Coolant flow
"Packing up", as you put it, is a rare problem usually only associated with flat plate style shrouds that come on the cheapest of cheap aftermarket electric fans. If a fan's shroud has flaps, that should be a dead giveaway is wasn't actually designed to flow air and that it was just slapped together and band-aided. There are a lot of aftermarket electric fans and shrouds that have no business on cars- their fan CFM ratings are too low, and their shrouds are simply a way to mount their cheap fans, not actually flow air.
I did read what you wrote, and you said "good mechanical fan" was necessary. It's not, a good electric fan and shroud work great. Maybe that's not what you meant, but that is in fact what you said.
You should care, because getting it wrong can mean cavitation in the water pump. The cars that had 1.3:1 and 1.4:1 pulley ratios had pumps with fewer blades. The reason is the RPM of the pump and cavitation, not the amount of water it's pumping. Running a high flow pump is good and the idea you can flow water too fast is silly, I agree. But, you still have to consider the RPM of the pump and how it's being driven. A 1:1 pulley ratio with a high flow water pump is one solution, but if your pulley ratio is 1.4:1 you need to account for that too. Some of the pumps are designed differently now, but the factory was looking at the pumps driven speed and adjusting the blades accordingly.
The majority of your points are right on and I agree, but you leave science behind on this point and just go with what you're personally familiar with.
The 180° temp thing is just left over from your drag racing background. Not every car/engine that gets discussed on this board is used the same way. If 180° was some magic number, the modern OEM cars would use it too. Yes, modern cars have to tune for a lot of other things too, but they all make higher hp/cube outputs than these cars ever did stock- they're more powerful and efficient. Sure, the engines discussed here usually aren't stock and don't have smog to worry about, but most of them also don't have nearly the control over their fuel delivery and ignition systems either. Literally no modern cars spec their water temps to be 180°, and a couple dozen degrees of coolant temperature aren't going to hammer your cylinder and exhaust temps so badly that you couldn't deal with meeting the smog and efficiency requirements. Modern OEM's could easily spec a 180° water temp if it made the most power or was the most efficient. They don't, and it's not because they don't know what they're doing.
If you were familiar with other kinds of racing, you'd know that pretty much only drag racing cars keep their engine temps under 180°. There are much crazier and exotic engine builds out there than make gobs of power for a lot longer than drag engines do and do it with much higher coolant temperatures. For a street car, it's not necessary or often even practical to keep the coolant temps between 160° and 180°.
Yeah, that's just BS. Modern cars pretty much ALL run electric fans, and some of them make more horsepower than dirt track cars too. Using a race car as an example is also usually a bad idea, since there are typically specific rules and regulations that require certain things and not others. And pretty much every automotive racing environment is highly specialized, and requires things that don't make sense on a street car. Why dirt track cars run mechanical fans instead of electric I don't know, but it's absolutely not because electric fans aren't capable of cooling those cars.
I have done the research on cavitation. And not just with automotive people. Cavitation is very rare unless the inlet side of the pump is restricted. Unless the hose is collapsing or some other issue is restricting flow to the pump the number of blades isn’t an issue. You’d have to show me real world examples of cavitation in automotive water pumps that were caused by too many blades.
180 degrees is the HOTTEST any of these engines should run and that’s not “left over” from my drag racing days. You are hung up on your number because you are stuck in your new car, hot coolant days. The “modern“ engine is nothing close to what we are discussing here. No one is using knock sensors and **** like that to pull timing on the stuff we are talking about.
Making power is about cylinder pressure. Cylinder pressure makes heat. Heat is power. Heat also promotes detonation. New (or “modern” like that means better…it doesn’t) engines deal with detonation by using knock sensors. They are also concerned with cold start emissions (I’m not), getting the cats lit (again, not a problem we are discussing here) and certain emissions levels (again, not relevant in THIS discussion) so trying to marry “modern” engine operation conditions to what most of what we discuss here is LUNACY.
But, here is the real clincher. Wait…I need to mention I haven’t done any work (as far as tuning and such) on any “modern” engine newer than about 2003 so keep that in mind…the real clincher is dropping the coolant temperature even on those engines increases power.
Now take off the EFI and all the related **** and drop a carb on one of those and run the coolant temperature up and see how fast detonation drops the power. It will start killing 20 HP so fast your hear will spin. And you have to add fuel and reduce timing (which makes more heat in the exhaust) which makes less power.
So get out of your head that coolant temperatures of 160-180 are a “drag racing” thing. Most drag cars have undersized, piss poor designed cooling systems that don’t control engine temperature like they should. That’s the big reason why drag racers (and corner turners) gain power when they switch to alcohol. They need the heat to vaporize the 2.2-2.5 times more alcohol than gasoline. Had they spent the money and time to unscrew their cooling system they would likely see little, if any gain from alcohol. And when that happens they see very little savings in fuel costs since it takes over twice the alcohol to make the same power as gasoline.
When I was tuning circle track engines (another group of people brainwashed that hot engines make more power) the FIRST thing I did after unscrewing their tune up was to make them buy a better radiator, a better pump and made them either sell or scrap their under drive pulleys. It was a fight for the first couple of people.
Once I was done, those guys finished 1 and 2 in points and neither one ran over 170 degrees. And all the long time smart circle track guys told them the engines would be junk when I did the freshen up at the end of the year. Of course, those morons were wrong.
I made them come to the shop on the weekends and they took their own junk apart. Then they watched me measure everything. We could have reused every part.
I have debunked the cool(er) engine temperature kills engines lie so many times its just stupid that it keeps coming up.
Again, these customers were running mostly on 3/8 dirt but they eventually went to 1/2 mile pavement. So the aero stuff doesn’t apply to them like it would to a car capable of more MPH, which is EXACTLY why cars at that level keep the coolant temperature as high as they do. I already talked about that somewhere else.
There is zero downside to running a cold(er) engine. I’d run mine cooler but at temperatures lower than 160 I can’t get defrost to keep the windshield clear.
