Temperatures

[gav]

Hi

I have a moderately upgraded sprint engine which turns out 155 BHP and 130 ft lb on the rollers in a very smooth and driveable manner. It starts easily and runs like a dream - so far so good.

I am running a Davies Craig electric water pump, installed as they recommend and after an initial tweek to lower the temp range of the controller, it too is running well.

The temp range when it is running is between 85 and 90 Degs on a very hot day. It never goes above 90.

The operating range can be adjusted by a pot on the control box. The question is, what is the optimum temperature for a moderately tuned big valve twink. (for power rather than economy)?

Thanks
Gavin

[rgh0]

85 to 90 degrees C sounds about right to me.

regards
Rohan

[elandoc]

Hi Gavin,
Otto 4 cycle engines (like ours) produce max bhp at 72 degrees Celcius. This isn't high enough to break down some of the combustion byproducts that contaminate the oil, so for road use 85-90, but for a sprint, turn it down to 72-75 (just change your oil more frequently).
Incidentally, at 7000rpm, and impeller water pump drains about 13 bhp in a small 4cyl engine (10KW). The electric pump draws about 7.5 amps flat out, which is 90W, so you've scored a fre 12 or so bhp (I've got one too).
Cheers
Patrick

[rgh0]

Hi Patrick

I have heard the 72 degrees quoted by others but never seen any authoritative source and struggle to understand it from basic engine thermodynamics. Directionally engine thermodynamics say the hotter the cylinder walls the more power is extracted assuming it does not effect in coming charge density. Formula 1 engines are run at around 150 degrees C.

Do you have any source for the information ?

regards
Rohan

PS the baby looks extremely cute

[elansprint71]

Tony Thompson reckons that somewhere in the low 70's is optimal for the TC motor, I'm prepared to go along with this; since I fitted his 26r ally rad and reduced my Sprint's running temp by 20 degrees, it has been a great deal more frisky and has not since gone above 85 degrees even in stationary traffic during the hot (up to 40 C) European Summer.

Pete.

[msd1107]

Where did you install the water pump, by the radiator or up by the engine? Did you remove the water pump impeller or put a blanking plate over the water pump?

And did you use the 8010 or 8020 controller, or none at all?

David
1968 36/7988

[elandoc]

The controller is the 8010, the only one available at the time. They were working on a digital one, but couldn't deliver in time for Targa Tasmania, so I used the 8010. You need to add a resistor across the sensor wires for it to kick in at a lower temp - I forget the Ohms, but I ended up doubling it to get it down low enough. Incidentally, don't bridge the wires like they say... a bit agricultural. I cracked the case and soldered the resistor onto the board - much nicer. I'm currently designing an LED bar light to monitor its behaviour - I'm petrified of it stopping without me noticing - but monitioring with a multimeter shows it coping quite well (haven't done an Australian summer yet).

Rohan, I can't recall where I got the figure of 72 degrees - I think a well respected British tuning manual - but I've heard it bandied about. It may be something to do with 60's metallurgy, but my experience supports the claim, and it would certainly help stave off detonation, etc. Claudia is very cute, but may prove an impediment to uss going to the Barossa next Easter - we'll see if the logistics work out closer to the event.
Cheers

[elandoc]

Sorry, forgot to mention the pump. It's mounted in the bottom hose, but the (custom ally) radiator is forward in the nose.
I'll try and figure out how to put a photo up...

[bcmc33]

Not that I'm in the market to do it right now, but if I change the radiator as part of next winter's projects, I shall seriousy consider changing to an electric water pump. The question is: who markets such pumps and what is really involved?

Brian

[msd1107]

bcmc33

There are a variety of electric water pumps available. The ones I see from the US (Morosco etc) are kitted to fit various American V8s, so don't adapt right away.

Ron Davis had one integrated with a 12X22 aluminum radiator, but is was too big for our engines.

The Davies Craig pump from Australia seems close to ideal for us. There are a few posts from Elan owners scattered about who have installed it.

It is available here:

http://www.racerpartswholesale.com/elecpump.htm

together with the 8010 controller. They can also order the 8020 controller. Talk to Amy Volk. [email protected].

Good luck.

David
1968 36/7988