Our '98 NSX received some...
Our '98 NSX received some cosmetic revisions with a '02 front-end conversion. The front bumper is a Downforce fiberglass front bumper, which is a more economical alternative to spending $1,500 for the factory piece.
The NSX was Honda's first attempt at building a supercar and was dubbed by many, the Japanese Ferrari. Based on its design, the automobile was considered exotic by many. With a mid-engine layout and superior handling capabilities, the NSX was engineered with the prowess of showcasing Honda's superior race technology. Powered by a 3.0L, DOHC, 24-valve, V-6 engine mated to a five-speed, the Honda NSX was regarded as the most exotic vehicle to ever be produced in Japan. With superior attention to craftsmanship, each NSX was hand-assembled by a special team of technicians at a dedicated factory in Tochigi. With the Tochigi plant producing 25 vehicles per day at a cost of $65,000 to build, the NSX was labeled as the most expensive Japanese car in history at the time.
With all the hype and attention that the NSX offered to the general public, the 270hp VTEC machine enjoyed a limited run in the U.S. from 1991 to its abrupt end in 2005. As a testament to the NSX's engineering and technological advancements, the vehicle has remained unchanged with only minor revisions during its production cycle from 1991 to 2001. From 2002-2005, the NSX received aero enhancements in the way of a redesigned front bumper, headlight revision, lower stance side skirts with door caps, lower rear bumper and small trunk lip spoiler. Even with these various minor changes to the exterior, none were as noticeable or as impacting as the aerodynamic modifications on the '02 NSX Type-R.
Downforce offers a four-piece...
Downforce offers a four-piece under panel aero kit for the NSX with promising results. Shown here is an image of the under tray, battery tray, gas tank cover and rear diffuser.
Various under panels and aerodynamic modifications were added to the second-generation NSX Type-R to create more downforce, minimizing parasitic drag and improving overall high-speed stability. Independent track testing has shown the Type-R's aggressive rear spoiler, hood vents and rear diffuser have improved its handling capabilities over previous NSX models and higher-powered vehicles on the track without horsepower improvements. The only setback found in the Type-R is the very limited production of NSX-R's produced in Japan; these parts were never available in the U.S. To say that getting their parts is difficult is definitely an understatement.
Based on the conceptual aero...
Based on the conceptual aero package design from the OEM NSX-R, the Downforce under tray (under the front bumper) and front battery tray is a simple bolt-on procedure that takes no more than one hour. Both the Downforce front tray (under the front bumper) and front battery tray was designed off of the OEM NSX-R piece.
Downforce, located in Orange, Calif., was our answer to improving our '98 Acura NSX's aerodynamic dilemma. Downforce has a reputation in the Acura community as specialists in carbon-fiber fabrication and manufacturing for the NSX. Downforce offers a full under tray package consisting of a front bumper under tray, aluminum battery tray, fuel tank cover and rear diffuser. The idea of having a better flow on the bottom of the car is to create two separate pressure zones. Ideally, if you want to have more downforce without raising the coefficient of drag you can design the car to work like an upside-down airfoil (airplane wing). When air hits the top of the car, it flows slower over the top compared to the bottom. Naturally, the air from the top wants to equalize the bottom (lower or negative pressure) so it squeezes the car down into the ground. This doesn't increase the drag; therefore, this is the most efficient way to create downforce without losing top speed power. Spoilers are becoming more dated because they aren't efficient and do more for fashion rather than performance. While spoilers can offer tremendous downforce, they also produce a lot of drag that will affect your fuel consumption, top speed, acceleration, etc. "Many people think that leaving the tailgate down on a pickup truck will reduce drag and improve fuel efficiency," says Peter Chou, owner of Downforce. "This is the exact opposite. By lowering the tailgate it will allow the high- and low-pressure air to create an excess amount of turbulence and this is parasitic drag."
Loosen the factory lip spoiler...
Loosen the factory lip spoiler using a 10mm socket and extension. Using the factory mounting points, the Downforce under tray slides easily into place and is securely fastened before installing the coinciding battery tray.
The front bumper tray is constructed...
The front bumper tray is constructed of handlaid fiberglass. The tray is finished in a dark gel coating so that it can be painted if the owner wishes to do so. The Downforce under tray and battery tray work in conjunction to completely seal up the front under paneling of the car to reduce turbulence and channel a smoother passage of air. The purpose is to contain any airflow passage between the bottom of the car to the mouth of the front bumper openings. This will create a greater lower pressure area and enhance the downforce available without creating parasitic drag.
The Downforce front battery...
The Downforce front battery tray is constructed of sturdy aluminum paneling and uses all of the factory bolt locations to mount in place.
Installation of the front...
