While a gap that is too wide may not allow the ignition system to fire the plug at all. However, if you drive at full throttle most of the time, you should reduce the gap by about 0.010" for better performance. This is a used plug from a small-block Chevy that had started out with roughly 0.040-inch gap and the copper core has worn to 0.050-inch. Why is my Minecraft server always using 100% of available RAM. A spark plug’s reach is defined as the length of the threads. One thing you can do to improve performance is by. An iridium plug uses an extremely fine wire (0.5 to 0.6mm or 0.019-0.023-inch) that, because of its small size, can reduce the required coil voltage by as much as 20-percent. Even though they only give a hard number, 2.4%, in relation to the former, I get the impression you can imply similar results for the later, although it would be nice to have a directly measure hard number for that also. The disadvantage is this will concentrate the spark on one side of the center electrode. Any weakness in materials or construction the spark will find an easier path to ground than the plugs. Think about spark the same as water thru a garden hose. You can now use your tool to adjust the bottom electrode. How does ambient temperature affect engine efficiency and fuel consumption? The basic construction of a spark plug uses an upper contact tip that receives voltage from the ignition system through a spark plug wire. Fine-wire plugs like this Denso Iridium (left) requires much less voltage to fire the same spark plug gap versus a standard copper-core plug (right). © 2020 Power Automedia. I have documented dyno sheet where we lowered a spark plug gap from .045 to .032 and picked up 35 hp. So we decided to talk to Director of Engineering for Autolite, Jerry Reeves, who not only knows this subject really well, but is a car guy, too. These three spark plugs are all tapered seat, projected nose yet when lined up at the seat, they are three different lengths. This process occurs thousands of times per minute, but for it all to work, the source of the spar… What does a healthy spark plug look like? The path for heat to escape from the center ceramic to the plug’s steel body is at the very bottom of the steel shell. Can I draw a better image? Replacing this with a fine-wire plug would allow running a decent plug gap and still offer the potential for improved combustion. Better for side-gapping a cut-back spark plug would be an old-school round wire gapping tool, carefully inserted at about a 45-degree angle. It can improve the acceleration profile of your vehicle. (Left) Often, a projected-nose plug (shown on left) with a long ground strap can build excessive heat and cause pre-ignition issues. As power from late model engines continues to escalate, selecting a spark plug that will live and not contribute to problems becomes a much more difficult assignment. Cold spark plugs offer a shorter heat path to the shell. An Iowa native, Smith served a variety of roles at Car Craft before moving to the senior editor role at Hot Rod and Chevy High Performance, and ultimately returning to Car Craft. (Right) This melted plug was destroyed when the nitrous system went lean. Large spark plug gap setting demands higher voltage (electrical pressure) for spark to jump the large distance gap. Motor Vehicle Maintenance & Repair Stack Exchange is a question and answer site for mechanics and DIY enthusiast owners of cars, trucks, and motorcycles. Tool to help precision drill 4 holes in a wall? Pre-ignition is where combustion initiates before the spark plug fires as the result of an extremely hot, glowing ignition source in the chamber. All rights reserved. So it’s best to install spark plugs dry. How to make particles on specific vertices of a model, How to create a spiral using Golden Triangles. Is there any utility for performing ICMP testing ("ping") in only one direction? Beyond manufacture's recommended gap range, is there any hard data on optimizing plug gap for maximum fuel efficiency? Hopefully we’ve managed to dispel a few myths and provide facts that you can use to make your next tuning decisions a bit more accurate. A wider gap increases the load on the ignition system, demanding higher voltage. This applies to fine-wire plugs as well, which use a copper core to improve conductivity. However, when dealing with a modified engine, you should adjust the NGK iridium spark plugs as needed. As you widen the gap, you need to increase voltage to cover the gap. Most competition engine builders commonly choose a colder heat range plug to prevent possible engine damage. ", Gorilla glue, when does a court decide to permit a trial. This compares an extended-nose plug (left) to a standard-reach plug (right). Pischinger and Heywood [10] found that the cyclic variation of flame propagation near the spark plug influences the amount of heat release at the spark plug gap and this greatly influences the so-called rapid burn angle. This Denso plug is called a U-Groove referencing the U-shaped ground strap. While the spark still occurs, it can retard the timing by as much as two degrees. Conical seat Spark plug is sealed in cylinder head with a conical (tapered) seat. This is a cold