Note: Allpar does not take responsibility for the veracity of any information or opinions here, does not claim expertise, and is not responsible for any consequences. Please proceed at your own risk.



Slant Six Swinger Turbo: Turbocharged Slant Six Revisited

Turbochargers can be harmful to your engine (and to you) - use caution. Allpar does not claim to have expertise in turbochargers and has not tested Mr. Holler’s methods or results.

This is the second part of a two-part article. Click here to read the first part.

Engine coolant is drawn from the heater core hose and is returned to the top of the radiator.  There used to be a thermo-switch in the radiator to activate the EGR valve.  Since the EGR can no longer function, it is mounted in place simply to plug the vacuum leak.  A “T” is used in the heater hose and a 3/8” NPT fitting returns coolant to the radiator.  Using both heater hoses with “T”s would also work if there were no fitting in the radiator.

T

Engine coolant is drawn from the heater core hose and is returned to the top of the radiator.  There used to be a thermo-switch in the radiator to activate the EGR valve.  Since the EGR can no longer function, it is mounted in place simply to plug the vacuum leak.  A “T” is used in the heater hose and a 3/8” NPT fitting returns coolant to the radiator.  Using both heater hoses with “T”s would also work if there were no fitting in the radiator.

choke cable

The automatic choke cannot be retained.  The “choke pull-off” becomes a “choke put-on” the first time you hit boost.  A manual choke takes its place.  A bracket was fabbed up to mount under the dash.  The choke cable itself was run through the firewall through a plastic plug next to the steering column.  The factory choke pull-off bracket was used to mount the cable using a modified bolt, nut, and washer.  In this case, push it in for choke-on, and pull out for choke-off.

carburetor for turbocharged slant six

You can also see the spacer on the top of the carb in the engine photo.  I made it on the lathe out of 3” exhaust pipe.  It gives the bonnet the clearance it needs so it doesn’t interfere with the choke operation, and so the stock air cleaner bracket and wing nut will work.  Gaskets are used both top and bottom.

This picture also shows the oil line running across the head.  Notice there are little brackets keeping it from flopping around.  Left bracket also has a ground strap, right bracket also has an AC bracket.  The other steel line to the left is for referencing boost to the fuel pump.  I chose to run a steel line instead of rubber hose for looks.  Note also the pull ties on all of the hoses.  Under boost, hoses sometimes have a tendency to pop off.  Besides, the blue pull ties add to the look of the conversion.

Timing control under boost is handled by an MSD Boost Timing Master.  This simple device is first and foremost an MSD box.  The factory ballast resistor and ECU have been disconnected and the MSD now runs the show.  For tuning purposes, you can dial in when boost initiates the timing retard from 0 to 5 psi.  Second, you can adjust how much ignition timing retard per pound of boost from 0 to 3 degrees.  The box and control knob were mounted in the driver’s kick panel out of sight.

grainger valve and MSD box

Boost is controlled by the wastegate activated by a Grainger Valve manual boost controller.  There is a spring and ball inside.  When the pressure is sufficient to unseat the ball, the wastegate gets pressure.  It is adjustable by turning the one end in or out.  Turning it in tightens the spring pressure and ups the boost. 

The G-Valve should get its reference signal from above the throttle plates.  During initial tuning, there was a horrible flat spot.  It seemed the turbo was spinning its guts out trying to build boost, but the throttle plates were barely cracked.  The manifold pressure was only about 5# of boost, but the float chamber was seeing probably well over 20#.   I moved the reference hose to a point above the throttle plates and the flat spot dramatically softened.

oil drain

The oil pan was marked for the oil drain, then removed.  Holes were drilled into the oil pan for the receiver bolts, and the oil passage.  Next the receiver was bolted in place and trial fitted on the engine.  After I was sure it was in the right place, I welded the nuts to the inside of the oil pan.  Being meticulous as I am, the pan got sand blasted, cleaned and painted.  New gaskets were set in place and the pan was reinstalled.  In all, the oil comes out of the turbo, makes a right turn toward the block, then makes another right turn into the receiver.

starter

For clearance reasons, the later “lightweight” starter is used.  You can see how much smaller it is than the original factory starter.

For automatics, be sure to bend the transmission cooler lines away from the hot exhaust side of the turbo.

floats

When rebuilding the carburetor for a turbo application, be sure to use phenolic floats.  These are the brown or black plastic floats.  The brass floats are hollow and might collapse under boost pressure.  The phenolic floats won’t.

turbosix

After the hard parts are bolted on, it is tuning time.  A boost gauge and fuel pressure gauge are needed to find out how much boost the fuel pump can handle.  By watching both gauges, you should see the fuel pressure go up one psi for every pound of boost.  This will work well up to a point.  On the Swinger, the fuel pump rise stopped at 16 psi.  Therefore, the boost was limited to 11 psi to ensure there would be at least 6 psi fuel pressure going into the carb.

Ignition timing was set to 11° BTDC.  The MSD-BTM initial retard setting was 3.5 psi boost, and 2.5° retard per pound of boost was used.  The secondary power valve needle was shaved just a tad on the drill press which helped to overcome a flat spot.  There is still a flat spot, but I’m just not good enough to get rid of it with a carb.

Goals were to improve on fuel economy, add at least 50% power increase, keep it grandma proof, and keep it relatively stock looking (hidden MSD and wiring).

In stock trim, breathing on the throttle didn’t do much of anything.  Now, a butterfly’s breath will start the speedo climbing.  WOT produces a substantial improvement over stock acceleration.  The exhaust is a tad throaty, yet relatively quiet.  I’d put this Swinger up against any factory 318 and probably win.  I don’t think it would take a 340 car though.  The turbo took this Slant from about 110 HP to a bit over 200 HP.  All internals are bone stock, so not a bad increase.

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
Headliner repair
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.

We make no guarantees regarding validity, accuracy, or applicability of information, predictions, or advice. Please read the terms of use and privacy policy. Copyright © 1994-2000, David Zatz; copyright © 2001-2016, Allpar LLC (except as noted, and press/publicity materials); all rights reserved. Dodge, Jeep, Chrysler, Ram, and Mopar are trademarks of Fiat Chrysler Automobiles.


Diamond Star plant to see life again?

One more last chance to order a new Dodge Viper

Giulia overlaps Chrysler, Dodge

Where’s the PUG?

All Mopar Car and Truck News



Dodge Challenger GT AWD Honey, we screwed up the truck High torque, long life: Jeep 4.0 The always-future Dodge Dakota pickup

Will the Wagoneer be Grand? Shelby Dakota: hot or not? Washer fluid bags! Chrysler Crossfire: fauxpar?