GtoRx7.

iTrader: (12)

So last time I posted up some semi p-port dyno runs, a couple members suggested that I try race plugs. Most of you were shocked I didnt already have race plugs in it. Me being a doubting Tomas, had to try it out though.
The result? Like 3 horsepower. And the engine actually lost a little torque. Before anyone asks, I gapped them to .015" and did runs with more and less advance. Still only 2-3 hp.

My opinion on the matter-

Race plugs are a crutch for a weak spark. Most guys seeing 10hp on 13b's must not be using strong ignition. I recommend using electromotive inductive coils. These plugs are not worth the $190 in my opinion. But other guys might have better results

13B-RX3

iTrader: (2)

The colder the plug the more heat it pulls out of the chamber (heatsink). Ideally you would only need a plug cold enough to fight off detonation but hot enough to self clean. I am assuming that the race plugs are a colder heat range than the plugs you were running.

GtoRx7.

iTrader: (12)

Yes I ran the 11.5 NGK vs. the stock 9's. I am not sure I am sold on the idea of colder plugs being a heatsink, but that is another subject. Everyone can agree however that colder plugs are of benefit for high boost turbo engines. In a n/a engine some people explained that the design itself is better giving a better burn. Looks like for n/a there is no point except for longer life.

13B-RX3

iTrader: (2)

I don't want to get off the subject too far. I have had extensive talks with one of the engineers at NGK and he really opened my eyes about plugs. The real advantage of the racing plugs is that they are made of smaller (more exotic) materials. The reason they do this is that a thinner electrode and ground will require less voltage to travel trough it. If they just used traditional materials and made the electrode and ground smaller they would overheat and begin to glow so they use materials with high heat conductivity and high melting points. In a N/A engine this is not as big of a problem as it is in a turbo engine because of the lower cylinder temperature. As far as the turbo engine the colder plug is not really a benefit as much as it is a necessity. As the temperature goes up inside the chamber and it exceeds the plugs ability to transfer heat from it'self to the cooling system (heat range) it will begin to glow and become an ignition source.

This is what NGK has to say on the subject.
"A: It is a common misconception that spark plugs create heat. They don't. A heat range refers to how much heat a spark plug is capable of removing from the combustion chamber.

Selecting a spark plug with the proper heat range will insure that the tip will maintain a temperature high enough to prevent fouling yet be cool enough to prevent pre-ignition. While there are many things that can cause pre-ignition, selecting a spark plug in the proper heat range will ensure that the spark plug itself is not a hot spot source"

Here is some interesting material if you care to read more.

http://www.ngksparkplugs.com/tech_su...2.asp?mode=nml

GtoRx7.

iTrader: (12)

I dont think we are off subject, since the subject is still about race plugs Anyway, when they say "remove heat from the combustion chamber" I think its refering to the plugs ability to withstand the temps, and cool down before the next event. Information everywhere else always is saying "a engine puts heat into a plug, a plug cannot put heat into the engine. Or vise versa. "

So lets take it literally with what NGK says. Wouldnt that mean the coolant temps would rise with a colder plug? And EGT temps lower? Heat has to be transferred somewhere right?

13B-RX3

iTrader: (2)

All plugs have an operating range. According to NGK their plugs are between 500C and 800C. The heat range determines the temperature that the plug operates at for a given set of conditions. The only way that the plug could do that is to either dissipate or retain the heat. In other words a cold plug would dissipate the heat
faster than the combustion process could put it in. On the other hand a hotter plug would resist the flow of heat causing it's temperature to rise. Imagine having a small propane torch and trying to heat a 1" washer. You set it flat on a steel table and point the torch at it. After hours of waiting the washers temp is still relatively low. Now take that same washer and stand it on its end, within no time it would be glowing. You are correct in saying that a plug can't put heat into the engine but it can definitely take it out. The more heat that travels trough the plug is heat that is not driving the rotors (or gay pistons). In theory you are correct, a colder plug should cause the EGTs to go down and the coolant temps to go up but i would imagine it would be a very small amount compared to the heat that the rest of the engine is putting into the cooling system. If 1/3 of the fuel you burn actually goes toward pushing the rotors and not going onto the cooling system or out the exhaust i would imagine that the plug would absorb less than 2% or that 1/3. I would even go as far as saying i bet your car would make more power on BUR7EQs than on the 9s

