I would like to reopen this discussion, hoping we can remain civil about it.
On the weight issue I would imagine that's pretty important on a mini.
Aluminum is under 1/3 of iron. Even though it's a small head,
the weight is reduced in a critical area.....forward of the front wheels.
The other thing that's important and seems to be irons advantage, is its retention of heat in a very critical area of an engine.
Given that the head is almost entirely encapsulated by the water jacket that is kept at a steady temp ....how is it that iron is thought to be better?
I know from experience from heating and bending steal and aluminium that steel holds its heat dramatically longer then aluminium.
My question is.......Does iron produce a hotter combustion chamber because it is relatively very slow at transferring the combustion heat through to the water jacket?

"I would like to reopen this discussion, hoping we can remain civil about it."
Tried it, didn't work.
Ended in a dispute and the ladies locked it.
Anyway, I know that it caused great 'Mini" people to leave this forum today. It's about how loud you cry, apparently.
Good luck with getting an even view.

my thoughrs are --->(& it`s only my opinion)

that if cast iron was the very best, & if there was any major drama/s using aluminum alloy & if the costs were similar ,,, etc etc etc --->then all car manufacturers would be using iron

Now don`t go jumping down my throat quoting costs of manufacture versus ability to do it`s job,,, i know car & bike manufacturers are always looking at saving money when-ever they`re making crap,,, but if it were any real drama with alloy then they wouldn`t use it

however,,, in the old days there were quite a few major dramas with alloy heads,,, poor casting procedures,,, poor quality material etc etc etc,,, some alloy heads were seriously shocking

now-days tho, it`s a Totally different kettle of fish --> quality of materials have improved dramatically, casting processes have improved immensely, metal treatments & machining processes have also seen major improvements in accuracy , strength durability & reliability, so it`s a whole new world now compared to 1950`s & 60`s

nearly all late model car & bike engines are made of alloy now,,, heads, blocks etc etc etc... weight is a factor yeah,,, cost is also another factor,,, ease of manufacture is another.... -->but how they perform , or rather the slight difference in performance between the 2 materials is pretty damn irrelevant in "OUR" wonderful little mini scene
(except for this type of healthy forum discussion where no-one abuses anyone else)

"""expansion index""" is another factor (which i havn`t seen anyone speak/type about yet) is also another important thing to consider

alloy heads tend to expand far more than iron heads & there are good & bad things regarding this extra expansion

however,,, i like iron heads on minis because that`s what they have,,, that`s what i`m used to,,, that`s what they`re "Meant" to have (if keeping to originality) we can even fit bigger valves in an iron head because with the "average" alloy head you will need some sort of hardened steel valve seat insert fitted which (in-turn) makes it pretty damn hard to fit big motha race valves (well not as big as you can in an iron head without hardened inserts) & also even if you did fit the inserts & then tried to make the hole as big as a non inserted head & fit those big motha valves in,,, well the insert would be so damn thin that it would surely just distort & fall out... & the results of valve seat inserts falling out are not a pretty sight

But still, that makes no difference to the "Average" road mini owner because the average road mini owner really doesn`t want "Massive" valves, & also "TOO" big a valve can create shrouding & make for a slower engine

So,,, for the performance inclined person,,, we have a slight dilemma havn`t we???

the alloy head would need slightly higher CR to "Perform" as well as the iron head,,, but the average "Race" mini owner would have high CR`s anyways (surely???)

& i must admit that i havn`t done any research on the different power results from one iron head to an alloy head of the same (identical) design so i can`t comment on the specific performance difference between 2 identical heads (one being in alloy & the other being iron) but i wouldn`t expect it to be very much,,, or at least i`d expect it not to be enough to warrant making all cyl heads out of cast iron from now on

i also havn`t checked to see if the fastest drag car in the world had an iron head or an alloy head

i don`t know if the fastest speedboat has an iron head or an alloy head

i don`t know if the quickest motorkhana special in the world has an iron head or an alloy head

but what i do know is that the fastest motorbike/s in the world """DO""" have alloy heads & are multi cam & multi-valve design

I LOVE twin cam 16v turbo alloy heads on minis tho

i also LOVE the alloy twin-cam, 20valve cyl head on my hill-climb car


be buggered if i`d bother to "Re-make" any of them in cast iron

now, i`m going back to replace the warped & cracked alloy head on my 3cyl Daihatsu Move

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

well my vote is alloy any day, but then my vote does not count.

