Chevrolet Cruze Forums banner
1 - 20 of 42 Posts

·
Registered
Joined
·
581 Posts
Discussion Starter · #1 ·
I havent been on here in a while but when i was i remmember there was much speculation about the plugs. Did we ever come to which are the best for this car and what the best gap is for a completely stock 1.4t? Thanks in advance
 

·
Premium Member
Joined
·
1,254 Posts
Gap them between .028 and .032 stock. As far as actual plugs go, the NGK Coppers are very nice, but will need to be re-gapped every ~10k. The NGK Iridiums are great, meant to last much longer, been running those for 20k miles no issues. I don't recall the exact part numbers, but someone will chime in. They're both like $30 for a set.
 

·
Administrator, Resident Tater Salad
Joined
·
17,353 Posts
I feel like the BKR7E-4644 (coppers) ran the best for me, but as mentioned, they need frequent regapping. The BKR8EIX-2668 are a close second, and will need gapping much less frequently.
 

·
Moderator
Joined
·
2,170 Posts
This is all very interesting and definitely something I need to consider doing soon. I have noticed a weird pulsing sensation under WOT acceleration, as the RPMs climb. I wonder if this would fix that, really only one way to find out for myself.
 
  • Like
Reactions: 203-CRUZER

·
Administrator, Resident Tater Salad
Joined
·
17,353 Posts
This is all very interesting and definitely something I need to consider doing soon. I have noticed a weird pulsing sensation under WOT acceleration, as the RPMs climb. I wonder if this would fix that, really only one way to find out for myself.
Yes, probably. That's the car pulling timing and boost because it's hearing knock/ping.
 

·
Administrator
Joined
·
25,596 Posts
This is all very interesting and definitely something I need to consider doing soon. I have noticed a weird pulsing sensation under WOT acceleration, as the RPMs climb. I wonder if this would fix that, really only one way to find out for myself.
Yes, probably. That's the car pulling timing and boost because it's hearing knock/ping.
The other possibility is that the plug gap as eroded enough that you're getting spark blowout. In either case it's time to check your plugs and ensure they're gapped properly. The Cruze will start experiencing spark blowout at 0.038-0.039", and it only takes one plug to make it noticeable.
 

·
Registered
Joined
·
279 Posts
I run the NGK BKR7E plugs in my Cruze and love them. I have gotten 30k out of them already, will probably be replacing them within the next 5k. As stated, have to re-gap every 10k, but no big deal. Car runs much better on them IMO. I can buy a set of 4 for less than $9.
 

·
Banned
Joined
·
10,296 Posts
Saw one of these at my Walmart store at only $3.68 each, perked my curiosity with that bright chrome finish and multi-electrode design. These were very popular in the 50's and 60's and still are in aircraft applications. A gapless plug and were very reliable.

Seem to be having problems finding the application catalog for these Bosch Platinum+4 Spark Plugs, maybe need another cup of coffee. But Bosch said how great their needle point iridium plugs were, put those in my 88 Supra Turbo and were a disaster. So went to Autolite APP series, a noticeable difference and far more reliable. Can't believe everything you read.

I put Autolite APP3923 in my Cruze 1.4 L when new, gaped at 25 mils and have been very pleased with them, but after 43K miles, plating is wearing off so time to replace them.

Of course there is the ignition system, wasted spark DIS systems were a bad joke, using one coil to fire two spark plugs, one on the compression stroke other on the exhaust, a bean counter thing. Least the Cruze does have a coil per plug. But still can't say much about the ignition system, single gated bi-polar transistor that barely replaces the points. Best system always and still is the capacitor discharge ignition system, but does cost a couple of extra bucks with an inverter and and all that.

In theory, can't improve an ignition system as long as you get a spark each time and at the correct time and under all turbulent conditions. But can't seem to explain this to bean counters, only interested in $$$$$, and in their pockets, not ours.

Worse thing is a misfire, even a mild one, O2 sensor interprets this as a lean mixture and pours a lot more unburnt fuel into the cat that fries and plugs that up. But would gives a darn, as long as it makes it through the warranty period.

Really don't know with plugs until you try.

 

·
Banned
Joined
·
10,296 Posts
Ha, one thing I never learned about spark plugs, the hex for putting them in was and still is English system of measurement, the threads are metric. Going back about 50 years on this subject, metric threads are even not standard metric sizes, we had to have special dies made for our automatic screw machines to crank out those metal bases.
 

·
Administrator, Resident Tater Salad
Joined
·
17,353 Posts
Don't run platinum in a turbo car, especially 4-prong ones. We've had this conversation before.

what is the differece between the 6 7 and bkr8eix?
Number is the heat range (6 warmer, 8 colder). E vs EIX is a nickel electrode vs iridium.
 

