Fitting a rev counter on a diesel car?

[jerrytug]

I am finding the web search bewildering, just looking for a simple, clear tacho and rev sensor for my Peugeot 205 turbo diesel.
It is a basic diesel with no electronics or computers, just a Lucas pump with a fuel stop solenoid.
I would like to fit a rev counter, is there a simple one which I could fit without any computer/electronic knowledge?
Maybe a dial in a pod, which I could screw on the dashboard. I would even be happy with a digital readout, if that is the only type available.
Maybe such a product does not exist, but I vaguely remember a rev counter which had a sensor that clipped on an injector pipe?
It is a bit concerning, belting this thing round the country lanes without knowing my revs.
Thanks for any simple, easy suggestions..
(Yes there is another 205 diesel model with a rev counter, but it would involve changing the whole dashboard, so not happening!)

 

[Kayos]

They read off the alternator, might need some sort of booster or other box of tricks to convert to nice pulses

 

[m_c]

As @Kayos says, diesel tachs typically take a signal direct from the alternator.
You need an alternator with a W terminal, but I have no idea whether a standard tacho would work, plus you'd need a tacho that could be suitably geared to the alternator frequency.

 

[8ob]

All I have ever done is solder a wire onto one of the three phases in the alternator, that will pulse an electronic rev counter. Use the trim screw if it has one to calibrate.

Bob

 

[Fastdruid]

Is it not something that was an option on a better spec version?

If so you could look at the version with one and see how it was done. Or even maybe swap over the clocks.

 

[jerrytug]

Is it not something that was an option on a better spec version?

If so you could look at the version with one and see how it was done. Or even maybe swap over the clocks.

A sensor on the bellhousing which I dont have. Just looking for a simple way. I will try and look at my alternator.

 

[Ubique]

I've not fitted one for years, they're basically a frequency meter connected to the un-rectified output (or directly to the windings as noted above) of the vehicle alternator.
Here's an example on Amazon.

Rev counter for diesel display 52 mm for alternator, additional instrument, additional display, instrument speed rev/min RPM universal. : Amazon.co.uk: Automotive

Rev counter for diesel display 52 mm for alternator, additional instrument, additional display, instrument speed rev/min RPM universal. : Amazon.co.uk: Automotive

www.amazon.co.uk

No experience of that particular item though.

BTW, with diesels, 1st gear up to 10mph, 2nd gear up to 20mph, 3rd gear up to 30mph, 4th gear up to 40mph, 5th gear for everything above that will keep you in the peak torque range, all things being equal. Also makes engine braking more effective.

 

[jerrytug]

All I have ever done is solder a wire onto one of the three phases in the alternator, that will pulse an electronic rev counter. Use the trim screw if it has one to calibrate.

Bob

Ok thanks, my car has non-standard belts, alternator and engine.
If the frequency of alternator pulses was sensed, you would have to calibrate the tacho from the belt pulley sizes at best.
They are all random non -factory parts.
Alternator sensing must surely depend for its calibration, on the original factory-build alternator pulley sizes, but this is a random bitsa, built to approach a 1.6 GTi performance using a turbo diesel 1.9 (from a Xantia is the most likely) and the Citroen engine is shoehorned in.
Isn't there a tacho which can get a reading from a dab of Tippex on a rotating part? Optical sensor? I'm in unfamiliar territory.

 

[DanZac]

They read off the alternator, might need some sort of booster or other box of tricks to convert to nice pulses

Is that still possible on the modern alternators which have overrun clutches on the pulley? I guessing that under deceleration the alternator speed differs to the engine as it overuns?

 

[jerrytug]

Is that still possible on the modern alternators which have overrun clutches on the pulley? I guessing that under deceleration the alternator speed differs to the engine as it overuns?

Thanks but there is nothing so modern about this car All that overrun clutch slippage would be dealt with by software today, I guess, but I am retreating back into primeval basic 1980's technology

 

[Ubique]

Ok thanks, my car has non-standard belts, alternator and engine.
If the frequency of alternator pulses was sensed, you would have to calibrate the tacho from the belt pulley sizes at best.
They are all random non -factory parts.
Alternator sensing must surely depend for its calibration, on the original factory-build alternator pulley sizes, but this is a random bitsa, built to approach a 1.6 GTi performance using a turbo diesel 1.9 (from a Xantia is the most likely) and the Citroen engine is shoehorned in.
Isn't there a tacho which can get a reading from a dab of Tippex on a rotating part? Optical sensor? I'm in unfamiliar territory.

You calibrate at tickover, which can be determined either from the donor vehicle specification or measured with an old-style timing light, you don't need to be that accurate,TBH. Setting it to indicate 750-800 rpm at tickover with a warm engine will be close enough, it's an indicator gauge not a measurement device

 

[jerrytug]

I've not fitted one for years, they're basically a frequency meter connected to the un-rectified output (or directly to the windings as noted above) of the vehicle alternator.
Here's an example on Amazon.

