TOV: Gapping Iridium Plugs
10-25-2002, 01:28 PM
#1
Cost Drivers!!!!
Thread Starter
TOV: Gapping Iridium Plugs
So could we make the gap slightly large than spec?
www.vtec.net
www.vtec.net
Introduction:
Iridium spark plugs are unique in that their center electrode has the ability to be made very thin (0.4mm versus a platinum's 1.1mm). The smaller electrode and lower material resistance equates to a lower firing voltage to achieve the same size spark. Therefore, one could run a slightly larger gap using an iridium spark plug compared to an inferior material. This larger gap creates a larger spark, which in turn creates more heat that ignites the air/fuel mixture more quickly and powerfully. In theory, all this combined yields an end result of slightly higher horsepower and torque values, as well as improved efficiency.
Denso Platinum vs. Denso Iridium
Procedure:
1. Using a spark plug gap measurer, determine if the spark plug already has the correct gap required for your vehicle. Generally, you can find the correct gap specification in your owner's manual or on a sticker under the hood.
Measuring the Gap
2. Assuming the preset gap is too small, wrap one side of a pair of needle nose pliers with electrical tape to prevent damage to the spark plug when gapping.
Wrap Pliers with Tape
3. Grip the ground electrode with the needle nose pliers between where the ground electrode is fused to the spark plug thread and the center electrode. Make sure the taped side of the pliers is on the bottom, as shown in the pictures.
4. Gently and slightly bend the ground electrode away from the center electrode, thus increasing the gap closer to the appropriate specification.
5. Re-measure the gap with the gap measurer. If there is still not a large enough gap, repeat steps 3-5. If the gap is too great, place the spark plug's ground electrode on the ground and gently apply pressure to bend the electrode and reduce the gap.
Reducing the Gap
6. Re-measure the gap. If it is still incorrect, repeat any of the above sequence until the appropriate gap is reached.
7. Remember to apply anti-seize lubricant to the spark plug threads before installing in your vehicle. This will make future removal easier by preventing the threads from seizing in the head.
8. When installing, you should use a torque wrench and tighten the bolts to the correct specification (13 ft./lbs. on Hondas). Also, be sure not to cross-thread the plugs.
Iridium spark plugs are unique in that their center electrode has the ability to be made very thin (0.4mm versus a platinum's 1.1mm). The smaller electrode and lower material resistance equates to a lower firing voltage to achieve the same size spark. Therefore, one could run a slightly larger gap using an iridium spark plug compared to an inferior material. This larger gap creates a larger spark, which in turn creates more heat that ignites the air/fuel mixture more quickly and powerfully. In theory, all this combined yields an end result of slightly higher horsepower and torque values, as well as improved efficiency.
Denso Platinum vs. Denso Iridium
Procedure:
1. Using a spark plug gap measurer, determine if the spark plug already has the correct gap required for your vehicle. Generally, you can find the correct gap specification in your owner's manual or on a sticker under the hood.
Measuring the Gap
2. Assuming the preset gap is too small, wrap one side of a pair of needle nose pliers with electrical tape to prevent damage to the spark plug when gapping.
Wrap Pliers with Tape
3. Grip the ground electrode with the needle nose pliers between where the ground electrode is fused to the spark plug thread and the center electrode. Make sure the taped side of the pliers is on the bottom, as shown in the pictures.
4. Gently and slightly bend the ground electrode away from the center electrode, thus increasing the gap closer to the appropriate specification.
5. Re-measure the gap with the gap measurer. If there is still not a large enough gap, repeat steps 3-5. If the gap is too great, place the spark plug's ground electrode on the ground and gently apply pressure to bend the electrode and reduce the gap.
Reducing the Gap
6. Re-measure the gap. If it is still incorrect, repeat any of the above sequence until the appropriate gap is reached.
7. Remember to apply anti-seize lubricant to the spark plug threads before installing in your vehicle. This will make future removal easier by preventing the threads from seizing in the head.
8. When installing, you should use a torque wrench and tighten the bolts to the correct specification (13 ft./lbs. on Hondas). Also, be sure not to cross-thread the plugs.
10-25-2002, 02:25 PM
#3
Cost Drivers!!!!
Thread Starter
Originally posted by 6spdmanual
You mean our regular plugs or Iridium plugs? By the way, anybody installed the Iridium ones? If so, any significant difference?
You mean our regular plugs or Iridium plugs? By the way, anybody installed the Iridium ones? If so, any significant difference?
10-25-2002, 02:26 PM
#4
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I thought I read somewhere that you weren't supposed to regap the Iridiums. It said something about the electrode being too delicate and that it could easily break. Let us know Zapata.
BTW, I have had the iridiums on for a while now and I really couldn't tell you if it makes a difference. Butt dyno when I first installed them said it made some more power. Who knows.
