Lexus-Toyota 1UZFE Spark Plugs

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Spark plugs are fun! Since we all run Toyota engines & *most* people are running Denso ignition systems… That pretty well limits us to two brands of plugs that will give consistently good performance over their life. NGK & Denso, so that’s what we’re concentrating on! (Besides. JDM owns anyways, we all know that!) *note* All plugs listed will be currently available now. That means old plugs with new names, replaced plugs. Who cares. This is 2/2006.
Stock 1uz-fe plugs: NGK Denso
Normal/OEM Iridium: NA IFR6T-11
Premium Iridium: BKR6EIX-11 IK20
Original OEM (Platinum): BKR6EP-11 PK20R11
Premium Platinum: BKR6EGP NA
Standard: BKR6ES-11 NA
Standard, Grooved Strap: BKR6E-11 K20R-U11
Blah blah blah .

Iridiums last 60,000-80,000+ miles on “unmodified” engines. Plats, Toyota specifies for 60,000 miles. Copper, 30,000-60,000 miles. (A year under boost) Then again. Most standard plugs cost $1.50-$2usd per plug… You do the math. Blah, blah blah .
Quick, random good stuff to know:
* You can not use platinum plugs with n2o. NGK.com (Not NGK affiliated) – “There have been instances where the platinum tip has lost its bond to either the center or ground electrode when they were used in a motor with nitrous.”
* Do not use platinum plugs under boost – never, never, never!

* Only use copper, or Iridium plugs under boost!
* Single electrodes guys. Single electrodes!
* It is advisable to run 2 heat ranges colder when going from NA to boost, plus 1 range colder per bar of boost. (Or one range per 70-100bhp)
* Advancing ignition timing by 10° causes tip temperature to increase by approximately. 70°-100° C.
la-la-la

Now, to understand the most critical part of buying a spark plug; It’s heat range!

Quote:
The insulator nose length is the distance from the firing tip of the insulator to the point where insulator meets the metal shell. Since the insulator tip is the hottest part of the spark plug, the tip temperature is a primary factor in pre-ignition and fouling. Whether the spark plugs are fitted in a lawnmower, boat, or a race car, the spark plug tip temperature must remain between 500°C-850°C. If the tip temperature is lower than 500°C, the insulator area surrounding the center electrode will not be hot enough to burn off carbon and combustion chamber deposits. These accumulated deposits can result in spark plug fouling leading to misfire. If the tip temperature is higher than 850°C the spark plug will overheat which may cause the ceramic around the center electrode to blister and the electrodes to melt. This may lead to pre-ignition/detonation and expensive engine damage. In identical spark plug types, the difference from one heat range to the next is the ability to remove approximately 70°C to 100°C from the combustion chamber. A projected style spark plug firing tip temperature is increased by 10°C to 20°C.

Quote:
The term spark plug heat range refers to the speed with which the plug can transfer heat from the combustion chamber to the engine head. Whether the plug is to be installed in a boat, lawnmower or racecar, it has been found the optimum combustion chamber temperature for gasoline engines is between 500°C–850°C. When it is within that range it is cool enough to avoid pre-ignition and plug tip overheating (which can cause engine damage), while still hot enough to burn off combustion deposits which cause fouling.
The spark plug can help maintain the optimum combustion chamber temperature. The primary method used to do this is by altering the internal length of the core nose, in addition, the alloy compositions in the electrodes can be changed. This means you may not be able to visually tell a difference between heat ranges. When a spark plug is referred to as a cold plug, it is one that transfers heat rapidly from the firing tip into the engine head, which keeps the firing tip cooler. A hot plug has a much slower rate of heat transfer, which keeps the firing tip hotter.

An unaltered engine will run within the optimum operating range straight from the manufacturer, but if you make modifications such as a turbo, supercharger, increase compression, timing changes, use of alternate racing fuels, or sustained use of nitrous oxide, these can alter the plug tip temperature and may necessitate a colder plug.

