Spark Plugs

[Galois]

Got mine at repco as well, just give them a call and ask what they have in stock? They'll surely be able to order some in as well.

[ClutchBurndout-:(]

instead of making a new thread

what gap should i use for 8-10 psi boost, rb25det with splitfire coilpacks, zorst and fmic?? 1.1 or 0.8?

rb25det

[Galois]

Try 1.1 mate, then if it misfires at full boost and high rpm go to 0.8. It's a bit of trial and error, but with splitfires you should be fine with 1.1 at normal-ish boost. Bigger gap is better for the flame front spread remember, so go bigger first.

[ClutchBurndout-:(]

Try 1.1 mate, then if it misfires at full boost and high rpm go to 0.8. It's a bit of trial and error, but with splitfires you should be fine with 1.1 at normal-ish boost. Bigger gap is better for the flame front spread remember, so go bigger first.

ok will give it a go

what do you mean by flame front spread?

[Galois]

When the air and petrol are injected into the cylinder there is heaps of turbulence. When the spark ignites at the top of the cylinder, it creates a small flame from the petrol burning. This flame spreads and becomes the explosion. This of course all happens in an instant. But the initial flame front will be larger for the larger gap spark plug, which leads to quicker spread and better (more intense) explosion.

That's why you always run the biggest gap possible. The problem is failing coilpacks generate less power and extra boost causes high turbulence and pressure which makes it difficult to get a spark across the gap. There's a really good explanation on here somewhere, I'll try to find it and post it up...

[Galois]

http://www.skylinesaustralia.com/forums/Ru....html&st=20

High combustion pressures does mean more resistance across the gap. This will obviously as stated earlier require more energy to get across the gap.

From here is were most went wrong. It doesnt leave some power over for the next fire, it doesnt make the next spark build quicker.

Dwell is the time the coil is turned on, and has to be long enough to reach full coil saturation. This means the the full power the coil can deliver.

Obviously as engine revs go up we have less time to achieve this, so our ignition system has what we call dwell extension. At higher RPM the coil is turned on EARLIER, which means the dwell is longer (cant be turned off later as when coil is turned off it fires, this would affect timing).

Most coils with dwell extension (ALL since contact points went) will always reach full coil saturation. This means that if our coil can create 50,000 volts at idle, it will do it at 7000 rpm as well. Now, larger gaps, or high resistance in the leads, HIGHER compression pressures and leaner mixtures is going to use MORE of that 50kv to get the gap to ionise, that is, become conductive, so the spark can jump the gap. We have 50kv there, but we want to use the least amount possible.

The reason for this, is that whatever is NOT used to jump the gap, keeps the spark burning for a longer period of time. More ionisation voltage means LESS spark duration, or time the spark is actually there. The longer the better because the air fuel mix is moving due to turbulance, the longer the spark is there the better the fuel is ignited.

[manuel]

I had standard bcp7 copper plugs gapped at .7 when i got my car tuned for 254kw at wheels on 16psi with my standard coils which have seen 120000klms and the silicone band aid treatment. Antything more than .7 was making car miss badly.

Got some splitfires and gapped the plugs back to 1.1 and the car runs perfect, no miss or hesitation. Big improvement in down low response and also revs harder up top.

My research indicates that a new set of coils or some splitfires will allow a better spark to the plug thus allowing you to run a bigger gap. Bigger gap means better combustion of fuel, bigger explosion=more power and igniteability.

I have seen this...... i have done this....believe me you want this.

[Galois]

My research indicates that a new set of coils or some splitfires will allow a better spark to the plug thus allowing you to run a bigger gap. Bigger gap means better combustion of fuel, bigger explosion=more power and igniteability.

I have seen this...... i have done this....believe me you want this.

I'm doing this this week, can't freaking wait!

You're 100% right there, there newer coilpacks can generate the required voltage quicker and reliably which ceases misfiring at high rpm and general stuff ups like only firing on 5 cylinders.

Glad you had success mate. My car's pretty much stock but I can't wait to run a bigger gap and stop the missing.