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Research is the difference between speculation and investment. Anyone who copys some one else will always be second
www.minisprintgt.com

Who went where

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Master of the Moggie Army & Founder of Awesomestock2010

ahh,,, there,,, you see,,,---> Old sayings are true after all

great minds think alike



or was that--> fools never differ???

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Can't we just say whatever floats your boat?

The truth ain't out there. Seriously, it's just taste.

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1964 Cooper UK 970 S 'CZ 4289'

I haven't followed these threads long enough to got the gist of who rubs who the wrong way and what the politics are, all that aside let's try and answer the question .

I do think their is a measurable difference between the two materials, which one is better may not be that hard to figure out, depending on the specific items were comparing.

Some of the questions raised appear to be;
(1) Dose the heat retained in the head affect the ignition?
(2) Dose the metal expansion rates affect the mating surfaces and head gasket seal?
(3) Is the weight saving worth it?
(4) is the price worth it?

Now like MG Rocket stated the thermostat should control the temp of the engine so if the alloy head cools down faster won't the thermostat simply restrict the flow of the coolant thus keeping the head and the coolant at 87deg C the same as a iron head dose.

Expansion rates, well look at other engines with cast blocks and alloy heads do they have problems with this? Id guess that their would be hundreds of thousands of cars in the world with this combo all from different manufactures and all being used in different ways, some with high power out puts others with low power outputs and I can't recall any speak of major problems with metal expansion rates.

Weight is a BIG issue with minis, their famous for their power to weight ratio so taking nearly 5kg or however much the difference is out of the car has to be a good thing, other wise why do the race boys cut and drill metal out of their minis?
Yes the weight saving may only be 1% but it definitely ain't going to hurt.

Now comparing a 5 port siamese head to a 7 port cross flow head is unfair but these alloy heads are a performance upgrade item so if they are lighter that will help performance and if they are easier to cool that will help performance.
Like Matt said alloy may not be able to take big motha valves but the head has better flow so simply it doesn't need the big valves a 5 port would need to make the same power.
If your going to fit a performance head your obviously going to need to re-set the air fuel ratio and the timing and the plugs to TUNE the new engine set up. Who is going to spend the time, money and effort to fit performance parts the their engine and then not tune it properly so the engine doesn't ping or detonate early.

I feel that I don't need to say this but I"M NOT HAVING A GO AT ANYONE it's just my point of view that if someone is fitting an alloy crossflow to their engine all the problems that have been raised as possible concerns should all be sorted out at the same time.
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Now if we are simply comparing materials, alloy to iron in the standard 5 port head designe then I'd have to agree that it's proably not worth the money and effort. in this situation I can only see 2 benifits, the 1st being 1% lighter and the 2nd being slightly eaiser to cool. I dont think these minumial benifits would be worth $2000.
For that money you could compleatly up grade your cooling system and swap your bonnet and boot lid for fiber glass items and then you proably would still have enough change left over for a tank of fuel and a carton of beer.

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Respect mine and I'll respect yours.

bugger this.. this topic is "too hot to trot"... and I can't be stuffed anymore....

As I said in the last two threads, I don't have a dyno, I can't do the testing... but going off what I know about the two materials... I would tend to believe that C.I would produce better thermal efficiency..

BUT

If I was to make a cyl head, I would do it out of Al because its:

-Cheaper to buy
-3.5 times faster to machine
-easier to polish

All points to cheaper production.. and that doesn't mean lesser quality, just faster to produce (and purchase raw materials).

And, again I point out, I can't test it to prove it, but I doubt that the difference in power would be substantial enough to be bothered (where Thermal Efficiency is concerned).

OH, the other thing, Al doesn't really have a smell.... personally, I hate the smell of cast iron when your machining it... and especially when you're grinding it, its got that gross smell/taste that burns the back of your throat very important

Ford quite successfully ran alloy heads on an iron block for years with the XF Falcons. If you look on the side you'll see a little badge "Alloy Head Mk II"

If Ford thought it workable for mass production then I am pretty sure it is workable for mini's.

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Cheers
Alec
1275LS - July 78 - XNFAD18Y/102918