I will be breaking in a new motor with the R85 single turbo.

I bought new plugs , all 9's and new wires. Will the 9's be good for when i turn up the boost after the break-in or do i have to go with 10's or 10.5? I have a streetport motor, and will keep the boost around 14-15 untill i buy my meth AI. I think i will be close to 450.

 

I've been running 9s with my HK$ twin power at 15 psi (and aquamist) with no issues. Should be around 425-450 rwhp on my setup.

 

making over 400 rwhp w 9s just may not be a good idea.

if you inspect used rotor housings you often see cracks around the sparkplug boss. my guess is that the cracks are from too much heat. which is not helped by a plug that is less able to transfer heat.

plugs are easy to swap and are inexpensive compared to rotor housings.

if you are going to be standing on the gas my opinion is you need colder plugs. around town stuff.... 9s no problem.

i am not saying that 9s don't make as much power in the low 400 range, just that i don't like what i see on most used housings.

howard coleman

 

I would run colder plugs, maybe just in the trailing.

 

i use all 10s and im not even at 350whp

 

Which 10s specifically?

I've run the b10egv's and didnt like them for a few reasons......foul fairly quickly (2-5k miles) and they don't have a resistor.

The NGK/Greddy 10/10.5/11 race plugs foul even more quickly.

 

dont remember the part number but they are resistor type, i had to ground a socket to install them due to being shorter.

ill try and find the part number. they work great so far, mostly street driven...

 

here it is: BR10EIX

running them with hks twin power, they work fine engine cold or hot