Engine upgrade

[Will N]

Gene, out of curiosity and perhaps putting my ignorance on full display here - where does the radiator factor in on the performance of the engine? Unless the engine is suffering from overheating does it make a difference there?

(I need a new radiator for my Fordor - hence the question )

\Dan

Horsepower = heat. The more horsepower and engine makes the more heat it makes and the more need for cooling capacity.

 

[alexiskai]

Horsepower = heat. The more horsepower and engine makes the more heat it makes and the more need for cooling capacity.

This isn't strictly true. Heat, beyond the amount needed to get the engine up to operating temperature, is a waste byproduct of combustion inefficiency. The input energy of the fuel is converted into either horsepower or heat. If an engine's efficiency is improved, it will run cooler because it's converting proportionately more of the input energy into motive force rather than heat.

The fact that higher-output engines tend to produce more heat is a function of the fact that those engines are consuming more energy overall, not a function of their HP output.

 

[Mister Moose]

Horsepower = heat. The more horsepower and engine makes the more heat it makes and the more need for cooling capacity.

This isn't strictly true. Heat, beyond the amount needed to get the engine up to operating temperature, is a waste byproduct of combustion inefficiency. The input energy of the fuel is converted into either horsepower or heat. If an engine's efficiency is improved, it will run cooler because it's converting proportionately more of the input energy into motive force rather than heat.

The fact that higher-output engines tend to produce more heat is a function of the fact that those engines are consuming more energy overall, not a function of their HP output.

Yes, efficiency gains come without a heat penalty, but that's really muddying the water mostly. At best, roughly 35% or just a third of the chemical energy in fuel gets transferred to mechanical energy, the rest is heat. When you up the horsepower and burn more fuel, you're going to produce more heat. That's just the way it works. "I'm going to completely rebuild and hot rod my engine and gain efficiency, but I'm only going to add efficiency gains, no big horsepower gains for me" said no hot rodder ever.

 

[alexiskai]

When you up the horsepower and burn more fuel, you're going to produce more heat.

The second part of that assumption is doing all the work. There are plenty of modifications to the A engine that substantially increase efficiency and do not substantially increase heat output. The original question was, why does a heavy-duty radiator "make all the difference," and I don't agree that you can address that by saying "more HP = more heat."

If the argument had been something like "well, when you modify the engine you tend to drive it more aggressively, which increases the load on the cooling system, and the original radiators often aren't in top condition, so installing a beefier radiator is a good safety precaution," I don't have a problem with that argument. But it doesn't, like, proceed irrevocably from the laws of thermodynamics.

 

[johnneilson]

Or, just the fact that the cooling system is in-correctly designed.
Water pump scavenging the engine induces cavitation, thermostat missing to control temp and water flow.

just observations........J

 

[jerrytocci]

I like the " 4 banger " as-is

 

[Gene F]

The high compression head actually makes an engine run cooler. You would think otherwise. As far as the radiator goes, it has more to do with just the comfort of driving than anything. It makes the passenger compartment cooler, for some reason. I thought that, and did not mention it. Then my wife remarked about it.

 

[Ernie Vitucci]

Good Morning...When the Model A was designed, the engineers lived in Detroit and the surrounding area...so they designed a cooling system that met with their experience. Cars coming to the southwest always seemed to have 'heavy duty' option radiators ordered for them. Also, at least in Southern California and Arizona where I have mostly lived...radiator shops have specialized in building larger radiators for all sorts of cars and trucks...also thermostats...a well tuned Model A will run at different temperatures in different parts of the county at different times of the year. On a cold winter day, maybe 130 or so, on a hot summer day, in the southwest 190 or even 200 was not uncommon. With a bigger radiator and a thermostat...160 to 180 can be maintained, the engine is pretty much happier at 160 in my humble driving experience. Ernie in Arizona

 

[BRENT in 10-uh-C]

Or, just the fact that the cooling system is in-correctly designed. Water pump scavenging the engine induces cavitation, thermostat missing to control temp and water flow.

just observations........J

No mention of natural thermosyphon water flow that overcomes the cavitation? No need to control the temperature with this system. The natural syphoning process pushes the water to the upper tank where it begins the cooling process. Remove the belt from the water pump and drive the vehicle through the hottest of conditions, and you will see that the thermosyphoning system works well. This in a nutshell is why the system works well as stock when the radiator is functioning properly.

The high compression head actually makes an engine run cooler. You would think otherwise. As far as the radiator goes, it has more to do with just the comfort of driving than anything. It makes the passenger compartment cooler, for some reason. I thought that, and did not mention it. Then my wife remarked about it.

You don't suppose the higher water capacity of the head with the chamber roof being lowered has any affect on this??

 

[alexiskai]

You don't suppose the higher water capacity of the head with the chamber roof being lowered has any affect on this?

Wouldn't that vary by head? The designer might just as well choose to fill the space with cast iron. Some aftermarket heads did have a reputation for being unusually heavy.

 

[johnneilson]

No mention of natural thermosyphon water flow that overcomes the cavitation? No need to control the temperature with this system. The natural syphoning process pushes the water to the upper tank where it begins the cooling process. Remove the belt from the water pump and drive the vehicle through the hottest of conditions, and you will see that the thermosyphoning system works well. This in a nutshell is why the system works well as stock when the radiator is functioning properly.

Brent,
you are correct, in fully stock form, everything working as it should.
My comment is somewhat cart before the horse. The time of the "T" and "A" probably did not have a thermostat assembly that was usable. And to your point the early "T" had no pump.

The factor of the pump placement and possibly inducing cavitation is from physics. By having the pump on the discharge of the engine, you can induce a slightly lower pressure in the water jacket and that can affect the coolants ability to resist cavitation.

I have no explanation as to the higher compression , higher HP output producing less heat in the engine unless it is a function of faster burn rate transferring less heat due to time exposure. My coupe with OHV and standard type radiator needs the thermostat to get above 130, or cardboard in the grill. With a 190, it runs there even with the ambient getting over 100 and stuck in traffic.

Best, John