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I know of one person who was making a solid 260rwkw through an rb25det, he ran BKR7 something.. Basically required heat range 7 and the BK plug as the BCP's were breaking down for some reason.

From my understanding the only difference between the bk and bc plugs is the plug height, bp being the japanese standard which is higher than the bk. :S

Edited by Cubes

I'm running bcp 7. I noticed no difference between the 6bkr and the 7bcp at startup or during cold running. And the 7's didn't break down and miss once i wound inthe boost

About the only thing i have noticed is if i start the car and move it out of the garage then shut it down it will usually start on 5 the next time until i blip the throttle a couple of times.

Cubes is right about the height thing, though why the 20 and 26 run bcp's and the 25 runks bkr's from factory (well the platinum versions) i dont know.

I'm running bcp 7. I noticed no difference between the 6bkr and the 7bcp at startup or during cold running. And the 7's didn't break down and miss once i wound inthe boost

About the only thing i have noticed is if i start the car and move it out of the garage then shut it down it will usually start on 5 the next time until i blip the throttle a couple of times.

Cubes is right about the height thing, though why the 20 and 26 run bcp's and the 25 runks bkr's from factory (well the platinum versions) i dont know.

I run the same plugs and notice the same problem with mine, have to give it a bit of a kick on the throttle for it to re-fire up again.

Mafia - I'd go to a heat range 8 - a few guys have said I should do this if I get new plugs.

Don't think cold start ups will be a problem up in Makay - I've got the 7's and have had no probs - sometimes a bit of a missfire on cold winter mornings but nothing to worry about.

but is there a chance that I could do damage to my engine by putting colder plugs in?

going from 6 - 8 is ok?

Also, took the turbo of this afternoon, took us 35mins to remove the intake, front dump pipe, lines and turbo. Luckily, my family members own an extremely large trucking company, so we pushed the car over a pit, and my cousin is a mechanic (17yo!) and he had a lot more experience that me under a bonnet and I'm 24!

Top job none the less. Car sits in the shed, with its balls cut of (no turbo lol) while the RB25 housing gets ground up this week to fit.

Saturday, I'll be fitting the turbo back on.

All I can say is, f**k it was easy.

In the meantime, I'm gonig to source a set of "8" heat range NGK plugs if I don't chicken out and get "7"s, and get some new gaskets.

While all of this is happening, I'll be ona road trip to cairns for work!

See you guys when I get back. I have a nifty litte gadget that allows my laptop to connect to the internet over a 10kb\sec link anywhere where there is mobile coverage so no doubt when I'm at a motel bored, I'll connect jump on SAU.

Thanks for your help guys, and if anyone could get back to me about experiences with "8" heat range plugs asap, I'll make a decision and maybe order a set.

Hey Marfia hurry up and sort this issue out so i can bum all the info... So i dont have any of these troubles... When doing my high mount install... LOL

Nah im about to start a high mount TD06-25 kit in the next couple of weeks..... Will start a thread when it all happens....

This kit is on a mates car so if it works well ill do it too....

ahhh, google is my friend..

Spark Plug Heat Range:

    A spark plug's heat range has no relationship on the actual voltage transferred through the spark plug. Rather, the heat range is a measure of the spark plug's ability to remove heat from the combustion chamber. The heat range measurement is determined by several factors:

The length of the ceramic center insulator nose

The insulator nose's ability to absorb and transfer combustion heat

The material composition of the insulator

The material composition of the center electrode

    The longer the insulator nose gives you a larger surface area exposed to combustion gasses and heat is dissipated slowly. This also means the firing end heats up more quickly. We are talking about exposed ceramic length, not extended tip length.

    The insulator nose length is the distance from the firing tip of the insulator to the point where the 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. No matter what the plugs are installed in, be it a lawnmower, a boat, your daily driver or your race car, the spark plug tip temperature must remain between 450°C to 850°C. If the tip temperature is lower than 450°C, the insulator area surrounding the center electrode will not be hot enough to deter fouling and carbon deposit build-ups, thus causing misfires. If the tip temperature exceeds 850°C, the spark plug will overheat which can cause the ceramic around the the center electrode to blister as well as the electrodes will begin to melt. This may lead to pre-ignition/detonation and expensive engine damage. (see the plug pictures that are part of this article)

    In identical spark plugs, the differences 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 temperature is increased by 10°C to 20°C.

