Project Infiniti G20 Racecar: Even More Power


That leaves us with but one option, and it's an option the SR20 was made for: turbo.  A simple T25 setup at stock boost can cough out 200whp even with a blind chimpanzee monkey setting it up, and has been OEM reliability tested by Nissan in every conceivable situation you can imagine.  To boot, this option was basically free to us.  You see, I've already went through the iterative game of boost addiction over the years.  I started with a T25 from a JDM Avenir, stepped up to an entry-level T3/T4 setup, then eventually went all out with a monster setup that made nearly 500whp.  Every one of these setups was subjected to my road racing habit, and I only used stock junkyard SR20DEs like the one already in our car.  As a result, I've not only learned a lot of lessons about keeping a turbo SR20 alive on the track, but I've also got old setups sitting on the shelves collecting dust. 

The final nod for turbo?  MPTCC rules limit weight:power, but there is no limit for weight:torque.  Turbo engines generally make power over a much wider range, and, if sized properly, make the engine just behave like a larger engine.  This means that with a turbo, we'll never need to worry about extracting every last revolution out of the engine to keep it on boil, and any time we find ourselves in a sticky situation, we're a stomp of the right foot away from salvation.  As they say, there's no replacement for air displacement, or something like that.  Winner winner, chicken dinner.


Project Infiniti G20 Racecar Turbo T25
Somewhere under all of that piping is a stock Avenir SR20DET T25.


That's not to say that a turbo isn't without its drawbacks.  It does have some unique considerations that a normally aspirated engine doesn't.  First, turbo cars run hot.  Compressing air makes heat, stopping up the exhaust to compress that air makes heat, running coolant and oil through that stopped up exhaust makes heat.  Second, more power means more stress on the drivetrain.  With the lowish power numbers we're planning on making, this shouldn't be a problem, but we weren't 100% certain.  Third, turbochargers, cast iron exhaust manifolds, intercoolers, piping and plumbing all add weight to the last place we need more: the nose of the car.  Last, turbo engines take some power application planning, as you will always have some amount of lag.  Even with these negative aspects, we felt that it still represented the best option for us.

To start our process, we decided to stick as close to OEM as we could, with reliability over power being the name of the game.  The centerpiece to our setup was a greasy JDM Nissan Avenir T25 and rusty cast-iron exhaust manifold that were literally sitting in the trunk of a long-forgotten project.  Why such a puny turbo, and not something that breathes better?  Simple, our power goal puts us squarely in the middle of this turbo's optimal range, and that meant excellent response, a wide powerband, and easy installation.  Since no one really wants these turbos, replacements are cake to find, though we doubt we'll ever need another unless we FOD one of the wheels.

The OEM fun continues with stock SR20DE cams, a stock Avenir throttle body adapter, Z32TT compressor outlet, stock mass air flow sensor, and completely stock internals.  For fuel injection, we pulled a set of OEM 370cc injectors that had been languishing in a box for the better part of a decade and sent them off to RC Engineering for their standard fuel injection service.  Why go through the trouble?  Road racing and Murphy's Law have a very close relationship, and we'd hate to start a car-b-que with ratty old injectors.  More than that, RC also provides flow-test results and spray pattern assessments with their injector cleaning service so we can be absolutely certain that all cylinders are seeing the same amount of fuel, and that the injected fuel is coming out properly. 


Project Infiniti G20 Racecar RC Injector Service Chart
Injector #1's low value before servicing could've put another mighty SR20 in our already overpopulated graveyard.


RC returned our injectors to us in 24 hours looking as good as new, and even replaced our damaged plastic retainers.  Due to the low cost of this service, we plan on regularly servicing our injectors.  Call it cheap insurance.  To feed our thirstier injectors, we swapped out our tired (and surprisingly still working) OEM pump with a Walbro 255lph unit also languishing on a shelf.


MotoIQ Project Infiniti G20 RC Injector service
Our injectors came back to us from RC in like-new condition.


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