Bosch Fusion spark plugs

[Samson]

My '01 is in need of some new plugs. I'm inclined to go with the OE Bosch +4 Platinum plugs, but the iridium + platinum Fusion is about the same price after rebate... anybody used them in their Boxsters? If so, what do you think? Go OE or get something that'll last longer?

Thanks!

[Lil bastard]

IMHO, exotic metal plugs are mostly hype. I always prefer to go oem.

The engine was designed to work with a specific plug with respect to indexing, depth and heat range. There is no universal standard for heat range, so it's difficult (if not impossible) to exactly match the heat range of the oem plug with another.

Part of the hype surrounding these exotic plugs is longevity which isn't necessarily a good thing, esp. when you consider the oem is already rated to 60k mi. (personally I wouldn't go even that long).

It's a good thing to occasionally, every couple years, pull the plugs and see what's going on such as integrity of the spark plug tube 'o' rings, condition of engine as displayed on the plugs, etc. And, plugs left in too long have a greater probability of reacting with the dissimilar metal head and seize. And, if you're going to go to that trouble, might as well swap them while you're in there. Plugs are pretty cheap as Porsche parts go, so I say swap them every couple years and go oem.

[Samson]

OEM is where I'm leaning. I have iridium plugs in the IS300, but that's just because they're OE and last around 100k miles.

I've been looking at the Bosch plugs and have come up with two part numbers - 7413 and 4417. Local places stock the 4417, but online places list the 7413. Both are platinum +4, and I assume both are a 7 on the heat scale. Do you know the difference?

[mptoledo]

I went with the ngk iridium as they were on sale. I doubt I see any difference, but I thought I would give them a try. Hype or not, there weren't any negatives, so really no down side since they were the same price. I have used ngk on my bikes for years and have loved them.

I too recommend pulling plugs occasionally to see whats happening. Its the closest thing to a window your engine has. I stuck my milwaukee snake light camera in the holes for two reasons, first to see If anything looked wrong, second, to justify my purchase of a snake cam .

Take it for what its worth(marketing), but still has some merit.
Q. What makes Iridium better?
A. Until recently, platinum was considered the best material to use on the top of an electrode because of its durability. However, Iridium is 6 times harder, 8 times stronger, and has a melting point 1200 degrees higher than platinum. Put that into a harsh environment such as an engine piston chamber, and you have a spark plug that can resist wear much better than platinum. Additionally, the DENSO Iridium Power alloy is so durable; it allowed our engineers to produce the world’s smallest center electrode (.4mm) which reduces the voltage requirements, concentrating its sparking power. Also, its smaller size, combined with the tapered U-Groove ground electrode, allows more room for the flame kernel to develop and produce a more efficient combustion.



Here is some propaganda..

http://www.spark-plugs.co.uk/pages/technical/iridium_spark_plugs.htm

OMG you gotta read this cheesey write up... "it comes form asteroids that killed the dinosaurs..."
http://www.densoiridium.com/faq.php

[Samson]

Heh, the dinosaurs make it strong!

Thanks for the info... I'm going to head over to NAPA tonight and see what they can do. Maybe they know the difference between the 4417 and 7413.

[Samson]

I decided to call Bosch and get this figured out... 7413 is the only plug they make for the 2001 2.7.

4417 is for the 97-99 2.5 and is a different heat range, despite all of the big auto parts store listings. Also, the Fusion will not work in my application. Good to know, and it's pretty cool that you can still talk to somebody on the phone at a company like Bosch.

[Lil bastard]

Originally Posted by mptoledo

...Hype or not, there weren't any negatives, so really no down side since they were the same price...

Well, except for possibly indexing, depth and heat range, you're probably right.

Don't get me wrong, NGKs are very good plugs, but the Boxster M96 engine was not designed for them.

You don't notice, but that doesn't mean there isn't a difference. If the heat range is off, even slightly, it could under some circumstances cause some knocking, possibly so subtle that you don't notice it, but the knock sensor might and force the DME to retard the spark or shift maps meaning a loss of performance or range. Then again, maybe not.

The point is, to notice any difference, you'd probably have to datalog them (and the oems) to know for sure. With oems, there's never any doubt.

Plugs and brakes have to be two of the most important components on the car. Why do people try to scrimp here?

[mptoledo]

Originally Posted by Lil bastard

Plugs and brakes have to be two of the most important components on the car. Why do people try to scrimp here?

I agree totally, and you might add tires to the list, even though most high end tires will be good enough. I just got my new shoes on yesterday (sumitomo III) and have had the radio off most of today on my joy ride to hear any defects. Boy those tires are nice and sticky and you can hear that engine purr!!

Hey ya little bastard ( )(sorry, its just fun to say) Since you seem pretty knowledgable, I have a question about oil. I am about one bar over full on my digital oil thingy and I am not quite all the way covering the red tip on my dipstick, I just did my oil change and put a little too much in(probably no more than 1/5 of a quart. Will this hurt anything?

[Lil bastard]

Originally Posted by mptoledo

...Hey ya little bastard ( )(sorry, its just fun to say) Since you seem pretty knowledgable, I have a question about oil. I am about one bar over full on my digital oil thingy and I am not quite all the way covering the red tip on my dipstick, I just did my oil change and put a little too much in(probably no more than 1/5 of a quart. Will this hurt anything?

Well, too much oil can cause foaming which is very bad - liquid flows, foam doesn't. You want your oil to flow.

Porsche increased the oil capacity spec several years ago in a TSB but never issued a recalibrated dipstick or digi gauge (do a search and you'll find more about it). So, you're probably OK. But, it's best to be sure. You can extract some oil one of two ways:

Unscrew the filter cannister (be sure to have a catch pan) - this will give you upwards of a quart, or you can extract it through the dipstick tube with a mity-vac or similar tool. Then add it back in until you get the level right.

[tnoice]

I would go with OEM, I went with the iridium plugs for my subaru and noticed no improvement to the performance of the motor. The only difference was the interval of replacement, but the price out weighed that.