Canems Rev Counter Mod

Canems Rev Counter Mod

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ChimpOnGas

Original Poster:

9,637 posts

178 months

Monday 29th September 2014
quotequote all
Saw this at the Neil Garner day on Lloyd Specialist Developments stand. Apparently this clever little box of electronics solves the bouncing tacho problem that's the only frustration I've had since moving to the excellent Canems engine management system. Configured specifically for the TVR Caerbont rev counter the little box gets fitted in three weeks time so I'll report back here on how it performs. Dave

SILICONEKID345HP

14,997 posts

230 months

Monday 29th September 2014
quotequote all
[quote=ChimpOnGas]Saw this at the Neil Garner day on Lloyd Specialist Developments stand. Apparently this clever little box of electronics solves the bouncing tacho problem that's the only frustration I've had since moving to the excellent Canems engine management system. Configured specifically for the TVR Caerbont rev counter the little box gets fitted in three weeks time so I'll report back here on how it performs.
Dave[/quote ?

Will it work with the Emerald ?

Hoofa

3,151 posts

207 months

Monday 29th September 2014
quotequote all
Emerald did a similar box but didn't work that well to be honest, in the end I sent the Rev counter to speedy cables to get it converted and it's been spot on since.

gacksen

680 posts

142 months

Monday 29th September 2014
quotequote all
ChimpOnGas said:
Saw this at the Neil Garner day on Lloyd Specialist Developments stand. Apparently this clever little box of electronics solves the bouncing tacho problem that's the only frustration I've had since moving to the excellent Canems engine management system. Configured specifically for the TVR Caerbont rev counter the little box gets fitted in three weeks time so I'll report back here on how it performs. Dave
sounds strage. mine does not jump but it´s a 94

Sardonicus

18,928 posts

220 months

Monday 29th September 2014
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You don't need a circuit as complicated as that link to sort the Caerbont gauge and wasted spark waving needle syndrome, but a more complex circuit probably won't do any harm the components cost shirt buttons only, a diode only circuit is ste and won't work properly i.e the early MS drawings on the subject.

ChimpOnGas

Original Poster:

9,637 posts

178 months

Wednesday 27th May 2015
quotequote all
Just to update this post, I'm pleased to confirm the Canems rev counter mod works a treat and completely solves the jumping & inaccurate rev counter needle issue.

The story wasn't quite as straightforward as I'd hoped, but did demonstrate the commitment of Lloyd Specialist Developments in partnership with Canems to us lot in the TVR community.

Firstly the box of electronics was specially designed for the TVR Caerbont rev counter, it is not a generic solution for anyone running an aftermarket ECU but is a specifically developed fix for Chimaera & Griffith owners running the combination of a Canems engine management system & a Caerbont tacho.

Secondly I have an early Canems ECU which as it turns out was not compatible with the clever box of electronics in question, I guess it was designed after one of the many evolutionary upgrades that reveals David Hampshire's total commitment to the continual development of his excellent products.

The solution came in the form of a new exchange ECU simply because that's easier and faster than sending my current one away for an upgrade, at this point it made sense to ask David for the addition of two extra inputs I wanted to experiment with (LPG pressure & LPG temperature).

The end result is a rev counter needle that's more accurate, faster to respond and smoother than back in the 14CUX days biggrin

And what of the gas pressure and temp inputs?

Well that's for another post, but suffice to say those two clever compensation tables in the Canems software seem to be delivering an even smoother drive and another useful slice of economy.

'Ol Gas Bag' she just gets better & better, next stop Le Mans thumbup

In true Top Gear challenge tradition the plan is to attempt the 381 driven miles from Hertfordshire to Arnage on one forty quid 65 litre LPG fill, driving at a steady 80mph plus...tongue out

Current estimates say I'll run out of gas and be forced to flick to petrol just 13 miles short of our destination rolleyes

But who knows, the "TVR to Le Mans on £40 of fuel" challenge may just happen.

