Power and Gas Mileage

[Brent Duey]

I was wondering how much hp and increased gas mileage I would gain by installing splitfire spark plugs, cheap wire set ($20-$30), and a k&n filter on my '91. 107Kmiles Thanks for the help

 

[MudManNM]

The filter will do some but you will won't notice a difference. it's not as much as K&N says it is. I put one on and wasn't to happy. It will pull in more air but the exuast is still the same, so you arn't gaining much that will be noticed. As far as the splitfire plugs don't waste your money! they will not do anything that a normal plug will do. I have had those in my boat, jet ski, car, and my truck......Over the years speaking with others I have found out that it's just a name and waste of money. I would go with a standard Bosch Platnum. less money same result. Others will tell you good/bad things on the filter but as far as the plugs I am willing to be that we all will same the same thing: "they arn't worth the money"
hope this helps..sorry for the bad/good news, just trying to save you a buck or two!



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Scott
91 EB

 

[Ira]

Brent,
My suggestion, go with the K&N filter, good plug wires and Bosch Platnum plugs. I put a K&N drop in filter in mine when I first got it but didn't know anything about drilling holes in the airbox or resetting the computer. I found a posting here about a month ago and when I drilled and reset it, it made a BIG difference in the way mine runs. It has more "seat of the pants" throttle response and sounds like a V-8 when I floor it. With the drop-in, you have to drill extra holes in the bottom half of the airbox to let extra air come in or you will not see a difference. I drilled a half dozen or so in mine about 1" in diameter.

K&N also makes a conical (cone shaped) filter which will replace the complete air box assembly and improve air flow. The only problem with these, from what I have heard, is that since you are pulling air from underneath the hood, the air is hotter from engine heat and the engine may not want to run as well in the summer. An engine works better with a cooler supply of air because of the density of the cold air.

Concerning the Split Fire plugs, forget them...I think they are a waste of money. If you figure it, a spark is going to follow the path of least resistance. Just because you have a split electrode, it will not matter. If you foul one side of the electrode, do you think it is going to fire across the other side instead of traveling thru the fouled part? It definitely will not. Again, it will follow the path of least resistance which will be the side of the electrode which is fouled, thus causing the spark to not be a spark...instead, it will be just like voltage running thru a wire and not sparking. It is easier for a spark to travel thru carbon or fuel (fouling) than it is to jump a .054" gap. Same story with an engine that is flooded...the plug is wet and the fuel caused it to short out and you don't have a spark. It is also easier to jump this gap when the plug is out of the cylinder than when it is in the cylinder and under compression. In other words, it takes more voltage for a spark to travel across a gap in a compressed area than to fire out in the open. Ever seen a bad plug wire arcing under the hood when it is dark? The arc will travel an inch or better before it will jump the .054" gap on the plug.

Hope this may help you. I am talking from my own first hand experience.

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Ira

91 XLT 4x4

 

[S.Matsushige]

Brent-I agree with Ira, I would go with a good set of plug wires and Bosch Platinum+4 plugs. I have a '91XLT with 140k on original motor and trans (5spd). I have the Bosch plugs along with Splitfire Duel Core wires. I also have a K&N dropin filter with hole cut out of the bottom half of the airbox. I also have a low restriction cat, a Ultraflo straight-through stainless muffler with custom 2.25 inch pipes from the cat back. It all works well together. I can't tell you how much of a HP gain you'll get, but I can definitly feel the difference. As for mpg gains, I gained approx. 2-3 mpg. Its hard though not to be tempted to make use of all the extra HP in which case, you'll have no mpg gains. Hope this helps.