Engine - Turbocharging
Turbocharging a Geo Storm usually takes one of two strategies. Either a complete transplant of an Impulse RS AWD
Turbo engine, or a custom built turbo system.
Engine Transplant from an Impulse RS AWD Turbo
Transplanting the Impulse RS AWD Turbo engine into a Geo Storm is simple and straightforward, just as described
in the previous
section under the engine swap topic. This will result in a very reliable 160 HP (in stock form),
and if the drivetrain is left FWD, the vehicle will weigh less and have less drivetrain loss than the AWD Impulse,
resulting in higher performance potential at the stock power output than the AWD Impulse.
Again, as described above in the
engine swap section, this is best accomplished with the donor car parked next
to the recipient car, shop manuals for both vehicles, and transplanting all of the engine and control system
direct from one vehicle to the other.
Further performance tuning above the factory160 HP is possible, but involves fighting with the factory system,
just as is involved with performance tuning an Impulse RS AWD Turbo. If significantly more than 160 HP is the goal,
it may be easier and more direct to simply build a complete turbo system from scratch.
Custom Built Turbo System
This is not a set of step-by-step instructions for building a turbocharging system, but a discussion of general
topics and concerns.
The first step is to thoroughly research the subject and completely understand how a turbocharger system works.
Turbocharging an engine is going to involve the following:
Lower Compression Pistons.
Turbo Connecting Rods.
Oil Squirters In the Block.
Plumb Block for Turbocharger Oil and Water Fittings.
It is a good idea to upgrade these items to at least the specification level of the Impulse RS AWD Turbo engine.
It is possible to run a high compression – low boost system, which will yield better low RPM response, but this
limits boost and requires more expensive and sophisticated engine controls.
It is important to note that the Non-turbo engine connecting rod and piston is not the same as the Turbo engine
connecting rod and piston. The Non-turbo piston and connecting rod is not quite as strong, and the wrist pin
is smaller in diameter and also not as strong. But, more importantly, the rod is drilled down the center of the
shaft to provide oil to lubricate the wrist pin. The Turbo engine connecting rod is solid without an oil passage.
The Turbo engine uses oil sprayers, aimed up at the bottom of the pistons, to lubricate the wrist pin, and also
to cool the underside of the piston. Using the Turbo connecting rod and piston requires also machining the block
and installing the oil sprayers to provide librication for the wrist pin.
Thin exhaust pipe, often stainless steel, is often used, though not recommended, because it quickly becomes brittle
and cracks. For longer service life, thick, mild steel pipe, such as Schedule 40 industrial pipe, is recommended.
The flanges and pipe to make a proper manifold and down pipe will likely cost $400+, before considering the labor
to put these items together. If someone is offering to sell a manifold that costs less than the value of the
materials to do the job right, then they are either selling something that is not durable enough to last very long,
or they are unloading something that didn’t work.
Purchasing a new turbocharger is recommended. A used turbo with a questionable history and condition will
inevitably lead to costly rebuild.
Turbo Hose Connectors.
This must be fabricated custom made to match the vehicle and the turbo configuration. A pipe flaring tool will be
needed to flare the pipe ends to prevent the pipes from separating under boost pressure.
Stand-Alone Programmable Computer.
This will provide for control of the fuel delivery and ignition timing.
Electronic Boost Controller.
The stand-alone engine control system will control spark and fuel. In lieu of the factory turbo model ECU to
control turbo boost, the electronic boost control becomes the stand-alone boost control device.
Vents excessive pressure and prevents damage to the engine.
Blow Off Valve.
Reduces stress to the turbocharger, allows for better boost response under acceleration and upshifting.
Larger fuel injectors will be required to provide the additional fuel required by a turbocharged engine.
Rising Rate Fuel Pressure Regulator.
Fuel Pressure Gauge.
Probably required if power is to be raised above the limit of the original fuel system.
Gauges – Boost, Wideband O2, Oil Temperature.
These are the tuning and diagnostic tools needed to make informed decisions on how to adjust all of the above items
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