Mishimoto Thermostatic Sandwich Plate, Gold

wstar

I hadn't seen this unit before, and I'm a fan of the fact that it's easy to swap to other temps, but...

I had to double-check their site after I read your description, and sure enough it says "The built-in thermostat prevents oil flow to the cooler until the engine oil reaches activating temperature". This is not the same way the normal Mocal thermostatic sandwich plates (used by most of the vendor kits and the DIY types) work. The way those work is they leave both pathways open when cold, and then as you cross the thermo threshold they gradually close off the bypass, forcing all oil through the cooler at higher temps (it's about a 10 degree range while it slowly closes it off, but that's a minor point).

Supposedly there are advantages to leaving both paths open under cold conditions: the oil still mostly takes the bypass as the "path of least resistance", so it still doesn't overchill the oil (unless temps are extremely cold and you're on the highway, in which case you need a blockoff plate), but the small amount of flow to the cooler that *is* happening while the oil's warming up also gradually warms up the lines and the cooler itself.

If this unit really operates as described, there could be a thermal shock if it suddenly sends 180F oil down to the cooler when the cooler's still dead cold.

Of course, there's also a good chance that the Mishimoto one works the same as the Mocal one, but that lots of people just don't get how it operates, including whoever wrote the text on their store. You might confirm it by physically looking at the passageways in the unit. It should be obvious: the "bypass" passage would have the thermostat, and the passageway that leads to the cooler lines wouldn't have any kind of valve in the way.

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flashgordon

Yes, this is one of many reasoning that I did.
And also I add: The cold oil is more dense, so in a radiator can upwards the pressure, (for this a termostatic is mandatory!).
So Mishimoto can have the risk of a "block of concrete" in the radiator when it switches!

BUT!

The termostat core does not switch On/Off immediatly. Before Mishimoto I tested Mocal in a pot over my kitchen (Fortunately, I'm not married...) to see how a termostat works (with the fire very very low...)...
It takes a lot of secs and I think that the Delta Temps was almost a ten degrees....

In the first warm-up of my car (with the bumper off), I observed that the radiator start to heat up a lot of time before the gauge starts to go.
So I think that a little quantity of hot oil circulate always.
Mocal instead, leaves the main pipes opened at all time with a little bypass that closes when the temperature reaches the value.
This can cause a very (In winter very, very, very) slow warm-up.

Cold oil is dangerous as too hot oil!

Mishimoto

Hey Guys,

We happened to come across this thread and our engineering team provided some input that should help explain our sandwich plate.

Great discussion guys, and you both make valid points.

"The built-in thermostat prevents oil flow to the cooler until the engine oil reaches activating temperature".

Yes this is a general statement, and the actual number is closer to 90-95% is block, not 100% percent. This is because you do want some oil to pass through the system (wstar mentioned this) and get the really cold oil out of the lines and oil cooler. “other companies” actual allow up to about 40% (estimated) of the oil to flow through the oil cooler during the warm up stage. This means your car will take a lot longer to heat up the oil than with the Mishimoto sandwich plate.

“If this unit really operates as described, there could be a thermal shock if it suddenly sends 180F oil down to the cooler when the cooler's still dead cold.”

This will not happen because some oil (5-10%) will circulate during warm-up and the thermostat takes several seconds to open. It is not like a valve that quickly introduces a rush of cold oil to the engine. It works on the same principles as a radiator thermostat. The heated liquid melts the wax in the thermostat and a spring moves the valve. It takes the thermostat anywhere from 20-60 seconds to fully open up. At that rate your engine should have cycled its oil a few times.

We have tested this theory using CFD software as well as a test rig that shows the change in flow rates with added temperature to the oil. We are thinking about a way to video the test rig and share this exact topic with the public. I’m glad to see that people like flashgordon are able to understand the product and its advantages over other designs.

We would be happy to answer any further questions!

Thanks

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