heat range plug so may not be a wise choice for every day street use. The gap spacing of general spark plugs is between 0.6 and 1.3 mm. It was reported by Hori et al. (Right) Sometimes a shorter spark plug can improve clearance with tight-fitting headers. Cut back ground straps are also useful in applications where a standard strap may interfere with the piston dome. A precise air and fuel mixture requires a precise and timely spark to burn it. It is widely accepted that the early flame development deeply influences the subsequent combustion phase [8]. That’s walking a very fine line. But if it’s a race engine with compression ratios of 13 or 14 or 15:1, with 0.030in or 0.040in plug gaps, the ignition system is greatly disadvantaged. There’s a war being fought out over the internet right now – and the first victim in this explosive war of words is the truth. First, we should define the terms “detonation” and “pre-ignition”. Spark plug companies don’t recommend anti-seize on threads because it lowers the torque required to install the plug. The recommended spark plug gap is designed to be adequate for cold starting and smooth driving on a car that is in need of an engine tune up. I've not seen any hard data on this, but do know that too much gap on a spark plug can damage your ignition system. 1. The larger the spark plug gap is, the longer the arc will be generated when igniting. We removed the threads on these two plugs to illustrate heat range. We should also define the term “copper core” when talking about spark plugs. While it is a platinum plug – that had little to do with its failure. Longevity is a key advantage of platinum spark plugs. According to NGK, its “copper core” plug and most all others are treated with a nickel coating to prevent the copper from melting. An accomplished engine builder and technical expert, he will focus on the tech-heavy content that is the foundation of EngineLabs. For high-load, max-cylinder-temperature track excursions, a colder, standard nose or even surface gap plug is the wisest choice. (maintenance details). Any given car is going to be different. If you pay close attention, you’ll notice that most racing plugs do not employ extended-nose center electrodes. A “hot” spark plug lengthens the depth of the ceramic which lengthens the distance from the center electrode end of the plug to where it contacts the spark plug shell. It’s even tougher if the engine is fueled by … The change to the hotter plugs improved the idle quality only slightly by reducing the unburned hydrocarbon (HC) count along with a slight improvement in CO2 which is an indicator of combustion efficiency. While spark plug gap does not have a direct effect on timing, excessive gap in a power adder application can easily cause engine misfire. There's no disadvantage to a wide gap. “I wouldn’t want someone to run a projected tip, standard automotive plug in a 1,200 horsepower, 32 psi LS engine because it’s street-driven.”. This makes it hard to come to a strict conclusion. If they are supposed to be delivered with a specific gap, why fool with them? We’ve seen statements from tuners claiming that fine-wire plugs run “hotter” than normal plugs and that you should avoid fine-wire plugs especially in supercharged or turbocharged applications. A wide gap creates a longer spark arc but without sufficient "juice" from your ignition system, (including amps), it can be weak and yellow in color. The results showed that the amount of crossover of the ground strap, the dimensions of the ground strap and the gap width are the primary factors affecting the spark onset, flame initiation and kernel growth. Changing the electrode gap is called a spark plug gapping. We recently added Holley’s Sniper EFI to a 468ci big-block Chevy, and while it seemed to idle well, we used an EMS 5-gas exhaust gas analyzer to help us dial in the timing and fuel. rev 2021.2.12.38571, The best answers are voted up and rise to the top, Motor Vehicle Maintenance & Repair Stack Exchange works best with JavaScript enabled, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site, Learn more about Stack Overflow the company, Learn more about hiring developers or posting ads with us, Good question. Choosing the most restrictive open-source license. Proper Spark Plug Gap A gap that is too close will not deliver the proper amount of spark to satisfactorily cause the air fuel mixture to burn cleanly. no, not wider gaps necessarily , they are just there for high energy systems versus the older points-based system, which had lower voltage coils and couldn’t jump the bigger gap. Another option for power-adder applications is to choose a surface-gap plug. With a traditional copper-core plug, the center electrode will wear much more quickly and the gap will increase. A performance ignition system allows you to open up the spark-plug gap. The spark plug itself, and the residue that forms on it, would indicate whether the gap is too big or too small. That means that there is higher voltage build up in the ignition system (ignition coil, distributor, ignition wires) prior to the spark discharge. How much does spark plug gap affect fuel efficiency? And for me, they work as promised. This grease is