Chatsworth conversation electric water pump. Green Griff

[britpower100]

Hi,

To the chap with the green Griff parked next to my Chimera, here is a link to a similar water pump I was discussing.

http://www.ebay.co.uk/itm/VW-CORRADO-2-9-VR6-ELECT...

Sorry had to dash off family issues required our attendance.

All the best

Andy.

[Alan461]

Thanks for that, I'll have a look.
Amazing this internet thing, who'd have thought?
Cheers Alan.

[philh]

The VR6 electric pump isnt a main water pump its only an auxillary one that runs after the engine is switched off. Id be wary of running it as a main water pump if that is your thought.

Phil

[Alan461]

philh said:

The VR6 electric pump isnt a main water pump its only an auxillary one that runs after the engine is switched off. Id be wary of running it as a main water pump if that is your thought.

Phil

Thanks for the comment, it was a random conversation about cooling/ lack of and poor performance from the rad.
I was wondering about the benefit of an electric water pump switched by the otter switch to run after engine switch off and low speed traffic.
My main concern was the drag caused to the flow if plumbed in series
plus any alternative configurations

[britpower100]

The discussion was using one in series with the existing pump to maintain circulation at low engine revs or on shut down to prevent heat sink effect. I have one fitted to my CVH turbo Caterham and it works to good effect in that. I am new to TVRs not sure if it's been tried before or people have a better way of controlling Griffin temperatures.

[ChimpOnGas]

Alan461 said:

Thanks for the comment, it was a random conversation about cooling/ lack of and poor performance from the rad.
I was wondering about the benefit of an electric water pump switched by the otter switch to run after engine switch off and low speed traffic.
My main concern was the drag caused to the flow if plumbed in series
plus any alternative configurations

You are describing the setup I run.

Here's how it works...

Fan one and the Davies Craig Electric Booster Pump (EBP) both run off the same circuit and are triggered by the otter switch, they both come on simultaneously at 90 degrees and stay on until the coolant temperature drops to 85 degrees.



The Davies Craig Electric Booster pump creates no flow restriction in the cooling system when it's not running, and only serves to improve flow when it is. This little pump is physically no bigger than a tennis ball so finding space for it is not a challenge at all, it has a maximum current draw of just 1.3 amps so strictly speaking no relay is required. However the fans have a far greater amp draw with each momentarily spiking at 22 amps as they come on and settling to 18 amps running, so clearly they do need a relay.

If both fans and pump were set to came on all at once (and given the spike) a single 40amp relay would be insufficient, I have a staged system avoiding the spike but I have still chosen to use two relays, one for the fan one/pump circuit and a second relay for fan two. The two relay system is far safer, it also makes sense to have two given there are two completely separately switched circuits and ensures load is completely removed from each switching circuit.

Fan two runs off output 1 from my Canems ECU which means I can customise the on & off temps as I see fit using my laptop and the Canems software, as it stands I have chosen to bring fan two in at 91 degrees and turn off at 87.

Firstly this gives the desired staged fan effect, with fan one coming on at 90 the coolant temperature actually continues to rise to 91/92 before it starts to fall again, so by triggering fan two to chime in at 91 degrees I have created an overlap cooling effect of both fans running simultaneously which the system definitely needs. Fan two consistently comes on two seconds after fan one, this two second gap is just enough to avoid the undesirable momentary excessive voltage drop and amp spike when both fans chime in at the same time as with the standard setup.

With both fans and the EBP all running together temps fall rapidly, fan two stops at 87 but fan one and the pump continue to run until my super safe 85 degree low point target is achieved.

Secondly the otter switch controlled circuit running fan one and the Davies Craig Electric Booster Pump is wired as a permanent live, this means on ignition switch off they will continue to run... assuming the following:

A. The coolant temperature has reached 90 degrees

B. Is still greater that 85 degrees

When you switch off the engine (If rule A & B are met) the EBP ensures water flow even though the mechanical water pump has stopped turning, with the flow of coolant continuing to pass around the entire system (including importantly the radiator) the still running fan one serves to rapidly remove heat from the entire cooling system.

The system ensures temperatures are always kept under control, avoids heat surge on switch off and the voltage drop suffered by the two fans coming on at once as previously described.

During normal driving above 30 mph air flow through my totally standard but recently refurbished brass tanked radiator ensures neither fan or EBP are required, my 88 degree thermostat keeps coolant temps maintained at this target 88 degree temperature.

