DazWaite said:
I binned my bkr's and much prefer the pfr6q's.....car idles much better imo
Daz
What.. cheeky sod disagreeing with me :lol: (j/k)
Actually ..I will agree to this extent
1.My 225 TT had pfr6q's in before remap and it went pretty well ( I thought)
2.After remap it still had them in for a few weeks and it was going yeh.. woohoo etc.
3.Changed to the NGK 7E gapped to .7 and It felt much better(subjective view) especially in the midrange hi boost area.
However.. and this is the agreement bit

it did and does feel marginally rougher at idle when the engine is cold only..for me.
Ill speculate a little "Oh God no"..and there go all the post readers :lol:
a)Lets say it is only cold idle, could be the colder plug doesnt like the vvt mixture compromise(BAM engine) but a tiny bit of roughness on idle doesnt bother me . In fact it gives the feeling/illusion if you like of a highly tuned race engine .
Admittedly , if I was only driving 5 miles into town, then back again on a continuous basis it probably wouldnt be good, then again a remap would have been fairly pointless too.
b)Compression ratio:
Thats fixed in terms of internal engine volumes:
Years ago..Heres where I lose a lot more post readers :lol: I skimmed the head of a normally aspirated engine.
I overdid it,
One of my methods to compensate was to try colder and colder plugs even different lengths.I eventually ended up on NGK 9 This improved things somewhat.Seemed to run and go ok even when cold without fouling.
Probably due to the big compression ratio , but it still had knock/pinking under accel.
This was long before knock sensors n stuff.
Adjustments didnt help, but it was liveable and as Robert Downey jr would say: "Never go full retard"
K back to TT. 225 BAM is 9.5 cr as standard( I think) and a qs,I dont know the engine code offhand, is 9.0.
Taking that as true .. and Im not certain of that , then the turbo thing comes into it.
In a petrol/gasoline engine the air to fuel ratio has to be fairly exact for normal ignition,or at least much more so than a diesel engine.
Right , so qs 239 and 222 BAM have the same turbo.If you factor in initial cr and the .5 of a difference,it would seem(to me)that the qs has more overhead for higher boost once the turbo starts spinning.
(c) But..stage 1/2 mappers in quoting for expected power /torque gains dont differentiate much, if at all between a mapped 225 and a mapped 240
Where does this mapped power and torque come in?..in general say mid range 3500 rpm in an overboost situation.. and there, lets say you dont want anything increasing temps, leading to a possible preignition situation and auto electronic ignition retard cos things are getting a lil warm.
Whats all the above BS mean?
To me
Im willing to sacrifice super steady idle/even off turbo accel when cold for best possible plug "coolness" under max boost conditions.
Why dont I try some BKR8E then and see what happens?
Ive been down that road (see above).. and I might have except they seem to be about double the price of 7's

and the only downside on the 7's is a minor idle variation for me when cold.
Platinum ngk 7's then ? ..maybe a cold idle would be better..or not, dunno
Plat ngk 6's I have, and I dont feel the need to put em back in again atm.
Iridium ngk 7's.... Ive never tried,could be theyre the best compromise.. I dont know,but theyre even pricer than platinums and I dont feel the need
If as is postulated(dont try that at home) ,copper plugs still give the best performance under max boost/max temp conditions and in my subjective opinion they do, thats good enough for me
