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NGK IRIDIUM XI Spark Plug 8 HEAT: Mazda 86-95 RX-7

Price :
  • Model: BR8EIX
  • Manufactured by: NGK


HR recommends NGK Spark Plugs for Street, High Performance and Race rotary engine applications. There are a few different options regarding spark plugs for the rotary engine. Let our decade + of hands on experience, testing, retesting & high HP yields do the work for you. We have broken proper plug selection down into an easy to understand, 4 basic categories. Standard, Platinum, Iridium & Competition. (see below)

This NGK BR8EIX spark plug is the IRIDIUM XI. For mostly Highway Driving, N/A only, No porting but high performance, 8 Heat.

Specification part number breakdown: NGK BR8EIX
B= 14mm Thread Diameter
8= Heat Rating
E= 19mm Thread reach
I= Iridium
X= Booster Gap (Firing End Construction)

For N/A & STOCK Turbo 13B engines that want a pure OEM plug for original reasons, zero performance or reliability gains, the rawest form of OEM plug available, one ideal configuration, installs with normal spark plug socket.
- Configuration: Use Two (2) Standard TRAILING (BUR9EQ) & Two (2) Standard LEADING (BUR7EQ) spark plugs per 13B engine... a total of 4 plugs.

For Stock or slightly Modified N/A or Turbo 13B engines. Same as the Standard plugs with slightly increased performance, a few cents more expansive, a little more spark intensity, longer electrode life, a more complete burn, Two ideal configurations, installs with normal spark plug socket.
- Configuration #1 (N/A & Stock Turbo engine w/ a few bolt-ons, stock boost level producing UP TO 220 HP) Use Two (2) Platinum TRAILING (BUR9EQP) & Two (2) Platinum LEADING (BUR7EQP) spark plugs per 13B engine... a total of 4 plugs.
- Configuration #2 (Modified Turbo engine w/ bolt-ons, slightly increased boost levels producing UP TO 260 HP) Use Four (4) Platinum TRAILING (BUR9EQP) & spark plugs per 13B engine... a total of 4 plugs.The colder Trailing plug (heat range 9) provides substantial detention resistance needed to keep the engine "safe" when boost has been increased above stock levels vs's that of the leading plug. (heat range 7) This WILL NOT make extra power however, it will help to protect the engine at higher boost settings.

For N/A & Turbo engines ranging from bone stock to hard-core race. The ultimate in plug performance, max yield, all (4) plugs will use a matching heat rang, the most potent spark, high output, long electrode life, complete burn, about the cost of platinum, superior, requires a thin wall socket to install/remove.
#1 BR7EIX (x4) Mainly City Driving, N/A only, No porting but high performance, 7 Heat.
#2 BR8EIX (x4) Mainly Highway Driving, N/A only, No porting but high performance, 8 Heat.
#3 BR9EIX (x4) City/Highway Driving, Street ported N/A, Non-ported Turbo with slightly increased boost & bolt-ons , 9 Heat.
#4 BR10EIX (x4) City/Highway/Race, BridgePorted N/A, high boost turbo, 470 HP, pump gas, 10 heat

For the most extreme performance, race only, max porting, highest boost, outright race. Short run times, zero street use, hard cold starting.
#1 R6725-10.5 (x4) 10.5 heat
#2 R6725-11.5 (x4) 11.5 heat


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