an insulator not a conductor. The spark gap is much wider than a typical J-gap plug (up to 3 mm) so a surface gap plug requires much higher firing voltages and a high performance ignition system that can generate a lot of juice. These seem particularly bad for RFI. Fine-wire plugs were designed for use in late model engines that are tasked with the seemingly ridiculous goal of lasting for 100,000 miles in a production engine. I'd probably hook vacuum advance to the manifold to provide more timing for more vacuum for the brakes. Why do my mobile phone images have a ghostly glow? While the fine wires are indeed poor conductors, Reeves tells us that the addition of the precious-metal portion of the center electrode contributes only a small amount of heat and is not a source of pre-ignition. Platinum also handles high heat, enabling the spark plug to wear better. Cuttting Ground Electrode. For street engines, the extended-nose is good for part-throttle efficiency. So a small intense spark is much better than a big, weak spark, especially when dealing with richer fuel mixtures and more volumes of fuel being burned. Why does my cat chew through bags to get to food? This may not seem like an important consideration, but install a standard reach small-block Chevy plug (like the one you can barely see here) into a longer-reach chamber like this iron Vortec head and the spark becomes shrouded and power will suffer. We'll send you raw engine tech articles, news, features, and videos every week from EngineLabs. There is a lot more information on the page which gives indication about how the gap affects things, so it's worth a read in my book. We’ll start with detonation, which is an uncontrolled combustion pressure spike that can occur at any time, even before the spark plug fires. The basic operation of an internal combustion engine, which describes your car's gasoline motor, is not particularly complex. Note how much longer the extended-reach plug’s ground strap is compared to the standard-reach. Rejecting Postdoc Extension for Other Grant Management Opportunities. So you might look around for a shorter plug to create more clearance for the spark plug boot. Then we discovered the engine still had the cold spark plugs in it from the previous year’s dyno test. The plugs were two steps colder than the stock heat range and appeared dark and soot-colored. List of the Advantages of Iridium Spark Plugs. E3 has taken multiple spark plug design features, such as cut back ground electrodes, sharp edges and surface gaps, and combined them to create a new ground electrode design. This can occur as a result of high cylinder temperature and/or pressure that causes the air and fuel to self-ignite. The spark plug also has a steel jacket, which allows the threaded end of the plug to be torqued into the cylinder head. A nice, fat spark exposes more of the air/fuel mixture to ignition, and starts the flame kernel more readily. Conversely, supercharged, turbocharged or nitrous applications will demand a narrower plug gap of 0.025 to 0.030-inch. Spark Plug Gap FAQs Q: Why Do You Need To Gap a Spark Plug? Accordingly, small differences in the kernel formation rate or location may produce significant in-cylinder pressure variations [9]. Stack Exchange network consists of 176 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. Another advantage of platinum spark plugs is that they run a little hotter, which burns deposits off the spark plug better and helps prevent fouling. Even with late-model fuel injection and data logging, reading a spark plug is still a viable art that is an important part of tuning. Spark plug gap refers to the gap between the spark plug center electrode and the grounding electrode. Copper is used as the core material for nearly all spark plugs. The addition of precious metal in the center electrode has nothing to do with the heat range of a spark plug. Spark plugs with a hotter heat range will burn off carbon deposits more easily than a colder plug. When you make the switch to iridium spark plugs, then you may notice an immediate improvement to your acceleration profile. As is stated at the end of the excerpt, you'd need to run your car on a dynamometer to find the best spark plug gap. The generalized statements about the gaps being too small causing insufficient burn and too wide having a weak spark are spot on. Why didn't Escobar's hippos introduced in a single event die out due to inbreeding. The 1978 plug gap spec was reduced to .040" and we gapped all future plugs to that spec with no more issues. A light brownish discoloration of the tip of to porcelain insulator indicates the proper operation of the spark plugs with the gap being ideal or close to ideal for the most recent engine speeds. The plug on the left is a cold plug with a shallow ceramic depth. It is important not to exceed the installation torque, however it is a good idea to torque the spa… The plug on the right is a much hotter plug with the ceramic connecting with the outer shell much deeper. So it’s best to install spark plugs dry. Changing spark timing to use a lower octane fuel? We promise not to use your email address for anything but exclusive updates from the Power Automedia