I was thinking about getting some of those Bosch quad fire's or some type of split fire but I wanted to know if it is really worth four bucks a plug when I could get all six for somthing like four bucks.
I have a 89 626, with the Bosch +4 and I really don't notice a difference in power or fuel economy, maybe with your six you will. But I did notice how clean the plugs were. I had some stock NGKs in my car originally. However when the valve stem seals went south for the winter, the NGKs got really fouled (prior to that it was fine). I replaced them with Bosch ones and those, according to bosch, get hotter FASTER than the stock.
These plugs burned off the oil and kept them clean during idle. After cruising all day the NGKs eventually got clean.
The Bosch plats last longer approx >=100K which is a plus. Versus the 30~50K on stock type. I would just get some regular plats which are quite a bit cheaper (1.99 vs 5.99) and probably have the same performance.
I've also heard that the Bosch Platnums may burn out faster on the turbocharged cars-It sounds like your car isn't but just to let you know.
I've had the splitfire plugs on another car ('92 Eclipse), and only noticed that it took longer on cold days for the car to run smoothly. There was no noticeable improvement in power or fuel economy. My fathers Ford f-150 8 cyl. noticed 2-3 better mpg (the eclipse was a 4 cyl.). I've read (SCC mag?) that copper plugs actually give the best spark, and they cost nearly nothing. The test showed something like a 3-5 hp increase over any other type. The problem, though, who wants to replace plugs every 15k miles?
I, and my mechanic friend recomend regular platinum plugs from bosch or ngk. Bosch seem to last longer...
I've had problems with Bosch Platinum plugs in the past. It seems that they would misfire much sooner if placed under stress (such as racing). I've even burned/melted the tips off of a couple. I started using NGK exclusively and have not had a problem since.
Are you using a large amount of boost? Or perhaps higher octane fuel to race (above 92 oct.)? Bosch makes thicker racing plugs, but htey are not for daily drivers. My friend uses the Bosch in a NA '96 Acura GSR, and they work great for him.
I've tried the NGK's and the Bosch plat's and the +4's and they all worked okay. The only ones I noticed an improvement on were ACDelco RapidFires.
I've been using them since january and I pulled them out to replace them a few nights ago and when I pulled them out, they were still in good shape! I replaced them with some copper electrode Bosch plugs and I would get a miss in the high end! So I re-installed the rapidfires and they worked fine again!
I tried the quad 4 on my mx6 and noticed a low difference in power in fact my gas miledge went pathetic, in first I was a bit swollen headed to blame it on the bosch quad 4's but in the end I went and bought a set of ngks which is way cheaper and noticed the tremendous difference, my advice to you is , expensive is not always good!
Okay, I may get argued with, but here goes. All these multi prong plugs are a gimmick, and a gimmick only. The only thing they have going for them is they last longer. Electricity always finds the shortest path. With normal plugs, the electrode wears away, and the gap becomes too large. With more than one prong, it has up to twice the life, since as one wears down, the spark goes to the other, and vice versa. I have tried them all, and never noticed a bit of difference in fuel economy or power. I am of the mind that if NGK's are good enough for Mazda to put in their cars, they're good enough for me to put in mine. I use NGK's. They're relatively cheap, and I have no problems with them. Then again, I never had any problems with the Bosch Platinums, Splitfires, AC Delco, or any other plug. If you use one of the higher dollar plugs, and you feel that they make a difference, cool. If not, I wouldn't waste my money.
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