Installation of the front under tray and battery tray will provide an improvement of -0.040 coefficient of lift over factory specifications to the NSX not using both pieces. These data numbers were wind tunnel tested by Honda Motor Co. Japan's test of the NSX-R. To briefly explain aerodynamics without needing a degree in physics, the term negative lift refers to providing more downforce to the vehicle, increasing the load to the front or rear tires depending on how the vehicle is setup. This increased load improves the lateral g-force allowing for more traction and better cornering abilities.
The gas tank cover offered...
The gas tank cover offered by Downforce was modeled after the Mugen fuel tank cover, which sells for approximately $5,000 in Japan. The fuel tank cover was designed to enhance airflow by extending the flat surface underneath the NSX even further to prevent turbulence from building underneath the vehicle. The idea is to have airflow under the car as smooth and fast as possible. Anytime you have drag or turbulence it creates a mini vortex vacuum that will pull the car backwards causing a parasitic loss.
Caption10The Downforce gas...
Caption10The Downforce gas tank cover, constructed from a fiberglass material, can be installed using the supplied bolts and screws. The aerodynamic also protects your fuel tank from road debris and foreign objects that may dent or puncture the fuel tank.
Metal brackets are also included...
Metal brackets are also included within the package to mount securely to the NSX's aluminum chassis frame.
Driving ImpressionsAfter installing the under panel aero from Downforce, we tested the new products and spread the NSX's wings with some spirited driving. While taking the car on a testdrive, the NSX was more stable at high speeds and also surprisingly quieter from road noise. This was possibly due to the fact that the air was basically gliding underneath the panels and didn't stumble into any open patches under the car. Some promising test results came when we encountered a sweeping 45-degree freeway interchange. We hit triple-digit speeds before we realized how fast we were going, but then had to slow down due to slower moving traffic. The NSX didn't flinch one bit and remained stable through the turn. We still haven't taken the car to the track to see how it performs, but we have good expectations for the aero mods.
Here's a shot of the rear...
Here's a shot of the rear undercarriage before the diffuser is installed.
|Battery tray ||$350 |
|FRP front bumper under tray ||$350 |
|Carbon-fiber front bumper under tray ||$500 |
|Carbon-fiber fuel tank cover ||$435 |
|Carbon-fiber NSX-R OEM small diffuser ||$450 |
|Fiberglass DF-R diffuser ||$675 |
|Carbon-fiber DF-R diffuser ||$825 |
|NSX-R hood exact replica FRP (MSRP $9,800) ||$1,750 |
|Carbon-fiber hood duct exact NSX-R replica ||$450 |
|Carbon-fiber hood duct exact NSX-R replica DF-R version ||$650 |
|Carbon-fiber rear wing exact NSX-R replica (MSRP $6,800) || $1,390 |
Using the supplied brackets...
Using the supplied brackets included with the diffuser, remove the factory sway bar bracket and mount both steel brackets on either side.
Using an Allen wrench, loosen...
Using an Allen wrench, loosen or tighten the two designated screws to adjust the rear diffuser to offer more or less wind resistance.
The rear diffuser install...
The rear diffuser installed.
Chou says the DFR rear diffuser...
Chou says the DFR rear diffuser design offers better exit flow when compared to the OEM NSX-R diffuser. The DFR design was based on the original NSX-R prototype design that offered longer strakes (fin design). Downforce provides both the NSX-R OEM diffuser and the DF-R versions depending on the owner's preference.
Info for the aerodynamics...
Info for the aerodynamics provided by Honda Co. Ltd Japan:
-The NSX-R carbon hood will result in -0.025 coefficient of lift reduction value. The number is negative because we don't want lift. The hood duct inside the hood will be -0.010.
-The front bumper undercover with the battery tray is -0.040.
-The rear spoiler is -0.085.
-The NSX-R OEM small factory diffuser is -0.002 and also has a Cd of -0.003. This is negative drag meaning the diffuser improves the drag coefficient.
-These lift reduction figures reflects wind tunnel testing with the NSX-R underbody paneling piece by piece.
Factory NSX-R wind tunnel...
Factory NSX-R wind tunnel testing data provided by Honda Co. Ltd Japan:
-Overall Clf (lift coefficient/front): -0.100 reduction value
-Front Clf: -0.040 reduction value
-Rear Clf (lift coefficient/ rear): -0.060 reduction valueCd (coefficient of drag): 0.32
At 112 mph, this data translates to a vertical force of 80 pounds on the front tires and 55 pounds on the rears. When planning to add aero to your NSX, be sure to properly balance the car. For instance, the NSX is balanced at 42 percent in the front and 58 percent in the rear. So ideally you don't want to add downforce only to the rear, because this will throw off the balance of the car-especially high-speed stability.
The Downforce NSX-R replica...
The Downforce NSX-R replica hood was designed as a true carbon-fiber piece, using a double-sided carbon design. A vented hood is a required piece for anyone planning to use the underbody paneling since the opening is used to vacate the air properly.