Spark plug know how.

Bosch

20 Plugs Fit 95% of Cars

Bosch Super Plus fits nearly all engines systems. With only 22 types, we cover virtually every make and model of car. With a simple part numbering system, just try our rough guide below to see which plug may fit your car.

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Click on the required search number to receive more information on the relevant spark plug type

 

Plugs for a 1992 928GTS:

W7DSR OEPLUG GAP=0.028"
4216 PLATINUM GAP=0.028"
7501 SUPER GAP=0.028"
4477 PLATINUM+4 Do not gap. Gap is not adjustable.
4310 PLATINUM+2 Do not gap. Gap is not adjustable.
7900 SUPER PLUS GAP=0.028"
4016 PLATINUM PLUS GAP=0.028"
4510 PLATINUM IR FUSION Do not gap. Gap is not adjustable.

0 242 235 590 Bougie Super WR 7 DTC
0 242 235 663 Bougie Super Plus +1, WR 7 DC+ In te stellen electrodenafstand 0,7 mm
0 242 232 504 Bougie Super 4 WR 78


http://www.boschautoparts.com/Resources/TechnicalResources/

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Thread type: M14 x 1.25 mm
Thread length: 19 mm
Wrench size: 21

======

Sorry Kevin,
I have no thoughts ......
but the plug gap (for '85 32V motors, Volume I-A, section 28, page 65) is specified at 0.7mm or, 0.02758" (+/-  0.1mm or, 0.00394") Hope that helps.

Best regards,
Dave
=============

>2. Which Bosch platinum plug would be best to run in my Canadian spec '88 S4 (WR7DP or WR8DP)? I have seen both listed as being correct for the S4.

i'd go with the 8. crappy plats have such a tiny electrode, it prob'ly needs the extra heat.

i switched back to the WR7DTC triple electrode copper cores...

dave

David R. Hendrickson
'88 S4 AT Silver Metallic

==============

I switched my 1988 928s4 plugs from WR7DP to WR7LT+ with good results.

The WR7LT+ is the Yttrium style triple electrode.

Theo

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Here is some info collected over time:

928 1985-1991: Bosch WR7DP

928 1980-1984: Bosch WR8DP

Q: What are the correct spark plugs for my car?
A: Check the manual, however the manual/Bentley/dealer may sometimes be
wrong.

Most 8V engines upto 87 can use Bosch WR7D? where ? = S, P

Q: What does the Bosch spark plug number mean?
A: For example: WR7DTC

W = Diameter (?) W= 14 mm (?)
R   = Resistor (Radio interference suppression, not vital(?))
7   = Heat Range (lower numbers = colder plugs)
D  = Length (?)
T  = Tri-cathode. If missing, single cathode
C  = Copper Anode.
Other values, Missing = Carbon, S = Silver, P = Platinum

Q: Should I use Platinum plugs?
A: Only if it is recommended by either the sparkplug or car manufacturer.
The results have so far been mixed. Some people feel a marked and
sustained improvement over regular copper or silver plugs others
felt a decrease in performance and cold starting.

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Spark plug know how.

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The heat range of a spark plug describes its ability to conduct and dissipate heat - a vital function which has to be tailored to engines individually.

Heat range is the key to the spark plugs' performance, and it is important to fit the right one for your engine requirements. The minimum temperature must be reached to prevent 'sooting' and associated misfiring, while the maximum temperature must not be exceeded to prevent automatic ignition.

Bosch spark plugs are individually adjusted to meet specific engine requirements, and the heat range is easily determined by the code number:

Low code numbers (e.g. 2 to 4) signify "cold" spark plugs, in other words, low heat conduction in hot engines (e.g. Ferrari).

High code numbers (e.g. 7 to 10) signify "hot" spark plugs, that is, high heat conduction for cold engines (e.g. VW Beetle).

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Temperature characteristics of spark plugs with different heat-range code numbers.

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Spark plug with high heat-range code number ("hot spark plug")

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Spark plug with medium heat-range code number

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Spark plug with low heat-range code number ("cold spark plug")

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Large insulation nose surface absorbs heat. Low heat dissipation.

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Smaller insulator nose surface than 'hot spark plug'. Reduced heat absorption. Improved heat dissipation.

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Small insulation nose surface absorbs little heat. Extremely good heat dissipation.

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