Last updated - October 21, 2022 at 07:38
After converting a vehicle to gas fuel (most often this is the installation of 4th and 2nd generation LPG), manufacturers of ignition systems recommend installing spark plugs for LPG on the car engine, designed specifically for operation on “CNG” and “LPG” (methane/propane) .
And indeed, some time after installing gas equipment, car owners notice a decrease in the service life of spark plugs, coils, and high-voltage wires.
In this article we will understand the difference between spark plugs for gas and gasoline. Should I install gas spark plugs, or should I limit myself to adjusting the gaps of standard parts?
IN THE TEAM - REPLACEMENT
Of course, you need to change the spark plugs. If only because all our previous publications (ZR, 2005, No. 10; 2007, No. 8; 2008, No. 9) invariably revealed a difference in the behavior of gasoline engines after replacing any of the “ignition” elements - from spark plugs to wires. And then - a change in fuel: the gas burns differently, and the mixture is leaner. The combustion rate is lower, the temperatures are higher - but it burns cleaner, therefore, there are fewer deposits. But these are precisely the parameters that influence the choice of at least the glow number of candles! So is it possible to use regular spark plugs there, as for a gasoline engine? And are there any special “gas” ones in nature?
The value of optimal clearances
Acceptable operating parameters at which the system remains fully operational are gaps in the range of 0.6–1.2 mm. Clear values are selected depending on the type of power plant, various power supply and ignition systems. You should focus on the following characteristics:
- old carburetor engines, which have motors with a low compression ratio and mechanical sparking functionality, will work optimally at 0.6–0.7 mm;
- similar power plants with modernized contactless ignition using electronics will be effective at 0.8–0.9 mm;
- for naturally aspirated engines reinforced with turbines and equipped with an injection type injection, it is preferable to provide a gap of 1–1.2 mm.
In order not to make a mistake with the value for a specific engine brand, we recommend that you study the user manual in detail. Various parameters are indicated there, including the preferred clearance.
VERY COMPLEX QUESTION
This is exactly how the Internet responds to the first attempts to find spark plugs for equally effective ignition of gas and gasoline. However, five participants were still identified. Germany is represented by a set of platinum spark plugs Bosch Platinum WR7DP, the Czech Republic - Brisk LPG LR15YS Silver. The honor of Japan in the competition will be defended by two sets of different companies - iridium NGK LPG LaserLine No. 2 and Denso IW20. The Ukrainian Plazmofor Super GAZ represents the Slavic brothers. The selection criterion is a win-win: all these kits are recommended for use on gas engines by the manufacturers themselves on their websites. And as a “zero meridian” for reference, let’s take the obviously good BERU 14R-7DU spark plugs from France, which, however, are focused only on gasoline and are not provided with a clear recommendation for use on “blue” fuel.
The reality of what is happening
A motorist whose car is equipped with gas-cylinder equipment should think three times before spending money on the purchase of adapted spark plugs, which are supposedly capable of working much more efficiently and productively with blue fuel than with gasoline.
More than once, motorists who have installed gas equipment and bought specialized spark plugs note that they are only a marketing ploy. So manufacturers are trying to sell products that are no different from ordinary candles at a higher price. Yes, they can use other, and more expensive, materials and change the design somewhat. But in fact, according to car enthusiasts, the costs are not justified. The performance of the motor remains at the same level as with conventional spark plugs.
It’s not enough to simply rely on subjective reviews. It is much more correct to refer to the results of tests and studies. And they clearly show that even the highest quality gas spark plugs do not differ in efficiency and performance from universal-type devices aimed primarily at gasoline power units.
Yes, if you compare cheap universal spark plugs and spark generation devices adapted for gas, the advantage will be on the side of the latter. But they will not be able to impose a fight against universal candles of a higher level.
NGK LaserLine 2
To understand the essence of what is happening, you need to take into account the key differences between gas or LPG devices adapted from conventional gasoline ones.
Firstly, gas ones use a smaller gap between the electrodes. This allows for similar compression efficiency of a mixture of gas and air, comparable to the compression of air and gasoline.
Secondly, devices for gas-cylinder equipment have a higher heat index. This means that such candles are able to withstand higher heat loads.
The practice and experience of motorists clearly prove that buying high-quality universal spark plugs is in many ways equivalent to using expensive devices adapted for gas-air mixtures. But all other things being equal, even taking into account the slightly longer life of gas devices, purchasing universal products will cost less.
Plus, universal, but high-quality spark plugs can provide a greater increase in engine power and reduce fuel consumption.
You are unlikely to feel the benefits of any type of spark plug if you install the LPG incorrectly, violate the setup recommendations, or do not follow the operating instructions.
Also, an adapted and universal candle will not work effectively if you initially buy cheap products. It's not worth saving on such details. Focus on a specific situation, try different options and experiment.
The main thing is that the selected candles are of high quality, they do not turn out to be fakes and work as part of properly installed and configured gas equipment.
