[DeTomaso] Stock 4V Heads vs alloy

[Will Demelo]

When I built my last stroker, the engine builder told me it would take alot 
of labour (read $$) to have the iron 4V's flow like the CHI 3V's. He 
suggested I just put the money towards the CHI's. The alum heads also allow 
for more compression which means more power. And they are lighter, as you 
already mentioned.
Will
----- Original Message ----- 
From: "LS" <lashdeep at yahoo.com>
To: <JDeRyke at aol.com>; <DeTomaso at realbig.com>
Sent: Tuesday, May 11, 2010 2:35 PM
Subject: Re: [DeTomaso] Stock 4V Heads vs alloy


> Thank you for the responses.
>
> You've offered a compelling argument for the Aluminum heads and something 
> to seriously think about.
>
> So, the next obvious question is...which ones?
>
> Thanks,
> LS
>
>
>
>
> ________________________________
> From: "JDeRyke at aol.com" <JDeRyke at aol.com>
> To: lashdeep at yahoo.com; DeTomaso at realbig.com
> Sent: Tue, May 11, 2010 2:12:18 PM
> Subject: Re: [DeTomaso] Stock 4V Heads vs alloy
>
> As you mentioned, the 35 lb per head weight-savings is one big advantage- 
> both in physically handing the castings and for the car's improved center 
> of gravity. Along with the intake manifold, the heads are the heaviest 
> high-mounted parts in your Pantera.
> A second is infinite repairability; I've heard of alloy heads BROKEN IN 
> HALF that were successfully rewelded.
> Third: the most desirable head configuration is the closed-chamber Boss 
> type and all alloy heads come this way. Converting any common iron heads 
> to Boss specs will cost close to the price of alloy heads. Reproducing the 
> high-efficiency alloy head exhaust ports in any iron head is impossible.
> Fourth, iron heads- even closed-chamber Boss heads- aren't very stiff; 
> during the '69-'72 period when 351-Cs were being professionally raced, 
> NASCAR shop mechanics developed a number of internal braces for the 
> combustion chambers to keep them from flexing at high rpm/high compression 
> running. All Cleveland cylinder heads are thin-wall construction just like 
> the blocks; some heads flexed enough to reverse the flow of cooling water 
> through the engine! This led to unexplained overheating and head cracking. 
> The
> required mods called 'posting' are outlined in Waddell Wilson's racing 
> engine prep book; Jr Johnson also had similar brace techniques.
> Finally, the cooling characteristics of alloy heads are far superior to 
> any iron heads; so much so that one can usually run 1/2 to 1 full point of 
> compression HIGHER than even a fully modified iron racing head. In these 
> days of low octane tractor fuel being sold as premium gas for many dollars 
> per gallon, being able to run pump gas without engine damage is certainly 
> worth consideration! The only time iron heads should even be considered is 
> if high-boost turbocharging is in your future. Iron heads retain mor
> e heat and boost than alloy heads- if you can keep the rest of the engine 
> together....
> My 2¢- J DeRyke (with SVO heads on the street since 1990)
>
>
>
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