The concern I have is incomplete combustion since there is no way you are reaching any real increases in effective compression with any of the NA mods to generate that amount of heat. Your plugs may foul faster and you may leave more deposits on your valves. One step may not be too bad, just doesn't seem at all necessary and could possibly effect performance negatively.

 

Blah blah, your worrying too much about what you've read online or been told. 1 step colder plugs on an NA engine will be fine 95% of the time, and not foul prematurely, or idle funny. I ran 1 step colder plugs NA on the Z (and in other vehicles), do my times look like they have been negatively affected?

 

blah blah?? I'm just wondering why someone would want to run colder plugs on a NA car without nitrous. Doesn't make any sense. Do you have comparison times with a normal heat range plug given the same mods? I personally think that for NA Zs a copper or iridium plug with a larger than stock gap should be used. That is what I am personally doing and have experienced better throttle response so far but need an engine management system to get my A/F under control. I will have an opportunity later on, with an EU, to tune the car and try some of these little tweaks to see just what effects there are on real world performance (1/4 mile). I may not have extensive personal experience with the Z on this topic but I do with other vehicles from the past and the same general theories should still hold true. We are fortunate that the Z has a strong ignition system already, which may prove in the end to eliminate some plug performance variations.

 

us Aussies did a group buy on the utec, and only our STi dealer can tune the Utec here in Melbourne

Our first Aus Z made 22rwkw with the utec, however there is a noticeable pause in acceleration on a trailing throttle at the point where the utec takes over the timing passing 3000rpm

I personally think its a tuning issue since the tuner has only tuned 1 Z so far, and TurboXS supply detailed instructions for tuning a WRX - not even TurboXS Aus have tuned a Z yet. But i am holding off installing my utec until this problem is sorted

Do you have the same issue?

Would it be possible to dl a map from one of you US guys, and use that as a base for modding on our own cars? Would that solve the utec switching problem?

 

Acceleration appears seamless when UTEC takes over for the ECU. I agree with your assessment...it must be a tuner issue.

Here is the base map that Turboxs offers. http://www.turboxs.com/downloads/350...ustMAFreva.txt

I'm not sure, but this might have already been included with your UTEC. I had mine tuned upon installation, so I have never relied on this or any other base map.

PM me your email address.

 

I understand your concern. Thanks for pointing out possible negative effects of having the step colder plugs. I recently had my UTEC retuned and gained 18whp...only changes were a JWT Pop charger (had an Injen CAI on originally), iridium one step colder plugs and test pipes.

As you can see, they didn't negatively effect performance. I don't give them complete credit for the gains, but clearly I didn't witness any losses.

 

you all are all correct...

rule of thumb is: For every 100hp increase, go one step colder in plugs. This helps keep combustion temps down when life in a cylinder gets more aggressive.

on the other hand... running one step colder plugs wont necessarily affect performance but its better if you have tuning done to ensure afrs are in check. you can run one step colder without it but it wont be "optimal" and i certainly dont think it will affect how the car performs on a daily basis.

 

thanks for your explanation eraz3r. My UTEC was tuned so AFR is in check. I also have a wideband on board in the tuner reg pro, so I can datalog and monitor myself as I go forward.