Bosch Platinum Plus 4 Plugs

I have a mechanic friend who does not like the idea of splitting spark up.. to him all it's doing it making you have a weaker spark.. and I agree..

Adair

He hit it on the head. I've never, ever seen a Chevy run as well or get as good gas mileage with the Bosch. Stick with the Delco's.

It won't split. The spark will jump the easiest gap, which isn't always the same one time after time. Multiple ground electrodes have been used for many years in the aviation industry. It shouldn't hurt. It could help by distributing wear.

Denso, back when they were ND and Nippon-Denso, decided in the late 1970's that a groove in the ground electrode was A Good Thing and marketed it as the "Hot-U". Their marketing wasn't as good as Microsoft or Splitfire as few remember or notice that to this day Denso plugs still have this feature. Compare it to a Splitfire and wonder just what did Splitfire do new?

IMHO the thin-wire platinum and iridium plugs really are good things. Very long life. And when operating in poor conditions I've seen a new plain-old-plug foul in an hour where an iridium plug had been operating for a year. Put the coal black old iridium plug back in and the motorcycle ran great.

Hello,

I put NGK Platinum in my 2000 5.3 Sierra. I found a nice increase in power as well.

I find the truck runs very well on them, but I have always had luck with NGK. They were a great improvement over the factory plugs, but that probably had to due with the age (55,000 miles) of the GM's. I was not going to pay the ridiculous amount for the new GM platinums...way I look at it, I would rather experiment until I find the perfect plug.

By the way, I have never liked Bosch or Champion...too many fouled plugs in the time I have used them and Bosch is far overpriced for what they are. In marine engines, NGK has never failed me, which is more than I can say for the other two, although my arms are stronger from rowing a boat a few times!

Clint

The one 'upgraded plug' that I've had luck with is the Rapidfire, but I didn't have a baseline to measure it against (they went in the 350 that replaced my 4.3 in my '85 C-10), and I have also heard many great things about them here on a.t.c.

Jeremy

They're crap. Use Delco Plat's or Delco Rapidfire's.

Doc

I've used the Bosh +4 for several years without a problem. HOWEVER, they only fire on one of the electrodes, not four. All deposits on my used plugs (three different engines) show that only one electrode was carrying the spark. I would wager that it has multiple electrodes so that they will end up oriented properly (or close to it) when the plug is installed in the engine. I am currently running AC Rapidfire plugs and I have seen no difference between them and the Bosch +4 plugs. I plan to stick with the AC plugs in the future.

Thats what I have always old people interested in buying them. The spark will always flow the shortest path, through the least resistance, so that will always be the case. Only way it would ever fire off more than one is if two of the ground electrodes were EXACTLY the same distance from the center, or the closest one got too many deposits and the farther electrode was a better path due to less resistance. In the case of two or more ground electrodes being exactly the same distance, it still would shoot the spark to both at the same time most likely, but instead possibly alternate between them. Highly highly unlikely they would ever be close enough to exactly the same distance apart for that to ever happen anyway.

One thing that makes the rapdfires a bit better is the tapered tip on the ground electrode. Basically an old racing trick ... it blocks less of the flame fromt from the piston.

The Bosch +4, like other "special plugs", are just another marketing gimmick by the manufacturers. I tried the Splitfires and was absolutely dissapointed by their performnce. I remember the J-tip plugs (Champion?) that were around in the 1970's and how good they were supposed to be. If you really want a strong ignition, build one that uses about 150,000 volts across a .090 inch gap and then hope that nothing goes wrong when it fires (that should rock the old bucket of bolts LOL).

the reason Bosch put four ground electrodes on the +4n is durability. The reason we even have to change plugs is that the center and ground electrodes erode from electricity burning metal molecules off the surface. The thing about platinum plugs is it doesn't erode. but that still leaves the ground electrode. So Bosch put two on some plugs and four on the +4s. As the ground electrode erodes the spark will find the next closest electrode, so on and so forth. I've only tried them in one engine and haven't had any problems but they only have 25,000 miles on them. as far as my Silverado I plan on using what the factory specifies. they are supposed to last 100,000 miles anyhow.

The better platinum plugs have platinum on both cathode and anode. The reason being that dual secondary ignition coils are very common these days and are wound such that one plug fires with positive current out one wire while the other fires with negative current. As a result one plug wears the center electrode faster than the outer while the other is just the opposite. Making it necessary to put platinum (or iridium) on both.

It's cheaper to make a coil that way. You get two coils in about the same amount of work as making one. I don't know where you got the positive and negative current thing, though. Is that off of a Bosch sales pitch, or chevy literature?

================================ Chevy, also it will fire the other cyl some time during the exaust stroke if I remember correctly.

Comes from several observations. One that often plugs wear in pairs. That the center electrode wears on half the plugs and the wire electrode wears on the other half. "Standard" tungsten plugs. Then on studying service manual schematics the secondary of the coil is not grounded. One end of the winding goes to one plug, the other end to the other plug. To spark the current must flow thru both plugs. Both most spark or neither will. One sparks positive to ground, the other sparks negative to ground.

Dual secondary coils do not *have* to be wound this way. Could wind it bifilar, two wires grounded at one end then wrapped together around the coil. Then you would have two sparks of the same polarity.

If the first simple dual secondary were grounded in the middle then it would be more likely the good plug would fire even when the bad plug didn't. Haven't been looking for one of these, but haven't seen any.

Have seen motorcycle coils where there were two secondaries on the same core.

I don't know why bifilar or grounded center tap secondaries are not used. Suspect it has something to do with internal potentials (voltages) between the windings when one or the other misfires. Suspect it also has something to do with, "So what if one sparks positive and the other negative?"

And yes, in all of the dual secondary systems one cylinder fires on the exhaust cycle while the other fires on compression.