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Old 02-07-2013, 01:49 PM   #20 (permalink)
Hydrogen Nut
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Join Date: Oct 2008
Location: California
Posts: 151

Smart Car ForTwo Pure - '08 Smart Fortwo Pure stripped
90 day: 51.35 mpg (US)

BMW 750iL V12 - '90 BMW V12
90 day: 26.4 mpg (US)

Wildfire 250C - '08 Shandong Pioneer 250C
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I recently replaced the spark plugs, rotors and distributor caps on the old 750iL V12 BMW I bought to convert to hydrogen enrichment. (That hasn't happened yet but it has become my daily driver. I am SO spoiled.)

This requires removing several items bolted to the fenders to gain access. The previous owner had installed conventional copper spark plugs.

None were oil fouled but all had picked up a coating of scale which is common at 40-50k miles and this was obviously affecting performance. This was particularly noticeable at idle (500 to 600 rpm) when the CHECK ENGINE light would come on after idling for 20 seconds at a stoplight.

This engine uses high output coils and comes with a warning not to mess around with the ignition system if you are not sure of what you are doing because IT CAN KILL YOU. Actually, it just says to take it to the BMW dealer because the high voltage CAN KILL YOU.

Those lawyers - a laugh a minute!

I had heard about Iridium plugs but didn't really know much about them. I just wanted the best plug I could buy because it was so much trouble to change them (about 3 hours). I knew platinum plugs had been regarded as the best for a long time. What was the difference? After a bit of research, I learned the process for making iridium plugs had been recently developed. The developers' goals were increased hardness and decreased surface area with as little compromise in conductivity as possible.

Well, the iridium is deposited as a thin layer over copper alloy. With high output coils, there is essentially no compromise. We almost all use high resistance spark plug wires anyway (so we can listen to our radios), so who cares? The only issue is cost. Bosch iridium plugs retail for $10. That's $120 to change my plugs, plus another $12 tax in California. But delivered 12 to me with free shipping, pre-gapped for my car, for $5.52 each. I was pleased.

But let me plug After I installed the spark plugs, I thought I'd pull the distributor caps and see how they were doing. There was a lot of corrosion on the conducting surfaces, so I placed an order and received a set of caps and rotors THE NEXT AFTERNOON with FREE FEDEX SHIPPING! And the price beat everybody. The guy who runs Pelican Parts is Wayne Dempsey. He says he'll match or beat any competitor's price. You gotta love it.

I was amazed at how tiny the electrodes are on iridium spark plugs! On the test drive, the engine sounded different. It sounded like a jet turbine! I floored it in ED ("Economy Mode") and the acceleration kicked me back in my seat stronger than it previously had ever done in SD ("Sport Mode"). I am actually afraid to try it in SD, now.

It's been 40 years since I had a car I was afraid of. That was a big block Ford with a stroker kit - but it wasn't designed to cruise at 150 mph like the practically milspec BMW. But don't get the idea I drive recklessly. My challenge is to break 30 MPG at highway speeds. I think it can be done using hypermiling techniques on a car like this. I've already broken 26 MPG with the dirty old plugs, so I'm looking forward to a 500 mile trip to the Bay Area to see what how the improvement in ignition performance effects my MPG.

Last edited by Ptero; 02-07-2013 at 01:58 PM..
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