Aluminum vs iron heads on a 9:1 daily driver

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travis
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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by travis »

dfarr67 wrote: Mon May 16, 2022 12:53 pm 305 heads might even work with small chambers and up rated valves.
Not easily it won't 😜 Did you mean 289 heads? That was my original thought but other than small chambers, there is nothing really special about them.
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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by dfarr67 »

travis wrote: Mon May 16, 2022 1:17 pm
dfarr67 wrote: Mon May 16, 2022 12:53 pm 305 heads might even work with small chambers and up rated valves.
Not easily it won't 😜 Did you mean 289 heads? That was my original thought but other than small chambers, there is nothing really special about them.
Sorry- wrong genre. The Chev's are a little easier to mix and match. As far as I know you have some selection of late iron. Was always a little jealous of Ford head support.
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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by n2omike »

mag2555 wrote: Mon May 16, 2022 11:53 am Sorry , but cooler air is dencer then air at a higher temp, this is what moves air around the planet and is why fearce windstorms take place when colder air is pushing hotter air around.
It's a basic principle of nature!
If there did Show a sliver more power from the Aluminum heads then it was due to the length of the Intake runner in the heads being cooler .
Air moves from high pressure to low pressure. Hot air = high pressure (expanding)... Cool air = low pressure (contracting). When the head/chamber is cooler, it will flow more air. It's one reason a cool engine makes more power than a warm one.

On a flow bench, the iron head flowed more air. On the running engine, the aluminum head moved more air. The difference was explained that the cooler chamber of the aluminum head created a larger pressure differential, allowing more airflow on the running engine.

An identical aluminum head will make more power than its iron counterpart. It will also be more resistant to detonation. This being said, the differences are not huge... a few horsepower... but they are there. The original poster will likely be happy with either one... as long as it does not detonate on his pump fuel of choice. If a true 9:1 and the cam isn't very big... it may be worth his while to try an aluminum head if he wants to run 87 octane.

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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by PRH »

Somewhat handy with a die grinder.
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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by PackardV8 »

Arent' most OEM heads today aluminum? And don't most OEM engineers and bean counters have to have very real, verified improvements to spend money on stuff?
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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by Momus »

dfarr67 wrote: Mon May 16, 2022 10:09 am
Momus wrote: Sun May 15, 2022 10:51 pm Aluminium everytime, if just for the weight saving and cooling improvement.

Iron heads are obsolete.
That's a very broad statement- and I disagree. I've run RHS iron and AFR alum on a 355, it's NOT a night and day difference- in fact I was disappointed at the difference. EFI application, I'll say a good iron head beats a poor alum head any day.
Your iron head was lighter and cooled better?
They were my criteria.

I made no comment about power.
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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by rebelyell »

Engine Masters TV
I watch it sometimes and find it (somewhat) both entertaining & educational. Is Engine Masters the oracle of truth ?
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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by lefty o »

rebelyell wrote: Mon May 16, 2022 11:24 pm Engine Masters TV
I watch it sometimes and find it (somewhat) both entertaining & educational. Is Engine Masters the oracle of truth ?
no they are not the oracle of truth. they do prove that under certain circumstances their results are valid.
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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by Tom Walker »

In an application where weight is not a very important part of the decision and massive porting out a lot of material is needed, then the durability and toughness of cast iron every time for me.
Aluminum has a very sweet weight ratio and is awesome when it is time to start grinding material out, but I still look at it as having a second rate durability rating compared to iron in an application such as a cylinder head used in daily or moderate performance work.
High end racing engines, then aluminum all the way.
Application specific.
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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by Tom Walker »

Was trying to say above, when a lot of material does NOT need to be ground out, then iron is great.
If grinding a lot, then give me aluminum.
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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by Geoff2 »

Agree,
For long life & durability, iron is hard to beat...
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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by DeezNutz »

If cost is not a factor Aluminum wins on every variable. Try getting a good repair locally on an Iron head. Aluminum makes equal or more power and is easier to machine, port, repair, etc... They are just better. As far as power, in every top class of racing they use Aluminum heads, and its not because Aluminum is cheaper... at the level of F1, NASCAR, Top Fuel, Funny Car , Pro Stock, tractor pulling, boats, motorcycles, the list goes on and on... if they found an advantage to cast iron, they would use it.

For the replies about diesel engines and iron heads..... tell me again how a sbf and a diesel are at all in the same category.... not at all relevant to the build question.
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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by CamKing »

If you are limited to 89 octane gasoline, the aluminum heads will allow you to run higher compression, without detonating.
That extra compression will increase the power throughout the RPM range.
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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by GARY C »

Both dyno and track testing shows an engine with cold water and cold air intake will have a significant gain in power over any chamber/piston thermal coatings indicating that high chamber temps are far less important than a cool intake charge, at wide open throttle an aluminum runner will cool much faster than an iron runner there for providing a denser air column allowing more air into the cylinder.

The combustion process happens so fast that aluminum has no time to hurt power by absorbing heat, this is why thermal barriers show little to no measurable power gain.

In context of the thread the factory heads the OP presented should be a good choice providing you can find some that don't need ship loads of money to make them usable.
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Re: Aluminum vs iron heads on a 9:1 daily driver

Post by BOOT »

Some say you need more comp with alum to equal iron because of the thermal loss with alum. Iron is more rigid and less sensitive gasket clean up. Some may want more weight in that area.

David Vizard modded an iron intake was really great at isolating heat and also used coatings on some of his EFI alum intakes to improve power.

Are OEM bean counters using weight cost ship/fuel efficiency, machining cost, worker healthcare cost or other to figure out the alum benefit?

The last several sets of heads I've bought are alum and the weight, metal type, time cleaning-up/porting doesn't really factor for me. It's the design and total cost that has. I like GM vortec heads but most will be well used or take more mods to bring them up to par as other cheap alum heads available. I also like the Sportsman II iron heads(I know they had an alum version) that I have but can't cost effectively change things or add iron to where I'd want it.
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