most efans became a factory standard because the engine bays became more cramped and the engines sideways and could not drive a mechanical fan. most trucks still use mechanical fans.

since the major switch to efans you also notice most cars have switched to front wheel drive.

i try to keep the mechanical fan until space becomes an issue with most any build, they are less problematic and generally can do MUCH more work than an efan can when they need to.

Yes, with an electronically controlled (by the ECU) clutch as opposed to a dumb viscous clutch you would find in a 2nd or 1st gen.

Interesting, the mechanical clutches are electronically controlled now? I wonder what's under the hood of my 02 Avalanche. It's definitely mechanical but I'd just assumed that the clutch was viscous with some sort of mechanical thermal adjustment.

Anyway, back to the topic. What's driving folks to set temps higher than 88C?

I did move mine to 91C this weekend. My temp gauge now hovers around 199F in traffic. I also played with pushing the car hard a bit. Pulled onto the freeway ramp at 199, WOT through 1st and 2nd, then 4th at 70MPH to the top of a small grade. I'm guessing two miles. The car spiked to 206 and then reduced to 195 by the top of the hill. It was probably 80F outside. ... of course temp dropped like a rock down the back side of the hill in 5th gear.

It's definitely hard to pull the temps down when the car is hot in the first place.

Anyway, here's one more bump to see if there are any interesting thoughts out there.

So, you changed the setting from 92 to 91? That"s very bold!!! :) I hope you didn't lose too much sleep. Come on James!! move that puppy to 88 (or lower)!! Don't be an outsider looking in.

:crackup:

I don't really like it cycling a lot, and the OEM thermostat isn't even fully open until 95C anyway (basically every Mazda rotary ever produced has a thermostat that opens at 82C and is fully open at 95C. To a certain extent it's just personal preference.

Getting theoretical for a second: from a fuel economy perspective, higher coolant and oil temperatures (up to a point) reduce friction, meaning less wasted energy. One way of measuring brake/net torque at the flywheel is Indicated torque - pumping losses - frictional losses. This can be calculated with cylinder pressure transducers.

For this reason some new engines are using electric temperature control, either through electronic thermostats (VW's upcoming TFSI engines) or electric water pumps (BMW N54/N55/N20, Toyota 2ZR-FXE Prius engine). These are probably used in conjuction with duty-controlled fans (as opposed to stepped fan control like the FD). So here is the temperature schedule for the upcoming generation of EA888 1.8 TFSI VW engines:

https://www.rx7club.com/attachment.p...1&d=1327976849

Interesting.

If I was to broadly interpret that chart I would say that extra cooling is only applied under load and upper RPMs. I would guess that the greater delta between water temp and engine surface allows for removal of the extra heat being generated. When the engine load drops, the cooling need drops as well.

My 07 335 had the N54 (I think). One interesting side effect of having a computer controlled water pump was a less than effective heater. Driving the car at 70mph on a cold day resulted in a barely warm heater output. My theory was that the pump wasn't pushing enough water for the heater core to warm the air effectively. The car regularly produced 30MPG on the highway though ... impressive for a 300HP car.

Now that I'm way off topic, my 02 Avalanche doesn't have an electronically controlled mechanical clutch. It's just a plain mechanical thermostat on the front of the clutch. It looks like Chevy just went to electric fans in 05ish. Some folks convert to electric and claim about a 2MPG return.

So, I'm happy with my 91C setting. It leaves plenty of thermal room for a burst of speed here and there. If I'm headed through the canyon or to the track I'll drop it to 85C.

It is easier to keep to a set temperature than to try to cool down to one. Especially when running high power.

Your chosen setting should be based on:
(1) how good your radiator cools. The Koyo "N" pass can be set higher than a stock radiator. In cold weather, my water temps will actually drop during acceleration due to the Koyo's great cooling capacity.

(2) power output of the engine. More power requires more cooling.

(3) emissions requirement. Higher temps are better for emissions.

(4) seasonal ambiant air temps. In the south during summer, lower is needed.
In winter higher can be used.

It is all logical!

My fans come on at 86C that i know....didn't start the car for about 1 month and when i did they came on at 88C. I have no idea why it did that but i need to look into it as spring is almost here and she is bout to get a tune up before she is back on the streets.