Watch this space wink

Edited by ChimpOnGas on Wednesday 27th May 18:54

gacksen

680 posts

142 months

Wednesday 27th May 2015
quotequote all
ChimpOnGas said:
And what of the gas pressure and temp inputs?

Well that's for another post, but suffice to say those two clever compensation tables in the Canems software seem to be delivering an even smoother drive and another useful slice of economy.
you mean they put in some new temp and pressure running corrections ?

ChimpOnGas

Original Poster:

9,637 posts

178 months

Wednesday 27th May 2015
quotequote all
gacksen said:
ChimpOnGas said:
And what of the gas pressure and temp inputs?

Well that's for another post, but suffice to say those two clever compensation tables in the Canems software seem to be delivering an even smoother drive and another useful slice of economy.
you mean they put in some new temp and pressure running corrections ?
Correct, the additions were made on my instruction & based of the fact I have long know nailing AFRs to be the secret to great LPG drivabiity, fuel economy & power.

We all know it's the same of petrol, but the thing is you notice it soooo much more on gas yes

Why is this confused

Well a gaseous fuel is subject to far greater fluctuations in volume than a liquid fuel, and volume changes quite simply & directly relate to AFR changes.

Q: What are the key influences on LPG volume?

A: Fuel Pressure & Fuel Temperature

Warm a bowl of water gently and you'll notice it's volume really doesn't change much, blow up a party balloon outside on a cold day & measure it, then go inside in the warm and measure it again. You'll be surprised how much bigger that party balloon has grown, what you're witnessing is a temperature influenced volume increase of the gas trapped inside that party balloon (in this case air).

LPG is just another gas so its behavior is exactly exactly the same as the air inside that party balloon, it's volume goes up & down like a haw's draws with very small changes in ambient temperature & pressure and this is what's screwing up your open loop mapped AFRs.

As a consequence open loop mapping those AFRs on LPG is a tricky (read impossible) art to master mad

In fact it's so tricky we discovered the only way to deliver any meaningful consistency was to to let the ECU reference lambda feedback and make the corrections multiple times a second (closed loop).

I spent many frustrating hours polishing the early open loop map only to find it all changed dependent on ambient conditions. Just when I thought I'd nailed it it would go all Pete Tong again so mapping became a frustrating process of chasing shadows.

As I say the answer came in the form of closed loop, but closed loop (as effective as it is) is a post combustion correction strategy. Essentially it's working with a waste product (oxygen content in exhausts gas) so the corrections made are based on yesterday's news and an assumption conditions are going to be exactly the same for the next combustion event.

That's a bit like making your investment decisions based on what the stock market was doing yesterday.

So what if you knew the gas pressure had fallen by say 25kPa, and you knew the gas temp had gone up by 10 degrees, finally & most importantly what if you knew all this before it even reached the injector?

Better still, what if you could then alter the injector durations to compensate for these changes thus ensuring the volume of LPG you're metering into the inlet manifold always remains consistent and in line with your given engine load, throttle opening, engine coolant & RPM inputs?

Keep the closed loop post combustion correction strategy in place with its clearly defined AFR targets and you can polish off and perfect what are already near as damn it the perfect pre combustion corrected AFRs.

The ECU has less work to do and it's doing the lion's share of the correction work before the fuel is even struck. Factor in some clever 3D ignition mapping that ensures you're embracing the very different burn characteristics of propane and you end up with absolute optimum LPG efficiency.

And efficiency doesn't just mean boring old fuel economy folks , it also means engine power and fat wads of creamy smooth torque too wink

What you end up with is the smoothest, most economical and still deceptively fast TVR you could ever wish for cloud9

LPG is funny old stuff, making it work properly is by no means impossible, it's all about compensation strategies and making super fast corrections on the fly.

