A Brief History of the F31 Leopard/Infiniti M30

(Translated from f31-leopard.main.jp)

Zenki (early model)

On February 18, 1986 a brand new car was created by Nissan in Ginza, Tokyo.  Using the best technology that Nissan had to offer, the two-door Nissan Leopard coupe was born.  The motivation to create the Leopard stemmed from Nissan's desire to capture a share of the market that the Toyota Soarer had already reigned over.  Unfortunately, the Leopard was met with failure.  It is widely accepted today that the Leopard hid in the shadows of the Soarer in success.  On June of 1987, every Leopard with the Grand Selection package came standard with the 6" TV monitor option (beside the 2.0L model). 

Kouki (late model)

On August 23^rd, 1988 only minor changes occurred.  Although there were only minor changes with the exterior, interior, and engine, it almost took on an appearance of a whole different model.  The top of the line model, known as the Ultima Turbo, shared the same engine as the Nissan Cima.  This engine, known as the VG30DET, was capable of putting out 255hp, which surpassed that of the Toyota Soarer (7MGTEU @ 232hp).  Although this was great move on Nissan's part, it was still unable to capture the interest of the public.  The Toyota Soarer would still prove victorious in sales. 

In February of 1992, the Nissan Leopard slowly faded out of the lineup.  During the six years that the Leopard was in production, there were roughly 38,000 F31s produced.  Surprisingly, today used F31 Leopards have become popular and go for a higher price than a used Toyota Soarer.  In Japan, the F31 Leopard is a rarity that is cherished by a rather large group of cult-like Nissan Leopard owners.

F31 Engines

Zenki

VG20E – The Zenki models from 1986 to 1988 (XJ and XJ-II) had the option for a 2.0L 60-degree V6 with a single overhead cam, 30-degree offset crankshaft, and two valves per cylinder.  This engine debuted in the Y30 Cedric and Gloria in 1983.  The maximum output for this motor came out to about 115HP (1PS = about 1HP). 

VG20ET - This SOHC motor debuted at the same time as the VG20E.  Also coming with the Y30, this motor was known as the "Jet Turbo", and came with the Leopard models XS, and XS-II Grand Selection.  Contrary to the VG30ET that came out in the US, the VG20ET came with an intercooler to push the horsepower output to 155HP, a great jump from the normally aspirated VG20E.  The turbo included with the VG20ET had two different settings.  At low speeds, the turbo's flap (wastegate?) would stay closed improving the response at low RPMS.  At high speeds, the flap would stay open, decreasing resistance and increasing exhaust flow.  At its maximum flow, the flap would open at an angle of 27-degrees, while the A/R ranged from 0.21 ~ 0.77.  Being that the VG20ET had a short stroke (78x69.7mm), it was thought to have insufficient low end torque.  Nevertheless, the VG20ET was a great improvement over the VG20E.

VG30DE – The Ultima and Ultima Grand Selection models came with the VG30DE option.  This twin cam motor was debuted in the Leopard before any other car in the lineup and was known internally with the code "EG1."  With the VG30DE, Nissan was able to create an engine with much greater power potential over the SOHC VG20E/T engines.  One reason for the increased output was the fact that it employed four valves per cylinder, rather than just two.  Also, the ignition system was revamped with an all new high tech system called NVCS and NDIS, which ignited the cylinders more efficiently then ever before, increasing the power output.  It is thought that this technology was taken from a rival company.  Although the VG30DE was technologically superior to the SOHC engines, the NA's power output of 185HP was still eclipsed by the Soarer's 3.0L DOHC turbocharged 7MGTEU (232HP).

Kouki

VG20E – The VG20E stayed in the line-up with the XJ and basically remained unchanged for the life of the Leopard.

VG20DET – The XS kouki model Leopard gets an all new turbocharged DOHC 2.0L V6 putting down impressive numbers for its time.  This motor debuted in 1987 with the Nissan Cedric and Gloria.  The output varied depending on its inclusion of an intercooler, but it was generally thought to have a maximum output of 210HP.  The technology of the motor gets a major boost with variable valve timing and a high flow ceramic turbo.  They engineered the housing and rotor to be optimally combined with the latest turbine technology called CNR-1.  What they were able to create was a turbo that could perform at the same capacity of a much larger turbo.  The year after the VG20DET was released, the turbo was fit with ball bearings, just as the RB series had.  This motor also came in the Y31.  The ball bearing turbocharged VG20DET withered away after the Leopard saw its end in 1992.

VG30DE – The kouki Ultima model also came with this twin came engine.  A 15HP increase takes the max output to 200HP.  This Leopard is fitted with dual-exhaust in contrast with the previous model's single exit.  This engine has a more linear acceleration, resulting in a quicker car.

VG30DET – The Ultima turbo model is fitted with the top of the line VG30DET.  Initially in the Y31 Cima in 1988, this motor made its way into the Leopard lineup.  By simply turbocharging the already beefy VG30DE, you are left with a powerhouse that screams performance.  This is the "ultimate" Leopard powerplant.  But a powerful engine is not everything when it comes to performance.  The Leopard and Cima's Achilles Heel was its suspension.  The strut symmetry was poorly engineered, thus giving the Y31 and F31 a lackluster balance.  With a total output of 255HP, this was the most powerful engine on the Japanese Domestic Market until the release of the VG30DETT (280HP) which came with the Z32 Fairlady Z.  Although Nissan's current production of V6 engines have moved to the VQ series, if one is to ask about V6 engines in Japan, one is implicitly implying the VG series.  The VG30DET engine is also known to be a rather compact engine in the sense that it's as long as a four cylinder engine.  In a way, it can be thought that the VG30DET was ahead of its times because it came out in a time when inline 6 engines were at its peak, but today the V6 has made a comeback. 

Enter the Infiniti M30

Another F31 joins the lineup in 1989.  In January 1989, Nissan unveiled its Infiniti lineup, introducing us to the M30 and Q45.  On November of 1989, Infiniti began selling their two introductory models.  The original base sticker price for the M30 was $24500.  In the year following, the convertible was released. 

The main difference between the M30 and the Leopard is as follows:  Steering wheel position, headlights, corner lamps, and side markers to name a few.  Being that America has higher safety standards, the M30 also came with a lower trunk mounted 3^rd brake light, 4-wheel ABS (Anti-lock Braking System), and a driver's side air bag as standard equipment.  Unlike in Japan, the air conditioner recirculation automatically changes to exterior circulation after 10 minutes, whereas in Japan it stays as recirculation mode indefinitely likely because of poor air quality in Japan.  The dash and gauge cluster are shared with the Nissan Skyline R31, but transposed to a Left Hand Drive car rather than a Right Hand Drive as in Japan. 

On March of 1992, the Infiniti M30 was replaced with the J30, which is known as the J.Ferie Y32 Leopard in Japan.  The engine that was loaded in the M30 was a SOHC VG30E with a 60-degree V6.  The maximum output for that engine is 162HP.  Why is it that the M30 was paired with an underpowered SOHC engine?  Could it have been that the VG30DE(T) didn't fit well?  Could it be that they wanted to create more room for the larger-bodied Americans with the more compact VG30e (lol)?  Could it be that they loaded the VG30e engine because the roads are wider and less windy than the labyrinth-like roads of Tokyo?  Could it be that they wanted to keep down the production costs?  One can only speculate the intentions of Infiniti's decision.

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