Look what came in the mail today
Bill,
I have been following your progress for the past six months. Actually you and turbo toad were the ones who inspired me to go this route. At first I was just going to upgrade the intake, carb, and headers but then after seeing your guys progress I figured why not. I have always wanted to build a turbo car and have always wanting something a little different.
The car that this is going in is a 67 plymouth valiant 2-door. It will be a long slow project but I am in no hurry to have it finished. I would like the engine to be done before the summer long with upgrading the brakes. As for everything else like body work and interior is not a concern for me yet.
This will be no news to you I am sure, but the underlying cause that made me want to supercharge or tubocharge a slant six was the design of the cylinder head. It is a virtual bottleneck that has a crippling effect on flow in and out of those six cylinders, to the extent that there is virtually no way to get a satisfactory amount of horsepower production using the normal, everyday, hop-uo methods that are commonplace, such as raising the compression ratio, increasing camshaft lift and duration, porting the head and installing bigger valves, and increasing glow through the engine with the installation of, say, a 4-bbl carb and a header. That head was designed for a 170 cid engine and it shows.
You can do all of the normal, conventional modificatioins, and end up with an engine that runs a lot better than it did, stock, but horsepower levels of 1.5 hp per cubic inch and above will not be in the cards, because there is just no way, given the small bore design, to move enough air through the severely-limited port and valve sizes possible, even with expert modification. The raw material is just not there. It's not.
The small bores prohibit it.
However, given that set of circumstances, when you look at the alternatives, such as forced induction, (turbo OR supercharging,) all that poor breathing just goes away because of the new lease on life available. The robust, rigid, overly strong infrastructure of the slant six block and crank is built for boost. It is designed to take large amounts of forced induction (boost) without suffering damage, and all of a sudden, the horsepower levels that can reach 2 hp per cubic inch, and, above, are available.
So, the little /6 becomes a new player in the "fun to drive" arena, with 300 horsepower easily available at moderate boost levels.
Tom Wolfe (Shaker223) put a junkyard Buick Grand National turbo, with a 4bbl carb and
no other modifications, on a 225 slant six in his 3,000-pound '71Dart and ran 12.95 @ 102mph. That takes about 300 hp. Getting that level of performance, from a normally-aspirated /6 would take a LOT of effort, and modifications oif the type that would virtually destroy street driveability.
Well, there is more than one way to skin a cat; in this case, it would seem that forced induction would be the most desirable way to go.
It's not particularly easy, but at boost levels of ten pounds and under, it's not necessary to run an intercooler, and a stock distributor and coil will do the job as long as you limiit the spark advance to 18 degrees, under boost.
The hardest part of the build is a satisfactory turbo-mount exhaust manifold, and PISHTA has come up with a good solution for that.
I apologize for the overly-long post; there just doesn't seem to be any quick way to say this.
Merry Christmas to all!!!!
