Project Black Betty
Wow, I really needed to see that post by Bill! Thank you. You inspired me. I'd already decided to keep my Duster (1974) with the I6, 225 engine. I'd like to take you (and others) up on your offer to help me get my engine where I want it. I want it to be as nimble as possible and, if possible (please don't laugh), a little louder and cooler sounding--if that's possible. Sorry if I hijacked the thread.
Well, I am glad that somebody else "gets it." These turbo slant sixes are a too-well-kept secret as far as I am concerned.
It's really easy to locate a junkyard 360/904 powertrain and swap it into a car like yours; after all, the factory put them in there, originally, so everything "fits."
But, consider these factors:
If you want a low 12-second car (3,200 pounds,) to get that kind of performance out of a 360 V8, you're probably going to need a pretty radical cam, a thirsty 4-bbl, some headers, an expensive 8.75" rear end, geared in the 4.10:1 range, more compression than you can get with stock, cast, pistons, a high stall torque converter, an Edelbrock Air Gap, or some other non-stock intake manifold, and at least a 2.5" dual exhaust system. What you will have is a car that runs well on the drag strip, but has a ragged idle that gets old fast around town, and a car that is turning 3,400 rpm trying to keep up with traffic on the freeway. Good for racing, and fun at stoplights, and that's about it.. and, thirsty....
A low 12-second turbocharged slant six that will live a long happy life, will need a set of forged pistons, and rods. Those are really the only expensive parts. The rest of the engine can be as cheap or as expensive as you want it to be. By that, I mean, for example, when we built our engine (a 225) we had to build our own header. Nobody I know of makes a turbo header for a slant six. We spent about $1,000.00 on that thing, but we COULD have done what FABO member PISHTA did, and bolted a piece of U-Bend exhaust tubing onto the existing cast iron exhaust manifold and bolted the turbo onto that, for much less than a hundred dollars. Might not look as spiffy, and MAYBE it won't run as good, but we don't know that; it might run JUST as well... and it was over $900.00 cheaper!:cheers:
Most of the financial advantages of this operation compared with a V8 swap, are gained in terms of the things you will NOT have to buy. For example, the entire stock valvetrain, including the cam, will work just fine. That means a stock idle. That means a stock torque converter will work very well. The exhaust system can be as little as you need it to be, (in terms of number of separate pieces, not diameter,) because a turbo homoginizes the sound waves and quiets things down to the point that you probably won't need a muffler at all; just a tail-pipe.
The most desirable rear end will be a cheap, 8.25" unit out of a late-model (1973/'74/'75/'76) Dart or Valiant. The strange thing about these turbo slant 6's, is their love for being loaded to the gills... so, where a V8 needs a 4.10 gear, the best gear for a turbo /6 is a 2.73:1, which the '74 Valiant probably already has. Tests have proven that the fastest times turned for the turbo '6s were done with final drive ratios in the 2's... weird, but really handy, because it makes for relaxed hiway cruising and is fine around town. Great for gas mileage, too...
No "new" transmission will be needed (your slant 6 transmission will not bolt to a V-eight) with a freshening up on the original 904, the only thing you'd probably want to to, there. Pretty cheap, comaparatively...
You WILL need a 4bbl intake manifold; I don't think with boost, it makes much difference wwhether its a Clifford or an Offy. They're on EBay for about $200,00, usually.
A 500-cfm Holley (2-bbl) on the 4-bbl manifold with an adapter, or that same carb on a Super six 2bbl manifold might be cheaper, and would probably work just as well. Either way, the only expensive part of that deal will be the blow-thru mods to the carb. There are people on this board that can help you with either locating someone to do it for you, or recommending a website that will explain how to do it, yourself.
Performance? Tom Wolfe (Shaker 223 on FABO) took a BONE STOCK 225 slant six, put a bigger carb and a Buick turbo and ran 12.95@ 104mph with it.
Here is the video: [ame="http://www.youtube.com/watch?v=pPe_vHwZsF4"]Slant Six Turbo 1970 Dodge Dart 1/4 Mile pass - YouTube[/ame]
The head was stock; the cam was stock... everything was stock except for the carb/manifold and the junkyard Buick G/N turbo.
To get into the low 12's, you might want to install some bigger valves into the head, or get a cam with more lift. I think those would do it.
Just some ideas here, to fire the imagination and show what is possible by thinking "ourside the box."
Tom has built a better engine for his car. Last time out, it went 11.02 @ 120mph into a 15-mph headwind! That's with bigger valves and a ported head (Holley 4-bbl, headers, and a different cam and converter.)
Here's the video for that run... and that's at 3,300 pounds
[ame="http://www.youtube.com/watch?v=EAxRmoDgsdY"]Turbo charged Slant 6 11.02 @ 120.56 - YouTube[/ame]
His engine isn't radical at all...
Think about what you'd have to do to a 360 to get it to run 11-flat...
You pays your money and you takes your choice... :)
Good luck!!!
Bill
