Rays TE37 SL Wheels
Selecting the perfect wheel to complement our project build was a tough decision. We knew that the OE aluminum wheels already came lightweight from the factory but were only 13 inches in diameter, not to mention hideous looking on the car. We were determined to select a wheel that not only looked good, but was also lightweight to justify our build. With that in mind, we contacted Mackin Industries for their expertise. General manager Eddie Lee suggested outfitting our ride with a set of Volk Racing TE37 SL wheels. The Black edition (overseas exclusive model) is a one-piece forged wheel that uses the latest technology and mold-forming tool to allow weight savings in comparison to the previous model TE37. We weighed our 15x6.5 wheel (smallest size allowable to fit our Falken ECO tires) to the tune of 10 pounds each.
Rays Duralumin Lug Nuts
The Rays Engineering Duralumin lug nuts feature a strong and lightweight design. In comparison, standard nuts are typically around 55 grams, compared to the Rays lugs, which come in at only 23 grams. The Duralumin is available in four colors and features one seven-sided lug nut per wheel for locking, which can only be removed with a special key for security purposes.
Evasive Motorsports Custom Alignment
Evasive Motorsports owner Mike Chang helped to mount and balance our wheel and tire combination before loading the car onto their Hunter alignment rack to dial in our vehicle.
Here is a side-by-side comparison of the new Falken Ziex Ze-914 versus our OE tire, which offers some visual insight into the tread design's superiority and large contact patch for achieving low fuel consumption and excellent handling and braking characteristics also on wet surfaces.
Since we lowered our Civic more than 2 inches on each corner, we asked Evasive to inspect our alignment a second time around and to no surprise, we were informed that both toe and camber settings were off. This was a problem we were glad to address, knowing bad alignments can impede fuel economy and cause rolling resistance, which leads to decreased fuel economy.
Falken Ecorun Tires
A key component in helping to obtain improved fuel economy was choosing the perfect tire for our vehicle. Falken recently introduced their Ziex Ze-914 Ecorun tire designed specifically for low rolling resistance, a perfect counterpart to our Rays TE37 wheels. Designed as a hybrid vehicle tire, Falken engineered the Ze-914 to deliver 20 percent less rolling resistance than its previous model Ziex Ze-912 thanks in part to a new silica infused compound that has been proven to deliver fuel savings. The Ze-914 Ecorun tires consist of an asymmetrical tread pattern, chamfered corners for improved wear/handling performance in both dry and wet conditions and a UTQG rating of 340, a grade that's typically not found on Eco-type tires sold on the market today.
FCS Custom Aero
When we first began mapping out a plan for our project a few months back, we knew aerodynamic parts would be vital in helping us achieve increased mpg. Keeping that in mind, we commissioned FCS Race, otherwise known as Fluid Control Solutions located in San Fernando Valley, CA, to fabricate a custom underbelly pan for our Civic. If FCS doesn't ring a bell, chances are you don't own a Honda. FCS specializes in a wide range of custom fabrication that varies from fuel cells to suspension components. When owner Jason Park isn't spending late hours at his shop, he can be found testing and tuning his 1,200hp 9-second Outlaw Street FWD Class Integra at the local dragstrip.
Typically, track cars running true flat bottom setups are also running a side dump exhaust. Since this isn't a race car, and we weren't willing to run a side exit exhaust, we decided to design a bellypan that covers the front subframe. Using an underbelly panel provides improvement for the aerodynamic drag with a smoother, more uniform surface for air to pass evenly without causing turbulence, thus leading to a lower drag. Using lightweight aluminum, FCS integrated an air dam to the front spoiler to improve drag by reducing the airflow under the vehicle. Dzus fasteners were cleverly devised into the two- piece panel to allow easy access to the oil pan bolt when changing fluids.
Sparco Quick Release Spring Latches
To give our Flex-a-lite (FAL) molded rear window an OE appearance, we installed some rubber trim, which we purchased at a local parts store. We then proceeded to secure the window using a pair of Sparco quick release spring latches we creatively powdercoated in Eastwood electric blue.
Sparco Fighter Bucket Seats
Marketed as a street performance seat, the Sparco Fighters are lightweight as well as comfortable enough for us to endure our soon-to-be trek across multiple states. Having owned/sat in numerous bucket seats in the past, we can honestly say that the Sparco Fighter is one of the more comfortable seats on the market today. The lumbar pads definitely help keep your backside from falling apart when driving in either harsh race or long road trip conditions.
Sparco recently introduced their newly designed seat rail. We used spacers on both the rails and under the seat to angle the buckets for driving comfort.
Fuel Sipping Engine Modifications
Prior to focusing on additional engine modifications, we replaced our OE head/catalytic converter and exhaust setup with a DC Sports 4-2-1 header, Buddy Club Spec II Racing exhaust system, and Blox Racing telescoping test pipe. While planning out an attack strategy on the D15Z engine, I struck up an interesting conversation with Doug Macmillan of Hondata. "Ever consider a hot air intake?" Doug asked. My initial response was "Doug, are you serious?" But upon research, I quickly realized why it would be plausible for our mpg vehicle. A cold air intake is a familiar part within the performance market and designed to ingest a denser, colder inlet charge to create power, which causes the ECU to compensate to run a richer air/fuel ratio and burn more fuel at the expense of sacrificing fuel economy. The hot air intake, on the other hand, is a concept that motorsports legend Smokey Yunick brought to fruition in the '90s with his turbocharged Pontiac Fiero that delivered a mind-boggling 51 mpg. The theory behind using heat was completely opposite of what many of us were taught over the years--that heat is your engine's worst enemy. Dubbed the "hot air engine", Smokey used coolant heat and exhaust waste heat to heat the intake air. The purpose of warmer/denser air allows the car's computer to lean the air/fuel mixture that in turn takes less fuel to complete a combustion stroke and allows a more complete burn, which increases fuel economy. Smokey's Fiero ran a mind-boggling 22:1 air/fuel ratio, and offered additional horsepower and better throttle response.
