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Turbocharging the Suzuki Samurai 1.3L

Posted in How To: Engine on August 1, 2017
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Samurais started out as small, budget 4WD vehicles with smallish tires by today’s standards. The factory 1.3L engine is a rugged little powerplant and has proven its reliability. However, many of these Suzukis have been extensively modified and now turn much bigger tires. Many of their owners long for more power and the ability to cruise comfortably at highway speeds with the bigger meats. Some owners opt for engine swaps to increase displacement under the hood, but a good, reliable swap can run into the thousands of dollars and requires skill. Zuks Off Road (ZOR) now offers an alternative for Samurai owners looking for more torque and horsepower.

ZOR offers a turbocharger kit for the 1.3L engine to encourage more ponies from the four-cylinder powerplant. The kit comes with all the hardware needed for the upgrade. It uses the same proven Keihin CV (constant velocity) carburetor as was used on Harley-Davidson motorcycles before they were converted to fuel injection. ZOR offers a conversion kit called the My-Side, which installs this 40mm or 44mm carb in place of the factory one to provide quicker throttle response, better off-road drivability, and improved fuel economy. The My-Turbo kit uses this same proven carb setup but adds a KO3 turbocharger to boost the intake air charge and add considerably more power.

A replacement exhaust manifold with a heavy, 1/2-inch flange is provided to direct output to the mounted KO3 unit where it spins the turbine. Intake air enters a filter connected to the input of the turbo and is then pressurized by the turbo with boost pressure of about 5 to 6 psi. That boosted intake air is piped across the engine compartment and into the intake of the Keihin carb. The turbo is pressure lubricated from an engine oil feed line and then returns the oil to the engine oil pan. A new electric fuel pump and all related plumbing components are provided, along with a boost-controlled fuel pressure regulator.

The kit can be installed in a home garage with mostly common mechanic tools. Some welding is required to complete the downpipe from the turbo and connect to the existing exhaust system. We visited the ZOR shop in Camp Verde, Arizona, to watch as a My-Turbo kit was installed on a Samurai owned by a customer in Alabama. Jessie White and Chris Kane installed the kit over the course of a day.

Once the installation was complete and tuned, rear-wheel peak power at about 4,500 rpm jumped from 37 hp to 75 hp, or double with the turbocharger. This is greater horsepower than most 1.6L 16-valve Suzuki engines can produce running small tires. Maximum torque went from about 54 lb-ft stock to about 98 lb-ft under boost, with peak torque occurring at about 3,200 rpm. The little Suzuki was far more spirited on the road, and the turbo spun up the power quickly.

The first order of business was to gain access to the oil pan for removal and to cut the exhaust downpipe in preparation for mating up new exhaust tubing. The original exhaust manifold and upper downpipe are discarded.
Engine oil expelled from the turbo is allowed to drain back into the oil sump through a fitting in the side of the oil pan. The kit provides a weld-on fitting or Zuks Off Road (ZOR) can provide an oil pan with the fitting installed.
With the stock mechanical fuel pump and carburetor removed, the My-Side carburetor adapter was installed on the intake manifold along with a portion of the support bracketry for the Harley CV carb. Coolant hoses are routed into the adapter for heating of the billet aluminum block. The supplied block-off plate was installed over the fuel pump drive on the side of the cylinder head.
Here is the installation of the Harley carb. ZOR modifies it to make it function correctly with the turbo boost. The two-piece mount bracket solidly sandwiches the side-draft carb to hold it securely in place.
The factory Samurai throttle cable is used to mate to the new carb. ZOR cut off the factory cable stop and replaced it to fit the Harley accelerator cam.
An electric fuel pump and prefilter are included in the kit and were mounted near the fuel tank. Rubber fuel-injection hose rated for high pressure is used from the pump up to an adjustable regulator mounted to the firewall. Its output goes through another filter and then to the carb. Excess fuel is returned to the tank, and a turbo boost line regulates the fuel pressure upward as boost increases.
The oil feed line for the turbo is tapped from the side of the block. In this case, a tee fitting is used to service this line and a mechanical oil pressure gauge.
The turbo encroaches towards the driver-side inner fender, so Chris Kane of ZOR removed the factory jack mount and jack from this area.
Jessie White installed the new ZOR exhaust manifold. Its outlet points upward to a flange that feeds into the turbo.
Here is the KO3 turbo used in the kit. The Audi turbo is a perfect size for small boost numbers.
The turbo was bolted to the top manifold flange.
With the turbo in place, White positioned the supplied downpipe tube sections and tack-welded them. Several pieces are combined to connect this exhaust to the lower portion of the old downpipe. A bung is included on one of the tubes for insertion of an air-fuel ratio sensor. ZOR provides thermal header wrap to place over the downpipe as well.
The turbo intake tubing is routed to the carburetor from the driver side. It uses metal tube and silicone hose connections.
A blow-off valve is placed in the intake tubing up near the passenger front corner. At idle the engine creates intake vacuum; at boost it creates intake pressure. When the engine returns to idle or the throttle is closed, the blow-off valve opens to release intake pressure.
White works to cut and assemble tubing where the boosted intake air exits the turbo and starts its travel forward and then toward the passenger side of the Suzuki.
The pressurized oil feed line is routed up the inner fender and connected to the inlet on the KO3 turbo.
A Spectre filter element sits just behind the radiator overflow bottle and connects to the turbo intake through a 90-degree elbow. Here you can also see the oil return line from the turbo that connects to the oil pan below.
Since there is increased heat up near the exhaust manifold, ZOR provides these thermal insulators to be placed over the spark plug wires near the head.
ZOR uses an air-fuel ratio meter to aid in the initial tuning of the turbo setup. Once this was done, the Samurai was taken back to Arizona Dyno Chip in Tempe for final dynamometer testing. The stock Samurai was previously tested before the kit was installed. Results showed a doubling of horsepower and about an 80 percent increase in torque.

Sources

Zuks Off Road
928-567-3061
zuksoffroad.com

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