I'm in the middle of a zetec turbo build with the head and block currently at the engineers, ive heard that cossie plugs are generally used on this conversion requiring the head to be retapped,

can anyone tell me what the benefits are and what work is involved?

many thanks

 

If you wish to run any more boost than approx 15psi, then the best zetec based plugs out there will fall apart on you (risking serious engine damage). Obviously cossie plugs are available to suit any state of tune, so this is why the work needs to be done.

Its a very simple engineering procedure really, the head just needs to be milled vertically, shortening the threaded hole in the head so that when the cossie plug is fitted, it sits in the correct place. The spark plug threads are the same, so there is no tapping / re-tapping to be done.

Hope this helps

 

cheers sketch

thats what i thought on a heat reasoning, gonna be running 14-20psi

ill get em onto it then

 

Focus RS plugs?

Also some decent plugs availible in the states I believe.

 

Ł30 or so to modify the head whilst its off and at the engineers.... versus getting some plugs imported from the states

Ello Phil, alright?

As for Focus RS plugs - not sure about that as a solution. I think Paul J used them and had a tip fall off, but im not 100% sure on that. Im fairly certain A plug tip melted on his, and did some damage to the head / valves or something, so worth doing the cossie plug mod IMO!

 

for Ł30 on top of the bill i have already it aint worth the worry of melted plugs

 

The problem i had was caused by normal Zetec ones which WILL fail at a bar+. Proved over and over until serious damage was done

I have found the RS one's so far to be spot-on @20psi tho. (my problem with the first set was specific to my car Sketch .)

TBH i would for the minimal cost have it machined, then slot in so NGK 9s from Stu.

 

Good man! Very sensible

 

uid go with that an all.

any ideas on cost for these plugs? n on average how long do they last ya?

i aint a believer in this 20k+ lark

 

If you want to use NGK 9s, they USED to cost Ł70 delivered from most places, although im not sure on the current price as a new version has just been released or something. Something to bear in mind though is that you need a different version of the 9s than what the cossies use (assuming you are using a coil pack on your engine). The cossies use R7234-9 and you need R7235-9. Using the wrong version will result in a small misfire issue as Stu @ MD can confirm ( i hope )

They should last quite a long time - they are the most highly reccomended and used plug (i would imagine) for the bigger powered cossies (ie 330+bhp)!!

 

cheers sketch

yeah running a coil pack, i shall have a word with stu when the time comes then