We took a page out of Smokey's book and created our own hot air intake using a galvanized air duct vent we purchased at the local hardware store. At first glance the duct looked awkward, primarily due to its shape, but after a few hours massaging the piece using a pair of shears and taking careful measurements, we were able to fabricate an intake plenum box that engulfed the headers' primary tubes that would be used to draw heat into the intake. If you haven't noticed by now, there's a reason why Honda designed the intake pipe so small. The small diameter, high velocity intake runners contribute to swirl in the cylinders, which promotes good combustion.
Hot Air Intake
The custom hot air intake was designed with an extended block-off panel to fend off excess air from the A/C fan as well as air coming through the front grille of the car. The piece was coated in high-temp paint prior to installation.
An inlet pipe was fabricated to draw hot air directly from the box into the intake resonator, which in turn is forced into the intake.
Hondata S300 Engine Management
Because the Civic VX has a special 5-wire front oxygen sensor, simply swapping out the factory ECU in favor of a P28 ('92-95 OBD-I Civic Si/Ex) the Hondata S300 wasn't an option. But Hondata had a simple solution being that they added the ability for the S300 to run closed loop on a 0-5V wideband input. This means that we can target 15-16:1 instead of 14.7 air fuel ratios at partial throttle, which requires an aftermarket wideband to run closed loop.
Innovate MTX-L Wideband A/F Gauge
We chose the Innovate MTX-L all-in-one digital air/fuel ratio gauge with built-in digital wideband controller for accurate and fast wideband readings for critical air/fuel monitoring. The Civic runs in closed loop off the wideband at partial throttle and switches to open loop at full throttle, similar to the function of the stock ECU. When we say that the engine runs in full closed loop, the Innovate MTX-L wideband 02 sensor is used as the primary and the OEM 02 has been disabled.
Gary Castillo of Design Craft Fabrication welded an additional O2 bung onto the Blox Racing test pipe for our Innovate MTX-L.
Hondata supplied us with a non-VTEC P06 ('92-95 OBD-I Civic DX) ECU prior to installation. It required wiring up an external relay for VTEC switching, which operates through the S300's designated external output settings.
SARD Fuel Pressure Regulator
Prior to tuning, we backed off the valve lash by approximately 10-11 thousands per recommendations from Honda guru Oscar Jackson of Jackson Racing and replaced our OEM fuel pressure regulator with an adjustable SARD unit. The SARD adjustable fuel pressure regulator utilizes an extra lightweight diaphragm assembly that provides excellent pulsation damping; to dampen the pressure spikes caused by high flow fuel pumps and cycling injectors (especially non-factory high flow fuel injectors). We installed the unit with their optional fuel rail adapter kit for the specific reason of bumping up the factory fuel pressure from 43 to 65 psi. Why the increase in fuel pressure, you ask? We found that the increase in pressure along with tuning the Hondata S300 allowed our OEM 190cc injectors to flow at a mere 40 percent duty cycle. In closed loop mode at part throttle the ECM will detect the increased fuel flowing from O2 sensor data and reduce injector pulse width to maintain proper AFR. Any tuner who has worked on fuel injection understands the immediate benefits of higher fuel pressure in relation to atomization and may help in power production if the fuel being used is completing the burn in the time available before the exhaust valve opens.
Tuned To Perfection
Doug went to work by leaning out the maps at partial throttle and idle until the engine ran roughly/misfired and then slowly added fuel. The fuel maps were developed completely from scratch, as we had no base maps for this engine.
Large changes in air/fuel ratio for this engine caused small changes in power. Doug stated he could have tuned the engine for WOT at 14.5-15:1 AFR with only a couple of horsepower drop compared to tuning it for 13:1 AFR that gave max power. That means about a 15 percent improvement in economy for about a 2 percent power drop (we didn't have the original computer to benchmark against so this is only a comparison to a non-VX motor).
Upon testing, we concluded at partial throttle. The car would run smoothly at 18 to 20:1 AFR with no misfiring. A Blox Racing adjustable cam gear was thrown into the tuning equation to find a balance between good fuel economy and throttle response.
Notice the D15Z1 engine makes the most torque in the earlier rpm from 1,500 to 3,000 rpm before tapering off. Our first run of the day without tuning and the P06 ECU in place netted 66.4 hp and 71.9 lb-ft of torque.
With proper tuning of both low and high cam, we were able to boast 100.3 whp and 115.8 lb-ft of torque for our final run. Impressive numbers for a car that delivers a factory rated 92 hp/97 lb-ft of torque. For those doubters who say you can't gain horsepower and fuel efficiency at the same time, well . . . the proof is in the pudding.
Following our tuning session, we took the car on the street for some partial throttle street tuning to see how the car would perform. We followed that with a quick spark plug inspection, which displayed a perfect brown hue--a condition that indicated our engine was ready to rock 'n' roll for our upcoming trip.
As our project build comes to an end, we're not done just yet; we're just weeks away from packing our bags and setting off on an adventurous trip to destinations unknown. The long days and nights invested into making our project a budding reality comes down to a true test for fuel economy and how well the car will fare as we take Project Sipper on a five-day road trip to see if our build has helped to increase the vehicle overall mpg. Stay tuned for a breakdown of our cross-country coverage in the next issue.