SaabGuy

OPPS I think I bought the wrong plugs for my car!! I ordered a set of stock leading and trailing plugs from Mazdatrix. They sent me some 7's for leading, and some 9's for the trailing.


So I pull all the plugs out of my engine, and OPPS!! The engine is running all trailing (9) plugs.

Should I put only 9's back in? The engine has a t04b, haltech, 10-15 psi of boost on 93 octane Engine is said to give about 350 rwhp at 15psi. The old plugs are old but look to have a perfect color of dark brown on all.

fastrotaries

IS "SAID"? that sounds a little skeptical it's possible, but I'd guess you're making less. At wich point the plugs you pulled out all "9" are what is normally recommended for that kind of power. You could run the stock set up plugs, and probably notice more than early foulment. BTW you don't have to order your plugs from california. I think you guys have O'reilley's in HOTLANTA. if that's the case just tell them you need a set of NGK BUR9EQ and maybe even add a "p" for platinum at the end of the part number.

SpooledupRacing

from what I have heard that the 9's are for what u seem to be running u could run stock but again they will prolly foul faster..

either way they wont hurt but u could just off the 7's and grab some 9's

SaabGuy

ya I just bought this car and havnt really felt its power potential, supposedly it made 350. I ordered from California basically cause I ordered a ton of stuff including an RB turbo back exhaust. Just threw in the plugs for conveinience.

OK I'll get some more 9's then.

dipsherry

well if u run a modded motor u want all 9's so that is a good thing to have all 9's i ran stock 7leading 9trailing and fouled out and had a huge nitrous backfire lol

RotaryForce13B

yeah, its usually better to run a little bit colder plug with nitrous??



here is a write up i got off of mazda trix's web site. just thought it would be interesting.

A common misconception of many people are the terms "Hot" spark plug, and "Cold" spark plug. The temperature rating of the plug refers to the running temperature of the physical spark plug - i.e. a "Hot" plug will retain more of the combustion heat in the plug itself, meaning not transfer the heat to the engine itself. This is why a "Hot" plug is needed for slower city type driving so the carbon deposits will be burned off the plug, and clean firing will still be possible even when combustion temps are low (idling, stop & go etc.). At the same time a "Hot" plug used in a highly modified engine that is driven hard consistently will simply retain too much of the extra combustion temperature and burn itself up (usually cracking the porcelain, and potentially doing major engine damage).

A spark plug that is too "Cold" for the engine/application will start harder, foul much easier, and generally be a pain to work with.

For engines that are not significantly modified for racing, we have had very good luck just running the stock plugs. For street ported engines driven hard on the street, the most we have had to do is move one or two heat ranges colder. This lack of change is because the engine is still driven at normal speeds and loads for 99% of the time.
Spark Plugs

Racing engines, for the most part, are above 7000rpm 100% of the time - these are the ones that require the colder plugs. Quite often a set of "hotter" plugs must be used to get the engine started and warmed-up, because the race plugs will not fire consistently below 4000rpm.

Spark plug choice, for any given engine, can then be stated as "Hot" enough to fire consistently at the lowest RPM and load normally needed (without fouling), and not overheat (and burn-up) at the highest RPM/load for the given application. This translates to : The "Hotter" the engine (turbo, modifications, load, usage, etc.) the "Colder" the spark plug needed.

SaabGuy

Cool I'll probably just stick with 9s since this car is really a racecar anyways. Plus I want upwards of 15-17psi of boost, fuel permitting, on occasion.

...My boost controller has a 'NAWZ' button. Raises the boost a set level for up to 25 seconds...

Sideways7

iTrader: (7)

Be very careful with that. You have to make sure that you have enough fuel for the raised boost or you will pop the engine.

SaabGuy

I will. Car has a wideband, 550 and 1680 injectors. I'm familiar with modded turbo rx7s, just a bit rusty as I sold my last one about 4 years ago.

andyfc3s

Didn't I give you the dyno sheets with the car? I'll see if I can find them