Jchiodi

I had this info and now can't find it.

Thought someone had said to use one grade cooler plug?

Jchiodi

PorKen

Best - NGK 2912 BP8ES, gap to 1.0mm/0.040" (colder, non-resistor)

Good - Bosch 7992 WR5DC, gap to 0.8mm/0.032" (colder, stock WR7DC)

Jchiodi

Thanks,coudnt find your other email to me.....

rexpontius

I have the s300s chips as well, what kind of improvement can i expect when changing the plugs to ngk2912 bp8es?

Brett928S2

Hi

Wow..Ngk BP8ES are 2 grades colder....I would have expected only 1 grade colder BP7ES considering the fouling problems at tickover with 8`s ?

All the best Brett

jbrob007

I'm not familiar with the terminology - I'm NOT a mechanic by any stretch... Please explain fouling problems at "tickover with 8's"...??? I have the same plugs with this gap and my Porkenized 86.5 is running like a raped-ape

They've been in the car for all of 25 miles which isnt enough mileage to determine squat, but it seems to idle smooth, great pickup/throttle response, etc...

Thanks, Joel

PorKen

32Vs don't have problems with fouling. S3s don't anyway.

I have no problems starting with either my '86.5 auto or manual in freezing temperatures. It may be a bit grumbly for a few seconds until the plugs warm up at very cold temps, but that's about it.

The larger plug gap possible with the non-resistor plugs is more efficient. Idle speed increases after installing them. Part throttle is improved. On the freeway, you barely have to press the throttle to roll along.

At 40F/4C (ie. UNCorrected), my 5-speed dynos 325 rwhp, so the spark is not 'blowing out'.

jbrob007

Ken, I dont want to steal John's thread but he and Randy will be asking this question too... Where should my idle be set with the NGK plugs?? BTW, my car is running slicker-than-snot!!! Thats a technical term

Thanks, Joel

PorKen

With the NGKs and TQrings, the idle screw can be almost closed to maintain the stock 680 rpm idle speed (when warmed up). However, this doesn't leave enough bypass air for the idle control valve to recover the idle when you suddenly close the throttle.

With the Bosch or NGK plugs, set the idle speed as low as possible where the idle recovers well when warm. IE. the idle doesn't drop too low, then bounce back up.

5-speed idle rpm will be higher than autos (because autos have a huge flywheel = torque converter). 750-800 when warm is what my 5-speed likes, but don't get stuck on the number. It will be different for different cars.

jbrob007

I've got the NGK and TQ rings. In general, were talking somewhere between the 3rd mark & 1000 rpm - correct? I'm assuming the 3rd mark is 750 rpm. Mine is set there and it recovers with a "bump" up in RPMs before settling down to 750 (when warm). Do I need to increase idle a bit more so it recovers without the bump in RPMs ??

Sorry for all the questions - just trying to get her in top operating condition.

Thanks again,

Joel

GlennD

Jchiodi,

Since you are asking on recommended spark plugs, do I take it then that your car is now running with Ken's chips?

If so, what did you find was the issue? Inquiring minds want to know

Thanks
Glenn

PorKen

It will normally jump up somewhat when recovering. What you don't want is it dropping too low in rpms initially, with stuttering or stalling.

When the engine is fully warmed up, try adjusting CCW, one whole turn at a time, until you are happy with the idle recovery, then try 1/2 turn CW, until you find the lowest rpm it is still good.

Brett928S2

Hi

To answer several questions at once...

Ok..NGK Plugs....I have run them on on my Nitrous system... starting with 6 then 7 then 8 and also for my top speed runs some motorcycle 9`s...

The reason you move colder ONE grade at a time i.e from BP6ES TO BP7ES is that the engine on any tuned car (by which I mean, chipped or supercharged or Turbocharged or Nitrous) will run HOTTER so you need a colder grade plug so you are still in the middle of the band where the plug will fire properly...

On an Ngk plug you move roughly 70 to 100 degrees C for each heat range. so as an example if you move from BP6ES TO BP8ES you move the firing point and the point that the plug can shift heat away from the cylinder by 140 to 200 degrees...UPWWARDS (temp wise)

That will always cause problems when the engine is cold as the engine is nowhere near the temperature range of the plugs.... usual symptoms are plug fouling, bad starting (if at all) and fuel flooding...and uneven running on tickover untill the engine is FULLY warm/hot...

To give an extreme example of this .... When I want to run my NGK 9s , I have to warm up the engine FIRST on 7s.... because the engine wont start on 9s unless I am extremely lucky...

As far as how cold you NEED to go, it depends on extra HP produced and the added heat from that extra HP...

For Nitrous , I needed to go to 7s when I went over 500hp...8s over 600 and 9s over 1000...

Plug gaps were REDUCED to INCREASE the strength of the spark...25 thou on 6s and 7s...20 thou on 8s and 9s

You do NOT increase the gap unless for some weird reason you want a weak spark (which wont fire properly)

I had to do a LOT of research on this and spent hours talking to NGK Tech support in the UK.... and extremely helpful they were as well

Hope this helps

All the best Brett

jbrob007

Glenn,

I'm not sure John has gotten to it yet... WORK keeps getting in the way

Ken,

Thanks for the guidance... and the parts

Joel

PorKen

With non-resistor plugs, you CAN increase the plug gap, because there is more voltage available. (Assuming dual coils.)


I tested both the Bosch resistor and NGK nons until I had the maximum gap which still allowed for some erosion, before the engine fades at high rpm.