well installed a heat range colder plugs, denso iridiums from z1auto and i noticed that the denso plugs are a little different than the NGK iridiums (stock). The electrode has an indent for the denso's versus a petruding electrode (hard to explain). Basically if you look at the denso's there is a half a square going into the electrode and the NGK have half a square coming out from the electrode.

Anyways....before I changed the plugs today i did some datalogging and I noticed at WOT at around 7k rpm...ignition adv was 8 degrees. After installing the new plugs, ignition adv at the same rpm was at around 12-14 degrees....WOW. Why is this? Is this because of the range colder heat range. Also, the car ran ALOT smoother and I definitely could tell the difference in the power band. Also, by boost was pretty steady at 20.

FYI...i changed the plugs at 16K miles

Here are some pics of the plugs at 16K miles

 

Another...

 

NGK on left versus the Denso.....

 

interesting......

 

What are the advantages of running a colder plug?

 

would you recommend new plugs for an oz? will it make much of a diff?

 

good post... what octane petrol do you use?
There is another post by a gentleman that was getting consistent fouling UNTIL he move to 8 plugs..

what are they gapped at?

Thanks

 

IW24 0.25

 

Great post.

Did it help smooth out the idle? Is your car stock or modded? What is the PN# of the Densos?

Was the 20psi you mentioned stock psi levels or did you turn it up?

 

i have a 3" Turbo back exhaust with test pipe, buschur cone filter, Hallman MBC set at 20psi, and Dynoflashed at 310whp 294ft/lbs torque. I was told by z1 that the plugs were gapped from the factory, but I looked in the manual and the gap for the NGK plugs are 0.7-0.8mm. The plugs I installed are 0.63mm but I am not sure how to judge the gap since the Denso plugs have a dimple in the electrode.

My was dynoflashed for 93 oct.

 

got step colder plugs from www.z1auto.com

 

bump...does anyone have any suggestions about setting the gap on the denso iridium plugs??

 

I found the same results and posted about it a while back. With the Power FC I could monitor the actual stock knock sensor knock count, but essentially you come to the same conclusion.
I had the Denso's in now for 7000 miles (a lot of road course track miles), they are still working great.
I am now trying to get a set of IW27's, two heat ranges colder than stock (even better). The IW24's are not even close to fouling so...

Here is my old post:

https://www.evolutionm.net/forums/sh...ark+plug+denso

 

Oh, I set them to .030" or .75mm, they seem to work fine up to 22PSI. Just be careful not to apply pressure to the lower electrode. I can't really say that I noticed any benefit from extending the gap, so you might just want to leave them where they are.

 

I've been told that the OEM NGK Plugs are the best because they are a Iridium / Platinum hybrid, and going to any other plug then OEM, would be going down a step in performance, granted my cousin works at NGK, but his engineers said you really can't get better plug then the OEM. NGK doesn't even have a retail plug as good. Can't say that i've had many troubles with mine plug wise.