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Need a rev counter and water temp? Read this!

53K views 60 replies 21 participants last post by  Anonymous 
#1 ·
Haven't ordered my cactus yet but gave it a good test drive. The lack of a rev counter worried me a litte, especially since the engine is rather quiet and I was surprised I was already at max rpm once. Haven't driven a turbo engine in a while and the 110 HP petrol engine really does have a rather flat torque curve from 2000 rpm up so it's hard to judge when you're actually maxing it out. Some people around here (Munich, Germany) have the habit of going full throttle when you're doing a lane change in town right as you go in front of them... as if they wanted to push you out of their lane. So having some rpm reserves available really helps. Same for highway overtaking, I don't wanna hurt that little engine by pushing it too hard, especially when it's not heated up yet.

Solution: OBD2 heads up display:


You plug it into the green diagnostics port (under the steering column) and it displays the information from the CAN bus, things like engine RPM, coolant temperature, battery voltage, etc. You put it on the dashboard and the light bounces off the windscreen and you have it right in your field of vision so you don't have to shift your vision to know what's up.

There's ones that display more information, but usually with quite a delay or updating only once every half second or with just one LED per 1000 rpm (i.e. useless). This "X3" model cost me 19€ shipped and does all I need. horizontal rpm bar on the top (accurate and fast enough to be useful) and some bar graphs for water temp and battery voltage. You can also have it beep at you if you go over a a set speed or rpm (that's what the other bar graphs are for). You can calibrate the rpm and speed readings, defaults were spot on equal with the dials in the car but you can also adjust it. You can press the button on the side to have the bit digits show either speed (kph or mph), water temperature (°C or °F) or battery voltage. It turns on and off automatically by the way.

Now the cool thing about the cactus is the LCD display above the steering column. It's nice and shiny and I think it should reflect light just right. on the top right, above the shift indicator, it doesn't really show anything besides the check engine light. I think you could mount the X§ HUD unit on the steering column in a way that the rpm bar reflects on the top right of the dash, i.e. above the shift indicator. just block out the stuff you don't need on the X3 with masking tape and boom, there's your rev counter and water temperature.

If that doesn't work, you can also put it behind the dashboard LCD and have it reflect off the windshield. Or you could just stick it behind the LCD so just the rpm bar sticks out either on top or to either side of the display if you don't mind having the little markers be in reverse writing.


Here's a good review video of that unit and I must say, I'm very impressed with mine, works great even when it's quite sunny outside:

There's also the X6 which seems to have a similarly good response time and rpm resolution. RPM display is round and adds a consumption meter as well.:

Here's an example of a bad one, way too much info, distracting colors and updates the information only every half second

If you try this out on your cactus, please post pictures of the different mounting options. If the cover over the OBD port doesn't fit back because the OBD plug is too thick, go get an extension with plat plugs on eBay or Amazon:
 
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#27 ·
berapotter said:
Rev counter would also allow me to use max torque as I wouldn't be able to feel or hear that. (apart from that gentle shove in the back) :lol:
surely part of the benefit is to effectively use the performance of the engine not necessarily to thrape the nuts off it.
to drive economically its an invaluable aid.
still I've only been driving for 40 years (cars and bikes) and teaching motor mechanics, so what do I know :lol:
Very true ...but only been driving 26 years :D
 
#28 ·
If you want to rev your engine no more than 4000 RPM, remember these numbers-

Do not drive over 21 mph in 1st ie 38 kph
Not over 39 mph in 2nd ie 63 kph
Not over 63 mph in 3rd ie 101 kph
4th and 5th ar overdrive ratios.

Calculations are for 110 HP Turbo petrol, manual gearbox, 16 in wheels.

To make it easier to remember- 20-40-60 in mph or 40-60-100 in kph. :D
 
#29 ·
Primekart said:
If you want to rev your engine no more than 4000 RPM, remember these numbers-

Do not drive over 21 mph in 1st ie 38 kph
Not over 39 mph in 2nd ie 63 kph
Not over 63 mph in 3rd ie 101 kph
4th and 5th ar overdrive ratios.

Calculations are for 110 HP Turbo petrol, manual gearbox, 16 in wheels.

