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HKS 50003-M40 Iridium M-Series Super Fire Racing Spark Plug

(Honda Civic 1987-96, Prelude 1985-91, CRX 1987-91; Toyota Corolla 1985-92, Celica 1987-89, Supra 1987-92, MR2 1984-89; Acura Integra 1991-93 + 4 more models)

Part of: HKS M-Series Super Fire Racing Iridium Spark Plug

Other options in this family: HKS 50003-M45iL HKS 50003-M45HL HKS 50003-M45XL HKS 50003-M50HL HKS 50003-M40XL

Manufacturer

Picture for manufacturer HKS

Part Number

50003-M40
14 reviews
Sale Price

$270.00

In Stock (10+)

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Usually delivered within 2 days

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Fitment guaranteed

Fitment guaranteed

Product Details

The HKS 50003-M40 is a high-performance M-Series Super Fire Racing spark plug featuring advanced iridium alloy construction for exceptional ignition performance, durability, and resistance to carbon buildup. Designed for enthusiasts running high-load applications and aggressive tuning, this plug delivers reliable ignition under demanding conditions.

Key Features:

  • 0.6mm iridium alloy center electrode for focused spark energy and extended service life
  • Platinum-tipped outer electrode for enhanced durability and wear resistance
  • Short-type outer electrode design reduces vibration damage
  • Thermal Edge technology optimizes heat dissipation
  • Spark Support Gap architecture improves ignition stability
  • High melting point iridium (2454°C) withstands extreme combustion temperatures and compression
  • Nickel-coated housing prevents premature deterioration

The M-Series is specifically engineered for turbocharged and high-compression applications where consistent ignition and anti-fouling characteristics are critical. The ultra-fine iridium center electrode maintains optimal spark performance while the platinum outer electrode resists erosion from high-energy discharges. Available in colder heat ranges to accommodate forced induction and high-output engine builds.

Note: Spark plugs are sold individually. Verify quantity needed for your application.

Products specifications

Fits

Honda Civic 1987-96, Prelude 1985-91, CRX 1987-91; Toyota Corolla 1985-92, Celica 1987-89, Supra 1987-92, MR2 1984-89; Acura Integra 1991-93; Nissan 300ZX 1984-89, Pulsar NX 1987; Lexus ES300 1992-96; Mazda 626 1987-89

Heat Range

8

Quick Site. Need better Pics of Parts

So far so good website was easy to manage cheka was a breeze we'll see how quickly they get order here.

Perfect Fit just what I needed received earlier than expected

I have a corporate credit card with separate billing/shipping address requirements. After my initial purchase I was then solicited to fill out an additional Credit Card form. very inconvenient.

Good experience, fast service

fast shipping , great price

.

Ok

you have the best price I will be back for running boards

Very easy to order parts but since I did ground delivery I am unsure when to expect them.

Easy ordering, Great price.

Quick, easy and inexpensive!

Quick and easy. Price was great also

Although there was a mix up with the shipping on my order customer service was helpful and expedited the solution and made it worth my trouble. I will be keeping Autoplicity in mind for any other parts I might need for my Jeep.

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