Spark plug gap questions

[TSITurbo95]

So after some searching, and browsing of threads, I see that everyone's spark plug gaps are different. I know for mostly stock, .28 is good, but why does everyone's gap vary? Is it due to spark blow out? Sputter, high boost, etc? ATM I am running .28 on NGK BR7ES, mods in my profile, and am at 28ish psi. Would I benefit from lowering the gap on my plugs? Thanks.

 

[SOADweskey]

I had mine gapped to .028" but as I started to run more boost I was getting spark blowout. I'm currently running BPR7ES plugs gapped to .025" and running 34 psi with no blow out issues.

You will only benefit from lowering it i you are breaking up at the upper RPMs now.

 

[JusMX141]

Seems to vary depending on the strength of your coil, fuel type, etc.

BPR7ES' @ .028" in a buddy's 2G back in the day would be fine at 25psi on a Frank L5 20G in warm air, but once the ambient air temp would drop below 60*f the car would miss at the onset of boost unless we tightened the gap to .025" or so.

 

[Boosted98gsx]

Just keep in mind, COP's do NOT boost your spark, and they will actually cause more breakup than they are supposed to fix. You cannot adjust the dwell time on them which is important because they don't match our ignition systems, and are not designed to be used in forced induction systems.

Get a Dynatek ARC-2 if you wish to retain your OEM coils / wires and have a spark delivery system rated to 700+hp.

 

[turboglenn]

I think that's a huge gap, I run BR8ES on alcohol (e85) gapped at .020 with an MSD box installed, and now without the MSD-DIS-2 i run them at .017 and am good in all weather here in nebraska (been down to 50* and up to 100*F) at 30psi (32 for a couple pulls/days) with no problems at all, just gap em right, tune to a crisp AFR (too rich and you'll put plugs out too)

I run 12.5:1 AFR gasoline reading on E85 and my engine loves it, if i go as rich as getting into the 11's on e85 it will break up. but pump gas won't take you far enough to worry about this issue safely.. if you're on E85 though the stock ignition system can take you to around 500hp or so from my experiences on my car

And the info about the COP, totally true, more for looks than performance unless you get a stand alone ECU that can divide them up into sequential spark instead of waste-spark and allow them to charge for the maximum alloted time you have between events(which is how COP is intended to be ran to be utilized). Otherwise go with the Dyna box, we used them on motorcycles for years and i wish i would have got the ARC-2 instead of the MSD DIS-2 (MSD is twice as much money and the Dyna is twice as good - you do that math )

 

[TSITurbo95]

Well I don't have any issues that I know of with spark blowout, or break up. Car pulls hard and strong, so I guess that gap is fine? Is it possible that if I lower the gap a little bit that it could take away some knock?

 

[turboglenn]

i don't know what effect it would have on knock, i've gone to a colder plug to cure some but if you're on 8's already that's as cold as most need to go. Look to noisy things in the engine or an overly active DSM knock sensor to be the culprit.

personally unless you're running DSMlink (as well as changing to a 1g sensor that's NEW) i would ignore the knock sensor if other than trying to eliminate noises elsewhere in the engine/trans, once you're past the basic mods and even once you're pushing a 16g the OEM sensor is a big PITA just crying wolf all the time and there's nothing going on. IN DSMlink you can filter/adjust to make it less sensitive, but i would go crazy dealing with the mitsu knock sensor honestly, it's just crazy about scaring you just for fun.

I run a GM sensor from a saturn engine with a stand alone box reading it and filtering what's really knoick and what isn't and i tell you from that alone i learned how horrible the DSM sensor is, I can make it trigger enough knock that it will pull all the timing back to 7-9* wide open and even part throttle jsut by triggering the AC compressor on and off, suspension noise gets picked up through it as well as bad lifters, piston slap, trans noises and much more. THose who make good power without hearing anything out of it know something i don't i tell ya that much. But i'd rather tune safely without it than to try and tune enough to make it happy with the same settings that i can use and just be SURE that nothing is going wrong. I ran 20-21psi on a 57trim at 16* timing at the lowest point up to 18-20* timing at redline for 9 YEARS on pump 92 with no damage done from knock, the stock ECU would have never let me have that much timing, much less the AFR's i was running but i knew they were safe, hell before i dialed it up to 20* i just ran a flat 16* across the board in all levels of boost for at least 5-6 years and NEVER had a head gasket go, or even show signs of knock on a plug.. plain and simple that thing is there to ensure mitsu doesn't see a warranty claim from you making too much power and running 75 octane gas that you got from a can that sat out behind the shed for 10 years.. (i can't stress enough how bad it fights you and how bad it's ruined a lot of people's knowledge of tuning with its trigger happy alerts.

simply put it scares 90% of DSM owners who tune their own setups from ever seeing the real potential of what the car could do because it has them affraid they are gonna blow the car up on very conservative settings. LIke i siad i'd rather not have on than to listen to the stock DSM unit!!!!!!!

 

[TSITurbo95]

I am running BR7ES, and the most timing I am able to run is 7-8 up top on my 7 bolt. And am using link to disable knock under a certain load/rpm.

 

[turboglenn]

OUCH!! Does that stop all knock sensor activity or at least drastically change it during a pull? Looks like a decent enough setup that you should be fine with plenty more timing. The one thing i've often wondered is if the SMIM resonates any noises from the head, amplifying them through the block and else where?? (justa theory)

But I do want to ask how much boost are you running and what type of fuel?

