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1991 Acura NSX - NSX STAT!

A mad doctor force-feeds the mighty NSX

Les Bidrawn
Dec 9, 2013

I spent several decades working for HT's sister publication, European Car. Obviously, the title specialized in hardware from across the Atlantic: Audis, Porsches, VWs, Lamborghini's, etc. For the most part, they're good cars, very good even. There were, however, a few exceptional examples, specifically those from Modena and the crew at Ferrari. While BMW, Mercedes, and Audi offer a similar experience; one does not soon forget a Ferrari.

The NSX belongs in the same "unforgettable" file. Not sure if anyone has ever actually referred to the NSX as a Japanese Ferrari but that's what it feels like ... to me anyway.

2017 Acura NSX
$156,000 Base Model (MSRP) 21/22 MPG Fuel Economy

That the NSX was years ahead in its design and construction is a well-known fact. Although it's been nearly a decade since the last NSX rolled off of the assembly line, the car has managed to stay current, both in performance and appearance, turning heads with neck-snapping double takes. The car on these pages does that too, only much faster. The inhale and exhale of forced induction will often do that.

1991 acura NSX downforce type r wing 03 Photo 2/8   |   1991 Acura NSX - NSX STAT!

After heavily modifying a 350Z and ultimately being unsatisfied with the car, Dr. Joseph Viggianelli needed to make some intelligent decisions on his next project. "The wife threatened profusely she would only tolerate one more project car," recalled Viggianelli.

"So I set out to find a low production vehicle that still had modification potential. It had to be an import with a rareness factor; essentially, I wanted something that would get me pumped every time I saw it—the NSX fit the bill perfectly."

After studying the different versions of the car, Viggianelli decided on an early production model primarily for structural integrity. The fixed-roof model narrowed the search to '91-'94 models. After finding a mint condition '91 with low miles, Viggianelli refreshed its appearance with a 2002 conversion and a few tasteful aftermarket upgrades. After converting the car's aesthetics, he focused on the suspension and brakes, both systems that his good friend and master mechanic Dustin Weinand was well-versed in. Weinand is a race car mechanic and fabricator by trade with a natural talent for thinking outside of the box.

Weinand did not disappoint, developing a unique and fully custom Bilstein coilover kit. After owning several name brand kits, Viggianelli wanted coilovers primarily for street use but something that could perform when needed. Weinand designed and milled a coilover sleeve adapter for the Bilsteins that could use the OEM NSX Type S springs. The suspension was finished with a race-spec STMPO rear strut bar, NSX Type R front sway bar, NSX Type S rear sway bar and Cedar Ridge non-compliance front clamps. Rolling stock includes gorgeous Advan RZ wheels measuring 17x8 and 18x10 respectively. Weighing less than 20 pounds per corner, these hyper-lightweight forged wheels are shod with Yokohama S-Drive tires sized at 215/40-17 and 275/35-18.

1991 acura NSX recaro pole position seats 08 Photo 3/8   |   1991 Acura NSX - NSX STAT!

Weinand fine-tuned a Stoptech big brake kit, removing the stock ABS system in favor of a Tilton proportioning valve with braided stainless lines. Now that the underpinnings had substantially more performance, it was time to throw substantially more power at them.

Given the choice between power or handling, 9 out of 10 guys will opt for horsepower. While Viggianelli wanted the increased ponies as much as the next man, he also wanted to strike a balance with the chassis.

"My requirements were simple," recalled Viggianelli.

"Pump gas, air cooled, and no cutting of the body. I wanted something the factory might do if it had gone the force-fed route."

There was virtually no NSX-specific info on a front-mounted intercooler setup, so Dustin began studying established rear mount turbo kits (i.e., STS Turbo). He used two-inch aluminum tubing to run all the way from the turbo to the custom-built Spearco intercooler. The size of the tubing allowed him to tuck the tubing through the AC tunnel under the car and over the steering rack with virtually no obtrusive low spots. Despite the overall length of the tubing, its diameter helped maintain flow velocity while providing a certain degree of cooling as well (a happy accident). Given the engine would retain all of its stock internal bits, cooler equals better.

"We were stoked to find that using only the stock radiator cooling fan and minimal supplemental fans on the DYNO, the FMIC kept the air temps so low, we could run it back-to-back with virtually no heat saturation," said Viggianelli.

1991 acura NSX difflow rear under body diffuser 07 Photo 4/8   |   1991 Acura NSX - NSX STAT!

"We tested three different turbo sizes before settling on the Turbonetics GTK 450. This turbo had virtually no lag which was surprising considering the length of the piping."

To address the new oiling needs, Weinand created a baffling system for the stock oil pan. He then designed a remote oil filter and thermo-fan controlled oil cooler kit. The fuel system was thoroughly upgraded with 440cc Bosch injectors, DeatschWerks fuel pump, high flow lines, Aeromotive fuel pressure regulator, and high flow fuel filter. Boost pressures run conservatively between 5 to 7 psi.

Although it sounded awesome, a prototype muffler system was too loud for daily street use. Keeping the exhaust decibel levels to a minimum was tricky considering the lack of space for a muffler. Weinand came up with a unique solution that would keep the exhaust unrestricted and the decibels down. He took a rather expensive Borla X-R1 multi-core muffler and hacked off the inlet and outlet. A 3- to 4-inch transition was made from the turbo to the muffler. The exit pipe is 4 inches all the way to the finisher. Dyno pulls before and after confirmed the exhaust system resulted in virtually no loss of power. To keep the engine secure in the car, Weinand modified the factory engine mounts to incorporate the lightweight aluminum brackets which house a polyurethane flanged cylinder bushing.