·
Banned
Joined
·
10,296 Posts
Don't run platinum in a turbo car, especially 4-prong ones.
Looks good on paper for 4 prong type, but what's wrong with platinum? Had very good success with platinum and talking about time long before you were planted here.
 

·
Registered
Joined
·
145 Posts
ACDelco 41-121 (some sort of NGK rebrand) has worked best all around for me, and they are cheap for an iridium plug.
 

·
Administrator, Resident Tater Salad
Joined
·
17,353 Posts
Looks good on paper for 4 prong type, but what's wrong with platinum? Had very good success with platinum and talking about time long before you were planted here.
That's the problem, actually. Yeah, you own a turbo Supra too, we get it. Technology, engines, etc have moved on since "long before I was planted here". We're running more compression on engines than before, we have much quicker, much more advanced engine control systems than in the past, knock sensors that "hear" ping far better than they did in the 80's, and we have forced induction that wasn't all that prevalent long ago. All of this means that the Cruze will run as close as possible as it can to "the limit", and will retard all power in a fraction of a second when it detects any sign of something wrong. Heat soak the car at a stoplight in the summer, don't slip the clutch very much, and tell me it doesn't bog down like crazy.

Platinum is actually a horrible conductor of both heat and electricity. Copper is great, but wears, nickel is slightly better, and then iridium is quite a ways off. Platinum is quite a ways off even from that - the very bottom of the heap.

It generates a WEAK spark, so much so that many turbo cars will blow out that spark entirely and stutter when run on platinum plugs. Don't believe me, go to a DSM, Volvo, or Saab forum and poke around. Many people with tuned Cruzes running higher boost levels than stock experience this blow-out and have to close the gaps on plugs or switch to a different plug altogether.

The stock IFR7G-whatever they are plugs use an iridium tip and platinum ground strap. That platinum ground strap doesn't scavenge heat well to the rest of the spark plug to get rid of it, and it causes pre-ignition, which is why those plugs run like crap in hot weather and at low RPMs.

Simply switching the plugs to one with a nickel ground strap and iridium tip (the BKR series) brings back so much low-RPM spunk into the engine it's hard to believe.

You could accomplish the same thing, I suppose, by dropping down a heat range, but they'll be unable to get to a temperature where they will self-clean and will carbon up.
 

·
Registered
Joined
·
86 Posts
I have had my Cruze for about 8k miles. One of the first things I noticed was bad mileage. This forum helped right away. Yup, the stock plugs were at 25 to 27. I upped them to 30 and torqued them down. Pulled them back out an went to 32. Mileage went way up, throttle response and power were also up. Many thanks.
 

·
Premium Member
Joined
·
8,003 Posts
The only advantage of multi gap that I can think of is that the wear on the ground strap is only 1/4 of a regular plug.
 

·
Registered
Joined
·
581 Posts
Discussion Starter · #17 ·
That's the problem, actually. Yeah, you own a turbo Supra too, we get it. Technology, engines, etc have moved on since "long before I was planted here". We're running more compression on engines than before, we have much quicker, much more advanced engine control systems than in the past, knock sensors that "hear" ping far better than they did in the 80's, and we have forced induction that wasn't all that prevalent long ago. All of this means that the Cruze will run as close as possible as it can to "the limit", and will retard all power in a fraction of a second when it detects any sign of something wrong. Heat soak the car at a stoplight in the summer, don't slip the clutch very much, and tell me it doesn't bog down like crazy.

Platinum is actually a horrible conductor of both heat and electricity. Copper is great, but wears, nickel is slightly better, and then iridium is quite a ways off. Platinum is quite a ways off even from that - the very bottom of the heap.

It generates a WEAK spark, so much so that many turbo cars will blow out that spark entirely and stutter when run on platinum plugs. Don't believe me, go to a DSM, Volvo, or Saab forum and poke around. Many people with tuned Cruzes running higher boost levels than stock experience this blow-out and have to close the gaps on plugs or switch to a different plug altogether.

The stock IFR7G-whatever they are plugs use an iridium tip and platinum ground strap. That platinum ground strap doesn't scavenge heat well to the rest of the spark plug to get rid of it, and it causes pre-ignition, which is why those plugs run like crap in hot weather and at low RPMs.

Simply switching the plugs to one with a nickel ground strap and iridium tip (the BKR series) brings back so much low-RPM spunk into the engine it's hard to believe.

You could accomplish the same thing, I suppose, by dropping down a heat range, but they'll be unable to get to a temperature where they will self-clean and will carbon up.
J Black so what exactly do you reccomend for me.? I dont want to have to regap for 25000-30,000. I dont want to regap every 10,000. Which is the best plug for me to get best performace without having to change every 10. ??? And then what should gap be set at??
 

·
Banned
Joined
·
10,296 Posts
Key reason why I gap my plugs at 25 mils, 0.025 inches. In the theory of electrostatics, electrons gather at a sharp point, so the edges of the electrodes have to be sharp. Did get more life out of my Champs by cleaning them with my ground walnut spark plug cleaner and using a point file to keep both the center and ground electrode square.

