23UC5

Hey guys, I'm new to posting here but I've been reading the posts here for over a year. I recently bought MSD 8.5 mm wires and Bosch +4 Platinum plugs. I know most of you love the TR - 55's and the AC Iridiums but I got a good deal on these off a buddy of mine. What is the opinion of this board about using these Bosch +4 plugs in an LS1? Anybody actually have them? By the way, for the last year I have enjoyed reading all of the great informative posts here - especially Bill Curlee's informative posts. Thank, Rob

RPOZ4Z

some people love them.

I tried them in my '85 corvette and lost power....
I took them right out and put in a new set of Accell U-Groove copper plugs that I was previously using, got my power right back.

and the best part about the accell plugs was the price, they only cost $13.00 for the set!

same is true with the TR-55's.


my opnion is................... unless you got the +4's for free, you spent too much.

JH

Are those the plugs with four electrodes?

If so, I have seen a number of posts on several different forums that said they reduce power because the four electrodes serve to shroud the ignition more than promote it.

Evil_Bob

I've run with the Bosch Plus Fours in my last two Corvettes and never had any power loss problems with them. Nor have I experienced any monumental horsepower gains, either. In my opinion, it's the other mods that produce the horsepower, not one's choice of spark plugs.

With that being said, I did notice that the engine seems to idle a little better with the Bosch Fours than with the stock plugs, and the throttle response seems to be a little sharper and stronger.

I tend to believe any platinum plug is better than no platinum plug at all, but I am also sure you'll hear a difference in opinions no matter which way you decide to go. But from what I have experienced, most of the platinum plugs that I have tried in the past perform about the same.

I just prefer the Bosch line of products over the others.

Lancer033

Some guys have had trouble with them others have run them with no trouble. I don’t' know why some have had trouble.

I do know that one of the Corvette magazines test the +4 plugs and showed a 5hp gain on the dyno. The problem is that they were testing old plug/wires vs. new stuff, so there probably would have been the same gain with any new plug. I don’t' know of any published test comparing new plugs to other new plugs. I doubt that there is any significant difference.

As far as copper vs. platinum: copper conducts electricity slightly better, so in theory it should produce a better spark. The down side is that copper will not last as long, so you have to change them more often.

My opinion on the +4s is that they are just an over-priced gimmick

David426

The Bosch + 4 wear(electrodes) much quicker than the NGK from my experience. I'd stick with NGK- Tr55. The design is a little gimmicky. I remember when the Split Fire plugs came out at 5.00 a piece. what a joke. they only lasted about 10,000 miles in my car.

23UC5

Thanks guys for some feedback. It looks like mixed feelings. My car is 100% stock, so I think I will try them and post my experience with them since I already have them. I agree that the +4 design is a gimmick, as is the split fire. However, I've always used split fire in my muscle cars with an MSD 6A box and did notice better throttle response. I've been driving my car for over a year now, so I know its characteristics. I'll post my opinion after a month or so of use. By the way, my car is a 2000 - Nassau Blue, 6 - speed. Check out the photo by clicking on "My Corvette Photos". I also have a Breathless Performance Air retractor hood, A Greenwood Wing and lower valavce, R K Sport side rocker moldings, and I just need to buy a front spoiler before I can paint everything and put it on. Thanks, Rob