Why do spark plug gaps in FI cars need to be significantly less?
 

I have mine at a little less than .035". People told me 0.030 while the stock GSR I believe is somewhere between 0.045 to 0.050?

My question is... why the small gap? THe only reason I found was that it prevents the spark from being "blown out", but I want better explanation if anyone has one.

Re: Why do spark plug gaps in FI cars need to be significantly less? (elpiar)
 

Blowing out the flame is a pretty common thing. We had a turbo motor with oversized valves that needed a gap of 20-24. We had to swap the head with a stock GSR head and we could run a gap of closer to 30.

Re: Why do spark plug gaps in FI cars need to be significantly less? (CompressionFed)
 

Yes i had my plugs gapped to .45 when i first got my turbo, sometimes when i accelarated i blew out the spark. Then i got a Code for random misfire. (on my OBDII with a blue box)

Anyone use the iridiums? What spark plugs do you use?

Re: (TheKingPin)
 

Air has mass. The more dense the air (mass per volume) the greater the spark required to jump the gap.

Kyle Ritchie

Re: (herecomesboost)
 

i run my plugs at .019 very small gap. but i run alot of boost on a big turbo

i learn something new every day when it comes to my turbo i've been running between 8 to 10 pounds do you think i should close my gap more i got it at .40 right now

Re: (red02s2k)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by red02s2k &raquo;</TD></TR><TR><TD CLASS="quote"> i learn something new every day when it comes to my turbo i've been running between 8 to 10 pounds do you think i should close my gap more i got it at .40 right now </TD></TR></TABLE>

take it down to .028

Re: (herecomesboost)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by herecomesboost &raquo;</TD></TR><TR><TD CLASS="quote">Air has mass. The more dense the air (mass per volume) the greater the spark required to jump the gap.

Kyle Ritchie</TD></TR></TABLE>

So closing the gap creates greater spark? Don't your spark gets smaller as the gap closes? (imagine the gap closing to near 0 gap, you get really really small spark, right?

Re: (elpiar)
 

hes not saying closing the gap makes a bigger spark, he said a bigger spark is required when going a longer distance. Unless you upgrade your ignition system you are going to want to run a smaller gap relative to how much power/psi you are running. Because the spark has less of a chance of blowing out if traveling a shorter distance.

Someone correct me if im wrong.

Re: Why do spark plug gaps in FI cars need to be significantly less? (elpiar)
 

Its not "blowing out". The spark doesnt "jump" across the gap either.
In simple terms, the spark is actually pushing through the air. The more air in the
cylinder, ie: more density, the harder time the spark has to bridge the gap.
The smaller gap is easier for a weaker ignition to push across.

yup i run bkr7e with a 0.30 gap at 10psi

Re: Why do spark plug gaps in FI cars need to be significantly less? (rioninja)
 

so why not run the smallest gap possible? Like say .10?

Re: Why do spark plug gaps in FI cars need to be significantly less? (rioninja)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rioninja &raquo;</TD></TR><TR><TD CLASS="quote">Its not "blowing out". The spark doesnt "jump" across the gap either.
In simple terms, the spark is actually pushing through the air. The more air in the
cylinder, ie: more density, the harder time the spark has to bridge the gap.
The smaller gap is easier for a weaker ignition to push across. </TD></TR></TABLE>

Thank god someone cleared that up, so annoying lol. https://honda-tech.com/forums/images/smilies/emthup.gif

Re: Why do spark plug gaps in FI cars need to be significantly less? (rioninja)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rioninja &raquo;</TD></TR><TR><TD CLASS="quote">Its not "blowing out". The spark doesnt "jump" across the gap either.
In simple terms, the spark is actually pushing through the air. The more air in the
cylinder, ie: more density, the harder time the spark has to bridge the gap.
The smaller gap is easier for a weaker ignition to push across. </TD></TR></TABLE>

I can see that. The denser the air, the greater electrical resistance it is. So with the same amount of voltage, the electrons can only jump through a shorter distance.
Thanks for all the answers guys.