Somebody was really smoking crack when GM came out with the HEI and using a 65 mil gap, took some careful bending to reduce that to 30 miles. So was Kia for my daughters Soul, what a name, gaped at 45 mils, she was getting misfires, change her car into a rocket by gaping to 30 mils.

Spark current is only in the order of 5 milliamperes, so resistance isn't even a factor. But having a sharp edge is. Platinum still holds longer, but instead of 10K miles, more like 40K miles. Whoever came out with a 100K miles was really smoking crack.

If you want to talk about resistance, resistant plugs have to be used in these electronic vehicles to reduce EMI, a carbon resistor is in series with the top terminal and center electrode that can be eaten away. Can be checked with an ohmmeter, should read about 8,000 ohms, can find some with a much higher resistance, this is why they invented trashcans.

Then there is always carbon buildup on the center electrode insulator, clean my plugs every 15K miles with my blaster, check the resistance and the gap, with my plugs, hold pretty well, but figure a life of only about 40-50K miles. Cheap insurance to prevent your cat from plugging up.

Issues were made about thermal resistance using a very thin coat of anti-seize, severely dislike those need point electrodes, in my professional experience, somebody else is smoking crack.

When I hit my start key, engine is running in an instant, when I hit the gas, Cruze takes off like a jack rabbit, ha a limping jack rabbit, but nevertheless, a jack rabbit.

When I first drove my new Cruze home, from the factor with 2 miles on it, engine would hesitate or even die when taking off in first gear. After replacing those needle point NGK's can ease out the clutch in either first or second gear without stepping on the gas for a very smooth take off.

This is the difference good clean plugs with good heat conductivity can make. Just filled my tank yesterday with mostly city driving, snow on the ground and winter gas. Still averaged 28 mpg.

Also toss in a can of Seafoam every 5K miles to clean up the rest of the engines carbon, even using only so-called top tier 91 octane ethanol free gas.

Very particular on how my engines run. Changing the plugs on the Cruze is fun for a change and only four plugs to deal with. But have to make darn sure all four of those coil springs are sticking out, hold the coil pack at an angle to assure contact is with all four plugs, move it backwards than push it down and have that torx screw handy.

Daughters Soul was even easier, using a coil per plug, cheaper too in case one coil would go bad.

Another advantage of a small gap, good conductivity, is with a misfire, that gated bipolar transistor will take a beating, is protected by a 50 volt zener diode, but the bean counters would never let us make those large enough. Putting all this stuff in the ECU was also nice for the bean counters, saves on wires, but also not good for the consumer.
 

·
Administrator, Resident Tater Salad
Joined
·
17,353 Posts
J Black so what exactly do you reccomend for me.? I dont want to have to regap for 25000-30,000. I dont want to regap every 10,000. Which is the best plug for me to get best performace without having to change every 10. ??? And then what should gap be set at??
Just keep your stock ones then. They were picked with long life in mind. 10k is like once a year for most.
 

·
Premium Member
Joined
·
1,226 Posts
Platinum is actually a horrible conductor of both heat and electricity. Copper is great, but wears, nickel is slightly better, and then iridium is quite a ways off. Platinum is quite a ways off even from that - the very bottom of the heap.
Actually, iridium has lower resistance and higher conductive heat transfer than nickel. This is from Wikipedia:

Nickel Electrical Resistivity: 69.3 nΩ·m (at 20 °C)
Nickel Thermal Conductivity: 90.9 W/(m·K)

Iridium Electrical Resistivity: 47.1 nΩ·m (at 20 °C) (lower resistance than nickel)
Iridium Thermal Conductivity: 147 W/(m·K) (higher heat transfer than nickel)

Platinum Electrical Resistivity:
105 nΩ·m (at 20 °C)
Platinum Thermal Conductivity: 71.6 W/(m·K)

Thermal conductivity is the ability of the metal to transfer heat. Higher numbers are better. Electrical resistivity is the resistance to electrical current. Lower numbers are better.Iridium is much harder than nickel, so it won't wear out as quickly. Iridium is really the best material for spark plugs. Platinum is the worst.

Simply switching the plugs to one with a nickel ground strap and iridium tip (the BKR series) brings back so much low-RPM spunk into the engine it's hard to believe.
I agree completely!!! There was a very noticeable difference in response and take off power when I switched to the NGK BKR7EIX plugs. The only problem I noticed with these plugs is that they have a nickel ground strap which wears out quickly, so you do have to check them every year or two.

I personally think that if you don't want to check or change the plugs very often, stick with the OEM plugs, and make sure they are gapped correctly.

I also noticed that if you reuse plugs after checking the gap then you run the risk of having a plug come loose because these plugs have a crush washer that is not meant to be reused.
 
1 - 20 of 42 Posts
Top