Re: re Velocewest's recommendation
Velocewest sounds very knowledgeable and if he is listening, perhaps he could explain any quantifiable performance or economy advantage(s) to the extra long extended nose plug (WR9LS) over the standard extended nose (W9DC). Likewise, other than avoiding radio interference, what is the advantage for the resistor plugs? Please bear in mind that most of our applications involve old school carburetors as well as the famous DJetronic - neither of which have computers that may require this resistance for feedback to operate efficiently.
Thank you in advance.
I don't know how knowledgable I am, but I know what has worked. A mechanic I trust (that's a very small population) who has been wrenching on BMW's almost as long as I've been alive (he's not the youngest mechanic) told me I should use the WR9LS in the e9. I did, it works. The car has not had the plugs changed in about 5 years because circumstances have limited its mileage in that time to about 3,000 miles. This may be a better endorsement than saying I got 2 years on a daily driver -- sitting around not running is a good way to get fouled plugs.
Re the use of the Silbers in the e12 -- the engine in that car started life in an e28, has the Motronic DME, and the WR9LS is the factory recommended plug.
On a pseudo-technical note -- if you look at the placement of the plug inside the comustion chamber in an M30, you'll see that it sits right next to the intake valve, right in the path of the incoming A/F mix. Since the combustion chamber is the same on all M30 heads from the first 2500's up through the M30B34 in 1988 or so, BMW must have found a good reason to start recommending the long reach plugs. The additional 2mm of extension of the electrode of the "L" plug does put the spark further into the path of the incoming mix, which I suppose helps get a better combustion event. For the record, it doesn't put the electrode appreciably closer to the piston, due to the shape of the combustion chamber and the angle of the plug hole. You know, Dreikurbelwirbelwannenbrennraum... :wink:
And, y'all can call me Tony, it's much easier to type.
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