Only a clever ECU with a decent processor referencing the right input data and making the correct rapid adjustment has any chance of doing this yes

Edited by ChimpOnGas on Wednesday 27th May 20:11

gacksen

680 posts

142 months

Thursday 28th May 2015
quotequote all
ChimpOnGas said:
I spent many frustrating hours polishing the early open loop map only to find it all changed dependent on ambient conditions. Just when I thought I'd nailed it it would go all Pete Tong again so mapping became a frustrating process of chasing shadows.
except of the pete tong part i kinow exactly what you mean biggrin

the map seems to be an ongoing process of things you find out
by yourself. after reading your post your wideband is connected
to the ecu then ? mine is not but sooner or later will change
that and i know quite good about chanseing numbers in regards of the afr.
it´s a chase you seldom win as the weather and fuel changes biggrin
currently it is running on open loop and quite happy with that.
T350 with canems is running closed loop until a certain point
and this refines the drive as you have already written.

interessting project btw. since i have bought a new TomTom Rider nav
for the chim my fuel consumption is north of 25L/100km if you push it.

ChimpOnGas

Original Poster:

9,637 posts

178 months

Thursday 28th May 2015
quotequote all
gacksen said:
ChimpOnGas said:
I spent many frustrating hours polishing the early open loop map only to find it all changed dependent on ambient conditions. Just when I thought I'd nailed it it would go all Pete Tong again so mapping became a frustrating process of chasing shadows.
except of the pete tong part i kinow exactly what you mean biggrin

the map seems to be an ongoing process of things you find out
by yourself. after reading your post your wideband is connected
to the ecu then ? mine is not but sooner or later will change
that and i know quite good about chanseing numbers in regards of the afr.
it´s a chase you seldom win as the weather and fuel changes biggrin
currently it is running on open loop and quite happy with that.
T350 with canems is running closed loop until a certain point
and this refines the drive as you have already written.

interessting project btw. since i have bought a new TomTom Rider nav
for the chim my fuel consumption is north of 25L/100km if you push it.
Pete Tong = rhyming slang for "Wrong"

http://en.wikipedia.org/wiki/It%27s_All_Gone_Pete_...

I've been delighted with my switch from closed loop to open loop, and on LPG it's virtually essential. The LPG temperature & pressure correction strategies are an effective further development and have proved very worthwhile.

Next up I'll be swapping out the rather basic but reliable 1.90 Ohm Magic Jet LPG injectors I've been running over the last year for a set of more sophisticated cylinder type Hana Golds.

In the early days of my dual fuel conversion I ran some lovely & rather expensive Keihin cylinder type injectors. The Keihins are fantastic injectors, allowed cold starts on LPG and gave a very refined drive, sadly being 1.25 Ohm their impedance was just too low for the Canems LPG injector drivers causing them to overheat & fail.

David Hampshire from Canems has now fully tested the 1.90 Ohm Hana Gold cylinder type injectors with his dual fuel ECU and given them the all clear, so these beautifully engineered LPG injectors will be my next development.

The theory is I'll get all the benefits of the Keihins with the reliability of the Magic Jets.

I'm confident the Hana Golds will work a treat, but lets see how I get on with some real world testing and I'll leave that until after Le Mans.






pjac67

2,040 posts

251 months

Thursday 28th May 2015
quotequote all
Hurry up and finish your R&D Dave before I book mine in with the Lloyds boys.....

ChimpOnGas

Original Poster:

9,637 posts

178 months

Thursday 28th May 2015
quotequote all
pjac67 said:
Hurry up and finish your R&D Dave before I book mine in with the Lloyds boys.....
Excluding the final 1.90 Ohm Hana Gold cylinder type injector testing it's all there ready to enjoy.

Even with the rather crude Magic Jets its already a dream to drive.

One last injector change and I'll be finished with the tweaking, but a few days later it'll be time to pull the trigger on liquid LPG injection, after years of issues the liquid injection components like the high pressure pump are finally becoming reliable.

When that happens you can take over my fully developed turn key gaseous system at a small discount wink

Gas is good, however keeping it all compressed in it's liquid state right up to the injector is even better biggrin