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I believe the D-Max has aluminum heads and that's why it's so quiet.
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Just throwing this out there, If you want more heat to stay in the head. Then why do so many guys run their water temps so cold?
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You want as much heat to stay in the combustion chamber during the power cycle, which cools as the gases expand and the piston goes down, more heat and pressure at the beginning, more power.
After the power cycle, exhaust, and then compression, you want the combustion chamber cool enough that hot spots don't preingnite the compressing charge. Having the block cooler helps with this. There is a boundary layer at the surface of the metal, whether it is aluminum or iron that keeps the searing hot combustion gases from melting or burning away the metal. Aluminum passes more heat than iron as it is thermally more conductive and therefore is less likely to get those hot spots. |
A bit of a segue, but would it be feasible to put a small blower like a B&M 250 on a 9.5:1, forged internals on a 502, and 91 octane pump gas? Would aluminum (Edelbrock Oval Performers) let you get away with that much CR under boost?
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I ran Iron heads on my blower engines for years and it wasn't terrible. However the boost was low (6-7lbs).
Almost all Mercury's forced induction and high performance engines now have aluminum heads. I think the last time Mercury put an Iron head on a blower engine was the 800SC? Not saying iron is bad... I kept mine for years because I was running in salt water. However, having switched over to aluminum and running them on a few other engines, I'm a believer. |
Originally Posted by MILD THUNDER
(Post 4395443)
Yes, they are. I payed a bit less than that. Actually they were 425 each to my door. They are a favorite in the truck pulling class that mandates iron head per their rules. There are quite a few guys making over 1000hp on motor with these heads, ported of course. Out of the box, they flowed 370cfm at 600 lift, and 388 at .700, .391 at 800. Keep in mind this is an as cast head, 320cc runner, with a 2.25 valve.
Ive talked with quite a few head specialists and engine builders prior to buying them, and read a bunch of posts over on yellowbullet and speedtalk, and couldn't find one negative about them. Once i got them, looked them over, had my head guy give me his opinion, he really liked them. Then once he pulled our darts off the flow bench, and started flowing them, he liked them even more. |
Rumor has it, that EQ may be stopping the iron heads...so, if you are going to use a set, I wouldn't wait too long. Or atleast call EQ to see if this rumor is true or not.
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Originally Posted by Mr Maine
(Post 4395553)
You want as much heat to stay in the combustion chamber during the power cycle, which cools as the gases expand and the piston goes down, more heat and pressure at the beginning, more power.
After the power cycle, exhaust, and then compression, you want the combustion chamber cool enough that hot spots don't preingnite the compressing charge. Having the block cooler helps with this. There is a boundary layer at the surface of the metal, whether it is aluminum or iron that keeps the searing hot combustion gases from melting or burning away the metal. Aluminum passes more heat than iron as it is thermally more conductive and therefore is less likely to get those hot spots. |
Originally Posted by SB
(Post 4395568)
Rumor has it, that EQ may be stopping the iron heads...so, if you are going to use a set, I wouldn't wait too long. Or atleast call EQ to see if this rumor is true or not.
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Originally Posted by Panther
(Post 4395562)
I ran Iron heads on my blower engines for years and it wasn't terrible. However the boost was low (6-7lbs).
Almost all Mercury's forced induction and high performance engines now have aluminum heads. I think the last time Mercury put an Iron head on a blower engine was the 800SC? Not saying iron is bad... I kept mine for years because I was running in salt water. However, having switched over to aluminum and running them on a few other engines, I'm a believer. Im not suggesting iron is better, im just suggesting that sometimes we cant ignore whats worked in the past. |
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