SPARK PLUGS FOR GAS AND GASOLINE: COMPETITION PROGRAM
We adjusted the tests to the dual-fuel principle - gas/gasoline. First, we ran our usual program, tested in previous spark plug tests, on a VAZ-21083 engine in a regular gasoline version. And then they repeated it on the same engine, having previously equipped it with Italian gas equipment. The principle is common: in the same modes - from minimum idle speed to heavy loads - power, fuel consumption, and toxicity were measured with each set of spark plugs. In addition, the temperature of the exhaust gases was measured: the main horror story of gas opponents is engine overheating!
Advantages
The mixture is used more efficiently, without forming soot from unburned resinous deposits that clog filters and accumulate in various nooks and crannies of the chassis.
The uniform supply of gas vapor does not remove the lubricating oil film from the cylinders and pistons.
The ignition parameters of the mixture make propane-butane fuel safer in terms of fires and explosions in a car than gasoline, in complete contrast to the popular myth about LPG, which is diligently supported and inflated by gasoline producing companies.
candles
Temperature models of BERU 14R-7DU (left) and Denso IW20 (right) spark plugs at a crankshaft speed of 2000 rpm (external speed characteristic, VAZ-21083 engine).
This is how the temperature in the engine exhaust pipe increases when switching to gas. Temperature models of BERU 14R-7DU (left) and Denso IW20 (right) spark plugs at a crankshaft speed of 2000 rpm (external speed characteristic, VAZ-21083 engine). This is how the temperature in the engine exhaust pipe increases when switching to gas.
On gas, the advantages of these spark plugs were even more pronounced. There is a more noticeable increase in power - up to 6%, and fuel economy - up to 7.5%. But the most interesting thing happened with toxicity. A significant improvement in combustion quality, which resulted in a decrease in CO and CH, was compensated by an increase in the content of nitrogen oxides NOx. Everything is clear: the intensity, and with it the combustion temperature, increases, and the yield of this rubbish increases. And the emergency cycle only made the picture worse.
Reviews
| № | Positive |
| 1. | Gennady: Grant has been a year and a half since purchase, no special comments. But the sound insulation is weak, and the vibration insulation is also poor. On the advice of my comrades, I additionally covered it with Visalis. Fortunately, the process is not complicated, I first read the instructions. |
| 2. | Vasily: the car is two years old, I’m happy with the assembly, after the showroom I immediately ordered additional sound insulation. There are no complaints about the body. I systematically carry out inspections at service stations, buy original consumables, and treat equipment with care. |
| 3. | Alexey: despite the fact that the car is in the budget segment, the assembly is decent, the quality is above average. Of course, there are breakdowns, but they are minor and can be easily fixed on your own. |
| 4. | Kirill: during the year of active operation of the machine, there were no comments; I made no capital investments, with the exception of the purchase of consumables for maintenance. Additionally, I sealed the perimeter of the card with a sealant, since it was knocking on the paving stones. Factory vibration isolation. |
| 5. | Dmitry: I’m happy with the car; finally, a domestic manufacturer has learned to make high-quality models. Of course, problems happen, but they can be easily fixed on your own, without going to a workshop. |
| 6. | Vasily: my positive review of the Lada Granta. The quality of workmanship, assembly of parts is above average, spare parts are available, prices are moderate. |
| 7. | Alexander: two years of active use of the car, no own garage, the car sleeps in the open air. There were no major damages, the plastic was not deformed, the fit was tight. |
| Negative | |
| 1. | Victor: the map began to creak already at 350,000 km. I didn’t contact the service department, I applied the sealant myself. At the 65,000 km mark, I replaced the plastic on the right side, it was deformed. |
| 2. | Gennady: after several times the car was idle under the sun, the plastic began to squeak and squeak. I ordered a bulkhead from the service station and additional sound insulation. |
| 3. | Ivan: problems with the car began after purchasing it: knocking, creaking plastic, depressurization of the interior. There are many shortcomings that need to be quickly eliminated. |
Removal of the door card is carried out in exceptional cases: accident, impact, collision, as well as if additional sound insulation is necessary. The process of adjusting the lock and replacing the door is not at all complicated, but it requires attentiveness on the part of the master. To avoid violations of the regulations, read the instructions in advance and watch video tutorials. Buy mostly original parts with factory catalog numbers.
candles
Why? Because the combustion rate of gas fuel is much lower than that of gasoline. And the more sluggish the combustion in the cylinders, the more important is the intensity of ignition of the gas-air mixture. That’s why platinum and iridium spark plugs, with their thin electrodes and inherent high discharge intensity, accelerate the flame front in the cylinders much more efficiently than conventional ones.
How to check and how to set it
What gap should be on the piston rings of a VAZ 2106
The process is not as complicated as it seems at first glance. To begin with, we simply unscrew the spark plugs, then look for damage; if there is none, then you can first clean it, then check the gap.
