How Hot is acceptable

Ian Anderson · Post by **Ian Anderson** » Wed May 07, 2008 7:14 pm

On the old forum I asked this question and after some infighting the Admins removed the thread.

Ok so I know there is probably no definitave answer but can anyone shed some light?

Today in the GT40 coming home - oh yes I had to show it off in the sunlight! the temp started off as it notmally is at about 84 - 86 degrees on the gauge.

coming past Hampton Court and through Hampton the traffic always crawls and it got to "mid 90degree c" (doing about 15 - 20 mph in 2nd gear - just over 2000rpm) the fans kicked in and were running but the temp still seemed to sit mid 90's (Fans did cyle on and off so the switch and relays all seem to be working) and I was looking for a pull over point when the traffic cleared a little and I got going at about 40mph (1800 rpm in 4th)

After a mile or so the temp was back on the South side of 90 and I felt a bit easier

So is this type of temperature acceptable - I know the fluid will not boil under pressure at this temp - but how hot can it go befre it's time to shut down at all costs?

Should I be looking at a cooler thermostat and cooler starting fan point or will this then throw out the Efi running (presumably it fuels dependant on temperature perameters)

Radiator is a Docking Aluminium race unit - said to be good to handle engines of up to 600hp (I wish that was achievable on a Rover)

Last of the rambling questions is - is it better to run the engine at higher revs to get more fluid flow (Engine at back rad at front and about 14 litres of fluid) or is the Rover water pump considered good at low revs?
Or should I be looking at fitting an electric pump to assist at low revs?

Perhaps the admins will repost the original thread (even after removing the "flame war posts" as I seem to remember it having a load of good info.

Cheers

Ian

v8man · Post by **v8man** » Wed May 07, 2008 7:39 pm

should be at no more than 80 degrees above that power comes down fast
for example a an engine that produces 300 bhp at 80 degrees only going to make 270 bhp with coolant at 100 degrees
if injection fuel enrichment must be turned off

hope it helps

Gil

Post by **katanaman** » Wed May 07, 2008 8:58 pm

Am not going near the temp subject but you might benefit from driving your pump faster by changing he pulley depending what you have at the mo. Trouble with that is when your running the engine at higher revs your pump will be too fast and will cavitate loosing power. Your pump was never meant to push coolant through the size of circuit you have and that probably isnt helping things much at all. Maybe an electric assister pump or something like that would work wonders?

davemgb · Post by **davemgb** » Wed May 07, 2008 11:15 pm

Personally I'd like to keep things below 90 C.

I know space can be a problem in the front of the GT40 - have you got the fans pulling or pushing through the radiator, are they shrouded and are they a good fit against the radiator matrix? i seem to remember the advice is the fans should suck if possible.

Bigger is probably better for the pipe and hose from engine to rad. It might also be better to use an electric pump in parrallel with the heater or bypass circuit to push coolant through an oil cooler type matrix with its own fan mounted in the engine bay to keep hose lengths short. Kind of a second cooling circuit on a thermo switch, would also help on track days - turn off the engine and leave the secondary cooler running for five minute to cool the engine.

Dave

Ian Anderson · Post by **Ian Anderson** » Thu May 08, 2008 7:12 am

Thanks for the replies

Fans are 2 high volume 11 inch units sucking through the rad, Fans mounted using "cable tie" attachment fixtures so as close to core as possible

Pipes running forward are 32 mm from memory

The heater circuit is an open loop - no matrix fitted.

Yes possibly time to look at an assist pump

What about a cooler thermostat - presumably this is opening at about 82 - 84 as that is where the temperature normally lives - is there a cooler one available and if so will it upset the EFi and emissions?

Next job after that is to get a lower temp switch than the Ford unit currently fitted so the fans cut in earlier.

cheers
Ian

ChrisJC · Post by **ChrisJC** » Thu May 08, 2008 7:29 am

What you really need to find out is whether the cooling system has sufficient capacity to stop the temp increasing when the 'stat is fully open. If it hasn't, then all changing the 'stat will do is give the radiadator an earlier start, but during continuous hot weather / high load, that head start will be lost and it will still overheat.

I guess to be scientific, you need to measure water temp in & out of the rad, and also measure water flow somehow.....

Chris.

kiwicar · Post by **kiwicar** » Thu May 08, 2008 8:08 am

For my 2p worth I would go for a high flow stat of the same value (the standard ones are a big restriction to flow)(running a block too cold is not good for wear of pistons rings and bores unless you have set the clearances to match. Fit a high flow electric water pump with a variable controller so it increases flow when it needs it not just when the revs rise. And make sure you have cold air flow through the engine bay, use some of the cold air intakes you have on the body and some air duct pipe to direct cold air from outside to run air down the valley and arround the exhausts (shield the rest of the engine from the exhaust if you can) put a couple of fans in the ducts to force air through when you are in traffic and finally ensure the hot air can get out from the engine bay. (I am assuming the engine is fed directly from outside)
Mike

Muttleys V8 · Post by **Muttleys V8** » Thu May 08, 2008 8:15 am

Try the EMP Stewart Water Pump.
10,000 hours motor life and can pump 56 gallons of water a minute,
Only problem is you cannot use it with a variable flow controller.

Steve

davemgb · Post by **davemgb** » Thu May 08, 2008 7:39 pm

Try restricting the heater circuit, mine flows from the inlet manifold to heater to pump.

This is probably flowing too much water if I have understood your reply correctly. It will not take much flow in the heater loop to keep a lot of heat from ever reaching the radiator. In fact you should be able to block the heater circuit completely since the heater valve normally does when you want cold air.

I'd have gone for larger pipes to the radiator, something like 42 or 45 mm.

The heater circuit is simple to try, just clamp a hose to restrict or stop the flow and see what happens.

Dave

Ian Anderson · Post by **Ian Anderson** » Fri May 09, 2008 11:04 am

Dave

Now that's interesting

It makes sense as this flow is bypassing the rad

But presumably a good idea to have minimal flow to ensure are bubbles don't collect.

As the 2 under plenum pipes at present just looped together (using 15mm plumbing fitings I'll make another set and fit an in line tak and "all but close the flow off"

Cheers
Ian

Ian Anderson · Post by **Ian Anderson** » Fri May 16, 2008 8:11 am

Ok
Typical GT40 Job

The heater matrix pipes at the rear of the plenum had been done in a free flow U using 2 90degree 15mm plumbing bends and 2 short lengths of 15mm plumbing tube into a 2 inch length of hose with jubilee clips.

Pulled it out over the weekend and fitted a plumbing fitting - an end stop.

Drilled a 2mm hole in the end stop

Refitted it and ran to temp but never got to drive due to other commitments

Ran it out on Wed evening and it ran well - got stuck in stow stuff on the M25 which was the killer in the past and the temp slowly raised - before starting to drop again when the speed got aboue 30 mph - but none of these crazy temp swings.

So a bit of a result - I think the cure has landed!

Thanks for the ideas and assistance everyone

Ian