Leeroy_25

I have just found out two of my trailing spark plugs are dead which I have never come across before. The engine has heat rating 9 trailing and 7 leading which I believe is the stock set-up from memory. Should I stick with this for a 500-600bhp flywheel set-up or go with something different. Some advice please. I will run 1 bar max boost by the way. No porting yet but will likely get a mild street port when it's rebuilt and open up or swap the silly exhaust sleeves for 13b ones. Just in case any of that makes any difference. Would you stick with the traditional rotary plugs like the BUR9EQP (5255)? I have used some other plugs in the past I think they were motorbike ones. Cannot remember the numbers off hand but look more like a standard plug. I ran them in a 13B no problem, but I remember reading horror stories about tips dropping off and destroying engines? don't know if there are any other options really?

Thanks for any input.

Lee

peejay

Oh my word no. I am on 10 heat range plugs with half that power. 9s all the way around were causing top end misfires under extended load.

racingdriver

ngk 10's is what most guys run over 15 psi

Leeroy_25

Okay so Ngk 10'S all round.. 14-15psi would be by absolute max intended boost. But I guess running the hotter plug won't hurt if I am just under that?
What part number on the plugs do you guys mostly use?

Thanks
Lee

lduley

iTrader: (1)

IIRC NGKs are backwards, the higher the number, the colder the plug, which in boost application makes sense

Leeroy_25

Oh really?! I thought as the number went up the plug got hotter!? As long as I get the right ones that's all I am worried about. Seeing as stock is 9's and 7's.. is there any benefit me running 10's and 9's respectively. 10's all round seems like a big jump on the leading plugs? Considering I won't go over a bar of boost for sure.. Or is there nothing to be gained..

Thoughts?

Thanks
Lee

Leeroy_25

The other plugs I heard about and in fact used in a 13B years ago were the B10EGV motor bike plugs. I thought since then I had read about a few instances where the plug tips had come off in engines and damaged them?
Would people suggest sticking to the regular BUR10EQP style plugs instead?

Cheers
Lee

Leeroy_25

So, I did some looking around tonight and also came up with NGK BR10EIX plugs. I cannot seem to find a stock style plug though in a 10 rating? A bur10eqp? Do you guys get them.in the states or are you all running traditional type spark plugs on a heat rating 10? And if so do they all require a modified socket to fit them?

Banzai-Racing

iTrader: (11)

There is not a stock 10 plug. NGK does not offer a R6725-10 any longer, they have the 10.5. If you want 10's then the Denso IRE01-31

Spark Plugs 93+ RX-7

Leeroy_25

Thanks for the info.. I have actually order some BR10EG plugs yesterday. I might look at the Denso as well though. I assume these fit in without the need for a special socket? What is your personal preference out of those two options?

Also I was hoping you might have a minute to look at my thread about finding TDC with APEX seal location from an engine with a know tdc already. I have a guy on here who has kindly given me some measurements from his 20B but want to verify it all before I post it for the world to see and hope someone like your self could agree the theory is sound and valid and there are no changes between engine blocks that could cause an issue?

The thread is here.

https://www.rx7club.com/general-rota...-hole-1105639/

Would be real pleased if you could spare a few minutes to measure an engine you have there? You may get a call from the guy helping me actually!

Thank you
Lee

Banzai-Racing

iTrader: (11)

I will not run motorcycle plugs. Both the NGK and Denso on our site use the standard socket.

Leeroy_25

Thanks for the reply.. Do you run into problems with the denso ones fouling? That seems to be a common downside people complain of with the OEM style plugs?

Thank you
Lee

Banzai-Racing

iTrader: (11)

No fouling, been running the same set for years. Sounds like there are people with bad tuning

Leeroy_25

Well, I have the BR10EG's with me know.Maybe as I will swap to the Denso when I replace them.

silverfdturbo6port

iTrader: (26)

Stock rx8 trailings work fine for anything you throw at it.

Banzai-Racing

iTrader: (11)

RE9B-T are far too hot and way too short for my liking

BLUE TII

iTrader: (9)

Only time I have had trouble with colder spark plugs fouling is when I was running 116 leaded race gas (Sunoco Maximal) and it really does foul easily, but clears easily with load as well.

110 leaded, 104 unleaded and 91 pump I have never had any issue with fouling.

Leeroy_25

I stumbled across this Bosch plug earlier F07CS0. The Nascar plug. Looks like a non resistor plug which might not be a good start but I did read somewhere about it being suggested for rotary engines. Anyone tried it?

BLUE TII

iTrader: (9)

I don't know about that F07CS0 Bosch plug.

But $24 each is more expensive than $17 for the NGK R6601-11 Mazda Factory Racing plug recommended for the car...

Leeroy_25

I just happened to find someone in the UK with surplus stock going cheaper that's all. Advertised for RX8 actually. but anyway.. That racing plug is interesting. Will have to look that up here. Says it could be prone to fouling on colder applications and requires a high energy ignition system? Presume stock coils are okay for that? Cannot see if it is a a resistor plug or not? Am I correct thinking that is a 11 heat rating?

May be of interest.

Have you used them?

Thanks
Lee

BLUE TII

iTrader: (9)

I haven't tried the NGK R6601-11. It is also available in 10 heat range. Yes, it is resistor style.

As in the thread below Gilgamesh on this forum tried the 10 heat range version. You could ask him more about them.

https://www.rx7club.com/single-turbo...-11-a-1079578/

I tried the Autolite AR3932X Nascar surface discharge plugs, but just for break in on pump gas- wasn't brave enough to use them under full load.

Sure enough, after a bit people started posting failures of the porcelain on rotaries...