Plugs...

[Mikeyredline]

What does it mean "one step colder" and so fourth?

[mantiskungfu]

here you go man

HEAT RANGES

The "heat range" of a spark plug refers to the heat-handling ability of the spark plug. Spark plugs must be run between 500°C and 850°C. A hot plug has more exposed insulator surface, so it dissapates heat slowly, thus heating up more quickly. A cold plug has less insulator surface exposed, and so it heats up more slowly, dissipating more heat over time.

If you raise the compression ratio of your engine, through performance-oriented modifications, you will need to run a colder plug, since raising compression raises the cylinder temperature, and you will otherwise raise the heat of the plug, potentially damaging the plug, and causing detonation. NGK suggests that for every 75-100 horsepower you add, you should go one step colder.

If you are experiencing severe oil or fuel fouling, you may need to move to a hotter plug, as your spark may not be occurring correctly. However, it is probably better to inspect plug wires and ignition timing.

I found this info here http://www.everything2.com/index.pl?node=Spark%20Plug

[Paulumbo]

The above is true. One thing to consider-ESPECIALLY in a forced induction engine is that detonation (which is different from spark knock) will always result in a lethal condition for the engine.

What happens is that a "hot" plug holds heat and it is more difficult for that plug to dissipate the heat it holds. The plug then becomes a hot point in the combustion chamber-heat a metal rod up in the flame of a torch and you'll see the tip is glowing red. Now as the incoming fuel/air mixture enters the combustion chamber-the "hot" plug can still hold enough heat to ignite the incoming charge-which results in uncontrolled ignition of the fuel/air mixture. Going one or in some cases two steps colder allows the plug to not hold as much heat and reduces or eliminates the chance of this uncontrolled ignition of occuring.

In the real world it doesn't happen this clear cut. What usually happens is that the plug dissipates just enough heat for the intake charge to travel into the combustion chamber, then the intake valve closes and the piston starts its journey to top dead center. As the intake charge is compressing-it heats up (adiabatic heating), this heating from combustion occurs with almost every gas known to man. Once it reaches a point where the intake charge gains enough heat on its own, the heat left in the plug can then light it off-regardless of whether it's at the correct time or not. Then as the flame propogates-the piston is still travelling upwards-and it reaches the time when the plug is supposed to fire-now there are two flame fronts travelling towards each other. This leads to unreasonably high cylinder pressures and uneven downward force on the piston which usually destroys ring lands, crankshaft rod journals, and I've even seen it destroy main journals as well. Forced induction engines are far more susceptible to this because of the increase in intake charge temps (that's why we have intercoolers and heat exchangers) from the added compression of the intake charge.

Going to too cold of a plug can make for the intake charge not fully burning which leads to a reduction in power as well.

All in all-it's a balancing act-a huge compromise.

HTH

[Mikeyredline]

It's really no different that any basic physics of thermo-dynamics regarding "fluid" movement and gas compression. I get it from that standpoint. Also like anything there seems to be an artistic standpoint as well. Also that could REALLY suck if you detonate. I think I have seen top fuel drag racers do that from time to time.

When running the Stage II with a CAI, is it necessary to run colder plugs? You are not running *that* much more HP, no?

[Paulumbo]

It's really no different that any basic physics of thermo-dynamics regarding "fluid" movement and gas compression. I get it from that standpoint. Also like anything there seems to be an artistic standpoint as well. Also that could REALLY suck if you detonate. I think I have seen top fuel drag racers do that from time to time.

When running the Stage II with a CAI, is it necessary to run colder plugs? You are not running *that* much more HP, no?

It's not necessarily a matter of more "hp" than it is heat. Think about it this way-you're now turning the s/c faster-Eaton even says it's out of it's peak efficiency with any other pulley than what GM sends it out the door with-which in turn generates more heat. Do you NEED to run a colder plug? Probably not-but that's a big probably. I haven't done any concrete observation with a straight up stage II-Doc would be one to ask that question to. I've considered going one step colder myself-I've got stage II-no cold air intake (I didn't feel that it was a good benefit for the cost), but rather just to be safe.

Here's a link to part of my "theory":
www.lobucrod.com
My thinking is that if I insulate the entire factory intake (not the intake manifold) then there is less of a chance for radiant heat to enter the air charge. This in turn allows the entire intercooler system to operate more effectively over the entire RPM band rather than adding HP at something like 6700 is what I believe K&N's numbers were. Also running the 2 pass end plate along with an additional heat exchanger out front will help to reduce heat in the intake charge. What doing all this *should* accomplish is keeping heat out of the intake charge which is THE enemy of FI engines which should reduce the absolute need for a colder plug. Keeping the plug as hot as practical will allow for the most efficient combustion-so I'd like to keep it as designed at least from the plug perspective.

Make sense?

[Mikeyredline]

It's really no different that any basic physics of thermo-dynamics regarding "fluid" movement and gas compression. I get it from that standpoint. Also like anything there seems to be an artistic standpoint as well. Also that could REALLY suck if you detonate. I think I have seen top fuel drag racers do that from time to time.

When running the Stage II with a CAI, is it necessary to run colder plugs? You are not running *that* much more HP, no?


Makes perfect sense. I don't think a colder plug will be necessary by all descriptions (especially all the RLF guys who are running factories with custom tunes and small pullies) but I agree with keeping the air cool. I was thinking of cutting out the window where the factory fog lights go and putting mesh there because the CAI pipe runs right there. it will also allow more air into the engine bay keeping EVERYTHING cool. I like your wrapping idea and may do some myself. the only thing is aren't you also encouraging the heat-sinking of the metal INSIDE the thermal blanketing to have an adverse affect? You will keep heat in as well as block ambient heat, no? There may be enough cold air running through there to keep it cool and I can be over thinking again. You know better than I!!!