BTW, I have had the iridiums on for a while now and I really couldn't tell you if it makes a difference. Butt dyno when I first installed them said it made some more power. Who knows.
10-25-2002, 02:35 PM
#5
Cost Drivers!!!!
Thread Starter
Originally posted by NSXNEXT
I thought I read somewhere that you weren't supposed to regap the Iridiums. It said something about the electrode being too delicate and that it could easily break. Let us know Zapata.
BTW, I have had the iridiums on for a while now and I really couldn't tell you if it makes a difference. Butt dyno when I first installed them said it made some more power. Who knows.
I thought I read somewhere that you weren't supposed to regap the Iridiums. It said something about the electrode being too delicate and that it could easily break. Let us know Zapata.
BTW, I have had the iridiums on for a while now and I really couldn't tell you if it makes a difference. Butt dyno when I first installed them said it made some more power. Who knows.
Right they are VERY sensative. However, the TOV website has pictures illustrating text. They use a needle nose pliers and wrap electrical tape around the end closest to the electrode. Unfortunately, TOV website now has their pictures posted so they can't be displayed on other websites.
10-25-2002, 02:37 PM
#6
Suzuka Master
Originally posted by NSXNEXT
I thought I read somewhere that you weren't supposed to regap the Iridiums. It said something about the electrode being too delicate and that it could easily break. Let us know Zapata.
BTW, I have had the iridiums on for a while now and I really couldn't tell you if it makes a difference. Butt dyno when I first installed them said it made some more power. Who knows.
I thought I read somewhere that you weren't supposed to regap the Iridiums. It said something about the electrode being too delicate and that it could easily break. Let us know Zapata.
BTW, I have had the iridiums on for a while now and I really couldn't tell you if it makes a difference. Butt dyno when I first installed them said it made some more power. Who knows.
If you stay away from the center electrode, it can be done (I had called them before and they recommend using factory-set gap for our cars ... and said that it could be re-gapped with care.)
YMMV
10-25-2002, 04:45 PM
#7
The Acura Granddaddy
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Another option would be to purchase them with a slightly bigger gap to begin with....kinda sucks waiting for the stock platinums to die though...
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10-25-2002, 05:07 PM
#8
Burning Brakes
You should not gap the Denso Iridiums. The gap is already set at 0.044mm. If you gap wider, you'll potentially run into misfiring problem. The wider the gap, the stronger sparks are needed to jump the gap. I would do this only if you have a high power aftermarket ignition unit. The gapping process is also very delicate if you've ever tried it yourself. A certain cylinder would not fire if the gap is too wide, resulting in fouled spark plugs.
10-26-2002, 03:01 AM
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I didn't notice any gains. I did notice, however, a slight vibration in the steering wheel as I pulled to a stop at lights. I assumed that it was from the recent addition of plugs. I reopened the front 3 banks and tightened 'em all a bit more. Vibrations gone.
10-26-2002, 09:47 AM
#13
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Re: TOV: Gapping Iridium Plugs
The catch is if it's too wide, you require more voltage to fire, and you risk the kernel being snuffed out before the engine can fire. It has less to do with the plug resistance, and more to do with the air resistance.
It's one of those things you'll see a benefit from if the gap was smaller. Keep in mind we do run 10.5:1 compression, so you don't want to blow out the kernel and have miss fires.
Here's a cool formula for ya:
Vbreakdown (kV) = 24.22*X + 6.08*SQRT(X)
where X = (293*P*D)/(760*T)
P = pressure in mmHg (760mm is 1atm = 14.7 PSI)
D = distance in cm
T = temperature in Kelvin (273 + Tcelsius)
Ok,
P=14.7 PSI at BTD, but once the piston reaches TDC, it'll be 10.5 X greater (because of the compression ratio), so P=154.35 PSI (7982.2 mmHg).
D=plug gap (convert from inches to centimeters). 0.044" = 0.11176 cm
T=cylinder temp. The engine is running at say 195F, so I'm assuming the air at ignition time is also 195F. The engine will heat the air (since the combustion chamber is much hotter than 195F, and compressing the air 10.5:1 will heat it as well, but since the air spends a very short period of time in the cylinder, I just use 195F=90.55C=363.71 Kelvin
You grunt the numbers, and the voltage that's required to fire the gap is 28.8kV.
I used it to calculate what the gap should be on my truck that runs 5.5PSI boost (since the pressure will be (14.7PSI + 5.5PSI)*Compression Ratio.
** Note: The above formula assumes pure air in the cylinder (it's basically calculating the dielectric of air). In my case, I just wanted to know the different ratio from boost to no boost, so I didn't care.
Check out this page, it's super helpful:
www.crownvic.net/tech/sp_101.html
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