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3. Turbo installations to Petrol EFI Engines

EFI petrol engines can be successfully aftermarket turbocharged with and without inter-cooling but require careful upgrading of fuel delivery and tuning to give normal engine life.
With modern automatic transmissions being controlled by the engine computer, total replacement of the engine computer with an aftermarket unit is not viable. By retaining the original management system in standard form and adding a secondary set of injectors with an independent fuel only computer working only on boost, correct fuel tune is achievable.
By reusing the original EFI system the vehicle retains all its normal basic driving perfection and serviceability for mechanics familiar with the standard vehicle.
Decompression of the engine is still required to give maximum engine reliability especially on 4WD vehicles which can be used where best quality high octane fuel may not be available.
The recent availability of purpose made high performance Garrett GT turbochargers with power choices from 50HP to 2000HP per turbocharger allows the perfect size turbo to be used for each application. The GT Ball bearing range is particularly impressive with perfect throttle response and no turbo lag and a power delivery which feels limitless compared to older technology turbos adapted from early production diesel engines.
High boost pressures are not needed to give effective power increase with the GT Ball bearing turbos with power gains felt from the start of boost.
The cost and complexity of aftermarket turbocharging of modern EFI petrol vehicle makes not a lot of economic sense compared to using a suitable factory turbo vehicle but the results can be impressive if you require a very special personalised motor vehicle.
Following are some Dyno sheets of EFI Aftermarket turbo vehicles showing the before and after measurements.