To make it easier to remember- 20-40-60 in mph or 40-60-100 in kph. :D
Bloody hell!!! I'm in 5th gear by the time I reach 39 mph
 
#32 ·
i agree a rev-counter would be nice on the 3cyl especially. There are certain harmonics with this engine that make it difficult to figure out where in the rev-range it might be. Add in the low-down torque and you can just surf around at reall low revs (i think that's how they eeked 50+mpg out of it) but i occasionally rag the nuts off mine and it'd be nice to know a bit more info. (yes i realise it's not a sports car but i like cars)
 
#33 ·
From another post I got the 5th gear mph/1000, however whenever I accelerate hard the gear change indicator is so annoying - when I change up to 5th at 50mph, and also the performance shifts in the interim too! I would like to see a rev counter, but as often mentioned this is not a performance car at all, even if the 110 cracks in 60mph in under 9 seconds. Whilst I have another car for fun, this is an unfortunate consequence of Citroen deliberately deciding not to promote this car as a performance car. Maybe a new model with a 130 version of this engine (as in other PSA models) might give us a rev counter?
 
#34 ·
The2ems said:
Primekart said:
If you want to rev your engine no more than 4000 RPM, remember these numbers-

Do not drive over 21 mph in 1st ie 38 kph
Not over 39 mph in 2nd ie 63 kph
Not over 63 mph in 3rd ie 101 kph
4th and 5th ar overdrive ratios.

Calculations are for 110 HP Turbo petrol, manual gearbox, 16 in wheels.

To make it easier to remember- 20-40-60 in mph or 40-60-100 in kph. :D
Bloody hell!!! I'm in 5th gear by the time I reach 39 mph
That might turn into a post-it note on my dash. And yes, city cruising worked well in 5th gear on the turbo petrol cactus. cruise control had no trouble on overpasses or turns. My normal driving is right up to 2000 rpm when the engine is broken in.

I hear the puretech has 2 cooling circuits and warms up rather quickly so the water temp gauge might really be unnecessary. I'd still would have welcomed that blue warning light many cars seem to have now to tell you "take it easy, engine still cold".
 
#36 ·
Ok just a quick note about fitting a HUD.
1. The ODB2 socket is on the passengers side on the UK model.
2. Autodata shows it to be on the steering column, it's not. Your local non dealer garage might need to know this at some point
3. The lead supplied with my X5 model is ridiculously short, so you will need an extension male to female ODB2 cable
4. It will need to be a 90 degree flat socket (£3.99 Amazon) because the panel won't fit back properly with a standard cable fitted.
Just thought I'd share!
 
#37 ·
berapotter said:
Ok just a quick note about fitting a HUD.
1. The ODB2 socket is on the passengers side on the UK model.
2. Autodata shows it to be on the steering column, it's not. Your local non dealer garage might need to know this at some point
3. The lead supplied with my X5 model is ridiculously short, so you will need an extension male to female ODB2 cable
4. It will need to be a 90 degree flat socket (£3.99 Amazon) because the panel won't fit back properly with a standard cable fitted.
Just thought I'd share!
Makes sense for it to be on the passenger side on the right-hand drive models. Typically glove boxes can't even fit the car's manual on the UK versions because the fuse box and other stuff doesn't switch sides along with the steering wheel and pedals. Most documentation and manuals assume you have the left-hand drive version except some Japanese makers.
If you get a HUD with MPG indicator, I'd guess it gives you the number for american gallons, not british ones.
I wonder if the MPG in the cactus knows the difference between british and american gallons... even though PSA doesn't sell cars in the US, the guys who they outsourced the touch screen interface to might not know the difference.

Primekart said:
You have the "blue warning", sort of...
Just look at the S&S "button ". If it shows the yellow bar, engine is cold and the S&S system will not start.
Nice find. It's not directly in view but better than nothing. I wish there was a menu page for displaying some basic diagnostic info like temperatures, rpm, boost pressure, tire pressures and error codes. That would be more appropriate than the calculator and calendar. :lol:
 
#38 ·
I agree about the passenger side. but I thought I'd check on Autodata (which is industry std) and it clearly shows it on the right hand side.
after I took the panel off it deffo wasn't there. so I whipped the other panel off and tahdah! there it was with little or no space between the panel and the socket.
that said it all worked!

whats the percentage difference between US mpg and imperial mpg?
 
#39 ·
berapotter said:
3. The lead supplied with my X5 model is ridiculously short, so you will need an extension male to female ODB2 cable
4. It will need to be a 90 degree flat socket (£3.99 Amazon) because the panel won't fit back properly with a standard cable fitted.
Thank you!
How long does the extension cable need to be? Have you been able to hide the connector between the X5 and the extension?