[Guest]

Get the NGK ones off ebay (think they're from the UK by memory). The same ones here were about $20 each, whereas the ones straight from the NGK factory over there are roughly $5-$6 posted each. Work perfectly and haven't had any of the old common misfire problems in months!

[Galois]

plats or iridiums? either way thats an awesome price!

[bluboy]

Just read through all 13 pages and didnt see an answer.

Would using a heat range of 7 on stock boost with just a fmic and 3" exhaust cause any issues on a s1 rb25det?

Edited October 5, 2010 by bluboy

[SKiT_R31]

Just read through all 13 pages and didnt see an answer.

Would using a heat range of 7 on stock boost with just a fmic and 3" exhaust cause any issues on a s1 rb25det?

It definitely won’t hurt anything... Providing you have healthy coil packs and the appropriate plug gap, the engine should operate as normal. Remember though you are pulling heat out of the cylinder and slowing/cooling combustion so while the engine is safer you will lose some burn efficiency which may impact light throttle economy/power and idle quality. Generally though you won’t notice the difference until you get to 8's & 9's....

[bluboy]

Thanks mate:-)

[Black_CSR]

u shouldn't run Heat range too cold for ur car as there is a risk of it not cleaning itself properly and fouling the plugs. A rough cold start will also occur and affect your idle.

I stick with heat range 6 @ 0.85mm with 300RWHP and runs fine.. I ran 7 Heat range and affected my idle and fouled the plugs..

[r32man09]

Hey

I have a rb20det with basic mods such as cooler,fuel pump,spitfires and exhaust system am I best of getting the Ngk IRidium ones?? Where can I get them online cheap?

Cheers

[migs]

i know the Nissan rb20det carries the

NGK# BCPR6ES-11

Specs: Traditional Spark Plug, 14mm Thread Size, 19mm (3/4") Reach, 5/8" (16mm) Hex Size, Gasket Seat, Resistor, Solid Terminal Nut, JIS Height,

Projected Tip, .043" (1.1mm) Gap, Heat Range 6

Champion also has a plug with almost the same specs i'm wandering it it can be used on the rb20det?

Champion# 3344

Specs: 14mm Thread Size, 19mm (3/4") Reach, 5/8" (16mm) Hex Size, Gasket Seat, Resistor, Copper Core, Projected Tip,

Platinum Tipped Center Electrode, V-Trimmed Ground Electrode, Heat Range 8.5

[migs]

^^^^^^ also i notices the heat range was 8.5

but on the site i found this

QUOTE:

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

[migs]

just found this chart

so i guess the Charmion 8.5 heat plug is just about the same as an NGK 6 or 7 heat

[TUF250]

I have an RB25det S2 with standard boost and a full exhaust and panel filter.

I run the BCPR6ES-11 with the gap set to 0.9mm

The car runs great, cruising, on boost etc.

I jsut got a job where I will do alot of highway driving. In fact 99% will be sitting at 100kph in 5th gear.

Will I get better economy out of a 1.1 mm gap? or will it be bugger all difference to the 0.9s. Note I have original coils but they are in perfect condition. No cracks etc.

Thanks

[fastjetjockey]

I have an RB25det S2 with standard boost and a full exhaust and panel filter.

I run the BCPR6ES-11 with the gap set to 0.9mm

The car runs great, cruising, on boost etc.

I jsut got a job where I will do alot of highway driving. In fact 99% will be sitting at 100kph in 5th gear.

Will I get better economy out of a 1.1 mm gap? or will it be bugger all difference to the 0.9s. Note I have original coils but they are in perfect condition. No cracks etc.

Thanks

Hey mate. It's my understanding that when you have a larger gap, and an ignition source that is able to strongly bridge that gap, your fuel will burn much more efficiently and completely. Whether or not the car is able to guage this, and reduce the amout of fuel needed to supply that same amount of power I don't know. But you will be burning your fuel better, and less will be ejected from the combustion chamber unburnt.