Edit: I should add, don't think of a plug as a power adder or remover but think of like this. You select the heat range of the plug to control it's temp. Just like you would put a larger radiator in a car with increased output do dissipate the added heat you would lower the heat range for the same reason.

j9fd3s

iTrader: (3)

interesting. here is the mazda graph from the SAE papre.

the "air gap" plug is the racing/rx8 style and the S.D. or surface discharge is the FC/FD style

engine is a 12A p-port. as you can see they tried CDI and a normal ignition AT THE SAME VOLTAGE/POWER and the engine made more hp with CDI

with the race plugs in an NA engine, they were recommended for the racing engines. so its a 300hp 13B running 9000rpms for up to 24 hours straight. so its not just HP, but HP/time. a street car sees a different duty cycle

arghx

iTrader: (3)

Well there are race plugs and there are heat ranges, but the thing is that most people run a colder heat range than OEM when they go with race plugs.

You'd be surprised what heat ranges are being used on heavily modified 4 cylinders. There are 400-500whp Subarus with the factory 6 heat range plugs. Most turbo piston engines are a 6, some are a 7 (like the Evo engines). It's not uncommon to run 30+ pounds of boost on turbos we would consider smaller and less efficient. An Evo X with bolt ons and a tune will peak at 30 pounds of boost with the stock 7 heat range plugs.

The Mazda OEM 9 heat range plugs are really a very very cold plug, and these race plugs are even colder.

just startn

iTrader: (33)

I think pistons engines are a whole diff ball game but deff. brought up a point. Pisotn engine, had 9's running c16, they had probably 15 pass on them and months of street driving. fould them out at a major event, took the stock plugs out of another car witch were 7's and kept going with zero problems. Forgot about them and realized it at the last event of of the year.

peejay

And a rotary's plugs light a mixture twice as often and are never exposed to anything but compression and combustion, so the plugs will get a lot hotter even in "normal" use so they need to be colder heat ranges in order to keep them from melting down.

Heat range is always described in the books as how long the path is from the inner portion of the plug to the shell, it's not so much about cooling the chamber as it is cooling the spark plug, since the spark plug itself is cooled by contact with the threads in the cylinder head/rotor housing.

I accidentally nuked an engine once by leaving the spark plugs loose...

ultimatejay

iTrader: (1)

You say that you only gained 2-3 horsepower. How many bolt ons are out there that can gain this much horsepower for 120 bucks?- you got ripped off for 190.00. Yeah, maybe for the average Joe, this is a waste of money, but for a full competitive racer, every little bit of power counts and by the looks of your car, I think you race it no? I think 2-3 horsepower is on the conservative side. What fuel are you using and what was the highest timing you put in? I know Racing beat got around 15hp+ on their dyno and althogh I never dynoed my car with the new plugs I gained a couple tenths in the quarter mile by using them.

I guarantee you that the Mazda racing teams out there are not using BUR9EQ's and they are using these race plugs for a reason.

GtoRx7.

iTrader: (12)

I am using 92 octane, and pulled out 10 degrees from the map with the BUR9's, then slowly advanced until it had pre-ignition. Less than 3 hp was the best of the runs

My car was built to race, you are correct. The only point of the thread is to prove or disprove a power gain. 2-3 hp on a 3 rotor engine is pretty small, but has a place for sure. On a two rotor that would be between .6 - 2hp. I have always been of the belief to use a plug based on operating conditions, not to gain power. However, once it was mentioned more power could result, I had to test the theory. And now we know that there isnt much power to be gained. In extreme track time, I am sure the race plugs handle the repeated 10k rpm longer without fatigue. So I will keep my set for track events

So nobody think for a second that I am bashing race plugs. Just stating that they will not gain more power, or at least hardly any at all.

