Aluminum Heads For The IDI

[icanfixall]

Can anyone tell the the usefullness of an all aluminum head made for our idi engines.. Whats the benifit of using that material. Better heat disapation or what.. I know they would be lighter and easier to handle but why is this such a used material in so many high hp engines. I understand all the extra seat machining needed but other than that whats the deal...

 

[justinray]

I'm no expert, but I believe it has to do with the heat dissipation properties, it may also have to do with the machinability though. As for the first reason, I would throw that to the wind because the first time the precup got to 1200* you could give up on those heads, and you have to remember that the precup is hotter than the combustion cylinder is hotter than the exhaust gas, so I would stick with what we have unless you plan on a coating of some sort.

 

[Devon Harley]

Mainly the mechaine work tht you can perform on the heads heat desperation an light wieght. However I would not use on an Idi head our heads are perfect we need to figure out how to work on the pre-cups as in coatings cryo treating or somthing! But that can't not be done do the the perfect fuel swearls that are on them. Mess with tht an your heads are toast. With a port polish clean up port match an good valves coated an bronze guides 4 angle alve grind they flow better than a 6.0 head stock before this work so the rest is profit. An there reusable the only place aluminum head go after being on an engine is straight to the trash can that's why there so light so you can carry more than one. I'm sure some guys here are all mocho but must wouldn't dare carring 2-3 of our heads to the trash ouch.

 

[riotwarrior]

It's cost of production, machining and heat transfer for the most part.

As for longevity, I'll take iron every time for a diesel. You are assured of like minded expansion and contraction rates of a singular material. Unlike using aluminum/iron where you can run into shift issues, due to different expansion rates.

Anything you can do with machining in AL you can do in FE too. Iron just wears out cutters quicker!

JM2CW

Al

 

[bike-maker]

If you had 2 identical pairs of heads, 1 set aluminum, and 1 set cast iron; the cast iron heads would make more power. Heat in the combustion chamber = expansion = power. Aluminum dissipates this heat more than cast iron does, resulting in a slight power loss.
The main advantages to aluminum are light weight and they can be welded back together even after a catastrophic failure.

 

[RLDSL]

Only plus to AL is weight. Yeah they can be straightened and welded after failure, but 98% of those failures wouldnt have happened if the heads were iron so its really a moot point. Iron can take oodles more torture and can take an overheat or water loss wiithout self destructing in most cases, AL is an almost guaranteed disaster if the needle goes up or there is a loss ( I say almost because there is always a chance, but I have NEVER seen one survive personally without major damage )

 

[G. Mann]

Aluminum / cast iron combination is death on a shingle. Any time you mate the two together, you get a galvanic reaction called dis-similar metals corrosion. The aluminum becomes the electrode for the cooling system and erodes... guess where.. at the head gasket surface...[contact area, through the head bolts acting like jumper cables] The pistons going up and down generate and electrical current [a low one, but enough to set off the corrosion path, and soon you have issues.

Anyone remember the Chevy Vega? Cast iron head against an aluminum block.. good example of what I'm talking about. There are others.

 

[Sw1tchfoot]

Mazda RF 2.0L diesels used an aluminum head. Corrosion never seemed to be an issue, but the heads always cracked between the valves.

 

[Devon Harley]

Aluminum / cast iron combination is death on a shingle. Any time you mate the two together, you get a galvanic reaction called dis-similar metals corrosion. The aluminum becomes the electrode for the cooling system and erodes... guess where.. at the head gasket surface...[contact area, through the head bolts acting like jumper cables] The pistons going up and down generate and electrical current [a low one, but enough to set off the corrosion path, and soon you have issues.

Anyone remember the Chevy Vega? Cast iron head against an aluminum block.. good example of what I'm talking about. There are others.

I love the chevy VEGA lol

 

[RLDSL]

I love the chevy VEGA lol

AH, the Vega... the car that wanted to be a camaro when it grew up

We can get you help... they have places for people like you.... THere is a cure

 

[RLDSL]

I play with a lot of european diesels and I love the VW 6 cyl diesels but those suckers are a iron block, al head combo with MLS head gasket and TTY head bolts torqued down so tight it will have you cryin for mama when you hear the noises stuff starts making when you either go to tighten one down or take one apart You generally only hear those kind of noises on big Cat engines, and usually not as bad, but those little VW engines are squeezed together TIGHT and that aluminum starts to flexing and squeeking like you wouldnt believe when pulling those bolts all the way down . They have about the same compresin as an IDI but commonly see boost numbers around 21,22 psi.
The things run great, but have zero tolerance for overheat ( main reason I found Evans Coolant , no more of THOSE expensive little problems, last nasty little pre Evans incident involving overheat and thermostat a long way from home cost me thousands)

 

[tbrumm]

Aren't the Duramax (Izuzu) Diesel heads aluminum? I thought I read that somewhere - another reason not to own one. What is Ford using for head material on the new 6.7L? I knew they have some new ****-bang high density cast iron or something for the block, but what did they do for the heads? I understand the concern over the dis-similar metals and different rates of expansion. How do they keep the lids on aluminum head diesels?

 

[RLDSL]

Aren't the Duramax (Izuzu) Diesel heads aluminum? I thought I read that somewhere - another reason not to own one. What is Ford using for head material on the new 6.7L? I knew they have some new ****-bang high density cast iron or something for the block, but what did they do for the heads? I understand the concern over the dis-similar metals and different rates of expansion. How do they keep the lids on aluminum head diesels?

Its a given that you need MLS head gaskets on aluminum head diesels . I know faithfully on the old 6 cyl VW diesels they came from the factory with composit head gaskets ( before MLS had come into being ( and it was a given that they would trash a HG at between 120 and 150k miles from the sliding back and forth during heat up and cooling cycles, the factory changed to an MLS gasket as soon as they were available. MLS gaskets allow for this by keeping the sliding betweeen the shim layers of the M:S gasket and a slight amount of flex where the rubber surface is embedded into the metal of the head and block or in the case of many euro diesels they come pre coated with hylomar to bond to the metal and allow for the flex movement''

Anyone that gets in an AL head diesel cold and takes off fdown the road under load before giving it a chance to warm up must be planning on trading that thing in before it hits 100k miles, because its a recipe for disaster

 

[Kevin 007]

Just like a dirtbike with an AL piston and a cast barrel. The piston will always heat up quicker and expand too quickley and sieze up time!!!

Many import engines including diesel used mixed metal engines. The L series toyota's and VW's were probably the most common, at least for me. And yes, they do seem to have H/G issues when they get hot but I have seen many of them go for the life of the engine/vehicle without being apart. Seems that if they DO NOT get too hot, they can be ok. Just like the 6.2. Still not ideal in my mind to have mixed metal engines.

 

[diezelcrazee]

Aren't the Duramax (Izuzu) Diesel heads aluminum?

When they first came out in 2001 I thought what a train wreck.... AL heads on a iron block?? Well, I'm still not a GM fan, but I will have to hand that one to those boys, that engine has been pretty successful.