Rev counter for diesel display 52 mm for alternator, additional instrument, additional display, instrument speed rev/min RPM universal. : Amazon.co.uk: Automotive

Rev counter for diesel display 52 mm for alternator, additional instrument, additional display, instrument speed rev/min RPM universal. : Amazon.co.uk: Automotive

www.amazon.co.uk

No experience of that particular item though.

BTW, with diesels, 1st gear up to 10mph, 2nd gear up to 20mph, 3rd gear up to 30mph, 4th gear up to 40mph, 5th gear for everything above that will keep you in the peak torque range, all things being equal. Also makes engine braking more effective.

Spot on with the revs Ubique, it's low geared and punchy, you don't get much chance to stay in 1st gear...by the time the pedal hits the metal you need second gear...it would be nice to have a tacho especially as, since I didn't pay much for this car and it has already been up-engined, I have sinful dreams of twiddling screws to liberate even more grunt..Lucas pump not Bosch but not interested in chip fat.

 

[jerrytug]

You calibrate at tickover, which can be determined either from the donor vehicle specification or measured with an old-style timing light, you don't need to be that accurate,TBH. Setting it to indicate 750-800 rpm at tickover with a warm engine will be close enough, it's an indicator gauge not a measurement device

Ok thanks

 

[Kayos]

Is that still possible on the modern alternators which have overrun clutches on the pulley? I guessing that under deceleration the alternator speed differs to the engine as it overuns?

Anything that modern and it will connect to the ECU

 

[bricol]

Can't remember the last time I looked at a rev counter in a car, other than to check it works, or to check the engine is actually running.

If I've got time to look down at it, I'm not driving hard enough

Only time I might have done in a slightly stressed fast driving moment would have been my first time sprinting my Westfield 30 yrs ago - putting a crash hat on suddenly muffled all the indications from the engine it was time to change up - hearing needed a lap or two to recalibrate.

 

[jerrytug]

Can't remember the last time I looked at a rev counter in a car, other than to check it works, or to check the engine is actually running.

If I've got time to look down at it, I'm not driving hard enough

Only time I might have done in a slightly stressed fast driving moment would have been my first time sprinting my Westfield 30 yrs ago - putting a crash hat on suddenly muffled all the indications from the engine it was time to change up - hearing needed a lap or two to recalibrate.

I scan the rev counter on my Audi, it's no effort, I feel informed and in control, what's not to like?.. and I sorely miss it on the Peugeot, (not so much on the Gardner 4LW...)

 

[rtcosic]

I am amused that current and previous cars both have rev counters.

Both are automatics.

This one has paddles the previous one had the much more useful J-Gate. Both have cunning Imps that either refuse to change down or automatically change up if the revs are inappropriate for the selected gear.

Still, it's the only way I can guess if the gearbox Imp has selected 6th, 7th or 8th. Not that it matters!

 

[Ubique]

I scan the rev counter on my Audi, it's no effort, I feel informed and in control, what's not to like?.. and I sorely miss it on the Peugeot, (not so much on the Gardner 4LW...)

Back in the day of rev counters being connected to the AC output terminal on the alternator, it was a useful indicator of charging problems if the rev counter was 'playing up' or not working at all. Sometimes it was just the indicator bulb blown in the dash or a wiring problem. IIRC old Massey-Ferguson tractors had a combined rev counter and speedo with the wheel speed scales printed on for the indicated rpm, they could have been mechanical from the back of the dynamo though...

 

[Agroshield]

For an overview of what is available, put 'bicycle rev counter' into Google and take your pick of many. Same thing available on eBay.

It would need to sense off the crank.

Avoid any that say 'inductive' in the description as you need a plug lead to wrap the sensor around. You need a Hall effect one.

E.g. https://www.amazon.co.uk/DIGITEN-Digital-Tachometer-Proximity-Switch/dp/B00VKAT8A2/ (needs voltage supply for sensor).

https://www.ebay.co.uk/itm/202055255777 (you calibrate these by putting in the wheel circumference, so with a bit of maths, it could go on any pulley, crank, alternator or water pump).

https://www.ebay.co.uk/itm/353640453428 (on this one, your aim should be to change gear when it reads 9999)

 

[jerrytug]

For an overview of what is available, put 'bicycle rev counter' into Google and take your pick of many. Same thing available on eBay.

It would need to sense off the crank.

Avoid any that say 'inductive' in the description as you need a plug lead to wrap the sensor around. You need a Hall effect one.

E.g. https://www.amazon.co.uk/DIGITEN-Digital-Tachometer-Proximity-Switch/dp/B00VKAT8A2/ (needs voltage supply for sensor).

https://www.ebay.co.uk/itm/202055255777 (you calibrate these by putting in the wheel circumference, so with a bit of maths, it could go on any pulley, crank, alternator or water pump).

https://www.ebay.co.uk/itm/353640453428 (on this one, your aim should be to change gear when it reads 9999)

That's great thank you. 'Change gear at 9999 rpm'