AMBIVALENCE Posted March 31, 2006 Share Posted March 31, 2006 Hi! I own a 2006 2.5i, and i was thinking of swaping into some better performance spark plug. but i have a few question unanswered, hopefully someone can help me. 1. What spark plug should i change into for a 2.5i model? (Brand and model?) And how much HP increase would i get? 2. Does changing to new spark plug increase fuel consumption? (I dont see anyone that brought up this topic in the search. but if someone can gimme some old post that already mention similar info that would be helpful as well. THX!) Link to comment Share on other sites More sharing options...
trohler Posted April 1, 2006 Share Posted April 1, 2006 I believe the factory plugs are either platinum or iridum (sp?) so there is probably no need or benefit to changing them out before they are bad or reccomended replacement interval. Tolly 07 Impreza 2.5i Special Edition 07 Kawasaki Ninja 250 Link to comment Share on other sites More sharing options...
robsontuning Posted April 1, 2006 Share Posted April 1, 2006 I think only the STi has the Iridium plugs and the rest are platnum. Not 100% sure, but I know the WRX is platnum and the STI is Iridium Link to comment Share on other sites More sharing options...
GTsleeper Posted April 1, 2006 Share Posted April 1, 2006 i believe we (LGT) have Iridium also. Link to comment Share on other sites More sharing options...
subatwo Posted April 2, 2006 Share Posted April 2, 2006 according to the subaru website the plugs for the 2.5i are platinum. GT's get the Iridium plug Link to comment Share on other sites More sharing options...
pillboy Posted April 2, 2006 Share Posted April 2, 2006 To answer your questions: 1) Use what the manufacturer recommends...are you smarter than them? I know I'm not. All the spark is doing is igniting the fuel/air mixture...how are you going to get more HP from a different spark? 2) I am sure someone will disagee with me, but I don't see how this is possible. Same amount of fuel is making its way into the combustion chamber regardless of what spark plug you have screwed into the hole. I could maybe see a decrease in fuel efficiency if you were to put in a radically incorrect spark plug that caused the engine to run poorly. If you are looking for a relatively inexpensive way to gain a few HP by replacing the plugs, I think you are searching in vain. It is still ugly. Link to comment Share on other sites More sharing options...
mccorry Posted April 2, 2006 Share Posted April 2, 2006 ^^^^^ Just to verify... the i's use Platinum... the GT's use Iridium. Spark plugs will not make more (significant) HP Replacing severly worn spark plugs can increase milage. Link to comment Share on other sites More sharing options...
MDTURBO Posted April 2, 2006 Share Posted April 2, 2006 Stock Heat Range http://marylandturbosolutions.com/catalog/product_info.php?cPath=119_22_23_35&products_id=51 One Step Colder Heat Range http://marylandturbosolutions.com/catalog/product_info.php?cPath=119_22_23_35&products_id=52 2012 Forester XT. Stage 2+ Retired from Racing. I used to build FMIC and more. Link to comment Share on other sites More sharing options...
AMBIVALENCE Posted April 2, 2006 Author Share Posted April 2, 2006 Thx guys for answering my question! Damn i always thought spark plug could increase HPs... Well. i guess i really dun need that much HP anyways, i am more towards gas-saving solutions. maybe i'll post another post by then =) Link to comment Share on other sites More sharing options...
robinlsb Posted April 2, 2006 Share Posted April 2, 2006 +1 for pillboy, Also proper gap is important. A colder plug will help per-ignition of a very hot motor(usually in racing). The disadvantage of colder plugs is that they can foul (missfire) at lower temps thus reducing performance. "Belief does not make truth. Evidence makes truth. And belief does not make evidence." Link to comment Share on other sites More sharing options...
GTsleeper Posted April 2, 2006 Share Posted April 2, 2006 ^^^ thats why u dont step down till ur after stage 2 Link to comment Share on other sites More sharing options...
AMBIVALENCE Posted April 2, 2006 Author Share Posted April 2, 2006 yes i gotta thx pillboy's info. that made me understand that spark plug does not equal to performance, i was wrong for several years. Or... was it just for legacy? =) Link to comment Share on other sites More sharing options...
robinlsb Posted April 2, 2006 Share Posted April 2, 2006 all engines "Belief does not make truth. Evidence makes truth. And belief does not make evidence." Link to comment Share on other sites More sharing options...
johnAWD Posted April 2, 2006 Share Posted April 2, 2006 Spark plugs can't increase power, but they can fend of detonation if you are on the edge. That would have the net effect of 'giving back' power that you've lost due to running too hot. Link to comment Share on other sites More sharing options...
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