As title, thanks.

 

John,

What plugs, and how much boost ?

Mark.

 

Depends on car, mods, boost, state of ign leads, state of coil packs/igniters, what ign dwell the ecu is using and so on. As Mark asked, what plugs and how much boost. I spend hours tweaking mine to get the best from them (sad I know). Currently running HKS S35i's with a 0.73mm gap. If I was using NGK PFR7B's I'd probably need to reduce that a bit to maybe 0.69mm. Thats with Link, Motec I'd probably be maybe 0.1/0.2 up on those figs. depending on the dwell.

 

NGK PFR7B
MY00 UK
Remapped JECS
19-20 PSI on a new turbo

Sounds like 0.7mm then?

I honestly can't remember what we reduced it to before, but we closed it 0.1mm from standard and it stopped hesitating - that was on the standard (NGK PFR 6B?) plugs.

[Edited by john banks - 4/26/2002 8:26:34 PM]

 

John,

Using the Jecs, I'd start at .7. I don't know if the software you're looking at can change the ignition dwell time, but if you can, you could increase it, and open the gap a little.

Bob, I'm surprised that you can get the benifit from such small changes (like .69, as against .7, or .73, as aganst .75) when the quality of fuel can vary so much. Does it make THAT much difference ? I could understand if it was under controlled conditions.

Mark.

 

John

IIRC We reduced your gap to 0.7mm from just over 0.8mm

Andy

 

Mark, when I measure something I use two decimal places, remember my penchant for precision, the dimension of the gap is of no relevence since its what was measured after a few tweaks to get it right (on my car in any case). Bit like oxy readings to three decimal places. So whether you set your gaps to 0.69 or 0.73, just adjust till its best for the car and the plugs in question. Its my view that small adjustments make differences and its something I'm pretty confident about. You won't notice it on the rollers or on the engine dyno but I can "feel" it in the car's behaviour ... as I said I tend to mess with the stupid things ...

Suprised you haven't had a go at this yet.

John, its very well worth experimenting a bit to see how the car feels. I usually open up the gap until I get hesitation and then close back up until I get pre-ignition, that gives me the limits for the set up, I then just tweak between until the car feels the best, I also log oxy readings as well as differences in the combustion process do show up. Your Delta dash software should be able to discern the differences, I usually plug in a Motec to do this as its got the better datalogging capability although the V5 Link software is at least as good as the Delta dash these days.

BTW 0.8 is too much using NGK plugs, if you use needle plugs (HKS electrode is 0.4 dia) to get the current density up at the tip then you may get away with it but PFR plugs have too big an electrode diameter. It will work for "normal" boost but not uprated.

[Edited by Bob Rawle - 4/27/2002 12:17:08 AM]

 

Bob,
Why does the car det with a very small gap?
tks.

 

Bob,

Quote:
"You won't notice it on the rollers or on the engine dyno but I can "feel" it in the car's behaviour ... as I said I tend to mess with the stupid things ...

Suprised you haven't had a go at this yet"

1) I forgot how sensitve your backside is

2) I gave up relying on mine......

However, on the engine dyno we did play with the gap, and dwell time, and found noticable benifits.

Glad to see you're posting again.

Mark.

 

Thanks all. I'm don't think the dwell can be adjusted on JECS but I'll look into it. Thanks for reminding me Andy! I've gapped them to 0.7mm and will see how it goes. They arrived pregapped at over 0.8mm.

[Edited by john banks - 4/27/2002 10:38:16 AM]

 

Bob - If you`re still out there.
If you remember I had the Link fitted back in Jan.to my 99my - UK, the only mod since being a P.E. high flow cat centre section. What grade and gap would you recommend for normal everyday use?
JohnD

 

Johnd, we discussed this on the day if I remember ... grade 7 ie HKS S35i or NGK PFR7b and gap at 0.7mm

Bob