Given I do not "race" per say and rarely am taking my car to redline, I could just be being a worry wart. I also run premium.....all the time.

[Paulumbo]

Most of the heat entering the metal duct work will come from the engine bay are-if you block the heat source, then the metal will not be as susceptible to heat sinking-another reason I chose to stay with the OE intake system.

Check out the pics in my gallery-I've got a couple posted of my fog light area. I made some pieces out of ABS and PVC pipe and used 4 inch dryer duct work to route right up to the radiator. Doesn't do much if you're sitting still, however back in the summer with ambients near 100 degrees if I was rolling at 30+ my temp gauge is about a needle width over the first mark-it used to be at almost the half way mark. I've still got the templates and plenty of PVC pipe to make more-lemme know if you want some.

[bc3tech]

just ask me what happens when you add 60+hp to your engine and use stock plugs. :ack:
kapow!

[Mikeyredline]

Most of the heat entering the metal duct work will come from the engine bay are-if you block the heat source, then the metal will not be as susceptible to heat sinking-another reason I chose to stay with the OE intake system.

Check out the pics in my gallery-I've got a couple posted of my fog light area. I made some pieces out of ABS and PVC pipe and used 4 inch dryer duct work to route right up to the radiator. Doesn't do much if you're sitting still, however back in the summer with ambients near 100 degrees if I was rolling at 30+ my temp gauge is about a needle width over the first mark-it used to be at almost the half way mark. I've still got the templates and plenty of PVC pipe to make more-lemme know if you want some.



VERY interested in the templates. I am a cooling freak with the engine...bottom line heat kills and the friggen FI does not help. It is when you are rolling your RPM's are way up anyway. I have never had heating problems, in fact I can only think of a few instances where I have heard my fans kick on. I am pretty good at fabricating. I will checkout the profile.

I really appreciate the help and advice:cheers:. On RLF you always seemed to be one of the people who ACTUALLY knows what they are talking about. And I may be able to design a circuit board, but this is a whole new area I am learning tons about.


BC3, you reccommend 1 plug colder for stage II with a CAI?

[Paulumbo]

just ask me what happens when you add 60+hp to your engine and use stock plugs. :ack:
kapow!

True-yours was a panty waste NA...it wasn't designed to be FI and the plugs used were also SUPPOSED to be used for an NA application......:thinkerg:

WOP

[Paulumbo]

VERY interested in the templates. I am a cooling freak with the engine...bottom line heat kills and the friggen FI does not help. It is when you are rolling your RPM's are way up anyway. I have never had heating problems, in fact I can only think of a few instances where I have heard my fans kick on. I am pretty good at fabricating. I will checkout the profile.

I really appreciate the help and advice:cheers:. On RLF you always seemed to be one of the people who ACTUALLY knows what they are talking about. And I may be able to design a circuit board, but this is a whole new area I am learning tons about.


BC3, you reccommend 1 plug colder for stage II with a CAI?

There's lots of intelligent peeps over there and over here. The one thing not a ton of people do is THINK about things. The K&N CAI is one of them. Look at their (K&N) dyno sheet-the curves are essentially the same until you're in a stratospheric RPM area then it starts to help make power-think about it for a minute....how often are you twisting the engine that tight? For me, on ramps and the occasional stop light grudge match and during a road race-not very often. Does it make sense to spend $200+ for a few ponies up top? Not to me. Most people get seduced by the sound it makes or that it looks cool or whatever-I can honestly say, ANY mod I do has a function first and looks second.

[Mikeyredline]

There's lots of intelligent peeps over there and over here. The one thing not a ton of people do is THINK about things. The K&N CAI is one of them. Look at their (K&N) dyno sheet-the curves are essentially the same until you're in a stratospheric RPM area then it starts to help make power-think about it for a minute....how often are you twisting the engine that tight? For me, on ramps and the occasional stop light grudge match and during a road race-not very often. Does it make sense to spend $200+ for a few ponies up top? Not to me. Most people get seduced by the sound it makes or that it looks cool or whatever-I can honestly say, ANY mod I do has a function first and looks second.


Yeah...learned that the hard way :freak:

I will say I felt an increase in throttle response from it, honestly. And I agree about winding the engine up. I rarely ever approach 6K. Even when I am "stretching it out" It's only to 5-5.5 anyway. It was not worth $200+, but the sound does make you pop a chubby. I am certianly not taking it out now that it's in..too much of a pain in the ass. That's why the questions from me, I need to make good decisions. That could have been traction bars for me.

[Doc]

Don't forget, a little heat is good ;)...just a little though

[Paulumbo]

Don't forget, a little heat is good ;)...just a little though

What've you seen with Stage 2 and stock plugs with your handy dandy HPT? Any need to drop to a colder?

[bc3tech]

BC3, you reccommend 1 plug colder for stage II with a CAI?
from what i've seen for gains after stg2, probably not. but once you start dropping that pulley down to 2.8, 2.7, etc then may wanna think about it as that increases heat. but also the tunes for stg2 and such take into account the timing of the spark which does help to alleviate the worry about hotter/colder plugs some, but not all.

[Doc]

With stage 2, I've seen both, its a personal preference to be honest. I'll have to agree with bc3 when it comes to dropping pulley sizes and the need for a colder plug. Considering the price difference (there isn't one normally) it wouldn't really hurt either way.

[Mikeyredline]

With stage 2, I've seen both, its a personal preference to be honest. I'll have to agree with bc3 when it comes to dropping pulley sizes and the need for a colder plug. Considering the price difference (there isn't one normally) it wouldn't really hurt either way.


Very good to know. I get the feeling that as I learn more I may eventually be doung things that require colder plugs ;)