Which Spark Plugs?

[BlackBox]

hey,

My R34 GTT sounds like the spark is starting to brake down when boosting under heavy load, getting progressively worse over the weekend. (Started off only going up hills at high rpm, now doing it when overtaking etc..)

It started after i washed the engine bay so i thought it may just have water somewhere, it went away after ~1 hour but came back a few hours later and has carried on all weekend.

I was going to do plugs anyway and perhaps send the coils away to get bench tested?

Im not 100% on what plugs to use tho, after searching i am leaning towards BCPR6ES - likely gaped to .8mm (Running 21psi) or would a 7 heat range be a better choice over 6?

[Josh080691]

Bcpr6es copper plugs /end thread

[Kane_R32]

At that boost I'd be running 7's

[Blackkers]

6 or 7's probably won't really matter. If E85, run 6's. If Petrol, run 7's.

What coils and how old are they?

[wolverine]

Bcpr6es copper plugs /end thread

Re-open thread 7's

[jay-rod]

i run BCPR6ES gapped to .6 on e85 @ 17psi

Edited July 13, 2014 by jay-rod

[Piggaz]

0.6 is tight. Do you really need to go that small?

[Josh080691]

Running 22psi on 6's at 337kw at 0.8 but dither or will work not much difference

[iruvyouskyrine]

I can pretty much guarantee that's it's water sitting in saturating the spark plugs underneath the valley cover. Have seen multiple other RB's with the same symptoms (misfire that gets progressively worse) and it's because the spark plugs are partially submerged.

Also I was told by Trent at Chequered tuning BCPR6ES for 15psi or less, and BCPR7ES for 16+psi

I ran the 7's in my car at .8mm with 21psi no issues.

[Dose Pipe Sutututu]

I run 6 with 0.8mm gap @ 1.5bar no misfires with just run of the mill Splitfire coil packs @ 2.5ms dwell time on E85

[r33_racer]

Dont be afraid about closing up plug gaps if you need to do it, especially with alcohol fuels like methanol/E85. We run 0.020"(0.5mm) on the race car. Using a CDI with crane Fireball CDI coil packs. bcp10es plugs, 9:1, methanol, 23psi 495rwkw. No ignition problems, even if it goes super rich which it does on cold start quite often going richer then 9:1 afr. We found going smaller on plug gaps didnt change power made, only stopped any missfires which would pop up if we tried going any larger then 0.025".

It is possible the plugs may have gotten damaged from the water, maybe the porcelain body has developed a hairline crack somewhere, possible thermal shocking. Plugs are quite delicate, it doesn't take much to damage them. Its also surprising how easy it is to crack one when removing one while hot.

What plugs do you have in there currently? Have you checked? Good chance the ones you are running are fine if they have been good up until this point.

[scotty nm35]

I run NGK Iridium 7's without an issue at 32psi on ethanol, I don't understand the need you guys have to change your plugs every 5000...

[Dose Pipe Sutututu]

I run NGK Iridium 7's without an issue at 32psi on ethanol, I don't understand the need you guys have to change your plugs every 5000...

Microtech days, plugs would be black on 98 after a few days lol

Fuel in or no fuel in. What's resolution and control? Lol

[scotty nm35]

Cheaper to buy a sand blaster Johnny.

[Dose Pipe Sutututu]

Cheaper to buy a sand blaster Johnny.

oh ferk off LOL

I'm as close to dino tech these days with those injectors

[Badgaz]

also i would like to input that cleaning your coils is important part of preventative maintainence. as shown in this video....https://www.youtube.com/watch?v=Qirx_G4x5i0

i've fixed three sets of deemed stuffed coils and this has worked everytime.....its not always the spark plugs or gap.

i've also gone back to a copper plug from iridium and also gone from 0.6mm gap back to 0.8mm

[R_34]

I was running bcpr6es gapped to 0.8mm with my 20 on the stock tune fmic highflow turbo 3" exhaust at 0.9b.

Went to bcpr7es gapped to 0.8mm at 1.4b once tuned.

No misfires with the oem coilpack so far, increasing the dwell during the tune didn't brought much (i didn't felt anything), so my coilpacks seems healthy.

[iruvyouskyrine]

Dont be afraid about closing up plug gaps if you need to do it, especially with alcohol fuels like methanol/E85. We run 0.020"(0.5mm) on the race car. Using a CDI with crane Fireball CDI coil packs. bcp10es plugs, 9:1, methanol, 23psi 495rwkw. No ignition problems, even if it goes super rich which it does on cold start quite often going richer then 9:1 afr. We found going smaller on plug gaps didnt change power made, only stopped any missfires which would pop up if we tried going any larger then 0.025".

It is possible the plugs may have gotten damaged from the water, maybe the porcelain body has developed a hairline crack somewhere, possible thermal shocking. Plugs are quite delicate, it doesn't take much to damage them. Its also surprising how easy it is to crack one when removing one while hot.

What plugs do you have in there currently? Have you checked? Good chance the ones you are running are fine if they have been good up until this point.

Thanks for the info, good to have some actual solid info that is tried and tested.

[scotty nm35]

Thanks for the info, good to have some actual solid info that is tried and tested.

Even if it's from a highly modified ignition system running large volumes of Methanol? Not really suited for comparison to stock 25's I would have thought.

The results I have seen prove the opposite about plug gap, I guess every setup is different, and people generally stick with what works for them.

[34GeeTeeTee]

Even if it's from a highly modified ignition system running large volumes of Methanol? Not really suited for comparison to stock 25's I would have thought.

The results I have seen prove the opposite about plug gap, I guess every setup is different, and people generally stick with what works for them.

I run 0.5mmm gap in my nugget...