heard stories about number 4 cylinder running hotter due to the unequal length manifold. first of all how much hotter are we talking here and secondly.. i know your meant to run matched sets of spark plugs but could running a plug 1 step colder (same spec and brand) just on number 4 help at all?

just a random thought i had..

 

Its all about the pulse lengths etc and the amount of time it takes to flow the gas away from the cylinder.

The solution is run equal length manifolds. I don't understand why people don't use EL headers on their cars. The benefits of lower spool and higher torque figures etc and less risk of high egts!

Plus it sounds 5million times better!

 

Number 3 runs the hottest due to the turbo being next to it....

 

I can't wait to get the remap done on my EL manifolds, just to show the difference!

 

so its number 3 that runs the hottest and not number 4? how much of a temp difference are we talking between cylinders here anyway?

yea i know the proper fix is to ditch the UEL manifold but it was just a though i had as my WRX only has a catback and panel filter, no mapping as of yet and i think its coming due for a set of plugs as im noticing some surging in power between like 1500-3500rpm or so before the engines warmed and i never noticed anything showing spark plugs being done in the history i got with the car so thinking of throwing a set of plugs in her.

 

I thought it was all to do with 3rd cylinder getting less fuel than other cylinders that makes it run hotter because of the fuel lines not being parallel

 

back from the dead..

just an observation but plugs were changed on my hawk eye and i checked out the old plugs and all looked to have a nice even colour on them so cant be that much of a difference in cylinder temps id have thought? also no fouling on the old plugs and i have been running an atmospheric BOV for months prior.