tedesco

Today I changed the plugs to the NGK platinum ones. Drove to the workshop with the usual BRP7ES and came back with the new plugs (same heat range). Have not been to a dyno and will not for the compare but what I directly noticed is an improved idle. Dead stable. All in all the engine runs smoother and I would call it "more precise"
Already before when I changed plugs I found the biggest differences with plugs at idel. So far I would call it an improvement

MPD47

Platinum are CRAP, get rid of them ASAP.

LFA951

Same here, Platinums are no good for turbos, stick with the basic NGK

tedesco

could you be more specific?

Why are so many 4 cylinder dragsters running them? I think they almost exclusivly run platinum or iridium stuff.

manticore33

Are those dragsters FI? I know many DSMs (2.0l 4g63 Turbo i-4s) run the BPR6 or 7ES plugs and are running 1/4mi times in the 12 - 13 second range (AWD). I could have sworn that platinum plugs run hotter than copper cores which makes the platinum plugs more likely to detonate. This is not so bad on a naturally aspirated car, but on a forced induction car, the intake charge is hotter and already more likely to detonate, so you increase your chances for pinging and knocking. I could be wrong, however.

Now, I did notice that when I ran BPR7ES plugs on another FI car of mine (BPR6ES is stock), the plugs were good for a short while and then I started getting some hesitation. When I pulled the plug, it was more black as opposed to the white/grey color. I attributed it to the plug not getting "hot" enough to self-clean and switched back to the BPR6ES plugs. The car ran much better that point forward.

Edit: Plus, at $2.00 a plug x 4 = $8 - $10 is not much to replace plugs ever 10-15k mi.

Rogue_Ant

BPR7EIX. Is what I run, 1 step colder Iridiums. Work great, it is the stock plug for the Evo VIII.



Rogue

tedesco

exactly that is the plug I use too.

I reffered to import dragsters (supras, DSM, Mitsubishi, Honda....). They run around 40PSI with alcohol or race fuels and use the iridium plugs almost exclusivly (and they are running 7sec !).

To me the arguments to use them are the much thinner electrode which makes it easier for the spark to jump the gap. This should be especially important at high boost where it needs higher voltage to fire. Other people upgrade iginition to achive that.
Another indication for improved ignition is the improved idel. At idel combustion conditions are bad too due to only very little mixture being available to ignite.

The only argumnet I once heard against those plugs is a danger of losing the very small centre electrode. Maybe that only happened with the very first ones.

Porschefile

From a metallurgic standpoint, copper is a better conductor than platinum is. Pretty much the only purpose for platinum plugs, AFAIK, is for economical reasons. Platinum plugs last longer and would therefore not have to be changed as often. In old cars like ours that don't have the best OEM ignition setups, platinum plugs can sometimes cause spark related problems. I've experienced this with my 951 as well as quite a few other cars. Generally, newer cars tend to have much better and more efficient ignition systems, such as coil on plug setups. Because of this, they can generally run larger gaps, less conductive plugs (platinum), etc as they tend to have a much cleaner and better spark than an old car might. This is really the main argument against platinum plugs. To be honest, our cars really don't have all that great of a stock ignition system. On top of that, considering they are forced induction, it is even more important that you get the best spark possible. Upgrades like a hotter ignition coil, MSD box, etc all improve on this and allow you to run a wider gap, platinum plugs, etc even in a 951. If parts of your stock ignition aren't in the greatest shape, I'd be willing to bet that you'd see ignition problems and misfiring when running platinum plugs. Copper is cheap and widely available, so I'd just stick with copper plugs unless your stock ignition is in perfect shape and/or you've done any ignition upgrades.

That being said, there are also some benefits with platinum/iridium plugs, especially for high hp/high performance applications. Platinum has a fairly high melting point, iridium electrodes are relatively small and require much less of a voltage drop, etc etc.

Here's a good page for more spark plug info: Link