GtoRx7.

iTrader: (12)

I think you are right about more power with a hotter plug. Next time on the dyno some 6's or 7's will go in the leading

13B-RX3

iTrader: (2)

Another thing to consider is the design differences between the plugs. The factory plugs are semi surface discharge where the spark is unobstructed where as the race plug is slightly shielded by the ground electrode. NGK use to make a 13 (IIRC) heat range surface discharge race plug for the rotary, when i asked the engineer about it he said that the plug didn't actually have a heat range but they called it a 13. I asked him how it was possible and he said that the porcelain contacted the shell for the full length of the plug and you could not make a plug any cooler. NGK no longer makes the plugs but i found something that should be very close. It's part number is BUE and i want to give them a try just for ***** and giggles, and the fact that they are cheap!

ultimatejay

iTrader: (1)

"And now we know that there isnt much power to be gained"

I think a better quote would be, " there wasn't much power gained for me(you)"
Like I said before, Racing beat has dyno over 15+ horsepower with these plugs and many others too.

Also, 92 octane is pretty low to take full advantage of these plugs. I would recommend trying some good race fuel from VP and start cranking the timing up and then see what happens.

t-von

iTrader: (8)

So if you change back to the race plugs AND add higher octane AND raise the timing, how are we suppose to know that the plugs themselves are responsible for the power increase? Logan installed the race plugs an ran the same fuel and varied the timing as best he could and didn't get much gain. Would he not gain hp by just adding race fuel and more timing with the regular 9's?

GtoRx7.

iTrader: (12)

I thought about that too, with the rotary having different surface spark wants/needs. So #BUE is the full number? NGK? I will definitely give anything a try!


Truely not trying to pat myself on the back, but if a engine that revs to 10,000rpm, makes more power than a majority of full race p-port engines is not seeing much of a gain....... why would a lower hp, or lower rpm engine see more of a gain? A weak ignition system is the only thing I see being different.

Racing beat did testing pretty far back in the day. Ignition systems have came a long way since then.

I cant see the reason as to why race gas would make the plugs more effective for power production. But, its something I havent tried. What is your thoughts on race gas changing the results?



Definitely true, only one way to find out however. In a few weeks I will throw in race gas and let her rip. Only temporary though, I like to make good power on plain old pump gas

13B-RX3

iTrader: (2)

Yep BUE, the stock number is 2322. If they make within a few ponies of what the race plugs make and don't foul too bad i am sold!!!


http://www.amazon.com/NGK-BUE-Tradit.../dp/B001RMA3XO


Do i see a spark plug shootout in the near future???

GtoRx7.

iTrader: (12)

The world will be a better place if that happens haha

ultimatejay

iTrader: (1)

Since your N/A I wouldn't go crazy with the octane but would recommend a oxygen enriched fuel. I would recommend first trying VP 100 octane street blaze.

Doc Holiday

iTrader: (2)

I like this thread

diabolical1

iTrader: (3)

^ +1

plus now i have a new plug to experiment with.

j9fd3s

iTrader: (3)

ive seen their dyno, its all MSD stuff, its pretty stout.

obviously your ignition works really well too, hence the surprising result.

ive got an easy one for the spark plug shoot out. try the autolite 2627 (i think, just tell em its an 81-85 rx7 12a), paul yaw had some big write up about how those are. they are cheap at least....

13B-RX3

iTrader: (2)

Please let us know how they work.

On a side not the surface discharge plugs require a CD ignition to work correctly.

peejay

Interesting... I've always had good luck just cutting down Autolite 3923s but I've also always run MSD.