There's stuff with DSMlink that others could help much more with (setup and calibration of MAF meter and such that i'm not familiar with) that may be attributing to it as well. But give me some info and i'll see if annything pops to mind.

 

[TSITurbo95]

I only stopped the knock sensor from picking up knock under like 50% throttle and above 3000rpm's. But the timing is low to stop all knock activity, and I still have blips here and there (phantom knock I would assume since it's not always there and constant). I am also pushing 29psi on 93oct. I am fairly sure my tune is good, maf comp, afress and wideband, and boostest vs actual boost.

The only reason I can think of with the low timing is it's just what my car likes, unless the knock phantom knock caused by the open dump wastegate, or something else in that nature.

I will be running meth here shortly to hopefully get some of my timing back.

 

[turboglenn]

yea, 29psi on pump gas, that's about all the timing you're gonna get on that setup, i'd say you're probably ok and jjust dealing with the normal noise the KS picks up

The alky setup should give you a few more degrees to play with, i would think you would be able to get up to about 13-15* peak on that. Personally like i said i didn't have a KS to worry about so it was nice for many years i would just set a decent buyt safe timing curve (or the locked 16* from the onset of spool to peak RPM) and go with it, never did see real signs of knock like puffing out the exhaust on the dyno or speckling on the plugs at all. I still think most of what the DSM KS picks up is other noises associated with making horse power above the stock ECU's limits.

I have no idea what the KS part of the log looks like for guys making 700+ hp on DSM link, or what their timing curve looks like

I've not played wtih V3 at all (but should) and i was wondering if it had the ability to let you ignore the KS completely and dial in the timing you want instead of what you "would like to have" and dealing with "what it will let you have"

 

[TSITurbo95]

Yeah, I can turn it off, but I personally do not feel comfortable doing that. But I kind of figured that from my boost it's limiting my timing. So I will just hook up the meth and hopefully gain some more timing back. I ignore the knock I have now, as I believe it is phantom knock as stated, its not constant.

Hopefully, I can tweak it some more to what the ecu "likes" and will "let" me have .

 

[my dreamt dsm]

To answer op's question every car will run different. I have mines gapped at .28 wither 6es or 7es. Many recommend to run 6es but 7es gives me less knock.
At least that's what a weeks of search came up with for me.

 

[VisionPaintball]

I am running BR7ES, and the most timing I am able to run is 7-8 up top on my 7 bolt. And am using link to disable knock under a certain load/rpm.

Good to hear. I just started tuning with link and I had to keep lowering my timing to eliminate knock. I wasn't sure if it was ok to run such low timing but the car feels good.

 

[Doubleot]

I'm running bpr7es with a .028 gap. Haven't had any issues might gap them a tad colder when I go e85 and 25psi+

Sent From My Sidekick 4g, Because I can.

 

[bastarddsm]

I've always gapped mine at about .025, I was good until I got to 30psi, then it started to break up. I had to gap em down to about .017" to get it to pull clean. I'm pretty sure having them that tight is bad for power. It certainly caused it to miss under light cruise conditions.

 

[turboglenn]

I've always gapped mine at about .025, I was good until I got to 30psi, then it started to break up. I had to gap em down to about .017" to get it to pull clean. I'm pretty sure having them that tight is bad for power. It certainly caused it to miss under light cruise conditions.

Really? I've been surprised with how well mine has ran overall since gapping them down that tight. Although i am thinking about opening them back up a little since i found my main issue was some faulty connections in the ECU to IGnitor wiring. Try and see how far i can open them back up before it starts going out. Then i want to go back to BR7ES from the BR8's since the ethanol is burning cooler than the pump gas was that originally put me on the 8's (plus cold weather is creeping in now so i'm sure it will be fine)

what plugs are you running??

I also was thinking about side gapping the plugs as its' been good to me in situations before on dirtbikes and other things like my old 5 liter mustang

I think my main issue was a horrible wiring birds nest and a bad connection in it though. (it was going from ECU > J&S safeguard > MSD DIS-II > ignitor > coil) Lots of splices, i removed the MSD and had horrible break up untill i rewired the entire system removing the MSD loom (which ran in cabin under the driver seat) then moved the J&S from rear seat to driver side dash and ran new wire from the Ignitor to coils. BUt i had a weather pack connector that the wire was only sitting there touching to make contact for the signal from the ECU to J&S (didin't find this untill pulling almost 40feet of multiple strand wiring out of the car) but enough babling, just pointing out ignition problems can be hiding in a variety of places (i thought i was chasing blow out from boost but really i was masking an ignition connection that was relying on the wires just holding in place to touch each other from me breaking my own rule of "solder everything" when i put the damn weatherpack connectors on )

I really want to put the MSD back in but i pulled it to sell it for some cash towards the ARC-2 box.

_______________
edit: downloaded ECMlink v3 software, i must say i'm liking this system alot more than the old unit, as well as being shocked that the price has stayed really low..great system!!

 

[TSITurbo95]

^ ECMLink FTFW!!!!!

And thanks for all the useful info. Turboglenn, would you mind looking at one of my logs and possibly give me some feed back?

 

[LandoAWD]

Start a thread in the tuning forum.

 

[TSITurbo95]

Already did, however he had not posted in it yet, and is a knowledgeable person Plus it has changed since then.

 

[turboglenn]

PM me link to your thread, I"ll be glad to help if i can.