Cooling tricks with iron headed hot rods?

[RobZ28]

Doing a set of irons for my Camaro with some porting, and decided to watch an episode on Engine Masters where they compared the iron to aluminum folklore testing the power difference between the two. The castings they used were Dart castings and pretty close if not exactly the same head design and the results were pretty interesting.

The aluminum head came out on top. Rather if this was because the aluminum was keeping the charge cooler (and therefore denser) or maybe because that head had another difference in it somewhere we dont know about. Flow numbers were close between the two giving the iron head a slight edge. Dulcich said maybe* the combustion cycle was too fast for iron to make the power difference but I assume this would work both ways... regardless of heat material. So I dunno. The thing that was most gruesome in the test was when Brule went to shut the iron headed engine off and it kept running. I will tell you right now, this also happens to aluminum heads in Texas. My Z28 will diesel on with 93 octane in the tank and even stutter on just mild days after I turn off the key. I run an octane booster to help this.

So I have to ask, has anyone else ever tested this theory and had different results? And are there any tricks to help cooling iron heads on a street car besides a better cooling system? Maybe like some slight opening up in the coolant ports or maybe even a different finish or coating material to dissipate heat? Thanks.

[rebelrouser]

In my experience changing to a pulley to spin the water pump faster makes them cool much better. Done it several times. And I have fixed a couple aftermarket belt drives because they had a smaller pulley than the stock setup and it made them run hot.

And never tested it, but the thing repeated used to be that iron heads made more power because the chamber did not lose as much heat on the combustion stroke compared to aluminum heads. IF the flow was the same.

[Tom68]

No tricks required.

[PackardV8]

On our obsolete iron heads:

Block the exhaust heat crossover
Large electric fan with shroud
Outside cold air intake
Fuel return line to the tank
Custom ignition advance curve; lots of initial advance and plenty of vacuum advance at cruise.
Tuning the carb with an on-board wide band O2 sensor.
As little antifreeze as feels safe. Water cools better.

To stop run-on/dieseling, go back to the '70s GM throttle kicker which completely closes the throttle blades when the ignition is cut.

[BLSTIC]

On our obsolete iron heads:

Large electric fan with shroud

I'll add to this and say that any air that can go around the core, will. So fill-in panels, foam stuffing, and undertrays are the order of the day here. You can easily double airflow through the core going from "really bad" to "sealed up".

Also if your cooling system doesn't AT LEAST have a recovery system I should point out the folly of knowingly having air in the cooling system and complaining about keeping it cool. A proper header tank connected to high points and the suction radiator hose would be best, but is harder to engineer.

[Geoff2]

Water pump should be over driven 10-30%.

More info here: www.stewartcomponents.com

[Bill Chase]

Take a look at what GM did for the 85-86 tpi Corvette, they were iron heads, close to 10:1 compression. Used a pretty thin radiator too. 7" crank pulley, and around 4-1/2 to 5" water pump pulley. They set them up to run hotter, but a thermostat and different fan temp settings and it's easy to keep them around 175-185° the factory usually spends a lot of time and money sorting out stuff like this, observe and copy. A good water pump helps too.

[F-BIRD'88]

Make sure that the chin spoiler is intact. It is essentisl. If your intake manifold has those 2 extra rear water ports back near the diz connect the drivers left side water port to the water outlet on the top os the water pump. VS the stock way they are connected. This helps stablize the thrermostst operation and iimproves cooling.
On the TPI (083) heads block off the exhaust EGR riser ports in the 2 center exhaust ports. I use heavy duty guage catering -cooking pan aluminum foil to stuff in those nasty EGR ports. You want to block off exhaust comunucation between the center exhaust ports. Stuff it in tight in both ports.
If you are willing (before the valve job is done) you can use melted down old cast aluminum pistons to HOT Pour into these EGR ports and smooth the exhaust bowls when done. Either way will work.

As said make sure that ALL the air is forced thru the radiator core.

[Walter R. Malik]

Cooler intake air temp is crucial for squelching detonation; even at under 200 degrees water.

[PackardV8]

Cooler intake air temp is crucial for squelching detonation; even at under 200 degrees water.

Just scanning through Motor Trend and saw some numbnuts hot rod shop, their high dollar build featured two K&N open cone air filters on a y-pipe right behind the radiator.

[Kevin Johnson]

On our obsolete iron heads:

Block the exhaust heat crossover
Large electric fan with shroud
Outside cold air intake
Fuel return line to the tank
Custom ignition advance curve; lots of initial advance and plenty of vacuum advance at cruise.
Tuning the carb with an on-board wide band O2 sensor.
As little antifreeze as feels safe. Water cools better.

To stop run-on/dieseling, go back to the '70s GM throttle kicker which completely closes the throttle blades when the ignition is cut.

It is worthwhile to look at the more advanced surfactants.

https://blog.amsoil.com/do-coolant-addi ... ectiveness

My father was a research chemist for Swift. It seems like he mentioned Amsoil or was acquainted with them (likely their founder) while working on synthetic lubricants.

[BOOT]

Too bad your engine bay isn't the size of a dyno room

Didn't see the show, so can't comment if the heads were sim design/shape enough for a good test(don't care what they flowed).

Brzezinski(cast heads) talks bout some Dart cast iron heads, having coolant flow issues in one of their vids if i rem right.

Back to my first comment, are you using a CAI setup? So many factors to consider, especially when testing.

I've used the slowest UD pulley crank and Water pulley combo i could get with iron heads, ran 170 in summer. Some circle track guys like super HOT temps. Depends on how things are set up for your combo in total.

[BOOT]

Just remembered EQ says they improved cooling on their vortec heads vs GM, so it matters what heads and not just iron.

[rgalajda]

You won’t get good answers from those guys (Engine Masters) .
First of all, run on or dieseling is caused by throttle blades open too far at idle given all else is correct.

This is what I have. BBC Monte Carlo 500+ hp with iron heads used for street touring.
I run a $300 2 core aluminum rad with wide tubes, has stock recovery tank and original fan shroud ,180 thermostat , original clutch fan and pulleys. Weiand aluminum water pump.
I can leave it idling , drive all day in traffic or highway, or run it hard to 140 mph on the hottest days (about 95 degrees) with temperature never exceeding 190 degrees. If I run a 195 thermostat the temperature never exceeds 205. No dieseling, run on. 900 rpm idle.
No drilled thermostat, no fill in panels, 50% antifreeze. No electric fan.

Timing is 29 degrees at idle with vacuum advance , lean cruise AFR, up to 21 mpg imperial.

The only complaint I have is that in cooler spring weather and late fall the engine temperature is too cool so I run a partial rad blocker then.

[Tom68]

First of all, run on or dieseling is caused by throttle blades open too far at idle given all else is correct.

Dieseling is auto ignition, injected motors don't get it because the injectors are shut off.

The thing that was most gruesome in the test was when Brule went to shut the iron headed engine off and it kept running. I will tell you right now, this also happens to aluminum heads in Texas. My Z28 will diesel on with 93 octane in the tank and even stutter on just mild days after I turn off the key. I run an octane booster to help this.
.

Injected engines that aren't burning oil don't run on because they shut the injectors off.

Carb'd engines that run on can use a solenoid that opens and leans the AF on shutdown.


No tricks required, just put the car together properly with OEM quality components and a less compromised tune than the factory has to use.