Ignition and Spark Plug Wire FAQ

Granatelli Motor Sports, a performance parts manufacturer in Oxnard, California. Our 0-ohm spark plug wires are made in the USA, and we offer more than 800 wire set listings for GM LS and LT engines and for over 25 vehicle makes.

Three things: a 0-ohm conductor that puts more of the coil's energy at the plug, a patented EMI/RFI suppression ring (U.S. Patent 7,185,622) that keeps the low resistance from interfering with radios and engine electronics, and 8mm silicone wire over a spiral-wound, stainless steel–dipped copper conductor with stainless steel snap-lock terminals. Sets come pre-assembled, so there is no cutting or crimping.

Yes. Granatelli wires use a 0-ohm conductor design, unlike resistor-style OEM wires that use part of the coil's energy before it reaches the plug. The patented suppression ring handles radio and electronic interference. More detail: What Are 0-Ohm Spark Plug Wires and Can They Really Increase Horsepower?

Copper dipped in stainless steel, spiral wound. The copper carries the spark energy with very little resistance, and the spiral winding works with the patented EMI/RFI suppression ring to keep interference down.

They are designed not to. The patented EMI/RFI suppression ring (U.S. Patent 7,185,622) suppresses radio-frequency and electromagnetic interference, so the wires work with modern ECUs and digital tuning systems.

They can when the ignition is limiting spark. In LSX Magazine's Project C700 test, a ProCharged LT1 Corvette gained 19.26 rwhp and 18.73 lb-ft after switching to Granatelli coils and 0-ohm coil-near-plug wires, with nothing else changed. Results depend on your engine, tune and combination.

Stronger, more consistent spark can help combustion, but mileage depends mostly on the vehicle, tune, engine condition and how you drive, so we do not promise an MPG number. Read Can 0-Ohm Spark Plug Wires Improve MPG?

Yes. Granatelli 0-ohm spark plug wires are made in the USA.

Granatelli spark plug wires carry a 1-year warranty, and extended coverage is available at checkout.

Yes with factory coils, when you choose the set listed for your engine. With aftermarket coils, confirm the terminals, boot style and length match before ordering.

The best set is the one with the right length for your coil location, the right heat protection for your headers, and low resistance. Granatelli LS and LT sets come in 8", 10" and 12" lengths (plus an 11" truck set), in standard, high-temp, Kevlar-boot and ceramic-boot versions, all with a 0-ohm conductor and a patented EMI/RFI suppression ring. Pick the length first, then the heat protection.

Measure one of your current wires from boot end to boot end and match it: 8" is the 28-1811 series, 10" is 28-1545 and 12" is 28-1629. Engine size alone does not tell you the length, because coil position varies between cars, trucks and swaps. The 12" 28-1629 series also fits 2020–2026 Chevrolet Silverado and GMC Sierra 2500 HD and 3500 HD trucks with the 6.6L V8.

Standard sets give OEM-level heat protection for stock manifolds. High-temp (HT) sets are rated for 800°F+ radiant heat, for headers and turbo manifolds. Kevlar-boot sets add tougher spark plug boots for tight header clearance. Ceramic-boot sets are for the hottest installs, where the plug boot sits close to a header tube. Read Ceramic vs. Kevlar Spark Plug Wire Boots.

Yes. Single replacement wires for the GM LS and LT sets come in every length, color and boot style and cost $38 to $42. The part number is the set number plus -1 and the color, for example 28-1545-1R for one red 10" wire.

Yes. Granatelli lists 0-ohm wire sets for more than 25 makes, including Ford, Mercury, Lincoln, Dodge, Chrysler, Jeep, Toyota, Nissan, Mazda, Honda, Mitsubishi, Subaru, Hyundai and Kia. Search by year, make, model and engine on the site.

Search by year, make, model and engine, or by part number, on granatellimotorsports.com. Each wire set page lists its fitment by year, make, model and engine. If your engine has been swapped or modified, call 1-805-486-6644 before ordering.

Not automatically: coil brackets, routing and required wire lengths can differ between trucks and cars. Match the part number to your actual installed ignition layout.

Engine identity alone does not confirm fitment; verify the terminal style, coil layout, boot clearance and length. Use the listed part number for the installed configuration.

The wrong angle can force the wire against a header or bracket or prevent full seating. Select the boot orientation that fits your actual cylinder-head and exhaust layout.

Custom ignition wire applications may be available. Contact Granatelli Motor Sports technical support with your engine, ignition configuration, desired lengths, and boot requirements.