Where have you placed the X5 unit? I'm guessing that for the display to be in a sensible place on the screen it needs to be on the forward raised part of the dash, near the air vent? If so, that's a shame because if it could be just in front of the speedo screen it'd be invisible to the driver.
 
#41 ·
OK, I've got an X5 unit now and set it up last night. It's great! Bit of a novelty but it works perfectly. I've set it to show engine temp below the revcounter scale. (84 degrees in this photo.)



The OBD cable isn't long enough, so you will need an extension with a low-profile plug.



It's just about bright enough in sunlight. Sits neatly at the bottom of the screen, where the display is visible without being intrusive. For £17 delivered it's well worth it. My only criticism is that the revcounter markings are quite coarse (every 250), which means at low engine speeds you can't see much detail. But it helps me to discover the minimum speed available in each gear, and when to change up.

I haven't discovered the rev limiter in this car yet, but over 4k rpm it sounds like it's getting close!
 
#42 ·
Well done, the pictures are really much appreciated. Here's what I found out about the X5 unit using it in my current car (Peugeot 207 CC, oddly enough built side-by-side with the C4 cactus in the same factory):

1) Didn't think it was possible to put the cover back on with the OBD cable plugged in. But those ultra cheap cables from Hong Kong did the trick, just put the excess cable in there with all the other wires and put the lid on.

2) The default multipliers for rpm and speed are set too high (so people don't speed). When I set the multiplier for speed to 100, it exactly matches the GPS numbers. If set by default, it read 160 when I was going 140 kph... yikes. Keep in mind the car's electronics doesn't know how big the tires are so the accurate multiplier for the shown speed might be anywhere between 98 and 102%, set it to something higher than 100 if you're not sure. 100% for the rpm appears to be dead on accurate for me, right up to the red line.

3) Hold the rocker-switch up to mute the speaker. That also makes the volume indicator disappear which cleans up the information a bit and it doesn't beep at you when you surpass 7500 rpm (the max rpm you can set for the alert is "75" which is 7500 rpm and that factors in the multiplier (117% by default), so in reality it's much lower.

4) If your mom is in the passenger seat, lower the multiplier for speed. :p

5) The reflections from the sun and tunnel lighting is slightly less annoying when you take the screen protector off.

6) You might want to set an alarm on the rpm right above 5500 rpm for the turbo petrol. According to this site, 5500 rpm is where this this engine has max horsepower: http://www.automobile-catalog.com/car/2015/2085905/citroen_ds3_puretech_110_sochic.html

7) Use this HUD display to learn the car and get the most out of it. It is actually quite fun to drive when you know it well. It can be distracting and the cactus is all about taking distractions away.
 
#44 ·
#45 ·
SiliconS said:
Crowbar said:
According to this site, 5500 rpm is where this this engine has max horsepower: http://www.automobile-catalog.com/car/2015/2085905/citroen_ds3_puretech_110_sochic.html
Thanks for that link. Here's the chart for my Puretech 82 engine. Peak torque is 2500rpm upwards:
http://www.automobile-catalog.com/curve/2016/2085500/citroen_c4_cactus_puretech_82.html :geek:
Thanks, I thought I saw torque curves on that website somewhere. Here's the ones for the 110:
http://www.automobile-catalog.com/curve/2016/2085530/citroen_c4_cactus_puretech_110.html

Too bad they don't have the redline numbers. I guess what they do is just look at where the red mark on the actual tachometer starts. Attached is a pic of a Ford F-150 pickup truck. "No redline, it just revs forever". :D

Looks like peak power for the 82PS is 5750 and 5500 for the 110PS (it says it on the top of the chart).
 

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#46 ·
NickKK said:
Dadioglasgow said:
The Cactus has a built in rev limiter, so it is unlikely you would be able to exceed the maximum permitted rpm even if you tried...
Dadio, where have you seen that information?
Does it mean, that it is impossible to turn up rev in any gear, so much it would have damaged the engine?
Does this apply to all models (engines)?
Kinda yes with all modern engines the throttle is not mechanical and the engine management system limits the revs, in my current car I can drive with my foot flat and each time I push down the clutch the revs leap to 6.5k and stay there until I come off the clutch. It's an Aygo by the way (I am looking at switching to a Cactus atm).
 
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