We met up with the good doctor in Newport Beach, CA, where exotics sprinkle the landscape like so many Starbucks. Despite being more than a decade old, this NSX garnered neck-snapping double takes (nothing is funnier than watching rollerbladers skate through the bushes). Dr. Joe and Dustin managed to pull off a brilliant balancing act; a car that dances about the edge of street car and track star. File this one "unforgettable."

1991 acura NSX stoptech ST 40 caliper 04 Photo 5/8   |   1991 Acura NSX - NSX STAT!

Bolts & Washers

Propulsion
Weinand Racing turbo kit
Danzio software
Turbonetics GTK-450 turbo (oil cooled)
Turbosmart Hyper Gate 45mm Waste Gate
Turbosmart Vee-Port Internal BOV
Spearco front mount custom intercooler
440cc Bosch injectors
DeatschWerks fuel pump
Aeromotive fuel pressure regulator
Aeromotive fuel filter (custom billet bracket)
Science of Speed oil pan baffle
Turbowerx remote oil pump
Science of Speed oil cooler kit
Canton oil relocation kit
Jegs catch can
Green High Performance air filter
Cantrell Headers 3-in
Borla X-R1 multi-core muffler
Rebuilt transmission by Weinand Racing
Science of Speed Short Shifter
RPS clutch

Power
391hp/331lbs ft tq

1991 acura NSX STMPO rear strut bar 06 Photo 6/8   |   1991 Acura NSX - NSX STAT!

Suspension
Weinand racing coilover sleeves
Bilstein dampers
Type R front swaybar
Type S rear swaybar
STMPO rear strut bar
Cedar Ridge front chassis noncompliance clamps
Weinand Racing urethane motor mounts

Resistance
Stoptech ST-40 four-piston calipers
2pc 328x28mm AeroRotors
Stainless steel brake lines
Tilton proportioning valve

Wheels And Tires
Front Advan RZ 17x8+37
Yokohama S Drive 215/40-17
Rear Advan RZ 18x10+35
Yokohama S Drive 275/35-18

Exterior
OEM 2002 hood
OEM 2002 front bumper
OEM 2002 taillights
JP Aero urethane front lip
Downforce Type R Wing
Downforce rear window garnish
Downforce engine cover
Zanardi mesh side vent
GT One side skirts
Dali Racing carbon motor accents
Downforce carbon fiber front under body panel
Difflow rear under body diffuser

1991 acura NSX JP aero front lip 05 Photo 7/8   |   1991 Acura NSX - NSX STAT!

Interior
Recaro Pole Position seats
Weinand Racing seat brackets
Momo Jet Steering Wheel
NRG hub and quick release
RM Racing harness bar
Schroth Rally 3 ASM belts
Dali carbon pillars
Science of Speed billet aluminum door handles,
Science of Speed carbon dash kit
Pioneer double din AVH P2400BT
Science of Speed stereo kit
Kicker drivers
Dali Type R Titanium shift knob

Electronics
AEM EMS Standalone
Turbosmart E-Boost Street Boost Controller
AEM Air Fuel Ratio Gauge
Defi boost gauge

Five Great Ways to Screw up a Turbo System

Use Gigantic Intercooler Piping ... it looks cool
Oversized IC piping causes boost lag and poor drive-ability. IC piping should be sized for the power levels you are trying to achieve with the turbo system. Just like you size your exhaust on your car for the power output the motor is making.

Pay No Mind to Boost Controller Configuration
The boost controller is highly dependent on how much exhaust pressure is pushing against the wastegate and the spring. With less exhaust pressure, softer spring and boost levels are needed at the bottom of the diaphragm to control valve actuation and boost levels. With good exhaust pressure on the wastegate, a stronger spring and pressure on top of the diaphragm is needed to keep the valve shut to control desired boost levels

Place the Wastegate Location Anywhere
The percentage of exhaust in contact with the waste gate is the percentage of control you will have. Proper placement of the wastegate in the exhaust ?ow path will dictate how efficiently you will be able to control the boost. No cheated bends should be used to accomplish the angles that are needed for proper placement.

Look For Cheap Turbo Deals ... They all Do the Same Thing
eBay knockoff turbos are all that is unholy in turbo charged cars, staining turbo kits everywhere with an undeserved reputation for lag, weak output and poor drivability. You get what you pay for when it comes to turbos. Do your research and it will certainly pay off in the end.

Use the Biggest Turbo You Can
Don't listen to your girlfriend ... bigger isn't always better. Use turbo ?ow charts to optimize efficiency. Figure out what type of power numbers you are trying to achieve and how the car/system is going to be used. Are you going to spend lots of time tickling 7800 rpm? Probably not. Choose a turbo based on how the car will be used.

1991 acura NSX advan RZ wheel 02 Photo 8/8   |   1991 Acura NSX - NSX STAT!

Sources

DeatschWerks
Oklahoma City, OK 73106
340-521-7070
http://www.deatschwerks.com
AEM Electronics
Hawthorne, CA 90250
310-484-2322
www.aemelectronics.com
Downforce USA
Anaheim, CA 92806
714-288-1630
http://www.downforceusa.com
By Les Bidrawn
242 Articles

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