2.6 Liter Engine Swap for 1985-89 Impulse Turbo
By Soren Rounds
Tips for swapping the 4ZE1 2.6L into a 2.0L 4ZC1 turbo JR Impulse
For this swap, you either need to start with a 2.6L long block or a complete 2.6L motor. You will need
some external parts for a 2.6L, so rebuilding a 2.6L from a wrecking yard might be a better way to begin.
Beginning with the long block assembly, you need to use the 4ZE1 cylinder head. The 4ZC1 head will
give too high of a compression ratio for turbo use, and the 4ZE1 has larger valves and runners anyway.
The 4ZE1 engine block has a deck height about 3/4” taller than the 4ZC1, so you will need to use the
timing belt and cover from the 4ZE1. The other major part you should use from the 4ZE1 is the intake
manifold. The 4ZC1 manifold will work and is very similar, except the intake runners are larger on the
4ZE1. I think that most of the sensors on the intakes are similar, but I switched over all of them just to
make sure the 4ZC1 computer in the Impulse would read the correct signals in case a sensor or two had
a different output between the two models. One of the temperature sensors on the 4ZC1 intake did not
have a matching hole on the 4ZE1 intake, but you can remove one of the plugs in the coolant passage
of the 4ZE1 intake for extra sensors the 4ZC1 might use.
Most of the external engine parts need to be reused from the 4ZC1 engine. These include:
Exhaust manifold and turbocharger
Power steering pump and bracket
Flywheel and clutch
Oil filter extension housing (the 4ZE1 does not have fittings for the oil cooler line)
Transmission bellhousing brackets
coolant pump, coolant return pipe, fan, and pulley
alternator and bracket
engine mount brackets
valve cover (I think either one works)
During the swap there are several things that need to be addressed in addition to swapping over parts.
Following are some hints:
My 4ZC1 water pump did not fit very well into the 4ZE1 housing, and the pump fins hit the block when
the pump turned, but the 4ZE1 pump extends too far forward for the 4ZC1 drive belts. I had to buy
gasket paper and make my own gaskets to fit both the 4ZE1 engine block and the 4ZC1 pump. I had to
use two gaskets on top of each other and file off the ends of the pump fins a tiny bit for internal clearance.
I also had to use ¼” washers under the water pump/fan pulley to get the pulley to line up correctly even
after using the double gaskets to shim out the water pump.
The 4ZE1 block does not have an oil feed port for the turbocharger. You need to fabricate an oil line that
will tap into one of the oil feed ports from the crankshaft main bearings. These ports are located along the
bottom of the engine on the passenger side; I used the one directly behind the oil filter extension housing.
I think the easiest way to make the oil line is to use some braided steel hose and hose ends from a
manufacturer like Earl’s or Aeroquip. I used Earl’s 4AN hose with a banjo hose end for the turbo side and
a 90 degree 4AN hose end with 4AN-1/4” pipe adapter on the engine block end. I ran the hose under the
oil pan (takes about 3 feet of hose), allowing oil to stay in the line after shutoff so the turbo won’t starve
The 4ZE1 block appears to have a port that matches the port on the 4ZC1 for the turbo water feed line, but
I was unable to get the plug out. If you can use the port that is fine, or you can tee into a heater hose or
even get a water feed from one of the plugged ports on the intake manifold.
You might need to make new intake piping flex hose sections because of the increased engine deck height.
You can get some nice silicon hose to replace that old accordion stuff now anyway.
The exhaust also has some issues with the deck height. My Stan’s brand downpipe bolted up without
modification, but the fit is very tight and it hits the body of the car sometimes. You might need to add ¾
inch to the length of the vertical section of the downpipe.
The power steering pump bracket can only bolt into the holes on the cylinder head, the holes on the engine
block won’t line up. This appears to work ok because the belt tension pulls downward anyway. You will
need to get a longer belt for the power steering because of the increased deck height. I removed the air
conditioning compressor when I did the swap; to do this you need to use the outermost groove on the
crankshaft pulley to run the power steering pump along with a different belt. You will not be able to adjust
the tension on the belt much, but a 45” belt just fit on the pulleys and required little adjustment for accurate
The 4ZC1 engine has a hose that runs from in front of the throttle body to the intake manifold right next to
where it bolts to the cylinder head. This is kind of interesting, the 4ZC1 has a passage in the intake
manifold/cylinder head mating surface that feeds air into little pipes that extend into the cylinder head intake
ports right at the valves, probably to modify the airflow characteristics under boost. The 4ZE1 does not have
this passage, you just have to plug off that air hose.
For injectors, you can use either fuel rail; I used the 4ZC1 rail because it has a return hose that exits from the
intake manifold in the stock location. I know of one person that uses the stock 4ZE1 injectors with this swap,
and another who uses RC Engineering 370cc units. I used Bosch brown-top Mustang SVO turbo injectors
(35 lb/hr). The stock computer is able to adjust the air/fuel ratio adequately with these injectors, and this size
of injector provides enough fuel for at least 14 psi of boost.
A couple things to keep in mind here, the stock turbocharger is kind of small for the 2.6L engine, and the
combination results in a lack of high RPM power. A turbo upgrade would really help in this situation. Also,
the 4ZE1 camshaft is designed for a naturally aspirated engine in a 4-wheel-drive SUV; an upgraded
camshaft designed for turbo use would likely add some top end power.
You need to get a better clutch, the stock 4ZC1 clutch will not hold the torque of the turbocharged 2.6L engine.
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