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You may (or might not) be right about 20mph being worse for emissions than 30mph.

Difficult to say whether or not for a given trip a higher number of total engine rotations is better or worse for total emissions for a given trip because emissions per rotation (firing cycle) will be different at different engine loads (and load isn't just about rpm, it's also about throttle position etc).

I know a bloke who years ago closed one direction of the M6 for a while after flipping his large caravan and Ford Explorer (not Gilbert lol). I asked him how he managed that, he said he was doing 90mph when all of a sudden it started snaking... But I've been in cars with him on test drives, wouldn't want to be in the car with him driving at the best of times and especially not while towing.

I was going on the cost per KWh figures, 29p for electric and 7.3p for gas.

Most of an engine's inefficiency is due to wasted heat (pumped out of the exhaust and sinked to atmosphere via the cooling system) but that heat need not be considered an inefficiency if the objective is to produce heat for heating and it can be captured.

Assuming the generator would be only around 33% efficient (gas KWh in to electric KWh out) it would be possible to generate electric at 21.9p per KWh, which in itself would be cheaper than buying electricity from the grid before even before thinking about making use of the heat that the generator's engine produced that would normally be wasted. Use the electricity generated to power a heat pump and make use of the engine/exhaust heat to heat radiators / hot water tanks directly.

I.e. Due to the difference in cost per KWh (gas vs electricity), for same cost we can use nearly 4 x as much gas as electricity. So even if a generator is only 33% efficient it still works out cheaper to make our own electricity at home using the genny than to buy it from the grid. But then the 67% usually considered the genny's inefficiency can be put to the same useful application as gas boiler.

The 'generator' wouldn't necessarily even need to generate electricity, it could run the heat pump directly from the engine. Unless you want to produce a lot of cheap (compared to grid price) electricity, maybe to charge an EV or large household battery powered invertor system from.

Burning gas is the most common method the UK grid uses to generate electricity anyway and they make a profit burning gas to make electricity to sell to you despite grid transmission losses (all those power lines and transformers waste heat to atmosphere).

I know it wouldn't be in the environmental spirit but could it work out cheaper (than using electricity) to drive the heat pump using an efficient engine fuelled by mains gas? It would also be possible to make use of the coolant heat (instead of having an engine radiator) and the exhaust heat.. Could maybe even run an alternator from the same engine to get cheaper electricity too.

Heh, thought once occurred that maybe it would be possible to claim to have had solar panels fitted (while not actually spending any money on them because none were bought), set up a genny running from mains gas, sell the leccy it made back to the grid (feed in tariff) claiming it was produced by solar panels.

Both of the above taking advantage of the kwh price difference between mains gas and electric.

Probably best to fit a replacement torque convertor at the same time if the fluid is full of bits?

Years ago I bought 2 x Rover V8's (old 3.5 motors), at that time I was fit and could carry one by myself, wouldn't be able to do it now lol.

Thanks Gilbert

How are the systems reversed (heat / cool a room) ?

karlos01 wrote:

hoping to get my 4.2 supercharger back on LPG so will give it a look
@Lpgc I did drop you a dm about my lpg

I have just replied to your PM Karl, sorry it comes late.

Regards, Simon

karlos01 wrote:

hoping to get my 4.2 supercharger back on LPG so will give it a look
@Lpgc I did drop you a dm about my lpg

I'll check my PMs now Karlos.

On a different forum someone posted this link to a 'save LPG' petition https://chng.it/JByWb6c6zw

I'm not sure who they're going to send it to etc but I've signed it and I thought others running on LPG might want to sign it too.

I've also posted about this on LPGforum

How are the systems 'put into reverse' to switch between heating/cooling a room? Does the motor spin the other way / done by changing which jets the refrigerant flows through / valve arrangement on the pump and/or evap / condenser? Are they by design more efficient at heating or cooling a room (and jumping the gun a bit maybe - are the evaporator and condenser the same size, even perhaps the same part number?).

It is an interesting subject.

I wondered about setting up a makeshift system for the house or caravan using car parts... possible? I could work it out but if you have the answer already you'll save me the job lol - How powerful an electric motor would be needed to drive a car AC compressor? I know another motor or 2 would be needed to push air through the evaporator and reducer. Maybe use Hanson quick release fittings to make for a portable system?

For the domestic systems (and I suppose EV systems which can also supply cold air or heat?) how is the system reversed... Surely not as simple as reversing the pumping action / spinning the motor the other way?

How much does external temperature affect the efficiency?

Not saying this is the case... but if it were very efficient at heating a room from 20C to 25C when external temp is 20C but on the other hand far less efficient at heating a room when external temp is 5C it wouldn't be as real world efficient as the first set of numbers would suggest (nobody would even use a heater when external temp is 20C).