Of course, the gap can be measured with conventional measuring instruments, just a ruler. However, it is very difficult to determine 0.5 or 0.7 mm by sight! Therefore, now in stores you can buy so-called sets of “feelers” or special keys for checking the gap.
The probes are similar to metal curved letters “G”, with different sizes; we simply place them between the electrodes and determine the gap with an accuracy of 97%. If it is larger, for example on an injector than 1.1 mm, then the contacts are brought closer to each other, you can simply tap with the handle of a screwdriver. If it’s too close, then we move them apart from each other, again checking with a probe.
Watch my video about the gap.
candles
Overlapping temperature graphs for the same set of spark plugs when running on gas and gasoline shows that gas fuel adds up to 60 degrees to an already hot pipe. And candles are very sensitive to temperature! Too low degrees are contraindicated for them: they begin to become overgrown with deposits - products of incomplete combustion of fuel and oil. High temperatures burn off these deposits, but can lead to glow ignition of the fuel. We remind you: this is when combustion begins not from a spark, but from contact with a hot part. And the hottest part in the cylinder is the spark plug insulator.
Why special candles for HBO?
Before discussing the question of which candles will be better for gas, depending on the financial capabilities of the consumer, we need to understand an equally important dispute. Experts who install gas-cylinder equipment on cars originally equipped with gasoline power plants recommend replacing traditional spark plugs with special ones designed specifically for working with blue fuel.
Experts who install gas-cylinder equipment on cars originally equipped with gasoline power plants recommend replacing traditional spark plugs with special ones designed specifically for working with blue fuel.
But many motorists and car enthusiasts do not understand why they should switch from existing spark plugs to some special ones, supposedly designed specifically for igniting gas. They are sure that this is just a clever marketing ploy, and there is no real difference between the devices.
It is important to note that traditional spark plugs are designed to ensure combustion of the air-fuel mixture, that is, a combination of fuel vapor and oxygen (air). And when they switch to working with air and gas, they can quickly lose their performance and completely fail
We must not forget about the higher electrical resistance of the gas-air mixture compared to the air-fuel mixture. Because of this, it is necessary that the gap between the electrodes on the spark plug be smaller to ensure efficient and timely combustion.
Having reduced the gap, manufacturers did not stop there. Currently, you can hear statements from manufacturers of gas-fired candles that only specialized high-quality products, for the production of which exclusively noble metals are used, can work with gas. That is, the most expensive, which is accordingly reflected in the cost of the device itself.
Denso IW 20
It is much more correct to argue for the need to use special candles by the fact that when gas is burned, the temperature turns out to be much higher than when burning conventional fuel. High temperatures cause accelerated wear and therefore shorten the life of the spark source.
All this indicates a real need to use high-quality products made from certain materials.
Modern and effective candles for HBO are based on 3 materials:
- The side electrode rods are made of copper. This is because copper can improve heat dissipation efficiency.
- Platinum. It is used to create soldering on side electrodes.
- Iridium is also actively used. It is needed as a material for creating central electrodes.
This is the general principle of forming a spark plug for gas equipment. Each manufacturer can make their own adjustments, experiment with the design, and apply additional layers of protection to the surface of the case. All this is aimed at reducing the activity of soot formation from combustion gas, increasing operating efficiency and extending the service life of the product.
But this all looks ideal only on paper or in theory. Based on practice and real operating conditions, it is problematic to find devices specifically designed for gas-cylinder equipment that provide a spark.
Given the constancy of favorites, it is possible to determine which spark plugs are currently best suited for gas equipment and why it is worth choosing certain options.
Brisk A-Line
candles
This is where the advantages of spark plugs with thin iridium electrodes appear once again. It is difficult to measure their temperatures - computational modeling methods have been invented for this case. So, the temperature of the central electrode of an iridium spark plug with a thin electrode is 60–80 degrees lower than for a conventional spark plug. Why? The heating area of a thin electrode is much smaller, and the thermal conductivity of an iridium alloy is much higher than that of a steel conventional electrode. Let us add that the heat resistance of platinum group metals is also higher.
WHAT IF YOU DON ' T CHANGE?
But what will happen if you leave ordinary candles when switching to gas? It's okay! This is evidenced by a comparison of ordinary BERU spark plugs and Ukrainian Plazmofor spark plugs specially “tailored” for gas fuel. But the resource of a regular spark plug using “blue” fuel will obviously be lower. However, a simple candle is obviously cheaper than an exotic iridium-platinum...
Our summary: for working on gas fuel, it is better to choose thin-electrode spark plugs recommended by the manufacturer.
Spark plugs, or Gas lighters
How does spark plug gap affect engine performance?
Spark plug gap
ignition - this is the distance between the upper and lower electrodes, necessary for optimal operation and ignition of the fuel mixture.
If this distance differs from the recommended standards, the engine
will
run
smoothly, and either twitching or detonation similar to “triple” of your unit is possible.
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