Bill,don't stop saying I need a Turbo,'cause you just never know !!
It's just such a difficult, uphill battle to make any real power, out of a normally-aspirated slant six because the head was designed for 170 cubic inches, and when you add 55 cubic inches (225)... that's 32 percent, (virtually 1/3) flowing thru the same ports and valves, it gets asthmatic pretty quickly... and porting with big valves helps somewhat, but it's still a non-breather, and because of the small bores, there's really not much you can do about it, short of adding a power adder of some sort..
Mark's car runs really well, but he's gone to great lengths to take weight out of the car. It's hard to generate exciting e.t.'s with a 3,300-pound /6 car (which most of us have,) without a power adder of some kind.
With the rock-bottom price of E-Bay turbos nowadays, I'm not sure at all, that a well-built, 13-second normally-aspirated /6 is any cheaper than a turbo-assisted one.
If you decided to limit your boost to 10 PSI, you could run stock (cast) pistons and rods, and still have a car that would
handily outrun a stock 340, I believe. Spend the money for forged internals, and all bets are off... LOL!!!
Speed costs money; how fast do you want to go??????:violent1: