1.8 spark plug
- Thread starter $ub$onic
- Start date
GeneralZod
New member
I found myself reading the whole thread one night. Some did have an improvement with MPG. Something tells me it will be engines without a tune, I think the stock tunes over fuel to create higher temps for emissions.
The gap might help burn most of the extra fuel. It also backs the 87 vs. 91 theory.
Just my guess...
The gap might help burn most of the extra fuel. It also backs the 87 vs. 91 theory.
Just my guess...
sx sonic
New member
If I had a 1.8 I would gap mine at .035". The reason for the recommened .028" gap is to prevent spark blow out which is much much more likely on the tuned 1.4t.
The reason being is that turbo engines have a higher dynamic compression ration which would be meauser while the engine as running (only done bt o.e.ms and top tuners). If you check compression with a normal compression tester you are measuring "static compression". NA motors tend to have higher static compression and lower dynamic compression vs a forced induction engine. And has to do with the volumetric effeciency of the two engines. NA is lower than ideal FI is higher.
This relates to spark plug gap because as the compression/combustion pressures increase so does the resistance across a given spark plug gap. so let's say hypothetically we have a .040" gap for both engines, the boosted engine expierences "blowout" where the spark is extinguished before complete combustion has started/finished due to the high pressures. There are really only 3 things to prevent this 1. Higher discharge voltages(stronger coil) 2. Lower boost psi or compression ration (expensive or bad for power) or 3. Tighten up the spark plug gap.
Its obvious the 3rd is the easiest and most economical and the reason it works is because a tighter gap lowers the resitance across the plug gap making it easier to fire. This is also why us turbo guys are running ~.028" (I'm at .030"). Its to ensure we don't expierence spark blowout and according to vince and apparently GM we don't have to worry about it happening under any foreseeable conditions at that gap.
But that's for us running very high cylinder pressures a bigger gap could be used for the NA engines. The benefit of a bigger gap is it exposes more fuel and air to the flame kernal (spark) which ensures more complete combustion. I visualize it like this a big gap is great for lighting off all the fuel when running "lean" and fuel is scarce, but it has more trouble firing at peak power when the pressures are high.
Will a bigger gap give you more power? Absolutely not, upgrading any part of the ignitions (sans timing changes) will not yield any power. BUT it Can prevent losing power and improve drivability as long as one doesn't go too big..
I know I've begun to ramble now and unfournately I cannot proof read my post on my phone without going mad. So in short you want as big of a spark plug gap as possible but not so big as to run into spark blowout under some load/speed condition. If .028 works for a tuned 1.4 then I would be comfortable running .032-.035 if I had a 1.8 NA. If you are unsure then .028 is for you.
The reason being is that turbo engines have a higher dynamic compression ration which would be meauser while the engine as running (only done bt o.e.ms and top tuners). If you check compression with a normal compression tester you are measuring "static compression". NA motors tend to have higher static compression and lower dynamic compression vs a forced induction engine. And has to do with the volumetric effeciency of the two engines. NA is lower than ideal FI is higher.
This relates to spark plug gap because as the compression/combustion pressures increase so does the resistance across a given spark plug gap. so let's say hypothetically we have a .040" gap for both engines, the boosted engine expierences "blowout" where the spark is extinguished before complete combustion has started/finished due to the high pressures. There are really only 3 things to prevent this 1. Higher discharge voltages(stronger coil) 2. Lower boost psi or compression ration (expensive or bad for power) or 3. Tighten up the spark plug gap.
Its obvious the 3rd is the easiest and most economical and the reason it works is because a tighter gap lowers the resitance across the plug gap making it easier to fire. This is also why us turbo guys are running ~.028" (I'm at .030"). Its to ensure we don't expierence spark blowout and according to vince and apparently GM we don't have to worry about it happening under any foreseeable conditions at that gap.
But that's for us running very high cylinder pressures a bigger gap could be used for the NA engines. The benefit of a bigger gap is it exposes more fuel and air to the flame kernal (spark) which ensures more complete combustion. I visualize it like this a big gap is great for lighting off all the fuel when running "lean" and fuel is scarce, but it has more trouble firing at peak power when the pressures are high.
Will a bigger gap give you more power? Absolutely not, upgrading any part of the ignitions (sans timing changes) will not yield any power. BUT it Can prevent losing power and improve drivability as long as one doesn't go too big..
I know I've begun to ramble now and unfournately I cannot proof read my post on my phone without going mad. So in short you want as big of a spark plug gap as possible but not so big as to run into spark blowout under some load/speed condition. If .028 works for a tuned 1.4 then I would be comfortable running .032-.035 if I had a 1.8 NA. If you are unsure then .028 is for you.
Bogus
Senior Member
If you broke that little orange clip on the connector, chances are they wont want to replace that under warranty for you. They didn't for me at first but Matt helped me out and they ordered the part.
Bogus
Senior Member
The only problem is you can't just get the clip, you have to get the whole connector/wire. :blankface:
Luv2xlr8
New member
Ok, so I didn't want to start a new thread so I'll ask here. Are the 1.8s using iridium plugs just like the 1.4s? If so, what brands are out there because I could only find AC Delco and autolite but NGK doesn't make one for the Sonics on their website? Any of you guys replaced yours yet, and if yes with which brand?
Yes I do know the GM OEM plugs they are using are NGKs but I can get half cost price from what the dealers asking price is.
Yes I do know the GM OEM plugs they are using are NGKs but I can get half cost price from what the dealers asking price is.
Last edited:
mitdr774
also a dinner prick
Luv2xlr8
New member
Thanks mitdr774, I searched that number and found something useful from Cruzetalk that I copied from an NGK specialist.
Below is an e-mail I got back from NGK-USA asking about the NGK/ACDelco 41-117, 41-120 and 41-121 spark plugs:
Hello,
41-120 cross to a IFR6Z7G, but this part has been obsoleted.
41-121 cross to a IFR7X7G #91039. This was just released this February 2012, so it may need to be special ordered at your local parts store.
Best Regards,
Andrew Hauenstein
Technical Training
Specialist
NGK Spark Plugs USA Inc
Below is an e-mail I got back from NGK-USA asking about the NGK/ACDelco 41-117, 41-120 and 41-121 spark plugs:
Hello,
41-120 cross to a IFR6Z7G, but this part has been obsoleted.
41-121 cross to a IFR7X7G #91039. This was just released this February 2012, so it may need to be special ordered at your local parts store.
Best Regards,
Andrew Hauenstein
Technical Training
Specialist
NGK Spark Plugs USA Inc
