I know lots of folks run colder plugs with pulleys, citing reduction of detonation risk as a key reason. But I've read varying opinions on whether the colder plugs help or hinder performance, and several cases of aftermarket plugs being blown out due to inadequate or self-reducting torque...:impatient

So I'm trying to determine if there are actual MINI owners out there who have had evidence of detonation issues with stock plugs and 15% pulleys, and who resolved this problem with colder plugs???

It's not that the plugs are a lot of money - but why do something if it doesn't really matter? And especially if it increases risk of an ejected plug?

Please - I know this kind of thread can go into the outhouse pit faster than a pit bull can perform a facelift - I'm not looking for opinions - but for folks with real detonation experience. And I'm not disparaging anyone's decision to purchase cold plugs - thanks for supporting the economy.

Thanks!

 

Oh and no detonation on 91 octane pisswater. But then again, I have used Chevron Supreme exclusively....

 

i don't know the engine dynamics behind it, but before i put my one colder plugs in my car was noticably twitchy on the trottle. the plugs clearly smoothed out the throttle and my car doesn't twitch now when i let off the trottle in 2nd gear while i'm slowing down for things like speed bumps.

 

next your going to ask why we should put a plasma booster in our cars. WE DO IT TO PLEASE THE VENDERS!!! now buy more stuff and quit your questions!

 

Well, I was taught that in many cases, especially those with 91 octane fuel rather than 93 and high temps in semi-arid to arid environments, that the anti-knock controls may prevent detonation with 15% pulley and OEM plugs. That's the problem. You don't want the anti-knock controls working to prevent something that is preventable by changing to cooler plugs. If that is what is happening, you are not gaining all the performance the mod can deliver.

 

And what anti-knock controls are you referring to?

The only anti-knock control I am aware of for the MINI (any MINI) is a knock sensor that feeds the DME. If there is no knocking detected by the knock sensor, then the DME does nothing. If knocking is detected, then the DME will pull timing and after there is no more timing to pull, it will dump fuel. So, if there is no knocking with a s/c reduction pulley and stock plugs, the DME will do nothing.

My personal experience (in 100+ degree temps this past summer) was that with a 17% s/c reduction pulley and stock plugs, there was no knocking. So, the DME was happy and I was even more happy - all on 91 octane pisswater.... But, it was Chevron Supreme 91 octane pisswater....

 

Interesting stuff. I'm NOT in arid/semi-arid conditions. And I'll be running 93 octane....

 

I've tried both the stock plugs and the denso ik-22's on my car. I've run the ik-22's for about 10k miles and the stocks for about 20k. I've also got a 15% pully and a cai.

To be honest... I don't notice enough of a difference between the stock plugs and the ik-22's to warrent worrying about blowing one of those plugs out of the head. The whole time i was running those denso's i would read the stories of people blowing them out of their motors and would cringe and go out to the garage with the torque wrench... I must have been checking them once a week. I never once found them loosened up, but regardless i put the stock plugs back in for piece of mind.

I always run 93 octane and drive the pants off my car whenever possible. I have driven my car in both wisconsin and tennessee with both sets of plugs and the only noticable difference between the two is that in wisconsin in cold weather my car does not like being cold with the ik-22's and will cold start stumble all the time.

otherwise no ce lights with either and no noticable difference.

 

If you run colder plugs, especially more than one or two steps colder, you run the risk of increased plug fouling, but with a 15% pulley, I think you're fine with either stock or one-step-colder plugs.

We left the stock plugs on my wife's car after installing the 15% pulley and haven't had any problems.

 

my mileage went down when i went back to stock plugs due to looking for a problem and then not putting the cold ones back in . detonation the cause? i can only assume so .

 

Please excuse the dumb question, but what type of plugs does the JCW use with its smaller pulley?

 

I believe the JCW uses a plug that is 1 step cooler.

herbie, that sounds about right. The ECU was probably pulling timing to keep detonation under control, thus lowering power an mileage.

 

a) OEM Plug is NGK BKR 6 EQUP
b) JCW Pkug is NGK BKR 7 EQUP, one grade colder

c) the colder plugs are not directly used to prevent pinging, they are used because if you inject more fuel to more air you will get a hotter burning. The plug needs to cool down between the ignitions and a colder plug will cool down faster and therefor there is no risk of burning the plug !

That's all....

Oh, and no, there is no need to use grade 8 or 9 for 17% or 19% pulleys. Grade 8/9 are used primarily for very high-reving engines with rpms > 10000 !

 

But, don't you see? When you use knock sensing to pull timing it costs performance.

 

I put in a 15% reduction pulley at about 25,000 miles. I put in BKR 7's (one step colder) at about 75,000 miles. I have not seen, heard or felt any difference. All miles were added with normal highway/city driving (plus a little track time) in temperate climates (Germany and Oregon/Washington).

I hope that helps,
dan

 

1) The ECU can pull timing before you ever hear it. In fact, you will never hear this type of ping because of the ECU. If you have carbon hot spots (and you will if you don't know) that will cause knock independant of timing, and that's usually what most of us who hear knock are listening to. Search on "Sea Foam" for more information here!

2) The only way to see what you car is doing is to log timing to see what it's doing. This is because you won't hear the timing pull.

3) I've used stock, NGK, and Denso plugs. one and two ranges cooler. I'm no longer a fan of the Densos, because the tip doesn't hold shape in our cars. I found about a 0.010 gap increase in the plug due to melting/rounding of the electrode. To be fair, it may stabilize here, but why screw with it? Two ranges colder didn't cause any fouling the way I drive.

4) One and two steps cooler did help timing pull somewhat, but didn't supress it completely. The only way I've been able to do that is to dump in some 100+ gas and hammer away with that!


Matt

 

I've had the Densos for a year or so~10000 miles. My pinging/detonation went away-likely carbon as I don't bang the snot out of it full time-during WOT. I will check plug condition and report on gap change! Thanks Dr. Obnxs!

Jeremy