225 Hemi head
I could talk to Radar from R&J Performance . He carves Hemi heads out of billet quite often. They scratch built a billet head for a John Deere pulling tractor. lol It would cost thousands and then the intake to make it work. Headers not quite so hard to fab.
Mike,
You bring up a good point; cost/effectiveness.
I have spent a lot of time trying to learn what I could about this engine from this and the .org message board, several books, including the three-volume set of the history of the making of the slant six by its designer, Willem Weertman (no typo) and all the evidence tells me one thing:
This engine was designed to be a small-displacement (170 c.i.d.) engine, with small bores. The cylinder head was a product of that line of thinking and the modification of the original design, to include a bigger displacement by stroking it a full inch, was obviously never a part of the original plan.
The fact that the cylinder head was not touched in the original enlargement was evidence that it was a band-aid approach to a bigger problem. It had no chance to breathe effectively through the same ports and valves that had worked so well for 170 cubic inches, with now, a 33-percent increase in displacement; It became a low-rpm workhorse, lugging station wagons around, and that it worked as well as it did in the 198hp Hyper-Pak 225 Lancer motor was a minor miracle.
The fact is, the small cylinder bores (and the resultant narrow combustion chambers, dictating small valves,) coupled with the rpm-limiting long stroke (talking about the 225, here) become a one-two punch that make the process of attempting to get a LOT of power out of that engine an exercise in frustration. You can spend money on high-compression pistons, radical camshafts, exotic induction systems, high-rpm ignition systems, electronic fuel injection and expensive ported and polished cylinder heads with thee biggest valves you can fir in them, and still end up with a motor that has a thoroughly un-impressive output... BECAUSE the head cannot be made to flow enough air to support the kind of air movement necessary to generate sufficient volumetric efficiency to do the job.
It might be possible to move the kind of air you'd have to have to make 400 horsepower, naturally-aspirated, with a 4-valve head (but, given the small bores, it would take a designer who knew exactly what he was doing... and it MAY even be possible to get a 400 h.p. slant six, naturally-aspirated, using a 2-valve, hemi configuration head, to gain enough valve-size increase, and the superior breathing of a cross-flow design, but at what expense?
The 400 h.p. slant six is achievable with the addition of such power-adders as nitrous oxide, supercharging and turbocharging because it was built, originally, as an aluminum engine... which, for whatever reasons, didn't pan out. When they changed the engine over to all cast iron, the cheapest thing to do was make VERY FEW CHANGES if thee design structures of the engine, so it was built with extra-thick main bearing saddles, a forged steel crank, thick top deck specifications, and an 84-pound cylinder head... with the result that this motor is especially suited for levels of boost that would make scrap metal out of most of the V8s Chrysler builds.
Both Tom Wolfe and Ryan Patterson (both, FABO members) have exceeded 25 pounds of boost with their slant sixes with no apparent harm to thee engines. Drag strip performances have shown that those engines each make approximately 500 horsepower...
It would seem, given all of the above, that is you want to make horsepower out of your slant six, the smart money is on a hair dryer... It's in the motor's DNA... installed at its inception when the small bores were mandated by the front office.
Mark Ethridge (GuzziMark on FABO) has gone impressively fast with an un-blown, all-motor early Valiant, and holds several records to prove it.
He did it through ingenuity, hard work and persistence. He was able to go that quick, partially, by putting his car on a serious diet; It only weighed about 2,350-pounds for some of his record-setting runs. Not by making 500+ horsepower...
Most A-Bodies weigh about 3,200 pounds, give-or-take, plus driver, so getting one into the thirteens without some serious weight-reduction, is a tall order...
That takes about 300 HP, which is somewhat difficult for a stock-weight A-Body, naturally-aspirated. Not so hard, with a hairdryer...
I know sone of you aare getting tired of me posting this amazing video, but it proves my point so well, forgive me, one more time!
[ame="http://www.youtube.com/watch?v=7QzUfV8iTpQ"]Turbo Slant Six 10.74 @ 127 mph 7-19-10 - YouTube[/ame]
All of the above is nothing more than my opinion... I am obviously no expert.
Thanks for listening!!! :cheers:
