Alloy heads

-

robertodonnell

Well-Known Member
Joined
Sep 11, 2009
Messages
62
Reaction score
5
Location
Newcastle, NSW. Aust
Hi guys,

I have been considering alloy heads for some decrease in weight over the front of my AP6. I am looking at doing some other things like alloy rad and fab up and alloy ancillary mount, but I want to know if the heads on the market are durable enough for some weekend track work. I currently have a nice set of ported heads, so it's not like I am looking for engine performance, just weight reduction. The last thing I want to do is make the old bus unreliable.

And apologies if this has been covered before. Feel free to link me to some threads if you know of any.

Regards,

Rob
Oz.
 
I'd look at Trick Flo, Edelbrock Victors (pricey), Brodix for starters.

You guys see more Chinese brands (I think) than we do. Rely on your Kiwi and Aussie friends to advise you about the ones we don't see here.

There are a few active threads here about Speedmaster right now.
 
From what I've read (performance related) you should NOT change heads to alloy simply because of weight
 
They are lighter. I hoisted in a box yesterday that had a pair of Speedmasters in it and I didn't pull a muscle or blow any body parts out! :lol:
 
aluminum heads are lighter, repairable, easier to buy enough flow or work them to get more, get the CC volume you want, bigger valves, etc. It's a win , win.
 
Robert. I don’t know what a AP6 is but....
Currently I would suggest a look at the Trick flow heads as a replacement and performance upgrade for now and the future.

The biggest problem with aluminum (Alloy) heads is the Dissimilar metals of the engine. Mainly the block. But there is also issues with water. There are minerals in water that eat away at aluminum as well. The water circulating through the block will introduce some of the blocks iron particles to the aluminum head (& other parts.) Pre-mixed anti freeze is one way to beat this. Expensive.
I remember reading a few tips here in the past on how to help or stop this. There was something fellas were dropping into the radiator.

I need some help here guys!

Otherwise, there is no problem with aluminum lasting a long time. Keep the anti freeze in excellent shape and the engine cooling part good and it will last.


Now, can I get a picture of a AP6?

Hi guys,

I have been considering alloy heads for some decrease in weight over the front of my AP6. I am looking at doing some other things like alloy rad and fab up and alloy ancillary mount, but I want to know if the heads on the market are durable enough for some weekend track work. I currently have a nice set of ported heads, so it's not like I am looking for engine performance, just weight reduction. The last thing I want to do is make the old bus unreliable.

And apologies if this has been covered before. Feel free to link me to some threads if you know of any.

Regards,

Rob
Oz.
 
I think we need to know more about your goals, performance level and budget. Right now mild to wild is my suggestion, any one of which may not work for you.
 
Apologies guys, yes you do need to know more. Was a quick post late last night.

Car, AP6, is '65 Valiant. Engine is SBM 318 with 0.40 over KB167 pistons, Comp XE268 cam. Still working on exhaust because car has a custom rack and pinion setup and T5 5 speed box. All that in a right hand drive car makes exhaust plumbing difficult! Currently running 600 Sq bore Holley on Eddy dual plane manifold, but intend to run EFI in the future.

I'm not looking for massive power, 300hp at the wheels would be nice. As I said, heads are already nice and have bigger valves but I don't know valve sizes. Heads were built by ex Chrysler mechanic for torque and good mid range.

So my only real logic in head change is for weight reduction. Car weight is 1400 kilos (under 3100 lb). I would love to reduce weight over the front to improve front to rear balance and cornering.

Cheers,

Robert
 
I think the new TrickFlow would be overkill and more expense than you need to undertake. Non-CNC'd Speedmaster, Promaxx, or Edelbrock heads would serve you well. Either complete ready to go or bare and you or your shop finish them off. The Speedmaster come from your neck of the woods so that is where I would start if I were you. Have whatever you get checked out before install (several threads currently running here on this topic) and then go forth and be merry.
 
No, they are not less detonation prone. Do a search on this forum. It's been based out more than once.

That's at best an old wives tale and at worst, it's a lie.

If you are stating that the higher ability of aluminum to dissipate heat from the combustion chamber is nominal. I'd bite on that. But there has to be more to it then.

My guess.. would be aluminum heads has better chamber designs. (smoother, shape, quench, etc) combined with engines equipped with these heads often having blueprinted deck heights, ideal cam specs, headers and even piston coatings affecting the engines compression/octane friendly traits.

