Slant Six Swinger Turbo: Turbocharged Slant Six Revisited
Back in 1999 I turbocharged my 1970 Slant-6 Duster; Allpar has featured the article I wrote about that project. Many readers have pointed out that there were several key details missing from that article. I just finished turbocharging a mint 33,000 original mile 1973 Swinger and have documented the process to bring it to you. I won’t rehash what was properly covered in the first article. This article is to fill in the blanks, add the little things, and elaborate on the tuning.
With the modified exhaust manifold, the turbo wants to hit the motor mount bracket. On my Duster the fix involved a hand grinder and a modified bracket. On this pristine Swinger, the fix was a ¾” spacer to move the turbo further away from the engine, thus preserving the bracket.
As the engine builds boost, it needs more fuel. The carburetor needle and seat can only effectively handle about 6-8# of pressure. An electric fuel pump that can handle boost pressure plus 5 lbs would be way too much pressure when out of boost. The easiest fix is to reference the fuel pump to boost. This provides a 1:1 rise in fuel pressure as the turbo builds boost. There is a limit and this time the limit was 16 lbs of fuel pressure.
The throttle bracket started life about 30 years ago on a LeBaron sedan with the Super Six 2-bbl. The factory placed the bracket on the bottom of the exhaust manifold. This part no longer exists on our turbo conversion, so it was relocated to the top of the intake manifold. This moved everything 2.75 inches higher. The fix was to cut the bracket, then weld in a piece of flat steel to drop the throttle cable mount and transmission kick-down linkage the needed 2.75”.
For the life of me, I swear the Duster had a 1/8” NPT oil sender. The Swinger has a 3/8” NPT oil pressure sender. For turbo oil supply, the sender is the easiest place to tap. A “T” is screwed into the oil pump, placing the sender in the leg of the “T”, and drawing the oil off the other port.
This certainly sounds easier than it ended up being. I couldn’t get the “T” to clear the block as I tried to screw it in. I then pulled the oil pump away from the block for added clearance. It certainly looked like a steel shim gasket from under the car with limited light. Alas, it was a standard gasket that proceeded to leak like crazy before even starting the engine during priming. Incidentally, the plugs were pulled and the engine was cranked over to build oil pressure before initial fire up.
Ultimately, I had to pull the engine up far enough to completely remove the oil pump. I cheated somewhat. I unbolted the radiator so it would rise with the engine and I wouldn’t break the coolant lines. The AC and other accessories were left in place, but the belts were pulled and fan was removed. The trans was unbolted and the engine lifted.
Both gasket surfaces were scraped clean. A new gasket was fabricated from a sheet of gasket making material. Apparently you can’t buy just an oil pump gasket any more. I could buy the pump with the gasket, or an engine gasket set with it. Even the dealer said they were NS1 for years.
To connect the oil to the turbo, ¼” steel brake line was bent to run behind the block, up across the head, over the intake manifold, and down to the turbo. There are 2 hydraulic rubber isolators to keep the steel line from kinking or breaking. The hydraulic line I used is rated up to 2500 psi. The steel line gets a flare to help hold the rubber line in place.
The bonnet started life on an 1981 to 1983 front wheel drive Chrysler product with the 2.6 liter Mitsubishi 4 cylinder. The carb is mounted just behind the radiator and the air cleaner box is in the back by the master cylinder. The bonnet connects the two. I first cut away the thermovalve area and shortened the neck a bit. Next a piece of pipe was welded in to direct the boost to the carb. There is a protrusion under the wing nut and gets in the way of the BBD air cleaner bracket. It gets trimmed. Afterwards, the whole thing gets sand blasted and powder coated. A thorough cleaning follows, making sure to get all of the sand out of the inside.
|Mike Holler, known on Allpar forums as mpgmike, also contributes to mpgResearch.com. He has contributed many columns to Allpar:|
|Interiors||Budget interior restoration: making the inside of your car look like new again
Red carpet treatment: Installing new carpet in an old car
|Porting||Porting heads for performance: step by step
Head porting example, part 1 | part 2
Intake manifold porting
Exhaust manifold porting (turbo)
Poly Quad heads: porting revisited
|Turbochargers||Turbochargers - all you need to know (interview)
Turbocharging the slant six for power and economy • Revisiting the turbocharged slant six
Budget turbocharger rebuilding (and Turbo Rebirth)
Installing a boost gauge
|Other||Powder-coating for a brilliant, durable finish
Custom pistons: roll your own!
Prepping valves for performance: grinding and polishing
Old cars: an opinion
Discuss Mike’s articles! (if you are not registered for the forums, register first )
Also see our 2.2 turbo page.