A rule of thumb is, one heat range colder per modification or one heat range colder for every 75–100hp you increase. In identical spark plug types, the difference from one full heat range to the next is the ability to remove 70°C to 100°C from the combustion chamber.
The heat range numbers used by spark plug manufacturers are not universal, by that we mean, a 10 heat range in Champion is not the same as a 10 heat range in NGK nor the same in Autolite.

Some manufacturers numbering systems are opposite the other, for domestic manufacturers (Champion, Autolite, Splitfire), the higher the number, the hotter the plug. For Japanese manufacturers (NGK, Denso), the higher the number, the colder the plug.

Do not make spark plug changes at the same time as another engine modification such as injection, carburetion or timing changes as in the event of poor results, it can lead to misleading and inaccurate conclusions (an exception would be when the alternate plugs came as part of a single precalibrated upgrade kit).

When making spark plug heat range changes, it is better to err on the side of too cold a plug. The worst thing that can happen from too cold a plug is a fouled spark plug, too hot a spark plug can cause severe engine damage.


Stock plugs for various FI’ed import vehicles:
Toyota
Supra – 2jz-gte Same as 1uz-fe. NGK heat range 6, .044 gap
Supra – 7m-gte (BKR), NGK heat range 6, .032 gap
MR2 – 4a-gze (BCR) NGK heat range 6, .044 gap
MR2 – 3s-gte (BKR) NGK heat range 6, .032 gap
Mazda
MX6 GT – 2.2L Turbo NGK heat range 6, .044 gap
Nissan
300ZX – VG30DETT NGK heat range 5, .044 gap
Audi/VW
Virtually everything FI’ed uses the same plug as a 1uz-fe.
etc. on down the line.
The moral, If it’s boosted from the factory & not a rotary, it most likely runs an NGK 6 heat range!Now for anyone doing some mild-medium FI, or n2o. The obvious choice would be the BKR8E / BKR8ES. The problem, is that while NGK still makes BKR8xx’s. They don’t make/distribute them anymore! The coldest they go in the BKR seires is the 7. On the other side… The BCR’s WILL fit, and DO go to 8.
There in lies the question… Swap to a colder plug with a different end, or stick with the BKR’s that don’t go as cold.
Here’s your answer!
Use the BKR8E! NGK Part no. 6097.
It’s the plug of choice for:
The modified 3s-gte crowd, nearly all the boosted/modified Supra owners (Even all NA-T’s), 300zx’s Audi/VW people.

Can you use Iridium plugs under boost? Yes! Despite my inital thoughts on the matter; research has shown they work very, very well! Like N/A, nothing currently works better. If you can afford them, NGK BKR7EIX no.6988 / Denso IK22.
(I would highly suggest doing all of your tuning on cheap copper plugs. Crappy tuning will show up faster as they get destroyed faster. Most of the time… You can replace every copper plug on an engine for what one good Iridium plug costs. Small mistakes, don’t tune into $80-120 mistakes!)

Lastly,
Plug gaps!
Stock gaps are .044… We’re running FI, and that’s no longer acceptable! For mild boost .031-.035 is the sweet spot! for heavier boost, drop down to .028-.031.
*Be very careful adjusting plug gaps. Most OEM’s say not to adjust it more than 0.008. Lame… Make sure they still line up when you gap them!

NGK plug reference:


Denso plug reference:

Do you have any questions? If so, please head over to the forums to get a quick answer or share your experience!

This is a freelance site with no support by huge companies.  I have been doing most of the R&D and technical write-ups by myself with my personal money and literally thousands of hours of my time.  I have taken extra steps to demonstrate in details how things are done.  Currently I am one of the few people doing Lexus V8 research and performance enhancement.  This effort comes from my personal love for this wonderful engine.  Most of the modifications are from trial and error. There's no cookbook for 1UZFE mods and its unknown territory for much of supercharger performance.  The parts, labor, web development and site hosting are 100% paid from my personal hobby money.  If you feel my efforts help you in any form, please do not hesitate to donate any amount of money to support this site. You have no idea how much I and the entire Lexus and Toyota community appreciate it!

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