which thermostat should i buy? i'm currently running 400bhp and have seen 82 deg, 88 deg, 92 deg thermostats available.

i take it that the 82 degree item is lowest available and keeps the engine cooler than the above other two options.

is there anything i should know about fitment or any tips on changing it.

reason for change is due to a leaking knackered gasket!!!

many thanks and merry christmas!

 

at 400bhp i would go for 82 one just remember to fit the stat the right way

 

Personally I'd go for the 92C, it's nothing to do with tune or power, I have a 88C, but notice a big difference in heater output between 82C and 88C, I was thinking of getting ahotter one still as it is just a general type fit one in 2wd, and running hotter is no more of a problem for headgaskets than a colder one.
tabetha

 

For once I'd disagree with Tabs - if you are using a big intercooler you will be glad of the cooler engine in traffic if you go for the 82 - which was put in as standard on the rs500 for that reason. I am of course thinking summer time here - remember those days?

 

i can't see the problem with using a 82 degree thermostat in the winter as a cosworth gets very hot indeed!

do people not agree with me!

 

The reason why the RS500 most likely had a 82C was because this is the one someone grabbed from the parts bin.
Having any particular temp stat is not going to offset any problem in even the most hottest of summers, if we ever have any, a 6C difference to the engine is nothing, and it is just as likely to boil with a 82c as a 88c or 92C.
They boil due to a fault not because of a hotter running stat, the RS500 type intercooler will indeed soak more heat through if using a hotter stat, that's natural, but this only applies to slow traffic work where boost is not being used anyway, it will have shed off this extra heat in seconds from the intercooler once on the move.
As a percentage the difference is 6.4% in heat(88 V 82) so it's not the end of the world, but will make a noticeable difference to heater.
A cossie can run 92C all day long as it is a pressurised system, with a lot of leeway when up to scratch.
tabetha

 

Tabs - the first 500s had the 88 stat but they were recalled and fitted with an 82 after some boil overs in traffic and associated complaints mate. All the main production ones had 82 as standard after that. They are sods to change sometimes too!

 

Ford recalled more than 3000 cossies to change the HEAD and head gasket, it was found due to heat build up around the exhaust ports that the head moved and killed the gaskets, after a hard use then slow work, ford's pathetic attempt at a bodge may well have been a lower running stat initially(I don't know) but certainly was not the problem.
Engines supplied by cosworth/ford when doing NVH at Southampton University had regular head gasket changes as they blew with std gaskets bhp etc, they even had a regular parcel delivery contract dropping off head gaskets, ford were well aware of the problem before they sold the cars to joe public, but wanted to cash in on the sales generated from the racing at the time.
It was rush design job, the YB hence the changes that had to be made continually, the cooling system was particularly weak.
A lot of cars run over 100C water temps, but this is due to economy reasons.tabetha

 

the fact is that if the thermostat is 82 rather than 88, when the car hits traffic (and hence air flow through the rad is restricted) there will be a greater capacity of heat soak available within the water system thus lowering the likelyhood of overheating

 

i put new thermostat in fourby yesterday and i put in an 88 degree,the one i took out was a 82 degree which ive never put in,maybe standard?ffsh ect when i got car,but the heater is brilliant!!always complained how cold heater was,but not convinced old thermostat was closing so didnt ever seen to get warm let alone hot,unless in town or booting it
col93saphcos

 

Mine stays in the warm in winter most of the time - lol! In the summer (and when it occassionally gets hot that is) I've really appreciated the 82. Its a common chatting point between five hundy owners. Silverstone 07 saw two overheat on the slow run back to the show area after the track session. Neither had 82s as it turned out.