Send your engine type, coil/distributor model, spark-plug type, routing measurements, header clearance and photos of both terminal connections. Include any existing Granatelli part numbers.

A ceramic boot is a high-temperature spark-plug end intended for applications with tight header or exhaust clearance. It does not eliminate the need to route the wire away from direct contact with hot components.

Select Granatelli ceramic spark-plug boots are rated for up to 2,000°F; verify the rating of your specific wire set. The wire jacket and other components may have different limits.

Select Granatelli protective sleeves are rated for up to 1,200°F, depending on the product. Check the listing for the sleeve supplied with your set.

Avoid continuous direct contact, even with ceramic boots or high-temperature sleeving. Secure and route the wire away from headers and moving components whenever possible.

No. Ceramic boots protect the plug-end area, but wires and other boots can still be damaged by heat, abrasion or direct contact with exhaust components.

Yes. After the engine cools, inspect each boot for full seating, header clearance and cracks; also check the cable jacket and heat sleeve for contact damage.

Do not install a chipped or cracked ceramic boot. Photograph the damage and contact Granatelli Motor Sports with the wire-set part number and purchase details.

No. Separators organize the wires but do not guarantee adequate exhaust clearance or protect every component from radiant heat. Use the correct high-temperature parts and routing.

Yes. Secure them clear of belts, pulleys, steering components, sharp edges and hot exhaust parts to prevent abrasion and heat damage.

Route the wire through the intended clearance path and secure it with heat-resistant separators or supports. Leave enough slack for engine movement without allowing the jacket to rub on a sharp bracket edge.

Engine vibration can abrade the jacket on a sharp edge and create a path for spark leakage. Use a protected routing path and suitable wire separators.

Use the most direct safe route away from turbine housings and exhaust tubing, with appropriate high-temperature protection and secure supports. Measure clearance at operating temperature and throughout engine movement.

Use the factory path only if it maintains safe clearance with the current headers, coils and accessories. After modifications, a revised supported route may be necessary.

Yes. A wire under tension can pull on a terminal during engine movement and become damaged. Choose a wire that follows a safe route with adequate slack and clearance.

Avoid tightly coiling or sharply bending ignition wires. Use the correct length and route the excess without contact with hot, sharp or moving components.

Do not assume one universal bend-radius specification. Route each wire in broad curves without kinks and contact support with the exact part number if clearance is unusually tight.

Do not cut a preterminated wire unless its product instructions specifically allow field termination. Cutting can damage the conductor or leave a terminal that cannot be reattached correctly.

Mark each wire by cylinder and coil position before removing the original set, and verify the final routing against the engine's firing-order diagram. Do not rely on wire color to identify a cylinder.

Let the engine cool, grip the boot rather than pulling the cable and twist gently while removing it. Follow vehicle-specific service precautions around high-voltage ignition components.

The boot should engage the terminal securely without being stretched or contacting nearby components. If the connection feels loose, stop and verify the terminal and boot are the correct type.

A wire change alone generally does not set the correct gap. Use the gap appropriate for your engine, plugs, tune and boost level.

Only use boot styles and wire sets compatible with each cylinder's plug and coil connections. If header clearance varies, contact technical support with photos and the part numbers you plan to use.

Provide a photo looking down at the spark plug beside the header, a view of the coil location and a photo of the current boot and terminal. Include the engine and wire-set part number.

Measure the routing path between the coil/distributor terminal and spark plug, allowing for bends, heat clearance and engine movement. Confirm whether the product length is measured end-to-end or by wire only before ordering.

Avoid aggressive solvents and abrasive cleaning unless specified for the product. Use the maintenance method provided with your wire set and inspect for physical damage after cleaning.

Confirm each wire is fully seated on the correct coil and plug, inspect routing and check for damaged terminals or incorrect length. Read trouble codes and inspect the plug and coil before attributing the misfire to the wire.

Confirm the terminal is correctly matched and fully engaged, then inspect the plug, gap, cylinder-specific wiring and coil. Read the stored trouble codes before moving components.

An incompletely engaged connection can open or arc as the engine moves. With the ignition off, inspect terminal fit and reseat or replace damaged components.

With the ignition off and engine cool, inspect the boot and spark-plug insulator for thin dark tracking marks, cracks or burn paths. Replace damaged components and investigate the underlying plug or seating issue.

Yes. Oil contamination can interfere with a secure connection and accelerate deterioration. Repair the leak and clean or replace affected parts as required by the vehicle service procedure.

Check wire routing and heat exposure, boot fit, plug condition and coil operation under the same conditions. Record the fault codes and avoid assuming the wire is the cause without testing.