OverLOAD

Has anyone swapped out their plugs for new ones yet? I had swapped out the plugs on my '96 MX-3 GS for Bosch platinum 4+ and found immediately, more power, and better idle..

I'm considering the same for the RX-8.. I was wondering if any other rotary owners could comment on their experiences with different spark plugs, and what they have had the best experiences with..

Thanks,

OverLOAD

BOOSTD 7

When you pull the plugs on your 8, you'll see there's no reason for the +4's. Trust me, don't do it. I've seen times when people used them in rotaries and electrodes fall off inside the combustion chamber.

jdl

I'd reconsider replacing the iridium plugs that came with the car -- they're almost certainly a better application than that +4 stuff, in this case.

gr8rx

keep the stock ones, they are made of irridium wich is a harder metal than platimum for longer life better spark efficiency as well, thats why if you have to buy new irridiums its like 60 bucks for 4

wakeech

*rolleyes* oh yeah, the power benefits of "better" spark plugs.

seriously, those mega plugs will help you with cold starts, and possibly even with your idle (if the plugs your'e replacing are dirty and need a change), but will never never never give you more power unless there are serious problems with the application of the other plugs you were using. if you up the engine's power potnetial and don't then adjust all aspects (including the heat rating on the plugs) you could have power missing (or worse, a plug which could cause pre-ignition), but outside of that, having four "magic" electrodes as opposed to one isn't going to make an entirely significant change to the combustion efficiency of the engine through most ranges of operation.

BOOSTD 7

And the funny thing is, there's still only one spark even if you do have 4 electrodes. It's not like you have 4 sparks going out in each direction. If that were the case, rotary plugs would have hundreds of sparks shooting out all over the place.

OverLOAD

I was under the impression that part of the reason that the 4+ works so well in piston engines (in my experience), is that the modified design of the spark plug encourages the spark to travel radially with respect to the cylinder, as opposed to the normal axial travel path. as well as having a more exposed center electrode, allowing for a slightly faster burn path in all directions, whereas a typpical plug covers the top of the (anode) electrode with the cathode, slightly reducing burn speed and efficiency...

??

I was figuring that it's more the design of the 4+ that gives it an advantage, rather than the material it's made out of..

OverLOAD

Sparky

Irridium plugs which come stock on the RX-8 are supposed to be superior to standard gap type plugs whether they be 1x, 2x, or 4x variety. Just spent $45 putting them on my Miata, the result being no perceptable increase in power but a smoother firing when hot. Supposedly they last longer than the stock NKG plugs though and will pay for themselves.

Why would anyone want to go backwards and put conventional electrode plugs on this car?

Not recommended.

OverLOAD

Can you post a pic of the iridium plugs?

Irish_in_a_RX8

iTrader: (1)

Stick with Iridium ( NBK or DENSO ). With older cars that use copper based plugs, swapping to iridium will perhaps feel a slight hp gain. Not going to make much differense on the 8, unless you rework the rest of the ignition system.

Mazda Monkey

Keep the stock plugs.

CERAMICSEAL

Do not mess with the stock sparkplugs.
This is the deal. Apart from the fact that you won't gain anything over the designated units(NGK), if you don't know what you're doing engine damage can easilly take place.
Mark my words.You heard it here first. The leading and trailing are not the same. Experienced rotorheads know that they are of a different heat range to each other. What I'm actually talking about is the structural difference. One has longer reach than the other.(new for the renesis) Swapping them could easilly cause rotor contact, so aftermarket for now should be considered completely out of the question.
Everyone is a tech these days(in their own minds), we'll see if this problem arises in the future.

boowana

The iridium plugs that come in the car were specially designed for the Renesis enginee. A lot of work was done by Mazda and after working with a variety of plug types, it was discovered that the engine needed a special plug as nothing on the market would work as well. Leave well enough alone.
They are designed to last for over 100,000 miles and should NOT BY CHANGED! You may want to check them for fouling if you did a lot of "short hops" on & off starting,. BTW, the replacement coast for the iridium plugs is $40.00 retail. They must be special.

smoothSevenz

Your only suppose to use the ngk's specifically and nothing else.
Thats the cardinal rule for rotaries, I dont think the 8's would be any different.......

rotarygod

I am one of the people who have had the horror story happen to them in regards to the Bosche Platinum +4 plugs. Paul Yaw has an article on his website about the advantages of using different types of sparkplugs (modified to side fire) in a rotary when using an ignition box (Crane, MSD, etc). On the older rotaries when done properly I can attest to this fact. Different plugs can work very well is some cases and poorly in others. The ceramic on the Bosche plugs is very fragile and very small. I had tried them, modified to 1 electrode with side fire. They lasted a little less than 1 week before an electrode broke and fell through the engine. The car still ran for many more months but it never got all of its power back after that. Paul had some similar results with ceramic electrodes cracking on different plugs but to my knowledge he caught them before they broke off. The ones that did work good and only with an MSD box or eqivalent were some NGK motorcycle plugs. These were tough and never showed any signs of cracking. They did foul easily in comparison to the stock plugs though. About 2 months after my Bosche breaking incident, Bosche released a public statement warning against the use of any of their plugs in a rotary engine due to ceramic failure. If only they had told me that earlier! The Bosche plugs when installed in other cars still don't last long. What usually happens is that they run great for about a week or 2 and then they are just there. Their lifespan is not impressive but their price is (high). Don't use them, not even in other cars. The only sure bet spark plugs are the ones that are recommended from the factory. Anything else is just an experiment.

smoothSevenz

To anyone out there....is your $30,000 investment worth trying some different plugs just because you had that little urge to try something different or you heard through the grapevine that a friend of a friend of a friend tried yada,yada,yada,yada.........go ahead give it a shot and take a chance at blowing your renesis.

Any similar situations is cause for tons of personal research before you believe what people tell you. This is pretty similar to the old synthetic oil issue which was being bantered about in another thread.

wakeech

although i've been a proponent of calling the engine a RENESIS (and not just a 13B) from the beginning, having found out that it's alpha-numeric official name is 13B-MSP, i feel obligated to now promote the much cooler pseudo-acronym.

(if you're wondering what the "MSP" stands for, it's Multi Side Port)

CERAMICSEAL

keech my good man, surely you didn't just realise that was the official designation of the motor? Anyhow let's get this thread back on track. You can start your own dedicated strictly to making sure people refer to it by it's alpha-numeric label

wakeech

it's not that, but simply until the booklets and stuff came out (which i've not actually read, nor even seen) that we've had official Mazda word that it's the 13B-MSP... until then, it was always the RENESIS in the media packages or whatever (can't think... late now. go to bed, sleep good).

[/thread creep]

R8N8SIS

no one in thier right mind will swap out their iridium plugs for platinum... the iridium performs better under high rev and high heat. keep the iridiums.

rotary-tt

Never had plugs which ran better than the NGK's which Mazda recommends. Had issues with running Bosche +4 in one car (motor did not like the heat range) and the car actually runs better with the cheap copper plugs. The +4 made the car run rich and crapped up my O2 sensor.

I wouldn't run anything other than the recommeded plugs unless you're running a stand alone ignition/fuel management system. Rotaries do not like knock so I wouldn't mess with anything which would alter the flame front. I've found over the years the main things which the motor likes is a new set of NGK plugs every 6 months to keep it running it's best. The electrodes tend to get worn down which increases the spark plug gap...

jtdwab

I think I read in the scheduled maintenance that he plugs should be replaced at 30,000 miles. I don't have the book with me right now but that is what i remembered reading.