I've had a bit of experience with heat pumps used to heat radiators, in mild external temperatures no problem getting the radiators hot, in winter when you need them all the radiators just luke-warm. Probably due to the heat pump system not being big enough for the job of heating all the rads in cold external conditions though might have been big enough to heat one room?

Yes, an emulator or perhaps just a relay that broke the positive connection to petrol injectors...

Easy enough to recheck how you did petrol injector breaks... If channel routing is OK then petrol injector breaks must match respective gas injector outputs and you can see which engine cylinders gas injectors are piped to (heh sorry for teaching sucking eggs).

Thanks Chris.

Apologies if already said but is it a case of no power to the OBD socket, or power is there (so Nano comes to life) but still no coms Bri?

I don't know if the Nano gets it's power from the OBD socket? Or if it doesn't whether or not it signals there is power to the OBD socket (if it gets it's power from OBD the obvious signal would be it wouldn't even turn on if not connected to OBD but if it doesn't get it's power from OBD it will turn on anyway but is there some way it signals there is power at the OBD)? Does a different code reader that gets it's power from the OBD socket at least turn on if plugged in?

I haven't looked at any wiring diagrams... But as memory serves I believe the Thor has a separate positive feed to injectors on bank 1 versus bank 2? Implying that at least the problem for several cylinders being reported as no injection pulse by the LPG ECU could be explained by lack of positive to respective petrol injectors. The problem with that theory is that LPG ECU channels 2456 probably don't all fall on one cylinder bank unless you've wired the LPG petrol injector break wiring up unusually. I don't know where the OBD port gets it's live feed from but would doubt it'd be from the same positive feed that provides 12v to petrol injectors on one of the banks.

Did this car previously have an LPG mixer system fitted?

Ahh I was thinking Gems in the point about Thor... But maybe they both have separate positive feeds to injectors on different banks (at least as far as a joint in wiring near the firewall)?

2 Of my cars are Jap imports and not usually listed on automated machines, a sticker under the bonnet says they should take 950grams of refrigerant.

Some firms charge one price for a recharge with up to 1kg of refrigerant, a higher price for more than 1kg. Got to wonder how wide spread this practice is and whether the vehicle manufacturer calculated that the ideal amount of refrigerant should really be 1050grams but went with 950grams to save dealers/customers money in future or to meet some sort of 'green' criteria?

How accurate are the machines at measuring weight of gas they recover and refill with?

I do use a Kwik Fit for AC charging but at this Kwik Fit they let me watch and give a little input, so I can make sure they set the machine to charge with 950grams (or a bit more). A lot of these places normally make customers wait in a lounge but if you turn up in overalls and work boots, explain that you're a mechanic (you're not going to break your ankle tripping over MOT brake rollers etc), understand the AC system and personally replaced components on it, have some concerns about it or how it's to be filled etc, some will let you watch the technician do the work. Or go somewhere else..

I can see the nitrogen test makes sense if the system is suspected of having a leak, because it is possible for a vacuum to close a leak only for the leak to return when the system is under pressure (although a vacuum test will still find the vast majority of leaks?). But surely if your aircon is still working OK a few years after it's last maintenance/regas (so the only reason for a regas is maintenance) there won't be a leak and the nitrogen test isn't necessary? While the system still needs to be vacuumed to get all the old stuff out?

If you've had a leak on an AC system and some of the oil has been lost, how do you know how much oil should be put in (besides obviously the amount of oil that was recovered by the machine) when recharging? Don't machines just put the same amount of oil back in that they recovered (and although they can recover all the gas they can't recover all the oil)?

Sorry if a bit off topic...

Years ago an ex's uncle was a rep for an engineering firm. His firm 'designed' a system that allowed hydraulic systems on vehicles such as cranes (Palfinger type) to be powered by the vehicle engine instead of by a separate engine or an electric motor. He started describing how this system worked... a hydraulic pump driven by the engine but which could be disconnected from the engine (so the pump wasn't running all the time) just by pressing a button on the dash. "What, like an AC compressor clutch?" I asked. '"Yes just like one of those"... And he got a £50k bonus on top of his salary for selling such systems to fleet managers, seemed like his job was too easy...

I'm afraid I wouldn't have been travelling with Rob, not particularly big but heavy lol.

Gilbertd wrote:

We even had a chart in the office of how much each of us weighed so we could match who could travel together too.

Clients always did wonder why your works always sent a little and large team out to visit them lol

Hypothetical situation... What would happen if you got flagged onto a weighbridge but the passenger got out and just walked away. Would they have the legal authority to stop the passenger walking away, assume a weight for him, or just have to go on the weight they could measure. You could say 'Ahh that was John, he looks burly but only weighs 4 stone and those heavy duty looking bags he was carrying were lightweight PVC and full of kids balloons'.