In other words, while I think aluminum heads are more compression friendly, I don't think it's as simple as solely changing the material of the head that equates to this
 
My understanding is that because heat is a major component of detonation and aluminum dissapates heat better than cast iron, this makes them less prone to detonation.
If all things were equal, an engine with aluminum heads would be less effective due to the loss of thermal energy. Cast iron is better at heat retention and keeps the fire in the hole longer whereas aluminum absorbs and dissapates the heat. Perhaps this is why you can bump up the compression with aluminum and retain some heat for the combustion process, putting that heat back in the hole where it belongs and not losing it through absorbtion.
 
Ahhhhh, no.


It’s a bit more complicated than that but in the end, aluminum is better.
It is a combo dependent thing on how far you can take anything.
All things being equal, I’d run iron up to a 10.5-1 & pump gas on a good street cam.
With Aluminum, I already at 11-1 and a smallish cam. 224@050 & 93 octane.
Compression is compression. Air fuel explosion is air fuel explosion.
The amount of energy released is the same on a otherwise everything equal engine. Efficient and effective beast removal from the head will allow more compression.
 
Last edited:
Aluminum are worth the investment. They are significantly lighter. They are more easily repairable. Better castings and give you room to grow. If you race the car, weight is EVERYTHING! Sooner or later your will get to the point that making more power becomes technically or financially prohibitive. What’s left? Shed weight.
 
Aluminum are worth the investment. They are significantly lighter. They are more easily repairable. Better castings and give you room to grow. If you race the car, weight is EVERYTHING! Sooner or later your will get to the point that making more power becomes technically or financially prohibitive. What’s left? Shed weight.
A hundred pounds is a tenth! I could be a tenth quicker if I only weighed 130# LOL
 
If you are stating that the higher ability of aluminum to dissipate heat from the combustion chamber is nominal. I'd bite on that. But there has to be more to it then.

My guess.. would be aluminum heads has better chamber designs. (smoother, shape, quench, etc) combined with engines equipped with these heads often having blueprinted deck heights, ideal cam specs, headers and even piston coatings affecting the engines compression/octane friendly traits.

In other words, while I think aluminum heads are more compression friendly, I don't think it's as simple as solely changing the material of the head that equates to this


That's part of the issue. There is nothing wrong with the OE MoPar combustion chamber. In fact, it's better than most of the junk out there being sold today. To get a closed chamber correct is not that easy. Anyone who has ever worked with a BBC closed chamber head knows what garbage that pig is.

The junk chamber in the W5 head is a crime against horsepower. Chrylser should have been ashamed to put that chamber out there. That's why most W7 heads (if not all of them) came without a chamber. That W5 chamber is J U N K junk but Chrysler gave all the whiners and snivelers what they wanted...a closed chamber head.

As I've pointed out in other threads, the material of the head makes ZERO difference regarding compression ratio AND ignition timing.

Detonation resistance is based as much on chamber SHAPE and plug location as much as cam timing is. Maybe a bit more.

A closed chamber isn't always a good chamber, and no amount of marketing can fix that.
 
My understanding is that because heat is a major component of detonation and aluminum dissapates heat better than cast iron, this makes them less prone to detonation.
If all things were equal, an engine with aluminum heads would be less effective due to the loss of thermal energy. Cast iron is better at heat retention and keeps the fire in the hole longer whereas aluminum absorbs and dissapates the heat. Perhaps this is why you can bump up the compression with aluminum and retain some heat for the combustion process, putting that heat back in the hole where it belongs and not losing it through absorbtion.


Nope.
 
Aluminum are worth the investment. They are significantly lighter. They are more easily repairable. Better castings and give you room to grow. If you race the car, weight is EVERYTHING! Sooner or later your will get to the point that making more power becomes technically or financially prohibitive. What’s left? Shed weight.


I don't know anyone arguing THOSE points. The issue is aluminum and CR.

And while weight is important, it damn sure isn't EVERYTHING.

I've added weight more than I care to say and went quicker almost every time. There are some chassis that just can't be fixed with anything other than a torch and a scrap bin.
 
A hundred pounds is a tenth! I could be a tenth quicker if I only weighed 130# LOL

Keep in mind you are not alone.

I watch Grand Prix motorcycle racing on occasion. The drivers are amazing. And they all weigh around 130 lbs. Big guys ride Harleys. -----Torque-----
 
Just because someone says something and they sound convincing, it doesn't mean that it is true.
 
-
Back
Top