Spark Plugs
Chapter 2 Spark Plugs
22
Extended
11
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This type of spark plug projects the center electrode
and ground electrode far beyond the bottom section.
●
Bringing the spark position closer to the center of the
combustion chamber improves the combustion
efficiency.
●
Extended spark plugs can only be installed in the
specified engines. If you use Extended spark plugs in
place of ordinary spark plugs, there is a danger of
interference with the valves or other parts.
Example : J16AR-U11
●
The U-groove ground electrode obtains large ignition
energy making it easy to ignite even lean air-fuel
mixtures.
●
Projecting the spark position into the combustion
chamber improves the combustion efficiency, fuel
consumption, and driveability.
Example : KJ20CR-11
KJ20CR-U11
●
For Mazda and Mitsubishi.
●
The KJ20CR11 has no U-groove.
The KJ20CR-U11 has a U-groove.
Semi-surface discharge
12
●
Semi-surface discharge spark plugs have surface
discharge from the entire circumference of the ground
electrode and normal discharge from the hook.
●
Giving the semi-surface discharge structure to the
ground electrode improves the ignition, fouling-
proofing, and durability.
- Semi-surface discharge spark plugs
Example : W20EKR-S11
W20EPR-S11
●
The use of semi-surface discharge improves ignition
and fouling-proofing.
●
The W20EKR-S11 is used in Honda and the
W20EPR-S11 is used in Mitsubishi.
- semi-surface discharge 2-electrode
spark plug
Example: W20ETR-S11
●
2 ground electrodes are adopted with the gap set to 1 mm.
●
Superior durability is secured by using two short
facing ground electrodes.
●
The ignition is improved with full projection.
●
The new auxiliary cap improves fouling-proofing.
●
Used for Toyota and Daihatsu.
- 2-electrode half-surface discharge
spark plug with shroud
Example : K20DTR-S11
W20DTR-S11
●
In addition to the half-surface discharge structure, the
thread tip is extended into the combustion chamber and
a shroud formed to improve the fouling-proofing.
●
Used for Daihatsu and Subaru.
12
Example: KJ20CR-L11
●
A taper cut is adopted for the ground electrode and a
thin center electrode is adopted to improve ignitability.
Example : J16AY
●
This spark plug is only for Daihatsu. It has two ground
electrodes and provides durability.
11
J16AR-U11
KJ20CR11
KJ20CR-L11
J16AY
7mm
7mm
5mm
5mm
K20DTR-S11
W20EKR-S11
W20ETR-S11