    The firing end appearance also depends on the spark plug tip temperature. There are three basic diagnostic criteria for spark plugs: good, fouled, and overheated. The borderline between the fouling and optimum operating regions (450°C) is called the spark plug self-cleaning temperature. This is the temperature point where the accumulated carbon and combustion deposits are burned off automatically.

    Bearing in mind that the insulator nose length is a determining factor in the heat range of a spark plug, the longer the insulator nose, the less heat is absorbed, and the further the heat must travel into the cylinder head water journals. This means that the plug has a higher internal temperature, and is said to be a "Hot" plug. A hot spark plug maintains a higher internal operating temperature to burn off oil and carbon deposits, and has no relationship to spark quality or intensity.

    Conversely, a "Cold" spark plug has a shorter insulator nose and absorbs more combustion chamber heat. This heat travels a shorter distance, and allows the plug to operate at a lower internal temperature. A colder heat range can be necessary when an engine is modified for performance, subjected to heavy loads, or it is run at high RPMs for significant periods of time. The higher cylinder pressures developed by high compression, large camshafts, blowers and nitrous oxide, not to mention the RPM ranges we run our engines at while racing, make colder plugs mandatory to eliminate plug overheating and engine damage. The colder type plug removes heat more quickly, and will reduce the chance of pre-ignition/detonation and burn-out of the firing end. (Engine temperatures can affect the spark plug's operating temperature, but not the spark plug's heat range).

anda bit of other interesting info -

How a Spark Plug Works:

    The basics of a spark plug is that it must perform two primary functions.

To Ignite the Air/Fuel mixture

To REMOVE the heat out of the combustion chamber

    Spark plugs transmit electrical energy that turns fuel into working energy. A sufficient amount of voltage must be supplied by the ignition system to cause the spark to jump the across the spark plug gap, thus creating what is called Electrical Performance.

    Additionally, the temperature of the spark plug's firing end must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. This is called Thermal Performance and is determined by the heat range of the spark plug.

    It is important to understand that spark plugs CANNOT create heat, only remove it! The spark plug works as a heat exchanger, pulling unwanted thermal energy away from the combustion chamber and transferring the heat to the engine's cooling system. The heat range is defined as a plug's ability to dissipate heat. The rate of heat is determined by:

The insulator nose length

Gas volume around the insulator nose

Materials and/or construction of the center electrode and porcelain insulator

  Now to the actual function: As the Ignition is triggered it sends the spark through the rotor, to the cap, down the wire and then it jumps the gap of the spark plug, a spark kernel is created that ignites the air/fuel mixture in the combustion chamber. Proper timing of this spark is not the only concern as described above. You must have the proper heat range (described later) as well as the correct gap.

Opening The Plug Gap:

    On weaker or stock ignitions, opening up the gap CAN increase the spark kernel size, thereby creating a more efficient burn. The problem lies in that any added gap creates more strain on the other ignition parts.

Coils may not have enough stored energy to fire, or in the least case, not enough energy to cross the gap, creating a miss-fire.

Plug wires will break down due to the added resistance as the spark tries to reach ground.

Rotor and Cap, as well as points (if you still have an interest in prehistoric ignitions), and the carbon bushing in the center of the distributor cap will show early failures.

  All of this is because the greater the gap and the higher the voltage requirement to jump the gap. Do not forget the gap between the rotor arm to the distributor cap too. A high performance rotor is a bit longer at the tip, allowing less spark loss or chance of spark scatter in the cap as the spark attempts to jump the plug gap.

    As many of us know that race, it is also possible to slow down a car if the gap is too big. I will get into this later when I describe proper spark plug gaps.

What I said - I'd go for the 8's - I will next time I do it - just not now though as my 7's are pretty new!

The guy I did my last dyno runs with said he's using 8's on a couple of supercharged Vt V8's no worries - you really want to get as far away from detonation as possible.

Bring on next weekend. Man I hope that turbo gets "woken up" by the housing change.

It couldn't hurt to try one heat range cooler than stock plugs, but the benefits are likely to be marginal for normal road use. Maybe worth slipping a set in if planning extensive dyno work or extended high speed/high load running.

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