Does anyone know the answer to my question I posted a few post back? What is the difference between the plugs between cars? is it the gapping or what?

gapping, heat ranges and longevity.

Generally, if you stick plugs that are too cold in a stock engine they just reduce the usable life of the plugs by a little bit.

the rx8 plugs are made for longevity and an even burn with the fine wire rare earth metals.

the downside of using lesser plugs is that you would have to keep an eye on them more frequently.

Plugs from other engines also have differant reach lengths, differant thread seats, and differant amount of insulator exposed. You need to get the spark in the right place in the combustion chamber too. And you don't want the spark plug to contact anything that is moving.

any comments on my plugs that I just pulled?

Ah ok, thanks guys!:icon_tup:

Not much that can be said other than use some anti-sieze next time. The thing that matters is the condition of the center insulator -- all your pics are of the outside shell, which doesn't say much about the condition of the plug...

The gap is wrong on RX-7 plugs.

The RX-7 gap is about .032 while the Reni gap is .050

You are probably costing yourself 10-15 HP

It is an entirely different style of plug.
The "gap" on the OEM plug is .049.
On the REW plug, there is no ground electrode, but 4 ground "blocks" that are also .049 from the center electrode.

my 0.02 is :

I hope you put Anti-Seize. is that rust on ur old plugs ?

cant really tell between good and bad from the picture, need to see the center of it. and I think your picture is too bright, take the picture with direct sun light behind you. That will give you some best picture.

Hmmm okay.

Since I sell plugs for the FC and FD in my webstore and gee I can measure the gap right now...

Whoops brand new 4 electrode plugs... gap at ...


.032

Try again. I have used and both the newer reni style plugs (NGK RE7CL and RE9BT), conventional NGK multiground RE plugs (BUR7EQP, BUR9EQP, BUR11EQP) and iridum (NGK IRL01-27 and 31) plugs in rotary 13BT, 13BRE and 13BREW engines for quite a while.

But I am sure using the older NGK multi-ground plugs are just fine in a Reni... they will last forever... just your gap is so small you are costing yourself both HP and gas mileage.

BTW, just for your info the factory spec for the BUR7EQ is .032 gap as well, so unless you have figured a way to re-gap a multi-electrode plug, you are using too small of a gap using that plug.

http://www.sparkplugs.com/productIma...1290%2D2%2Ejpg
BUR7EQ and EQP

actually my choice for plugs for a 13BT/RE/REW is the NGK RE7CL:
http://www.sparkplugs.com/productImages/1/re7cl%2Ejpg
Of course when using it with an older ignition set up as found on a FC or FD, you'll want to drop the gap back to about .038 when using a CDI system or .034 when not, for peak HP. But at $20 each (retail), they are by far the best price for a full Iridium plug used in automotive applications