Inspector

iTrader: (1)

Looking for opinions on which heads would be better for a low boost Gen VI 502, the Race Series Heads with 320 cc intake ports or the Pro 1 Heads with 325 cc intake ports. In talking with Dart they recommend using the Pro 1s as they are good flowing as cast heads which do not need port work. They said the Race Series Heads have more material which allow porting and could have the intakes opened up to 349 cc with their CNC porting. I am leaning towards the Race Series 320s just because it seams like I am hearing of a lot of issues with the Pro 1s (could be caused by high volume production?). Also, with the Pro 1s having less material they sound somehow less durable? I already have one set of the Older Race Series 320s which have not had any port work done. Dart tells me the major difference between my older head and the currently produced ones is the type of spark plug used so I could use a newer set to match my older pair.
Thanks.

MILD THUNDER

iTrader: (3)

What they told is right on. I have the race series heads myself. Mine are the older ones which take a tapered plug, newer race heads get a gasketed plug. I believe they have thicker decks than the pro 1 series also. These heads I have, are actually the 308cc aluminum race series, which they don't make anymore. But, with mild port work, 6lbs of boost, hyd roller cam, made 804HP@6000RPM on my 468's. I know of a few guys running the 320's and 360's making some big numbers with blowers also.

mike tkach

iTrader: (3)

i have the 320s on my 548s in my cat making 950 at 6200 rpm,they are not ported,just cleaned up a little.the pro 1 325 is also a good head and i believe the output would be close to the 320s.