Are there racing thermostats?

[GP]

I'll give up then

[de Bounce]

X2
Managed to totally confuse me

[Boags]

I think you could summarise as follows:

Speeding up the water flow through the correct channels in the engine will NOT cause overheating. It will, in fact, aid in cooling more efficiently.

Removing the thermostat could change the direction of flow of water through the engine - meaning that coolant does not flow through the correct channels of the engine. This causes over heating.

If the removal of the thermostat did NOT change the flow through the engine, the increased speed of the coolant flowing through the engine would aid cooling.

[Boags]

The important question is: is the MX5 B6/BP an engine that will have more efficient cooling without a thermostat? Is the thermostat imperitive to the correct direction of flow of coolant?

[manga_blue]

Yeah, well put, Geoff. This becomes an problem that can't be solved empirically and we fall back to previous experience or trial and error. My learnings from all this might be:
1. Stock 85C or 75C thermostats work OK most of the time and should be used most of the time.
2. Gutted stock thermostats (i.e. de facto restrictor plates) seem to work OK, at least they don't cause the localised issues arising from major changes to coolant flows.
3. Removing the thermostat or restrictor plate entirely is riskier than leaving it there due to potentially bad coolant re-routing, not fast coolant flows. There doesn't seem to be much of a body of knowledge about it either.
4. A super high flow thermostat (big bore/wide opening) might function like no thermostat or restrictor when open and could also be considered risky.

So I'm back to Option 1 most of the time and Option 2 on extreme days. These coincidentally are the two cheapest options.

[Okibi]

There's only a couple of turbo MX-5 race cars in W.A., perhaps some of the Queensland members could ask around and get some info from their racers.

I remember that Ian's car has an after market thermostat set-up, I need to look through more photos but this looks like it has a thermostat built into the upper radiator hose.

[Okibi]

I had to search my archives but here she is, looks like a custom set-up with aftermarket thermostat housing.



John Bennett from Ecotrans who developed the Ecotherm can be located at Innovative Technologies Pty Ltd, 36 Lillee Cres, Tullamarine. Tel 03 9338 1988.

[GP]

Speeding up the water flow through the correct channels in the engine will NOT cause overheating. It will, in fact, aid in cooling more efficiently

Sorry, Speed up the water flow and the engine will run hotter

Removing the thermostat could change the direction of flow of water through the engine - meaning that coolant does not flow through the correct channels of the engine. This causes over heating

Maybe on some poorly designed engines

If the removal of the thermostat did NOT change the flow through the engine, the increased speed of the coolant flowing through the engine would aid cooling.

Sorry again. The speed the water travels through the radiator determines how effective the cooling will be.
I apologize for hijacking this thread but I hate to see mis-information spreading. I design cooling systems for Landbased and Marine Engines so this is pretty simple stuff.

[orx626]

I design cooling systems for Landbased and Marine Engines so this is pretty simple stuff.

So do you design the waterpumps and thermostats for these engines?

[Boags]

I've had a look at the cooling system on the racer, as it has an electric water pump.

There is NO thermostat. This shows that the B6 is an engine that does not suffer from incorrect flow without a thermostat.

The temp gauge on the EWP controller shows that even in traffic on a track the temp never gets to 90C (stays between 85 and 90 the whole time). It will get to 90 once we slow down entering the pits (no thermo fan).

Just an observation, with the radiator cap off, the flow is ferking fast. That adds nothing to this debate though, as I haven't had the cap off a standard car with the coolant hot enough for the thermostat to be open.

GP - perhaps you'd like to offer an explanation as to why the speed of flow causes overheating; instead of just labling it mis-information.

[TieNN89]

I've had a look at the cooling system on the racer, as it has an electric water pump.

There is NO thermostat. This shows that the B6 is an engine that does not suffer from incorrect flow without a thermostat.

Depending on the electric water pump you can get a controller which will adjust the rate of the flow and as far as they hook up to the thermal switch so do not run during warm up

so pretty much an electric water pump is just like a water pump with a thermostat
apart from the fact its not running off a belt and you can keep it running while the engine is off (there's isn't much point in the fan spinning if the water pump isn't running)

[Mokesta]

Speeding up the water flow through the correct channels in the engine will NOT cause overheating. It will, in fact, aid in cooling more efficiently

Sorry, Speed up the water flow and the engine will run hotter

Pretty simple hey? Well on my engine the water pump runs a fixed ratio to engine speed, so when the engine speeds up, the pump runs faster and (to the point of cavitation) the water goes faster throught the engine. So speed and load goes up and, according to the quote above, my cooling efficiency drops. Hmmm.

Last I learned, from J.P. Holman's Heat Transfer book, was that water has a specific heat and a heat transfer coefficient, but there was no mention of these dropping lower as flow rate changed. That's like saying wind chill is less on windy days than still days.

If you push your pump to cavitation or you cause flow issues in the engine due to the inertial of the water "jetting" through apertures, recirculating or cavitating, then you may find poor heat transfer. This could happen on a large diesel with cylindrical cylinder barrels in a large cooling jacket when you effectively get flow separation around the down-stream side of the barrel but I reckon it's an issue related to engine geometry not a blanket faster = worse theory.

So the OP who has cooling issues may well have a water pump issue that means it cavitates at high revs or the thermostat may have been sticky like mine recently was, but the diagnosis isn't helped by statements without the backing of an undertanding of heat transfer and fluid flow.


M