Only 12,000 miles on it but decided to put 8.5 MSD wired with heat shields. Talked to a friend of mine (who is part owner) at his NAPA parts store. This young man really does a lot of research into almost everything they sell. I asked him to look up the parts # for Bosch 4'S for the Vette and he said he thought I should wait until I can get some feed back from people who have done it. The reason being they have had some people return the 4'S claiming poor idling and other reasons. He seemed to think it was because they took more voltage to fire than most plugs. So how have they performed with the stock coils? Thanks in advance.

 

Biggest problem is the three that arent firing[electricity always takes the path of least resistance] are taking up space that normally would be filled with a/f mixture. One of the reasons platinum and iridium have become so popular is the electrodes can be made extremely thin, and those materials will last a very long time.I pulled my factory platinums at 18k, they were like new....

 

There have been several recent threads about spark plug indexing, which means locating the ground electrode away from the intake charge. This is done to give better performance. With four ground electrodes, that's not possible. Consequently, the spark is always shielded which is less than ideal

 

I purchased the +4's and after 500 miles took them out returned them (I was still using the stock wires).

When I took them to the return counter, the guy behind it told me why I was returning - before I had gotten a chance too. Was the same... rough idle and ramdom missing. He told me that the Bosch +4's were too cold a plug for the LS1, and he sees them returned often. He then sold me the Delco Iridiums and they worked perfectly - with the stock wires too.
I think most people on the forum that had good luck with the Bosch +4's also changed their wires at the same time. Maybe that's the recipe for success with the Bosch +4's; plugs and wires... ???

 

I also have a set of +4s. I have put them in my last 3 cars. The car idles smoother, IMHO

 

Does anyone remember Splitfire plugs? And better yet, Splitfire wires? Both of these products made claims that denied the laws of physics. Electricity takes the path of least resistance and in the case of spark plugs, you can only get a single spark at each ignition firing event. You can't get four sparks at the same time just because you have four electrodes.

This is marketing hype at its best making promises of better performance and mileage while making your wallet lighter. These plugs are very expensive and for the cost of eight I could probably put 4 sets of standard copper cored plugs and keep my engine running more efficient.

The big switch by the OEMs to platinum was so they could sell consumers on lower maintenance costs. Have you ever seen what happens to plugs that get left in aluminum cylinder heads for too long? They wind up seizing and then breaking off when being removed. Now you have to remove the cylinder head(s) to fix the problem. Wouldn't have been less expensive to have replaced the plugs several times?

Materials like platinum and iridium do last longer but because of the higher density of the material require more powerful ignition systems to make the spark pass through the center electrode. This is one of the reasons the center electrodes are made thinner.

From a performance standpoint, having multiple electrodes impedes the ability of the spark to ignite the fuel air mixture. The multiple grounds create a sort of dome around which the air fuel mixture must navigate around and does not provide the best exposure to the spark. Multiple ground electrodes were used for many years on large industrial engines, and still are, for the simple reason that the plugs would last longer since there were more electrodes and downtime on these huge engines was a major consideration.

One final point. Indexing of spark plugs will never provide a performance increase. It is done in those cases where interference issues between the piston and plug exist and it is critical to position the ground electrode to prevent piston contact. For that matter, Formula 1 cars have spark plugs that have no ground electrode at all. These are called surface gap plugs and they are used because there is no room for any ground electrode at all.

Sorry if this is a bit long but I don't like to see people get taken by fancy marketing strategies or erroneous information when a simpler method will do.

 

Knock off the "expert" post. Because someone
will believe the bs and repeat it. Then bad info gets spread around.
You my friend need some good info.

The amont of Voltage needed jump the gap is determined by the air gap. The Plug material resitance is determined by the amont
of valence electron's in the metal. NOT density of any metal.
Platium and iriduim last longer than copper or steel to stop gap errosion.Which makes them stay within spec longer.which makes them higher priced.Thin to lesson
spark shrouding
The bosch +2 and +4 Are designed to fire out the top. None of the
2 or 4 ground electrodes are over the top of the center electrode.
Designed for performance, no spark shrouding thus no indexing.
One thing I see that I can agree with is electricity takes the least path of resistance.
Plugs were never indexed do to "piston contact"
"maybe " shimmed back, were talking for spark shrouding.
So we have many plug manufactures worried about shrounding.Why?One caase in point:
Indexing is free measureable Hp. Makes a nice difference.

Dyno sheets are obtainable.

 

Quite simply, I took the OE plugs out of my 2001 coupe after 2000 miles, or so, because I didn't want any errant "pucks" in my engine. I put in a set of Bosch +4s. That was 8500 miles ago, and my car runs just fine........

 

Gee, I wonder what spark plug company you work for? Guys like you can't stand it when someone tells the truth. What experience do you have? I won't get into my background but I can assure anyone on the forum reading my post that my comments come from experience in spark plug design and manufacturing, racing and dyno testing. So knock off your "expert" remarks. The fact that you would say indexing makes a hp difference only proves your ignorance on this subject. I'm not going to try and dispute any of your points as it would be a waste of my time.

 

vetpet,

you're making sense to me!

all I know about bosch +4 plugs is that I put them in my '85 corvette, and it LOST power, and I don't want to hear the "they need higher voltage" story because I had an accell super coil and 8mm wires on the car, after about 2 weeks of this I decided to buy a new set of accell U groove copper plugs (these are what I had in the car before the bosch +4's) and the change was night and day, I gained my lost power back.

the bosch +4 plugs are just a marketing gimmick, nothing else!

I'm running NGK TR55's in the pace car and I have NO reason to ever put a different plug in it! I change them every year wether they need it or not and at $13.00 a set, it's cheap insurance!