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[Datsun 1200 encyclopedia]


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Category: Emission Control And Tune-Up

Nissan Anti-Pollution System (NAPS) was the market name for Nissan's collection of emission controls. Sometimes confused with the Nissan Z Engine, NAPS was used from late 1975 on many types of Nissan engines, including A12 and A14 engines. A catalytic converter was the heart of the NAPS system.



NAPS日産排出ガス清浄化システム -- Nissan NAPS exhaust gas cleaning system.

エンジン改良+酸化触媒」- slogan "Improved engine + oxidation catalyst system"


32-page publicity booklet from 1 April 1975
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1975 advertisement


NAPS L-series Carburetor Specifications 1975 service manual 330
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1976 Cedric Model 330 trunk lid emblem (L28 powered hardtop)

1980 280ZX


NAPS A-series Engine (127 pages)
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Datsun 1200

Oct 27, 1975: B120 Datsun 1200 Pickup B120

  • H-emissions (H-B120) 50年度排出ガス規制適合。
  • 50th-year relevant regulations of emissions (Showa 50 = 1975).
  • Nissan catalyzed oxidation of exhaust gas cleaning system "NAPS" adopted

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昭和50年10月 H-B120型車( ダットサン サニートラック1200・NAPS)の 販売に伴う整備変更点の紹介のサービス回章 11ページ

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Fuel economy - Emphasis on driving performance
Nissan exhaust gas purification system



NAPS emblem for Japan-market Datsun B210
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マーク エンブレム NAPS


To meet 53-year (1978) emission standards in the larger four cylinder engines, NAPS-Z was introduced.Engine. Fast burn combustion chamber with dual spark plugs to reduce noise. This head was fitted to the L-series block and renamed Z-series. To improve power a turbocharged option engine was available (Z18T).


High fuel efficiency is realized by the adoption of a fast-burn combustion system, made possible by the development of a high-speed swirl system and twin-plug combustion chambers. Advanced EGR with a VVT valve obtains precise control. EGR distribution is improved by modification to the inlet manifold.

4 cylinders, 8 sparkplugs
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However, regular NAPS was modified to meet the 1978 emission standards, so the NAPS-Z was not entirely necessary. For example, VVT was adapted to the A-series engines with similar effect.


1982 Nissan Stanza (T11) -- the first Nissan-badged car sold in USA -- with trapezoidal-shaped combustion chambers for California models. In 1983 NAPS-X was fitted to all Stanzas. 46 mpg highway, 32 mpg city was very impressive. This was basically the same Fuel Economy as the smaller Datsun B310 (the T11 was a compact car, the B310 a sub-compact).

46 mpg (US gallon)
5.11 liter/100 km

NAPS-X CA20E 2.0 1974cc compared to NAPS-Z Z20E

  • Shorter than Z20E
  • Narrower
  • 77 pounds lighter
  • More HP
  • Better fuel economy
  • 88 HP with dual plug version


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