Would there be a significant hp advantage to a hemi 99 style head for 2nd gen hemi or is a Predator head already there? I understand that this head does not currently exist, but is there any reason to develop it? Is there an inherent disadvantage to the Hemi 99 versus a canted vale head for a normally aspirated engine?

IMO I think the 99 was developed using the whole package. Why put 11,000 rpm potential in a 7,000 rpm block?

The Predator head is probably one of the best bolt on combos a Mopar can have.

But the guy that can answer your question better is Goodwin Racing engines.

http://www.goodwincompetition.com/products-and-services/gc-5-0%e2%80%b3-semi-hemi-650-c-i/?-semi-hemi-650-c-i/

If you get to the point where you need a Hemi 99 style head to compete in your form of racing you probably better be moving to a bigger Bore space anyways.

Moving away from the mopar 4.800 and rarer 4.840BS stuff was the best thing we ever did.

Is your hemi a 484 bore spacing

I believe the one in the truck pull picture above is either 5.0 or 5.3 BS.

The Hemi 99 and it's later brother (04?) isn't a true Hemi head, it's a canted valve like the Predator head. Calling it a Hemi is all marketing. The position of the plug through the valve cover like the Gen II Hemi are the only real similarities.

Anyway, as stated, block is going to let you down. I don't imagine you'd get the pushrods where you need them without doing a new block. I wouldn't bother with a 4.8" bore space block. Noonan are doing 4.9" bore space billet Hemi's now for Blown alcohol racing now, I'm sure if the rules allowed, the bore spacing on Pro Stock would be wider now.

Our Hemi is one of Goodwins Billet 5" bore space. And your right they are a "hemi" head with pretty much the only thing in common with a true Hemi is the plug through the valve cover.

I was saying before that we tried competing with the GM and ford engine for years with the 4.840 B1-TS stuff and there is just no way to keep up with the tech and advancements the GM and Ford guys have, especially when they started moving to the 4.9 and 5" BS stuff in truck pulling.

Hemi 99 or 06 stuff is specific parts period. They are on a 4.9(pro Stock)5.0 Goodwin or 5.3(IHRA Pro Stock) versions. The parts DO NOT fit any block but a dedicated piece for that head. I ran a 99/06 Hemi for a couple years, it is still out there doing its thing in a heavy car. They make really good power to be sure, its a pro stock engine after all. A lot of them out there and pieces for sale if you know where to look. I currently have a Predator deal and as far as I'm concerned the jury is still out. I have had mine on the dyno, found some stuff we did not like and the heads are off now getting more attention and a new intake will be built as well.