I chose to move from the original 82 degree thermostat used by TVR to the hotter 88 degree one as there are combustion efficiency benefits in running 6 degrees hotter.

Later P38 Range Rovers actually ran closer to 95 degrees proving the Rover V8 will happily tolerate a far higher running temperature than the 82 degrees TVR were trying (yet often failing) to achieve. What you absolutely must avoid is reaching 100 degrees or worse still exceeding it, which is why I've chosen what I consider a rather conservative but safe 88-90 degree driving target.

Even at idle on the hottest day making your way at walking pace in stop start traffic (the very worst scenario) my staged fan & EBP system ensures the coolant temperature never exceeds an absolute high point of 94 degrees, and even if it does touch this high point it only stays there for seconds before both fans and the pump all working in unison rapidly bring the coolant down below 90.

If the car has been idling for a period and you switch off the engine fan one and the EBP will continue to run for up to 40 seconds until the coolant temperature falls to 85 degrees, at which point all goes quiet.

It's also quite common to switch the engine off with no fans running at all, then to hear fan one fire up after you've locked and are walking away from the car. This proves the system is dealing with heat surge as designed, in such circumstances I've found fan one & the EBP tends to only stay on for 20-30 seconds tops before they drag the coolant temp down to 85 degrees.

Other than for the limited time the fan & pump stay on with the engine off there is no parasitic drain on the battery, even then the drain is extremely minimal.

The system is also fail safe to some degree, by this I mean my testing has proved a single fan alone is capable of maintaining coolant temperature at 95, it just ends up staying on fairly permanently. Because each fan is on a completely independent circuit and they are run from different sensors... if one fails the other will keep things safe.

[Alan461]

Thanks Dave, excellent info.
A bit off topic but I was also thinking about this mod for the Stag.
The water pump in said abomination is in the top of the vee, so in the event of any loss of coolant it's the first thing to run empty and melt down occurs. Good effort Triumph!
Lecci water pump at low level would help in this matter.

With regard to the Griff, I'm shelving this for now as things have changed with the cooling.
Found a recored rad on here this week which seems to have sorted things out,
prior to this cooling has been barely adequate, I've done a bunch of things that would improve matters and with each job had the idea things were sorted only to find limited improvement later.
I've been resistant to the "they all do that sir" griffs run hot line.
The temperature differential across the new rad has been up to 60 degrees c with the fans on and 90*on the gauge proving the thermostat and bypass are working and the fans can cope. Best I could get from the old one was 20*
Hopefully sorted now, just took a bit of persistence and help from here. Cheers phers

[blitzracing]

ChimpOnGas said:

Later P38 Range Rovers actually ran closer to 95 degrees proving the Rover V8 will happily tolerate a far higher running temperature than the 82 degrees TVR were trying (yet often failing) to achieve. What you absolutely must avoid is reaching 100 degrees or worse still exceeding it, which is why I've chosen what I consider a rather conservative but safe 88-90 degree driving target.

That's an emissions thing as the Range Rover P38 was made to run hotter to reduce pollutants and it was one of the reasons for the higher failure rate of the P38 engine. Peak power is still around the mid to low 80's and drops off significantly as the temp goes up.

[spitfire4v8]

Alan461 said:

Thanks Dave, excellent info.
A bit off topic but I was also thinking about this mod for the Stag.
The water pump in said abomination is in the top of the vee, so in the event of any loss of coolant it's the first thing to run empty and melt down occurs. Good effort Triumph!
Lecci water pump at low level would help in this matter.

With regard to the Griff, I'm shelving this for now as things have changed with the cooling.
Found a recored rad on here this week which seems to have sorted things out,
prior to this cooling has been barely adequate, I've done a bunch of things that would improve matters and with each job had the idea things were sorted only to find limited improvement later.
I've been resistant to the "they all do that sir" griffs run hot line.
The temperature differential across the new rad has been up to 60 degrees c with the fans on and 90*on the gauge proving the thermostat and bypass are working and the fans can cope. Best I could get from the old one was 20*
Hopefully sorted now, just took a bit of persistence and help from here. Cheers phers

Popular stag mod was the essex v6 belt driven water pump, but supplies of good units have all but dried up I believe?
Many have used an electric water pump either as an auxilliary pump or stand alone pump.
If you were going that route though I'd advise the excellent pierburg electric pump as OE fit on BMWs etc .. rather than the mixed-review DC pumps often fitted. Pierburg pump required a controller to work at 100 percent though, just driven from 12v it runs at 85 percent. There is an excellent controller on the market though.