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As the topic says - are there thermostats available for our cars that give the sorts of reponse times and accuracy that we need to race?

As background, I'm finishing an engine rebuild that began with the car boiling at Winton on the hot weekend. On that day the temp gauge moved from cool to total toast within half a lap, several times.

I've just been testing the thermostat. It has 71C stamped on it. At a steady 75C it's open but if you drop it cold into water at 75C it takes 6 minutes to open. Drop it in to water at 85C and it still takes over 4 minutes, equivalent to about 3 laps or about $2,000.

I'm thinking that load and cooling conditions change several times per lap on the average circuit, so we should be looking at sub 20 sec response times. Are there such thermostats?

I just got another one of these in the mail today ..



They also have a nice 78" thermostate with a bigger/longer opening.

http://www.maruhamotors.co.jp/miata/parts/watertempsensor.html

If you want a quote email Saiji via info@maruhamotors.co.jp.

Just punch the centre out of the thermostat and put it back in. Will be a pig for cold starts but you will have no flow problems

I think it's coming to that, GP. Use a stock one day to day and an angle grinder special for track days.

Along the way I tested 2 other replacement units - both slower than the first one.

manga_blue wrote:......equivalent to about 3 laps or about $2,000.

I was wondering why a "racing" thermostat would be needed or warranted.
The above comment had me wondering no more.... ouch

manga_blue wrote:Drop it in to water at 85C and it still takes over 4 minutes, equivalent to about 3 laps or about $2,000.

Not that it takes away any pain, but the thermostat being closed (or at least restrictive) is helping increase the boiling point. The real question is how quickly does the 'stat open when exposed to flowing coolant at 120C?

The fact that your temp rose so rapidly suggests you had a dodgy thermostat, a poor radiator, or both. It was a stupidly hot day, everyone was overheating. My gauge was climbing, but never fast enough that I couldn't avoid it going off the scale.

[quote="manga_blue"Use a stock one day to day and an angle grinder special for track days.
[/quote]

Just leave the whole thermostat out? Be careful with the thread as it is easy to cross (grumble...)

Okibi wrote:I just got another one of these in the mail today ..



They also have a nice 78" thermostate with a bigger/longer opening.

http://www.maruhamotors.co.jp/miata/parts/watertempsensor.html

If you want a quote email Saiji via info@maruhamotors.co.jp.

Hey Okibi, how is Maruha's service? and how long did it take for it to land here.

Matty wrote:... The fact that your temp rose so rapidly suggests you had a dodgy thermostat, a poor radiator, or both.

All the rest of the system was good, Matty. Detailed examination of the pump, hoses, block, radiator and the remnants of the head confirmed that. Fuel and timing were re-checked afterwards too, not sure about valve timing tho.
I actually tested thermostats before I went there cos the forecast was so bad, but all I did was confirm that they were open at a reasonable temp in the saucepan. I was testing them again to try to work out why a thermostat that opened OK in the kitchen appeared to be shut in the field - hence my thinking about response times.

philz wrote:..Hey Okibi, how is Maruha's service? and how long did it take for it to land here.

First one I got from Ocean at www.chikaramotorsports.com but this time I thought i'd try from Maruha themselves. Saiji was easy to deal with and I was able to pay via paypal.

I'd buy again from either business.

I guess it shows how important it is to let your engine warm up in the pits and do an easy warm up lap to put heat in the tyres and make sure your engine temps are right and the thermostat is fully open.

Have you had the car on the dyno, could it be running too lean and heating up? Which coolant are you using? Might even be worth getting the radiator and cap pressure tested.

Sounds like a bad day out

The only time I had cooling issues was after I had the core cleaned out. Replacing the radiator fixed it. So even if you think it's OK, and people have tested it, doesn't guarantee it's perfect.

try this for thoughts:
http://www.google.com.au/search?q=therm ... cmiata.com

Just leave the whole thermostat out? Be careful with the thread as it is easy to cross (grumble...)

No you can't do that, The water will flow too fast through the radiator not giving it enough time to cool.

GP wrote:

Just leave the whole thermostat out? Be careful with the thread as it is easy to cross (grumble...)

No you can't do that, The water will flow too fast through the radiator not giving it enough time to cool.

I think there was something else wrong with your engine or the thermostat was jammed closed. Plenty of MX-5s run in sprints etc. here with standard engine components in very hot ambient conditions with no overheating problems. My 1995 NA could go all day without any temperature rise - as does the NC.