toy4two

Spark Plugs
http://ngk.com/

NGK IX iridium 3764 BKR6EIX-11 0.044 DOHC $6.95
NGK Iridium plug 4589 IFR6T-11 0.044 DOHC (Original Equipment Manufacturer, and/or Original Equipment Service Part) $8.07

NGK lists 2 different Iridium plugs for the RX300.

Are the expensive ones any better than the IX plugs? The only difference I can see in the tips, is the IX has a tapered tip, and the regular iridium OEM has a non-tapered "long lasting" tip.

What did you guys go for?

toy4two

Looks like the tapered cut gives better fuel economy and performance at the expense of longevity, but they are cheaper.

The traditional OEM cut is made more for durability.

So I'm going for the cheaper, better fuel economy tip in this day and age

"The ground electrode has a tapered cut at the firing end which reduces quenching for better flame core growth and increased ignitability. The combination of fine wire center electrode and tapered cut ground will increase performance, improve acceleration, and fuel efficiency."

http://ngk.com/more_info.asp?AAIA=1363586&pid=2383

Lexmex

The real question you should be asking rather than price, is what do you want to accomplish with the plugs, performance, MPG, etc.?

As I mentioned in my last post, the super plugs like Torquemasters really didn't do it for me until I did the air, electrical and exhaust modifications.

TunedRX300

Lexmex,
To feed your racing habit, a colder plug would be better
I like Denso's Iridium Power plug, center Electrode 0.4mm, U cut ground electrode for better performance. http://www.densoproducts.com/results...artNumber=IK20

Their FAQ is great, even with Denso's marketing pitch.

Q. How long will Iridium Last?
A. Iridium use represents the most significant technological advance in automotive spark plug manufacturing, since platinum was introduced in the early eighties. As vehicle manufacturers produce increasingly complex and efficient automobiles, there is a greater need for long-life plugs that can tolerate leaner fuel mixtures and improved combustion processes. DENSO has responded to this need by developing its Iridium alloy, originally for OE applications. For example, many newer Lexus’ and Toyota models carry an ultra long-life Iridium plug variation (.7mm with platinum tipped ground) that is capable of up to 120,000 miles of service. DENSO Iridium Power plugs, with their .4mm center electrode, have been developed for performance applications. Because gradual wear will “round-off” firing points over time, the concentrated firing power and voltage requirement benefits will be reduced. For this reason, DENSO advises replacement after 30,000 miles.


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Q. Why is the U-Groove special?
A. The patented U-Groove allows the flame kernel to fill the gap formed by the U. This ball of fire develops a larger and hotter flash front a complete combustion. The flat ground electrode design of ordinary spark plugs crush the spark, inhibiting its growth; this effect is known as a “quenching effect.” The simple, but efficient, U-Groove feature results in better fuel efficiency, improved throttle response, and greater firing energy.


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Q. Why are there different heat ranges? Which one should I use?
A. Part of your spark plug’s responsibilities, in addition to firing a spark, is to remove heat from the combustion chamber. This is accomplished by channeling the heat through the insulator material and metal housing. From there, the heat is transferred to the cylinder head where the engine cooling system can go to work. A spark plug’s heat range is its ability to dissipate heat. The “colder” the plug, the more heat it can channel out of the combustion chamber. In a performance application, colder heat ranges may be necessary to handle the extreme temperatures brought on by higher compression ratios, forced induction, and high RPM’s. While “Colder” plugs may seem to be the way to go, please remember that the spark plug must achieve its “self-cleaning” temperature where it can burn off fuel and carbon deposits. Otherwise, the plug could “foul out” where it is prone to misfiring and poor acceleration. A plug that is too “hot” can overheat, also causing power loss, detonation, pre-ignition, and possible engine damage. A good, general rule of thumb is to start with the factory recommended heat range. For every 75 to 100 hp you add to your engine, you may go to the next colder step. DENSO heat ranges move up as they get colder; 16 would be our hottest Iridium Power plug, 34 would be our coldest (ranges; 16,20,22,24,27,31,34)

Lexmex

[QUOTE=TunedRX300]Lexmex,
To feed your racing habit, a colder plug would be better

and a Turbo

HarrierAWD

When it comes to spark plugs, always use the exact model that your vehicle comes with. Doing so will keep your engine running at optimal condition.

Those into racing obviously need to find something else that fits the application, since many components under the hood would be modified.

If a plug promises better gas mileage or performance, steer away from it.

toy4two

I like the way you think. So DENSO's are what come stock on the RX300? Is Lexus the only place I could buy them ($$$), or could I get the same model number at Toyota?

06Harrier

[QUOTE=Lexmex]yeah dude! might havta change the plugs on the 5k oil change as well as the air cleaner

TunedRX300

[QUOTE=06Harrier]Didn't he ran without air filter at the track

TunedRX300

On your owner's manual, P247 is the Engine Specification section, it lists
DENSO SK20R11
NGK IFR6A11

DENSO's IK20 Iridium Power Plug has the same heat range as SK20R11.

Also note that even Iridium spark plug uses Platinum as ground electrode.

Lexmex

[QUOTE=TunedRX300]That's right, I run with no air filter, RX runs faster, but not initially, one needs to give the ECU a chance to recognize the change.

If you have an engine management system (like eManage), leave the air filter on if your race, just one of those things.

At sea level, I would leave the air filter on all the time, even when racing, as the oxygen level would be A-OK.

Lexmex

[QUOTE=06Harrier]Changing the plugs won't do much as I mentioned earlier or even moving up to Torquemasters or a K&N filter (though a K&N isn't a bad idea, I noticed a slight difference up here over OEM), but at sea level, nada. You have to modify your engine more if you want the benefit.

You have to pull on of the plugs out (open up engine cover, take of screw for engine coil, unscrew the plug and take a look).

Lexmex

Densos are what came stock on my RX, though NGKs are listed in the service manual, too. No other brand is mentioned. I am sure there are tons of places to get the Densos other than at Lexus or Toyota, probably someone here knows as I will be using TorqueMasters until something better comes along.

toy4two

I did some research and found out the Torquemasters are the best, but way too expensive for me.

There is a good site that compares all the different plugs:

http://www.silverbulletrx7.com/plugs/

Then I decided either NGK or DENSO. I found a site that compares the NGK vs. DENSO iridium and I'm going with the NGK Iridium IX's:

http://www.spark-plugs.co.uk/pages/t...park_plugs.htm

The DENSOs give better performance, but shorter service life due to the .4mm center electrode, the NGK's have a .6mm and give less performance but longer service life. The RX is too much of a pain to change spark plugs every 30k. Plus, the NGKs are still a better performer than the stock DENSOs which use a .7mm center electrode (longest service life).

This FAQ has the "Which iridium plug should I buy, DENSO or NGK?"

http://www.spark-plugs.co.uk/pages/t..._plugs_faq.htm

Lexmex

[QUOTE=toy4two]I did some research and found out the Torquemasters are the best, but way too expensive for me.

There is a good site that compares all the different plugs:

http://www.silverbulletrx7.com/plugs/

Ah yes, the infamous Mazda RX7 and the TorqueMaster Plug Problems. This scared my buddy Michael (you remember him on the temperature gauge post) away from these plugs for his RX7 and he went with some Greddy Plugs. BTW, L-Tuned parts charged me $12.50 per plug, not $20 as they list on this site above.