Moroso 73731 Ultra 40 8.65MM Sleeved Spark Plug Wire Set GM LT1 LT4 Series Engines


  • GM LT Series (Coil On Plug)
  • Matching Plug & Coil Boots
  • Black
  • 8.65mm
SKU: MOR73731 Categories: ,

Highest spark energy transfer. Highest EMI/RFI suppression. Highest horsepower gain. The Ultra 40 Race Spark Plug Wire’s extra insulation extends spark plug wire life against exhaust header heat, chaffing and contaminants. Closely woven fiberglass, impregnated with high-voltage-leak resistant silicone adds up to 8,000 volts of extra insulation. At 40 ohms of resistance per foot, Moroso Ultra 40 Race Spark Plug Wire incorporates a spiral wound nickel/copper alloy conductor wrapped at the optimum ratio to produce the highest level of spark energy while producing the lowest level of electromagnetic and radio frequency interference. The Kevlar core is four times stronger than other aramid fibers cores, allowing an increase in the tensile strength of the wire while reducing the center diameter and at the same time increasing the surrounding insulation resulting in greater dielectric strength.


  • The standard in high performance ignition wire
  • Optimiized EMI/RFI resistance
  • Used in the highest level of racing applications ranging from dual mag Top Fuel Cars thru NASCAR Sprint Cup Series
  • 7mm or 8.65mm diameter wire with 40 ohms of resistance per foot
  • Incorporates a highly engineered spiral wound conductor
  • Maximizes energy transfer and minimizes electro magnetic interference (EMI) and radio frequency (RF) interference noise

Note: Straight plug boot kits are bendable to 45 Degrees.

Weight 1.682 lbs
Dimensions 9.3 × 9.25 × 3.7 in



Manufacturer Part Number



There are no reviews yet.

Be the first to review “Moroso 73731 Ultra 40 8.65MM Sleeved Spark Plug Wire Set GM LT1 LT4 Series Engines”
Prop65WARNING: These auto parts can expose you to chemicals including phthalates and lead. Installing or using these parts can expose you to other parts containing these chemicals and to engine exhaust, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to