What Temp should it be?????

[Snapper]

My 1.6K-series with a supersport tune, Six Speed and Anti Cav tank & Ali rad, was running at about 88-90 degrees during a very cold night (about 2-3 degrees) at about 60-70mph. Is this right because I though the K-series should run about 80-84 degrees on an average mid temperatured day.

 

I am a bit worried because when I get to Spain in the car later this year the ambiant temp could be about 40 degrees and the car will be running hotter without the colder air being able to keep the car cool. I know last year in the hot weather my old car would run running alittle warmer on hot days compared to cold days.

 

What can be done to keep the temp down???????.

 

 

 

 

 

Edited by - Snapper on 7 Feb 2002 12:23:32

[First Man]

Snapper

 

I think the normal coolant temp. for a Supersport (at least for the 1.8) is 90 degrees.

 

First Man.

[MK_Indy]

Surely your thermostat will vary the amount of water allowed through the radiator to keep the engine temp constanat. So if the ambient is cooler, the stat will open less, when the ambient air temp is high, it will open more.

 

Paul.

[Peter Carmichael]

The thermostat does not keep the temp constant. It keeps it from varying very much. The k-series thermostat only starts opening at 88 degrees. No k-series should be running under 88 degrees but the gauges always lie. The k-series thermostat is only fully open at 100 degrees.

 

So first off in diagnosing this you have to ignore the numbers on the temperature gauge but look at its overall behaviour.

 

The thermostat is a non-linear feedback device. Its particular characteristics include its hysteresis (behaving differently when cooling down to warming up) and its speed of response. These need to be matched to the characteristics of the cooling system. With the Seven, cooling system selection is fairly arbitrary, with a selection of radiators fitted at the owners whim and according to the vagaries of fashion. Sometimes the cars have heaters, sometimes they don't. Real car companies have huge budgets for getting the cooling system just right and have hot and cold testing as part of the development process. The Caterham solution is just to stick a bigger radiator on the front until it appears to work most of the time.

 

I don't think Caterham have the right solution for cold running with the k-series. The k-series running temperature is tied to the opening temperature of the thermostat because the radiators are generally too good at keeping them cool. This can cause the thermostat to cycle. With the thermostat completely closed, the bypass circuit will overheat - the thermostat will then open in a hurry and let in a gulp of cold water from the radiator. This will then cool the circuit sufficiently to close the thermostat again. Where the temperature ends up on average is a matter of chance.

 

So as a starting measure, block off the sides of the radiator and see how you get on (leave the area covered by the fan open). This will mean that the return water from the radiator will never be that cold and the cycling of the thermostat will stop. You will get more understandable temperature behaviour presuming that everything is healthy with the car in general.

 

 

 

 

[Snapper]

Hi Peter

 

The car is brand new and it does have a heater in it which was on because it was cold.

 

There was a small over heating problem when I collected the car, and all the gauges, sensors, thermostat ect have been checked by Caterham and confirmed to be working correctly.

 

So from what you are saying is my car ok?

 

 

[NoLimits]

Snapper you know what to do!

 

I think its time for me to patent and produce the product we manufactured for spain last year.

 

A few tweeks and we would have a perfictly servicable "manually controlled" system.

 

I had settled on running the new SLR on the appropriately supplied thermostat. You and Peter have set me thinking again over my louvres!

 

When i spoke to Minister last year about temperature b4 making the kit they were quite adamant that the optimum temp was 75 - 80 deg. And if poss should never go above. The ali head etc can not take the heat.

 

Hence in Spain last year while everyone was a little concerned in Andora about 40deg air temps let alone the water temp in the car i had a manual fan no thermostat and a water temp i could control by adjusting louvres and fan.

 

Where is the patent office???