Doesn't matter what it is, I always put in the plug the manual recommends. I figure those that built it know the most about it.

I run what the manual recommends and nothing else. Modern ignition systems can be very finicky with the type and even brand of spark plug.

Take for example the Hemi V8 in my 2012 Jeep Grand Cherokee. It has cylinder deactivation to (supposedly) save fuel when cruising and that system alone can get messed up by spark plugs that have a different resistance and/or electrical properties than the stock plugs. This aside from the fact that, as another poster alluded to earlier, the Hemi takes 16 spark plugs (2 per cylinder) which makes using relatively cheap copper plugs much more economical. The manual recommends changing them every 30,000 miles since copper plugs do not have a long life span but the plugs are around $3.50 a piece and the job is pleasant if not a bit longer than 5-10 minutes. I typically get around 50,000 out of mine and am due for a change now so this thread was a great PSA for me!

+1

quote:

Originally posted by Scurvy:
Use whatever the manufacturer used from the factory. There's almost no performance improvement changing the spark plug type from factory spec unless the engine is highly modified.

In fact, you can hurt engine performance if you choose wrong.

The plugs I just replaced in my wife's Nissan suv had 160k on them, they were factory originals and WAY overdue. But they ran good until they didn't all of a sudden. I'd call that pretty good performance for a spark plug. The were NGK Double Plat iirc. The dealer specfied a different plug, but I replaced them with the exact plug the truck came with from the factory. All six of them looked the same and I thought looked pretty good for being so old. That was encouraging meaning none of the cylinders differed from one another, which is good news for an engine with that number of miles.

quote:

Originally posted by wrightd:
A Question about spark plugs

IN GENERAL, which type of spark plug delivers the best engine Performance ?

This one is easy. If your car was made in the last 20 years, you pull one OEM spark plug out, you get the part number off of THAT plug, and you buy that same exact part number (except Fords with the exploding spark plugs, you buy the recommended replacement instead). Modern cars are a designed system, and they test/evaluate the OEM plugs. Changing the OEM plugs can cause drivability issues. So just buy what the OEM manufacturer put in the car. Also, many/most cars have 100K miles spark plugs in them. That is no exaggeration. These plugs are good for that long. How long are you going to keep a car? Most folks MIGHT have to budget for one spark plug change in the car, before they get rid of it. Most people don't keep cars to 200K miles, necessitating the second spark plug change.

Small engines - Briggs and Stratton, stick with made in America Champion copper plugs, they work and are high quality. Imported small engines, I typically like NGK copper plugs. Chinese engines with Chinese Torch plugs, I run the Torch plugs until they fail, and then put a NGK copper plug in.

quote:

Originally posted by VBVAGUY:

quote:

Originally posted by GT-40DOC:
My 300ZX TT calls for twin platinum, so that is what it gets.

What year is your TT ?? I have one too God Bless

1991

I’m one who thinks there can be a ‘new & improved’ plug available for an older vehicle. Of course the OEM type will work.

I have cross-referenced plugs in a 8+ year old vehicle & seen plugs that are improved over the original, may be iridium, whatever.

If doing it yourself, savings is already there to pay the difference. It’s good to get the plugs out after a handful of years, don’t want them ‘frozen’ in place.

SplitFire! Oh, wait.

It is important for good gas mileage to make sure the side electrode is not blocking the spark. I always have the open end facing the intake valve.



I have found that the copper plugs last about 20K miles and then the mileage drops off. The insulator breaks down and the plug arcs inside the plug and not at the tip.

I built a capacitor discharge ignition in 1966 for my Corvette. It started easier and idled smoother and seemed to have more power.

Then one day it started to break down on the high end at 5000+ RPM. The plugs had high mileage...50K or more. I took the plugs out and tested them with a B29 magneto. They were arcing down inside the plug and not at the tip which caused the miss when firing.

I use a MSD ignition on all my vehicles and even my Bolens lawn tractor. The points on the Bolens last forever and it starts better in cold weather.

quote:

Originally posted by Black92LX:
No performance improvement.
I use whatever factory calls for but change them at 1/2 the interval the factory calls for.
Cheap and easy.
For me Factory calls for 100k change and .035 gap. No way I’d ever go that long.

For 53k are those upper insulators burned too much, or could that be normal for that particular plug and engine ?

IRIDIUM.

quote:

Originally posted by mikeyspizza:
SplitFire! Oh, wait.

When I said earlier not to use "gimmick" spark plugs, this is what I had in mind. I've pulled these out of engines that were setting off random/multiple misfire codes. Although not visibly missing, there was apparently just enough tiny variation in crankshaft rotational speed that the computer flagged it as misfires. Are those things even still around?

In the past, before I knew what I know now, I have had trouble with Champion plugs in GM carbureted engines. With no other changes, the engines would run very poorly at idle, mimicking a vacuum leak or carb out of adjustment.

Don't use this plug in an engine not designed for it. It will run like shit and/or set off misfire codes (in a post-1996 engine).



They also come in four (called, natch, "+4") or a single side electrode(s). The commonality is the center electrode/insulator.

What about using them in older vehicles like 1990. I have an MSD on my truck and found a good price on plugs like this where you don't have to worry about spark blockage.

Heat range is the important thing about plugs to keep them clean.