1994-2002 [Subscribe to Daily Digest] |
Hi everybody-
My fuel economy problem is solved, and my verdict is against platinum spark plugs. I changed the spark plugs about 700 miles ago to platinum NGK BCPR7EVX-11, gapped to 1.0 mm (.039"). A few days ago I re-installed the stock plugs (they weren't too bad to begin with).
After a tank of gas I think my power and gas mileage are up noticably ... to 25 city/30 highway. I know on this board there are those that are firmly in the platinum spark plug camp, but I'm back to copper and happy. I did some more searching on the net, and below I've attached part of the Saab Turbo Club of Sweden's FAQ at http://www.saabturboclub.com/faq/turbofaq.html . The FAQ content is contribued by a Saab engineer, among others. Translated from the Swedish by your's truly.
Note that it doesn't mention NOT to use platinum plugs explicitly, but I'd interperet it to say, "Use BCPR7ES-11 or else."
-tim
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5.1 What sparkplugs should I use in my Saab Turbo?
The majority of Saab Turbo drivers seem to agree that NGK brand plugs are what belongs in their cars. They work best and don't usually cost that much more than any others.
For how to read a spark plug condition, take a look at https://ngksparkplugs.com/en/category/resources?category=37&page=2
For cars with Direct Ignition (DI): (all 9-3)
Unusually calm driving: NGK BCPR6ES-11
Normal temperature for a STCS member: NGK BCPR7ES-11
Racing: NGK BCPR9ES-11
The difference is in the plug hardness. High exhaust/combustion temperatures require harder plugs. So that there is no misunderstanding I will state: Don't deviate from Saab's recommendations if you're not having any problems with your plugs. Change to harder plugs only of the plugs you have show clear signs of overheating. If you've modified your car, follow the tuning vendor's recommendation.
Cars with DI should have resistor spark plugs. Remember that the DI system uses the spark gap as a sensor which makes it especially important that the plugs are the correct type and are gapped correctly. (Knock tendencies are deduced from the ionization current measured by the Trionic System). Considering this, it's not hard to understand that this information is garbage if spark plugs other than the ones Saab specified are used (BRISK etc...).
The right spark gap is 1.0 mm with the tolerance (+0.1mm/-0.0mm), or 1.1-1.0 mm. If you're running higher pressure, then a smaller gap (closer to 1.0 mm) can be good. Too large a gap might result in misfiring at high pressures, too narrow can result in a rough idle.
For cars without DI:
Unusually calm driving: BCP5EV
Normal driving: BCP6EV
Hard driving: BCP7EV
Other cars:
99t BP7ES
900t8v -84 BP7ES
900t8v 85-83 BP7EV
900t16 BCP7EV
900t 94- BCPR7ES-11
V6 turbo BKR5EK
Change Plugs Often. The harder you drive, the more often you should change. Aggressively tuned, hard-driven cars EAT spark plugs.
Information from Dr Boost and others.
posted by 156.153.25...
, Thu, 15 Nov 2001 22:06:50
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