Slant 6 Turbo 68Dart Project
Okay, another $200 spent. $50 soon to come on some more stuff, but I just got me the final exhaust pieces for the exhaust minus the tubing for the downpipe, which I'm hoping an exhaust shop will maybe have and be able to fab up. I'm doing this in such a way that the exit on the turbo will be shot straight back, then down near the stock exhaust location and hopefully mount up before the cutout. The U bend I got has 6" legs on each side, and a 12" diameter, which should space the turbo away in a couple different options depending on where I cut it.
02 Sensor bung and plug: $5.00
U Bend exhaust tube in 2": $20.00
Thick Exhaust flange to mount to manifold: $4.00
28 x 7 intercooler and different 2 1/2" pipe bends: $140
Aluminum pieces to assemble carb hat solution: $25
Thinking this may shoot over $1k, with the addition of what's going to amount to $250 worth of fuel delivery equipment... but... wishful thinking right?
I have read all the notes pertaining to this build and to me, it seems that you have researched just about every aspect of it pretty completely, and made excellent choices that will make it work well for you. I think you'll be astounded at the amount of extra power produced at 8 pounds of boost. I think you're looking at an easy 250 horsepower and maybe more. According to the Wallace online calculator for drag racing, that should put your car (assuming correct chassis setup and tires, at 3,300 pounds,) into the high 13s, and would allow you to run favorably with similar weight STOCK 340 cars.
I can only recommend one course of action that I have not seen you address; When running a stock reciprocating assembly ( cast pistons, stock rods, etc.) detonation MUST be avoided at all costs.
You can ensure this by limiting your total spark advance to 18 degrees while under boost AND making certain that your A/F ratio stays between 11 and 12:1 under boost.
As far as I know, there is only one way to be certain of that; check it assiduously while the carb is being tuned with a wideband meter designed for that purpose. To do less is to invite disaster and, it won't be cheap, and it can happen in the twinkling of an eye.
Those meters are not cheap at $300+, but are a whole lot cheaper than replacing all those destroyed components if it leans out...
I just built a turbo'd slant six and i cannot IMAGINE trying to accomplish it without a wideband meter. It's easily the most important part of your build.
Good luck; this car will put a BIG smile on your face!!!
Bill