Re: Why do spark plug gaps in FI cars need to be significantly less? (adseguy)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by adseguy &raquo;</TD></TR><TR><TD CLASS="quote">so why not run the smallest gap possible? Like say .10?</TD></TR></TABLE>

My guess is that you are sacrificing the amount of spark you're getting. We need to get as much spark as possible, given that the electrons are capable to go accross the air. So we need to get it as big as possible but not too big, i believe this is the same principle that the engineers use to determine spark plug gap.

Re: Why do spark plug gaps in FI cars need to be significantly less? (elpiar)
 

If I am running a .044 gap in a 95 Civic EX on about 9-10 psi could that cause hiccuping when in a high gear and low rpm's?

Re: Why do spark plug gaps in FI cars need to be significantly less? (LiLQtPiE)
 

NGK says for every 50hp(flywheel) should lower gap by .004 from your stock gap. https://honda-tech.com/forums/images/smilies/emthup.gif

Ie. My stock gap is .044 and i currently have it gapped @ .036 and it runs perfect. No problems.

DAN

Re: Why do spark plug gaps in FI cars need to be significantly less? (ginoboy1978)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ginoboy1978 &raquo;</TD></TR><TR><TD CLASS="quote">NGK says for every 50hp(flywheel) should lower gap by .004 from your stock gap. https://honda-tech.com/forums/images/smilies/emthup.gif

Ie. My stock gap is .044 and i currently have it gapped @ .036 and it runs perfect. No problems.

DAN</TD></TR></TABLE>

DId a tech support tell you that?

Re: Why do spark plug gaps in FI cars need to be significantly less? (LiLQtPiE)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LiLQtPiE &raquo;</TD></TR><TR><TD CLASS="quote">If I am running a .044 gap in a 95 Civic EX on about 9-10 psi could that cause hiccuping when in a high gear and low rpm's? </TD></TR></TABLE>

detonation?

Re: Why do spark plug gaps in FI cars need to be significantly less? (elpiar)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by elpiar &raquo;</TD></TR><TR><TD CLASS="quote">

DId a tech support tell you that?</TD></TR></TABLE>

Yes they did.

I called them last year and thats what they told me. It's just an approximate/averaged number. It has been working great on my car, so I am pleased.

DAN

Re: Why do spark plug gaps in FI cars need to be significantly less? (elpiar)
 

I've seen many turbo hondas blow out spark at stock gap. I usually gap them down on a basic setup to around .028-.032.

Re: Why do spark plug gaps in FI cars need to be significantly less? (elpiar)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by adseguy &raquo;</TD></TR><TR><TD CLASS="quote">so why not run the smallest gap possible? Like say .10?</TD></TR></TABLE>
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by elpiar &raquo;</TD></TR><TR><TD CLASS="quote">
My guess is that you are sacrificing the amount of spark you're getting. We need to get as much spark as possible, given that the electrons are capable to go accross the air. So we need to get it as big as possible but not too big, i believe this is the same principle that the engineers use to determine spark plug gap.
</TD></TR></TABLE>
Exactly right.
Generally, you only want to gap as close as you need to. Well, a tiny bit more than you need to, to play it safe and consistent..

Re: Why do spark plug gaps in FI cars need to be significantly less? (SOHC_MShue)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHC_MShue &raquo;</TD></TR><TR><TD CLASS="quote">I've seen many turbo hondas blow out spark at stock gap. I usually gap them down on a basic setup to around .028-.032.</TD></TR></TABLE>
you can;t blow out the spark!!!!!!!! the denser the air in side of the cylinder(more boost) the higher the voltage that is needed to ionise the air and bridge the gap.
thats why you will need a smaller gap! if it cant bridge the gap it will bridge the cables or even the coil.

Re: Why do spark plug gaps in FI cars need to be significantly less? (dnbruut)
 

Uden Holland? Its cool seeing people from across the globe on here https://honda-tech.com/forums/images/smilies/emthup.gif