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this may apply to all atvs so i didnt want to put it in one particular section.. (700, 660, 350, etc). I saw on powerblock tv today where they dynoed a 383 stroker i believe with 2 different sets of plugs. They gained 5.5 hp just by changing the plugs. Since this is true can the myth be broken about the eix (iridium plug) not making anymore hp and or making a less "brake specific fuel consumption"...(the better plugs used slightly less fuel.)
 

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I am smarter than you....
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it has more to do with the engine tha particular plugs are in. some engine just prefer different plugs so the best way is to buy 3 or 4 different kinds and run em to see if you can tell a difference
 

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ya i plan on pickin up a good plug for mine once i can get a ride whats the best plug to get and where to get it???
 

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But how do you compare it to a single cylinder motor? On a simple level breakdown you'd need to find the percentage increase in hp (probably around 2% or less depending on how much hp the stroker made) and then divide it by 8 since you're only doing it once...

That works out to 1/8th of a hp on a 75 hp build.

Now I realize it's not quite that simple and it might work out to be a bit higher, but the difference is unlikely to be greater than the fudge factor in the dyno's readings anyway so it'd be hard to prove for these engines.
 

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hey md if it were as simple as a percentage the percentage would be the same. so if you had a 500 horse v8 and 100 horse single and the plug gave a 2 percent improvement it would be 2 hp for the single and 10 for the v8. anyways it depends on compression, ignition power, fuel used and the heat of the engine.
 

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Discussion Starter #7
yea im sure there wouldnt be good gains for the rappy as there would be from the stroker SBC but it seemed like a pretty cool idea to throw out there.
also they tested the two sets of plugs at the same water/oil temps. All factors was the same in both tests.
 

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hey md if it were as simple as a percentage the percentage would be the same. so if you had a 500 horse v8 and 100 horse single and the plug gave a 2 percent improvement it would be 2 hp for the single and 10 for the v8. anyways it depends on compression, ignition power, fuel used and the heat of the engine.
Help me on this phucker;

The benefit of the plug on the 8 cylinder engine would be the difference that one plug makes times 8. One plug by itself in one cylinder wouldn't yield the same 5.5hp. The total gain is the result of 8 plugs working together. I'm not saying you're wrong, just that I could use some help understanding how 1 plug in 1 cylinder should produce the same percentage gain as 8 plugs in 8 cylinders put together. Shouldn't each cylinder on the v8 gain about 0.7 of a hp, which add up to around 5.5hp for the whole motor? And the percentage the v8 gains per cylinder would only then be comparable to what a single cylinder, single plug head would gain?

Now again I realize it's not so simple as a direct 1:1 percentage comparison, there are other factors to include. And I know it depends on other factors as well, but assuming for the purposes of simplicity that the single cylinder is just one of the v8 cylinders on it's own and all other factors being equal, why shouldn't it's gain be the same as 1/8th the total gain on the v8?
 

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KUNG FU SAND PANDA
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We have only been into quads for the last few years, but when I was drag racing we used to "Index" our spark plugs. Will that work on our Raptors? Do you think it help any?

-Johnny
 

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wouldn't you need multi cylinders?
Are you referring to the indexing?

Indexing a plug just means installing it so that the open part of the plug gap faces the center of the cylinder. The number of cylinders in the engine has no bearing as it's done on a "per combustion chamber" level.

A cylinder with less open space in the combustion chamber at the point of ignition would be more likely to make a difference in burn efficiency.
 
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