Network. The plug melted because of excessive heat in the chamber. If you don't, the spark will not jump the gap as efficiently and therefor you won't get the best performance out of your vehicle. The new plugs were a different brand (Champion) and the spark was arcing from the plug boot down to the plug base. 2/1000 is less than 5% so I would think that is fine. Thus, to check the spark plug gap at high engine speeds, you'd need to run at full throttle and immediately turn the ignition off without allowing the engine to idle. We’ve seen a 20 hp loss from incorrectly installed plugs like this on a 500 hp engine. The center electrode ends in a gold or palladi… I ran across a scientific journal article which provides some statements with some hard data and some additional references: Impact of spark plug number of ground electrodes on engine stability. One of the most contentious areas of disagreements surrounds fine-wire spark plugs. The way an engine is used has a big effect on choosing the proper heat range. While a gap that is too wide may not allow the ignition system to fire the plug at all. The recommended spark plug gap is designed to be adequate for cold starting and smooth driving on a car that is in need of an engine tune up. Spark plugs that do not have the proper gap lead to premature wear, ignition system stress, and even cylinder misfires. I've read conflicting reports regarding how plug gap can affect fuel efficiency. The colder plug on the right has a much shorter path for the heat to travel; it pulls heat more efficiently from the plug tip so it will not burn off carbon as easily. The assembly of spark plugs with this kind of sealing requires an especially sensitive approach. A commonly-held, yet mistaken conclusion is that the center electrode contributes to pre-ignition because iridium and platinum are poor conductors of heat. Expect higher plug erosion with smaller gaps. If the ignition can fire it, and the elecrode clears the piston, wider is better. As an example, the supercharged production 2018 Dodge Hellcat—which makes 707 hp from its 6.2L Hemi—specs an iridium spark plug. As the ground strap length increases, this adds more mass and can slow the growth of the initial flame kernel. For subdued street driving, a standard heat range, extended-nose spark plug would be a great choice, but only if the engine is not called upon to make maximum power. You might partially compensate for over-retarded factory "emissions" timing in midrange by having a smaller gap, due to it sparking milliseconds sooner. For tuning these engines, it’s best to start with a very cold plug with a short ground electrode. From there, the heat is dissipated into the cylinder head and eventually into the cooling system. Also, as you increase pressure at the top of the compression cycle, you'll need to either increase the voltage output to the spark plug and/or reduce the gap of the spark plug. As the hot gases from the explosion expand, they push a piston, which in turn is linked to a shaft that transfers power to the transmission and ultimately the wheels. All-in-all, I've not found any empirical data which shows exactly what the difference is between gaps on any given vehicle, but as I've stated, every vehicle line is going to be different anyway. Why The LS Is Superior To The Small-Block, How To Order Custom Valves With Ferrea Racing, Fine Finish: How Engine Pro’s Nitro Black Valves Stay, AMSOIL Supports New Smaller, Half-Ton Diesels With Two New, PerTronix Is Expanding Its Line Up Of Late Model FlameThrower, High Performance Education: How SAM Tech Prepares Its, 2020 Product Showcase: Whipple’s New Superchargers for S197, Engines of the $10K Drag Shootout 3: The Year Of The Junkyard, The Answers: DeatschWerks’ Responses To Your Fuel System, Your Questions Answered By The Experts At Ferrea Racing, How Exactly Does Dual-Fuel Work on a Gen 3, Quicksilver’s Crate Engine Program: Past, Present, And The, ED-OP: Is The Evolution Of Building Horsepower A Good, April Fast Talk With Jeff Smith – Industry Awards And, Six Things You Need To Know About Running Sixes With A, Five Reasons To Upgrade Your Ignition System On Your Hot, What To Look For When Buying A Used Holley, 2020 Product Showcase: Big-Block Mopar B/RB Main Caps From, 2020 Product Showcase: Koul Tools Nylon Fuel Line Assembly, SEMA 2020: New DeatschWerks Products to Feed Your, SEMA 2020: Wayne’s World Brings Us RaceTec Pistons’ Autotec II, SEMA 2020: COMP Cams Introduces LST Blower Cam, IMIS 2012: Wiseco’s Second-Gen Quick 16 BBC Drag Race, IMIS 2012: Canton’s New Road Race/Street Coyote Oil, IMIS 2012: Milodon’s New Drag/Road Race LS Dry Sump Oil, High-Performance Racing Fasteners: How ARP Fasteners Are, Engine Pulleys — Old-School Tradition Meets New-School, Brotherhood Built: Behind The Scenes At Firepunk, Ford vs Chevy Comparison – Size, Weight, and HP Per, Video: How To Install COMP Cams LS Rocker Arm Trunion Upgrade, Why The LS Is Superior To The Small-Block Chevy, How To Order Custom Valves With Ferrea Racing Components, Fine Finish: How Engine Pro’s Nitro Black Valves Stay Strong, Video: 460 Windsor — Big-Block Cubes From A Small-Block Ford, A Guide To Ford V8 Engine Block Casting Numbers, 1952-1996.