Ngk bpr7es
Turbo Mini Forums

Sorry again gents and ladies, but this is a N/A engine question.
Replaced all clutch thanks again to sprocket, and mini now fully rebuilt. The issue is is now developed a miss fire on full throttle over 3000 rpm. Did all usual checks and in the end replaced plugs with a set of ngk bp6es I had sat around. Mini now runs great again.

The question is are the ngk bpr7es right as theory have only done 1000 mile ?
Mini produced 97bhp on rollers last time and is fitted with a 45 weber. J

What the mind can conceive the mini can achieve
MITP 2012 17.01 seconds 1/4 mile against "The Don"
MITP 2013 16.83 seconds 1/4 mile

ive recently have a similar problem with these plugs on a high comp n/a engine .does anyone have any ideas why the plugs are failing

Do have hi comp pistons fitted too

What the mind can conceive the mini can achieve
MITP 2012 17.01 seconds 1/4 mile against "The Don"
MITP 2013 16.83 seconds 1/4 mile

I went through a bad spot at one point are you sure its the right plug and the fueling is correct? I run 6es in the turbo motor and a lean idle i have not had a problem since

Yes i moved to the darkside

Instagram @jdm_brett

Fueling was right when set up on rollers with bpr7es fitted. Just been out in it and runs ok with ngk bp6es or should I change them to bpr6es :?:

What the mind can conceive the mini can achieve
MITP 2012 17.01 seconds 1/4 mile against "The Don"
MITP 2013 16.83 seconds 1/4 mile

If you have supressed ignition leads, you need a non resistor plug, if you have un surpressed leads, you need a resistor plug.

Surpressed leads and resistor plugs together is bad as the overall resistance of the HT circuit will be too high.

If you are running any sort of electronic ignition, you should be running un surpressed leads and resistor plugs.

#7's against #6's should not be that much different.

What sort of ignition system are you using?

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Well ok, answer me this. why use both resistive leads and resistive plugs when one or the other will do the same job?

honestly no idea sprocket, but rover, honda, toyota, mazda, ford, vauxhall, subaru, nissan and mitsubishi use resistive plugs and leads in all applications where leads are present. to the best of my knowledge i cannot think of a single example where non resistive items are used. on some engines the longer leads have 3x the resistance of the shorter leads, so one would assume the actual resistance is pretty irrelevant, only that they are resistive. given the resistance of the air gap, the resistance of the leads (2-6kohm on average) is neglegable, but there must be a reason they do it. I wouldnt mind knowing why right enough. perhaps EMI reasons? like how a solid wire will always produce reflections and ringing but a resistive one will not. so any part of the HT circuit that isnt resistive could cause oscilations and therefore interference? just speculating, but heres a good article on the subject of transmission lines:

http://www.vagrearg.org/?p=transline

while thid deals with signal level electronics, a wire is a wire and a change of potential is a change of potential. again just speculating, if you find any direct info w.r.t ignition systems i wouldnt mind reading it :)

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Ooooppppppssss looks like I've opened a can of worms here. Running standard rover electronic dizzy and that's it (no radio or anything else). Has minisport leads which are now being changed as well as plugs.
So looking for non resistive leads and ngk bpr7es plugs.

What the mind can conceive the mini can achieve
MITP 2012 17.01 seconds 1/4 mile against "The Don"
MITP 2013 16.83 seconds 1/4 mile

on topic but i have had the odd ngk plug die, particularly the ones with the skinny electrode. Denso iridiums seem the worse for it in my limited experience, never found a reason/pattern to the failures.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Going to order new plugs and leads in the morning so the next question to open a tin of worms is "what leads are any good and where from" going to stay with bpr7es plugs but ditch the minisport leads as found one to be poorly fitted on the dizzy and had to bend the internals to get it to grip on the dizzy.

What the mind can conceive the mini can achieve
MITP 2012 17.01 seconds 1/4 mile against "The Don"
MITP 2013 16.83 seconds 1/4 mile

Ive been through a load of NGK's recently, one would die about every 500 miles, ive got some denso's in there at the moment, and its been fine for over 1000 miles.

also Ive found that resistive leads and non resistive plugs send my ecu nuts,

unsure if leads are resistive or not as they are from sport :( goint to go for non resistive leads and ngk R plugs hopefully this will finally sort mini out or its an engine change or should i really say forced induction :)
just need a couple of ppi claims to come it

What the mind can conceive the mini can achieve
MITP 2012 17.01 seconds 1/4 mile against "The Don"
MITP 2013 16.83 seconds 1/4 mile

pretty much all leads these days are resistive, you'll be hard pressed to find some that arnt,

Thick I'll just order a new set of ngk plugs from mini spares then and see what happens. All leads fit again now so hopefully that dam misfire has disappeared and all plugs will be a nice light brown again

What the mind can conceive the mini can achieve
MITP 2012 17.01 seconds 1/4 mile against "The Don"
MITP 2013 16.83 seconds 1/4 mile

measure the leads with a multimeter, they should all be within a k-ohm or two of each other. if you have one thats like 30k and the other 3 are 4k you know its duff.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Edited by Sprocket on 27th May, 2012.

well when there is no discharge across the spark gap the HT resistance is very high, but soon as discharge occurs the gasses around the gap ionise and the reisistance of the gap degreases massively (think of a tig welder requiring 1000+v to initiate a spark yet can sustain the ark with 40 odd volts) if you have a non resistive HT system the current ramps up heavily once the arc is struck. if you have a resistive plug OR lead, this current ramp is reduced significantly saving wear on the HT components. and that would back up your initial post and i would imagine is fine for points and a condensor But there must be a reason all the OE's on electronic ignition use both resistive leads and plugs :) im just not smart enough to know why lol so cant give a reasoned explination, only a guess :(

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

I would say the 7s are too cold for an NA application, stick with 6s.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph