I can't speak for the DD numbers specifically (and why would anyone?
) but heads do indeed make a difference on a blown engine.
Just because the engine utilizes forced induction does not automatically mean that poor flowing heads are no longer poor flowing.
A better flowing head will fill the cylinders better, and in fact might do so while showing less boost on the boost gauge (since the manifold/plenum is not as backed-up with the charge).But when it comes to blown engines, there is a LOT more to consider in a cylinder head that those silly flow numbers. To this day I am perplexed at how people place so much weight in flow numbers, asking "what do they flow?" when in fact there are so many much more important factors to consider when evaluating cylinder head design for a given application. I have known of heads with lower flow numbers generating more horsepower on a shortblock than a pair of heads with higher flow numbers....thanks to the overall design of the cylinder heads with the lower max numbers.
Flow schmo. But now I'm off on a tangent, lol.
Back to your question: The more radical you get with a blown engine, the more things need to be considered about a cylinder head design, and to some extent the other factors begin to rise up the ladder relative to the flow number statistics. Things such as spark plug placement, deck thickness, chamber shape, etc. are pretty important and rise in importance as boost and/or power (such as nitro) increases.
So yes, in a blown engine good heads will typically shine over not-as-good heads. That being said, in a mild blower build you might be surprised what you can do with not-as-good heads that have been properly warmed over.
LO
p.s.: this sounds like a job for your Dad's Hemi HEads.
