[DeTomaso] Stock 4V Heads vs alloy

[LS]

Ok, that's interesting. I was under the impression, admittedly with limited data, that the 4v heads flowed enough to warrant comparing them to Al even with all of the other benefits outlined below.

70lbs is a lot of weight too. I may end up keeping the stock engine intact and building a new stroker separately.

Thanks,
LS



----- Original Message ----
From: Will Demelo <wdemelo at cogeco.ca>
To: LS <lashdeep at yahoo.com>; JDeRyke at aol.com; DeTomaso at realbig.com
Sent: Tue, May 11, 2010 2:51:08 PM
Subject: Re: [DeTomaso] Stock 4V Heads vs alloy

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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