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View Full Version : cant gap plugs bigger then 0.23" but why?


spools420a
10-13-2021, 11:01 AM
Car was gapped at 0.30" when i was runnng stock t25 on redtop,after installing generic 2871r/550cc/walbro pump/enthalpy ecu/z32 maf and the plugs are NGK BKR7E.the car would buck under boost.to fix this i had to tighten the gap,the most i can run is 0.23" but why?

since this happened right aftter the 2871 swap and was running fine on stock gap this says its not a issue with compression or engine but somthing with the turbo upgrade.

afr are at 11-0 - 11.3 at full boost 15 psi on 91 octane

i put a spark tester and tested the spark from each coil and it has no troubl jumping a large gap making a nice crisp snap and nice looking spark,that tested perfect.

I feel that such a tight gap will make me lose some of the power,is this normal to have to gap this tight?would leaning the mix a tad help you think to maybe 11.5ish? we only have 91 octane here so im trying to stay in the safe zone.if its normal to have this tight a gap then thats great but shouldnt i be able to run closer to 0.28"?

note: i posted this on another thread and appologize for having two topics on this but i cant delete the thread as i intended.

tuzzio
10-14-2021, 08:59 AM
Sounds like you have an SR.
I don't have much knowledge with the SR, but I know the stock coils suck. May be time for an upgrade if you're experiencing spark blow out.

Also, I assume you got a tune after your upgrades?

spools420a
10-28-2021, 10:21 AM
Yes its enthalpy tune.
Do you think the small gap will rob me of any power?If not I wont worry about it.

Is there a rule of thumb for how far the spark should jump on the sr when testing spark I couldnt find it in the FSM?

if its not robbing me of power I can live with it even though its a little ruff at idle on cold starts.

silviaks2nr
10-29-2021, 11:30 AM
That gap is fine. Hell go to .020

Kingtal0n
10-29-2021, 01:42 PM
You don't want a small gap because it will reduce efficiency & economy, and will cause tuning related (spark timing) offset depending how dense the cylinder charge is (low density + small gap = more timing required) which creates a dangerous or inefficient curve depending how the tuning is done


It sounds like a grounding issue or a age-related issue. The coil packs are 20+ years old then its probably age.
otherwise I would unwrap the wiring and re-wire the grounds/harness and increase ground wire size and attach to multiple sites around the engine not just the one on the back of the head.

Also make sure you are using the correct plug

tunermt
04-06-2022, 06:54 AM
Stronger coils will go a long ways! I ran Honda k series coils for year but recently changed to R35 ignition coils (https://www.brewedmotorsports.com/product/ignition/coil-packs/velocity-element-racing-products/r35-gtr-igntion-coil-vr38-cop/). Plugs gapped back out to .029” and running strong at 21psi. Looking forward to testing with more boost :)
With the r35 coils you can also remove/bypass the ignitor.
I used the extended length coils and plugs/pins to make my own harness.
https://brewedmotorsports.com/wp-content/uploads/2020/11/VE-R35-coil-long-boot-600x400.jpg

spools420a
11-19-2022, 10:43 AM
update:
for anyone with this issue,i went and swapped coils with audi r8/harness/and icm delete and no able to run 0.40" without blowout.no joke the car feels soo so much smoother especially at idle,the revs are much cleaner and smooth,it made a huge improvement all around,it feels like a before and after when getting a tuneup on a car that needed it.
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spools420a
11-19-2022, 10:46 AM
That gap is fine. Hell go to .020
it really wasnt fine at 020" the idle was choppy,the revs were terrible and power a little off.using r8 coils was a dramatic improvement and id go as far to say a must in my case.

anyone with this problem i cant recommend this upgrade enough

btw thanks for all the imput,thread can close if needed.

jr_ss
11-21-2022, 02:21 PM
it really wasnt fine at 020" the idle was choppy,the revs were terrible and power a little off.using r8 coils was a dramatic improvement and id go as far to say a must in my case.

anyone with this problem i cant recommend this upgrade enough

btw thanks for all the imput,thread can close if needed.

You were blowing the spark out at that gap. The factory coils/ignition system is weak and you cannot increase dwell much on the factory coils before they start to melt.

Upgraded ignition components were your only option. I had CBR coils with a factory ignitor at .025 and no issues. I have since upgraded to VQ coils.

tunermt
11-26-2022, 10:29 PM
My personal favorite coil atm is the R35 coils.
Super hot spark compared to any other COP option, cheap, easy to find, replacement boot/stalks, simple 3 wire coil with built in ignitor.
I?ve ran the ngk r35 coils (https://ffrides.com/product/ngk-2016-09-nissan-gt-r-cop-ignition-coil/), VE r35 coils, hitachi r35 coils and oem Nissan r35 coils all of which work like a charm and can be triggered directly off ecu no need for ignitor.