________________
From: piclist-bouncesmit.edu [piclist-bouncesmit.edu] On Behalf Of John Gardner [goflo3gmail.com]
Sent: Tuesday, March 08, 2011 6:57 AM
To: Microcontroller discussion list - Public.
Subject: Re: [EE]: VW engine RPM question

Let's pick an RPM which is user-friendly.

If engine speed is 6000 rpm, the crank is making a complete
revolution every 10 milliseconds. Since the engine is a 4-cycle,
a complete Intake, Compression, Power, & Exhaust cycle
takes 2 crank revolutions - So the camshaft & distributor turn
at half the crank speed, or 3000 rpm.

Since its a 4-cylinder engine, an ignition event comes along every
90 degrees of distributor rotation, so...

3000 rpm is 1 rev every 20 milliseconds, so you'll have an ignition
event every 5 ms, a frequency of 200 Hz.

In practice, you'll see some phase jitter because of gear backlash,
contact bounce if you're using (gasp!) points, and the "advance" &
"retard" built into most mechanical distributors.

Still not clear? Tell me what you don't understand...

Jac
For testing and experimenting,

Remove spark plugs.

Rotate engine by hand and observe the rotor.  You will see that you
must rotate the engine twice to get 1 rotation on the rotor.

Using a straw you may also like to probe for the position of the
pistons and you should see that each piston must go up and down twice
for the rotor to do one revolution.

You should also see a relation between when the piston is near the top
and the associated magnet and sensor on the rotor (or points and it
associated lobe).

To rotate engine you may be able to use a socket on the crank shaft or
perhaps put the car in highest gear (4th?) and push the car in either
direction while observing crank position and rotor position.  Or while
OUT of gear in Neutral very briefly get someone to turn the engine
over using the key, this is my least prefered.  I tend to prefer
putting in the highest gear and push.

Justin

On 8 March 2011 05:40, Andre Abelian <abelian.andreyahoo.com> wrote:
{Quote hidden}

>
{Quote hidden}

If it is possible to remove the valve cover, you can also see how the valves operate and you will see that each valve needs two engine rotations to open once.

With a mechanical distibutor you can then clearly identify which cylinder each spark plug cable should go to. In case you forgot when you disassembled it :-)

/Ruben

==============================
Ruben Jönsson
AB Liros Electronic
Box 9124, 200 39 Malmö, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
rubenpp.sbbs.se
==============================

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