Need a rev counter and water temp? Read this!

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Crowbar
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Need a rev counter and water temp? Read this!

Post by Crowbar » Sat Jun 11, 2016 8:37 am

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: Image

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.
Image

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: https://youtu.be/hw3qp97Gp7g

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.: https://youtu.be/7LzDh0S8YGE

Here's an example of a bad one, way too much info, distracting colors and updates the information only every half second https://youtu.be/cfUmRj976qE

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:
Image

SiliconS
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Re: Need a rev counter and water temp? Read this!

Post by SiliconS » Sat Jun 11, 2016 8:58 am

That's pretty awesome, and for a surprisingly low price. I'm tempted. Thanks for the info.
I've been convinced that an RPM app must exist for my phone though, which (with a bluetooth ODBII dongle) would achieve the same thing, since my phone is always in its cradle on the windscreen.

Edit: Found the X5 online for £18 delivered: http://www.gearbest.com/car-audio/pp_237573.html
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davew
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Re: Need a rev counter and water temp? Read this!

Post by davew » Sat Jun 11, 2016 9:45 am

This idea has previously been discussed, written up and implemented - might be interesting to compare.

viewtopic.php?f=11&t=448

The2ems
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Re: Need a rev counter and water temp? Read this!

Post by The2ems » Sat Jun 11, 2016 10:26 am

Sorry, but I don't understand why you need a rev counter to tell you how fast you are going, or how fast the engine is going. You can feel it.
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Primekart
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Re: Need a rev counter and water temp? Read this!

Post by Primekart » Sat Jun 11, 2016 11:43 am

I have installed the OBD extension cable, linked it to a wifi dongle and used DashCommand on my iPhone. The engine temperature is stationed between 95 to 100 degrees C. The engine turns at 2100 RPM in 5th gear at 110 KpH. There is no need to accelerate the engine over 4500 RPM. After i got accustomed the the engin's noise, i have disconnected the OBD link.
This is not a sports car and it is designed and built for comfort.
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Crowbar
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Re: Need a rev counter and water temp? Read this!

Post by Crowbar » Sat Jun 11, 2016 10:50 pm

well, occasionally you need to rev it to overtake quickly and safely. I like having lots of headroom when overtaking for safety reasons. The cactus has unusually long gears and down-shifting smoothly (with rev matching) is tricky but it can be done. Makes the clutch last forever as well. Water temperature lets you know when you can go fast without hurting the engine. Driving slow on the autobahn during commuting hours is quite dangerous, people see you as an obstacle and do dumb things around you. You gotta keep with the herd or get stepped over.

The cactus is actually surprisingly agile and predictable. Pendulum turns are effortless, appropriates brakes (drums on the rear worked great on the turbo petrol), suspension is soft yer firm enough in evasive maneuvers, stability control does its job without being annoying, goes straight as an arrow when driving through a puddle on just one side. It's a fantastic balance between comfort, economy and fun, the simplified and low dashboard really does a lot in terms of being relaxed. Not a fan of the stock (Kleber) tires in the rain though, I'd hate hitting a deer or smartphone-zombie because it was raining a bit. I wonder if you have different ones in the UK market.

There's loads of OBD2 apps for smart phones, there's even ones that play silly supercar engine noise matching your engine rpm (albeit on quite a delay), in general very useful for trouble codes and finding issues before they get serious.

Dadioglasgow
Posts: 265
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Re: Need a rev counter and water temp? Read this!

Post by Dadioglasgow » Sun Jun 12, 2016 11:14 am

Crowbar wrote:well, occasionally you need to rev it to overtake quickly and safely. I like having lots of headroom when overtaking for safety reasons. The cactus has unusually long gears and down-shifting smoothly (with rev matching) is tricky but it can be done. Makes the clutch last forever as well. Water temperature lets you know when you can go fast without hurting the engine. Driving slow on the autobahn during commuting hours is quite dangerous, people see you as an obstacle and do dumb things around you. You gotta keep with the herd or get stepped over.

The cactus is actually surprisingly agile and predictable. Pendulum turns are effortless, appropriates brakes (drums on the rear worked great on the turbo petrol), suspension is soft yer firm enough in evasive maneuvers, stability control does its job without being annoying, goes straight as an arrow when driving through a puddle on just one side. It's a fantastic balance between comfort, economy and fun, the simplified and low dashboard really does a lot in terms of being relaxed. Not a fan of the stock (Kleber) tires in the rain though, I'd hate hitting a deer or smartphone-zombie because it was raining a bit. I wonder if you have different ones in the UK market.

There's loads of OBD2 apps for smart phones, there's even ones that play silly supercar engine noise matching your engine rpm (albeit on quite a delay), in general very useful for trouble codes and finding issues before they get serious.
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...
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carson
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Re: Need a rev counter and water temp? Read this!

Post by carson » Sun Jun 12, 2016 6:58 pm

dadio,
please, do you have to repeat how you were a rally driver with good hearing and no one ever needs a rev counter when so many disagree with you?

Dadioglasgow
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Re: Need a rev counter and water temp? Read this!

Post by Dadioglasgow » Sun Jun 12, 2016 7:09 pm

Simply stating a fact...
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NickKK
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Re: Need a rev counter and water temp? Read this!

Post by NickKK » Sun Jun 12, 2016 8:13 pm

Dadioglasgow wrote: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)?
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