KevinW

iTrader: (1)

i have a T61 running 15 lbs of boost and just had the car tuned right at 11.0 AFR. 2 days after the tune doing some 3rd gear pulls i could feel the car pull hard than not than pull hard than not all the way throught the RPM's. Did this for a day or so thani decided to change my plugs, went with the BUR9EQ all around car has been back to normal for 3 days now. Well i just went out for lunch and got on it a few times and it's back to stumbling on and off with the power again all through third and fourth, so i turned the boost down to 12 psi and same thing if it's the plugs again what could be causing this? and is there another plug i can use instead? i do drive the car everyday and put quite a few miles on it regularly, is there a colder plug thats not any more expensive than the 6.00 i pay for these?

Jack

iTrader: (2)

If you are fouling out the plugs due to a rich mixture, you might try the stock 7 leading and 9 trailing for the street. The stock 7 leading will burn hotter and foul less. For track use, I would run colder plugs due higher continual EGT's.

ghostrx7

Stock ignition? sometimes an ignition amp helps with the plug fouling.

Carl Byck

Post your entire set up, and we can help. DO NOT RUN hotter plugs than you tuned with without consulting your tuner. as for 6.00 plugs, if you have a six dollar motor I say go for it

Jack

iTrader: (2)

Why?? Our EGT's on the street never get above 1250-1350f maybe 1400f briefly on the highway (all reading's are post turbine). Stock plugs were specificly designed to run in a very rich A/F combined with oil from the MOP. On the track this discussion is mute due to the EGT's which are 1450-1500f for an extended duration. Street driving on colder plugs than 9's with 11-1 A/F are going to give you idle/fouling problems. BTW this info was passed on to me from a NGK engineer.

Jack

iTrader: (2)

Good reading



http://www.ngksparkplugs.com/techinf...000&country=US

Carl Byck

Well, with an E6K my drivability, and response was far better than stock with 6725-11.5 plugs. At 11.0:1 if you are fouling plugs you have other problems. At 10.0:1, I do not have fouling. Hotter plugs retain heat which in turn increases the likelyhood of detonation. Unless you know how hot those plug tips are EGTs are not in and of them selves enough to say you can run hotter plugs. Basicly anything you can do in a rotary to reduce heat that does not adverly effect performance should be done. If you take every litttle heat reduction opportunity you will have a more reliable longer lasting engine...There are so many variables that can effect our motors that every safeguard you can take is a good one. You'll notice that the top drag and road racers spend at least as much time, if not more on reliability vs absolute power. So, do as you wish obviously, but lie running a dyno tunedc 11.0:1 on the street, boosting 16-18 lbs on 91-93, running close splits at high boost, etc do relatively little for power, and drasticly decrease reliability. I've had the same motor for 4 years, it has seen 28+ psi plenty of times and it's running strong. Compare that to the norm... BTW,You asked Carl

Jack

iTrader: (2)

Well... since I don't know what a E6k is, I can not comment on your application regarding a/f. Hotter/colder plugs are specific to the application intended. First off, I would never run 16-18 psi with a 9-1 compression ratio motor on 91-93 octane. I know from reading's on this list people do, however if you have ever read an engineering graph with repect to octane/psi/compression requirements, you would find you are in the danger zone. Second, 11-1 a/f is an overly rich fuel bandaid to deal with detonation due to other design problems with th RX7. The cooling system is completely under par even when modified. When was the last time you were at the track and after 20-30 minutes your water temps were 195F???. Due to the thermal runaway of the coolant system, the lubrication system gets over taxed driving the oil temps to well over 250F+ There are hot spots forming on the housings where the coolant is boiling and detonation is lurking around the corner. In addition, the heat soak in the motor is so high, the fuel coming out the rear injectors is on the verge of boiling as it enter the combustion chamber. So what to do?? run the largest RACE radiator and oil cooler(s) you can fab in the nose. Duct everything so its as airtight as possible, fab ducts in your hood, run water injection, Evans coolant and the largest intercooler that will fit, properly ducted. Now you have a platform for a proper a/f ratio which would be closer to 12-1. You can run a colder plug for your higher power knowing fouling will not be an issue.