Fit for Battle

• February 12, 2021
• Story By
  Luke Munnell

This car is an ode to all who feel there's something truly awesome about doing more with less, and facing down tough competition.

The Underdog

Yes, the fastest all-wheel-drive or rear-wheel-drive platforms will probably continue to own the records in the top classes of competition (unless you’re one of those never-give-up Canadians!), but taking any of them out in a machine designed to transport frugal young adults around town for as little of their parent's money as possible is always more impressive than making a fast car faster.

It’s a discipline Honda owners and builders know well, but none so much as those who take to the wheel in Honda’s lesser-know lukewarm-hatch: the charming, practical, thoroughly non-threatening Honda Fit. 

Not unlike the fabled 300 warriors at Thermopylae, Mario Mojica loves the challenge of fending off larger foe and impossible odds in battle. His Nitto NT01-clad weapon of choice seen on our digital pages is as challenging a platform as any with aftermarket support. And rather than convert its mechanical underpinnings to those of an Acura RSX Type S (like countless other Honda and non-Honda wheelmen), he went a step farther into the underdog realm and retained the econobox’s 1.5L inline-four!

Trouble Ahead

Mario’s ethanol-swigging, fire-breathing honey badger didn’t evolve easily into its current form. It took a lot of trial and error, which have led to the flummox and demise of many a Fit driver’s dreams. Fortunately, Mario’s the sort of kind-hearted track warrior who’s not afraid to shed some light on his learnings.

The Fit’s diminutive appearance and nimble characteristics (thanks in part to its unusually stiff unibody frame and low center of gravity) motivated him to scoop one up as a daily driver to his ‘08 VW GTI weekend track car. But one look at Japan’s famous J’s Racing machine, in all its race-prepped, B-spec glory (along with someone crashing into his GTI), was all it took for him to change his direction with the car completely. 

Mario knew the value of starting out a track build with just the basics — in his case, with $3K worth of bolt-on mods. But when that only returned about an 18hp gain, he knew some forced induction was in the cards. His first solution was to Sprintex-supercharge the bone-stock L15A7 engine to the tune of 194 whp, nearly doubling its 118hp factory output. But after some automatic transmission slippage and a broken connecting rod in just his first outing with the new setup, Mario rethought his entire approach. 

The Battle Plan

Rather than retain the Sprintex supercharger, Mario sought to make the most of the L15’s single-outlet exhaust ports (similar to the K24Z engine) by bolting a turbocharger to it. 

Step one was just to have Joe at Palmdale’s inconspicuously named Eastside Muffler fortify the engine block, replacing its notoriously weak internals with forged Wiseco pistons and K1 rods. The L15 block has proven capable to withstand up to 26 lbs of boost on stock sleeves (Mario later saw 28 lbs repeatedly in his testing), so the decision was made to retain them for best reliability. 

Cole, of Badguys Wordwide in Valencia, CA, worked his magic on the head, opening the L15’s restrictive intake and exhaust ports, replacing the valves and actuating equipment with lighter/larger options from Supertech and Bisimoto, installing a Rocket Motorsports Stage 4 cam, and gasket-matching the L15’s intake ports to a custom Golden Eagle aluminum unit, and enlarging its single-exit exhaust port.

Mario’s goal was never to build the Fit to unlimited-class spec, but to strengthen its weak points and enjoy it in streetable form. No monster turbo here — instead, a modestly sized (T25 frame), quick-spooling Mitsubishi TD04HL-19T (64AR) unit, exiting to a custom intercooler and exhaust built by Joe.

Mario’s previous engine management system was a piggyback unit lacking true speed/density metering, which would fall into limp mode after only about 10 lbs of boost. It sufficed for use in the bolt-on supercharger kit, but wasn’t up to the task of the new turbo. 

Research and networking connected Mario with Pingping Pradana, and Indonesia-based tuner and owner of Engine Plus, who has traveled here to compete in Global Time Attack competition and whose work can be found in some of the highest-profile track-raced Honda builds on our shores.

At Pingping’s suggestion, Mario scrapped the Band-Aid fix for a true solution: Haltech’s 1500 stand-alone ECU and e85 temp/content sensor, Golden Eagle fuel rail, Grams Performance 750cc/min injectors, Acuity Instruments’ SAE quick-connect fuel line, and Quantum 265Lph in-tank fuel pump, all tuned by Pingping and RaceFWD's Robert Hoffman to a fat and flat 256 whp and 217 lb-ft of torque — perfect for a streetable, track-driven 1.5L engine.

Challenges Emerge 

Mario’s Fit ran near flawlessly in its first shakedown sessions, save for two concerns; the first being excess heat. A 118hp, naturally aspirated L15 driving a bone-stock Fit around town well below its factory 6500rpm redline doesn’t generate much of it. But Mario has been revving his out to 8200rpm now, hitting full boost and triple-digit speeds on every straightaway.

A SpeedFactory tucked radiator with Chase Bays elevated filler neck, Vibrant Racing fittings and lines, a Spoon thermostat and cap, and some custom air guides helped a lot, as did the vented JDP Engineering carbon-fiber hood, PTP blankets on the turbine housing and watergate, and all that flashy reflective gold foil. 

As previously mentioned, the Fit's factory automatic trans began slipping way back in the stock-engine/supercharger days, so there was no reason to expect another factory replacement to fare better. Plus, as we all know, the answer is always "manual." Mario heeded that sage advice and has his Fit converted to a proper five-speed — one retrofitted with a Clutchmasters FX400 six-puck clutch, Mfactory LSD, and Hybrid Racing shifter.

The Fit's factory manual trans has proven reliable at power levels north of 300whp, but its axles are well known to be no match. Packing them with high-temperature grease has helped Mario keep them alive longer at the track, but with an excess of traction thanks to Nitto's DOT compliant competition road course tire the NT01 on all four corners,  he’s eyeing a switch to stronger DriveShaftShop replacements as soon as they become available. 

Fit owners know well of their cars’ suspension shortcomings. A rear torsion bar (common in less expensive vehicles) isn’t necessarily advantageous, but it’s not a huge drawback in and of itself. They can even provide some valuable rotation in FWD vehicles with the right springs. The problem lies in torsion-bar-suspensions’ lack of camber/caster/toe adjustment, which is important in a track vehicle, and also in the Fit’s case, its small rear springs which all but rule out progressive replacement springs in lowered vehicles.

Add to that the Fit’s narrow from strut towers which severely limit camber/caster adjustment, and you’ve got some genuine roadblocks.  

Aftermarket rear shim kits and even replacement rear torsion bars are available, and some minor cutting up front is all it takes to find adjustment with bolt-on aftermarket top-hats. At the moment Mario’s content with finding out how much performance can be eked out just in spring and damper tuning in the rear, combined with the same along with FTuned camber/caster hats up front, and some Cusco support and aero all around. 

Winning the Day

With everything relatively stable, Mario’s been able to drive his Fit to and from the track, and break his personal-best times nearly at each event; currently clocking fastest times of a 2:06 at Buttonwillow, 1:31 at Streets of Willow (clockwise), and a 2:19 at Chuckwalla Valley Raceway in his first time there.

His, and one other Fit (with a K20 swap), are the fastest at Buttonwillow, and Mario feels breaking the two-minute mark there is only a matter of improving his skills to match his car’s new capabilities.

Considering the throngs of track battlers in S2000s, STIs, EVOs, and even higher-performance machinery who never realize that goal, we find this Fit a formidable underdog any Spartan warrior would respect.  

Specifications: 2010 Honda Fit Sport