ASH8

I was just pondering the need for Rotaries using a Cooling System Thermostat.

We all know rotaries develop a lot of heat and warm up very quickly, so do they need a thermostat at all?

I know this may sound dumb to many and yes I understand the reasons why internal combustion engines require thermostats but I was just interested in your views concerning the use in rotary engines.

Ash

takahashi

Thermostat in our car open at 82 degree... is that what you are referring to???

A termostat opens when it reaches temperature. I doubt a better thermostat will do the job since it will just get running over sooner - but the heat will eventually build up and reaches the same coolant temp again.

auzoom

My understanding (and will probably be corrected) is the job of the thermostat is to ensure the car is operating at its most efficient temperature. If you remove it, you risk (although probably unlikely once the car is warmed up) running the car to cold, however as a minimum you need it to warm the car up.

olddragger has a thread somewhere on changing the thermostat to one that opens earlier.

Cheers

Andrew

thisllub

the job of the thermostat is to ensure the car is operating at its most efficient temperature more quickly

Basically a thermostat reduces the volume of coolant in the engine during the warm-up phase meaning the the engine gets to temperature faster.

Brettus

iTrader: (2)

it does both -
*gets the engine to temp quickly
*keeps it there

In a cold climate you could be running at a temp way below optimum which would not only be inefficient but would probably wear the motor out more quickly.

olddragger

iTrader: (3)

yes --the rotary needs a thermostat.
yes--- the rotary needs to run cooler.
no--- removing the thermostat does not affect the capacity of your cooling system.
the cooling system needs enough heat exchanging capacity to keep the engine at the desired temps. That is where Mazda and the rest of the world differ---it seems.
Thermostat also prevents the engine from having a wide heat variances while it is running. This is especially important with the our engine since we have so many different metals involved.
it is bad to swing from 220F to 180F in 2 minutes , just as it is bad to swing from 180 to 220 in 2 mins also. Much better to stay at 190F!
Quick warmups are good---but not too quick and not too much load on the engine while doing so.
Thats the reason Mazda developed the bypass system. They did not want hot spots forming if NO flow was occurring during warm . Never plug the bypass without providing some flow before the thermostat opens.
olddragger

ASH8

Thanks OD, yes it is how I remembered, just needed confirming.

In piston engines it is bad in cold climates to run without a thermostat as the engine runs too cold as Andrew said.

On a separate issue I still believe with the Series II that the engines are running too hot in summer, ie the cooling fans come on at a too high temperature.

I wish I had Accessport (for S2), or Access without doing the known relay and additional temp sensor mod that RB sells for S1.

The Hot throttle Body is also BS, why in Australia do you want to heat up fresh air to well over
100c!, I just don't see the point, there should be an option to switch off TB coolant flow in Summer.