rpm

[lip5er4]

Hi guys, heres my question, How can find the RPM on these great listers? Tachometer? How do you monitor the RPM? Newbie" lip5er4 thanx.  brian, detroit

[listerdiesel]

The most popular instruments in the UK for the engine guys are the Smiths Industries hand-held mechanical tachometers, later badged as 'Ventura', but still the same basic instrument.

There are loads of other methods,  look on ebay for hand-held digital meters, they are quite cheap these days.

I'll post some pictures of a couple of the tachos that we have later.

Peter

[agroot]

If you are driving a generator, the Kill-A-Watt will give you the frequency.  You can calculate the RPM from the frequency, if you know the diameters of the pulleys.

RPM = (f*60/Np) * Pg / Pe

f = frequency
Np = number of poles on generator (2 for 1500 or 1800 RPM generators, 4 in 3000 or 3600 RPM generators)
Pg = diameter of pulley on generator
Pe = diameter of pulley on engine

[taeuber]

Np = number of poles on generator (2 for 1500 or 1800 RPM generators, 4 in 3000 or 3600 RPM generators)

Or better vice versa.

Lars

[duh]

lip5er4,
You can also use a bicycle computer (one with a cadence counter). It's cheap and easy:
http://www.diesel-bike.com/Lister_Gen/Videos/Lister_Bike_Tach.wmv
http://www.diesel-bike.com/Lister_Gen/Videos/Lister_Tach_Sensor.wmv

Good luck,
duh

[asavage]

Two more: low-tech Vibra-tach (I've owned one since about 1976), and high-tech Tiny-Tach.

[fattywagonman]

This is what I use....

http://cgi.ebay.com/Stewart-Warner-hand-held-shaft-speed-tachometer_W0QQitemZ230073181383QQihZ013QQcategoryZ48712QQcmdZViewItem

[sid]

Fattywagonman/// you must be the one I am bidding against on e bay on the stewart 757 tachs..sid

[jtodd]

Two more: low-tech Vibra-tach (I've owned one since about 1976), and high-tech Tiny-Tach.

asavage -
  The tiny-tach you reference interests me.  A few questions: any idea how these things work?  What size fuel line version did you get?

I've been researching various hall effect pickups for my flywheel, but this seems a lot simpler.  The downside is that I can't use this tach for an input to my (still in shipping) Crompton generator control computer, I don't think.   However, this seems like a fairly simple backup to an otherwise complex system.

JT

[asavage]

I haven't purchased one.  They use a piezo pickup, like my Kent-Moore J-33300 Tach-n-Time units do, or the Snap-On MT257(a).  The pickup clamps around one of the injector lines and senses the injection pulse.

[MikeyT]

I tried the Tiny Tach on my Jetta a few months back, simple to install and etc. but the "refresh" rate (1 sec) was way to slow to suit me... I sent it back.

[Jim Mc]

I use one of these:

http://www.ietlabs.com/Genrad/1531.html

Search Flea Bay for "optical tachometer" for another option.

[asavage]

I tried the Tiny Tach on my Jetta a few months back, simple to install and etc. but the "refresh" rate (1 sec) was way to slow to suit me... I sent it back.

To some extent, that's a problem with every digital tach I've seen.  Even my expensive Kent-Moores are fairly slow to update  -- but they were state-of-the-art 20 years ago 

[dkwflight]

Hi I like the strobe units.
I wonder if they wouls show the variation in speed in between the firing strokes?
Dennis