In a Greddy turbo kit install, when would the suggestion to 'run 4 trailing plugs' be relevant?

Is there a certain psi/boost level?

What is the need and advantages, and are there any disadvantages?

S

 

I had some NGK BUR9EQP FD trailing plugs in the leading spot and didn't notice a difference, except for more difficult starting.

It should also be noted that people using FD trailing plugs are changing them more often. They don't have the Idrium tips and aren't lasting that long.

I just swapped mine out for OEM due to a misfire issue I have and am trying to diagnose. Once I get solved I may swap them back in.

 

Never, if you plan on sticking with the turbo from the GReddy kit.

Typically, the factory plugs are until 60-70 h.p. (+/-) above the stock power levels.

Biggest advantage is that the FD plugs cost less than the RE7s.

 

so with 300 whp+ i take it the fd trailing plugs are the best option? any thing else that can be used as a alternate that will last longer?

 

Actually, HKS, NGK, and a few others make the Racing Iridiums for the RX-8 in cooler heat ranges but they are kinda pricey. It's not so much that the FD plugs are the best but, perhaps, the most reasonable option when all things are considered.

 

there was a suggestion from MM that runing stock plugs is dangerous as the tip can break off and break your motor ........

I run the rx7 plugs and they seem fine - only done 8000kms on them so far though .....

 

Jeff and I don't necessarily agree on everything and this is probably one area where we don't. The fact that I have a customer using some NGK Iridiums in the 10.5 heat range (and that NGK makes them for the Renesis) without issue helps me to be confident in my disagreement.

 

Don't forget - they stopped selling the "beamed" leading plugs.
The current design is just fine.
A colder range is only necessary if you have already done everything reasonable to stop detonation.
Running more octane is a better option that colder plugs.

 

My opinion on that; Mazda has a few cases with the RX-8 where they have "grasped at straws" in an effort to solve a particular problem/issue so I don't generally take one change they make as indicative of anything nor a basis for any conclusions.

I also don't think that two guys from the same team disagreeing on certain matters is a bad thing, either.

 

dont know why but the colder version denso plug has a much higher resistance (sic)?
OD

 

Denny, if I may ask; which plug are you looking at?

 

Doesn't have much to do with boost levels per se but more about load. In this case, chamber temps. What I would recommend on a boosted 8 setup would be to use four trailings; use a plug that's a single electrode design with either a platinum or iridium centre. NGK based plugs; use atleast a 9 heat range. Will probably suffice for quite a bit of load before the plug becomes "too hot".

B

 

I don't recommend the BUR7EQ/9EQ style of plugs due to the four, outer electrode design. Will have misfires at high RPM especially under heavier loads. Stick to a single electrode plug in atleast a 9 heat range and make sure it's a resistor plug.

B

 

Interesting. Do you have a range of scenarios under which you have seen this?

The OE plugs are a "cross" design in the leading position and a "beam" design in the leading.
I use the "cross" design in the leading (all 9 heat ranges) and I don't have high-RPM misfires, even at at AbsoluteLOADs above 200%.

I do, however, have a problem with the plugs "going away" rather quickly that I'd like to solve.

Knowing that the Renesis leading plug is the same size as the 13b's plugs, exactly what plug would you recommend be put in that position?

 

Yes, on my Turbo II but I'm running significantly higher loads than most the folks here so my issues were more prevalent prior to swapping out the BUR plugs.

You may think you don't have any misfires (I'm not talking about the big, heavy-duty ones) but you do. At high RPM (6krpm and above), you'd be surprised how many misfires one can get. The practical end-effect is a bit of 'drag' on the motor, higher EGT's, weird stuff if all of that is truly being watched. And, the problem compounds itself the more load that's being run.

I use an NGK R-679410 packaged in a GReddy box. It's a race plug admittedly but the 10 heat range may not be a bad thing especially for the 10:1 RE motor running boost. Also far superior in design to the BUR style plug as it's a single electrode setup. Much better for high RPM and heavier loads. Still hot enough, even on my 8.5:1 partial-bridge RE setup, to be run on the street.

 

On the dyno, even the lightest misfires appear as a pretty distinct "signature" in the plot.
I don't have any of that.
Egts continue to drop after the torque peak and power follows the expected arc.



Looks good. I'll try those at some point.

 

In all 4 positions? Any washers needed?

 

Those are too long (21.5mm) for the trailing position on the Renesis, which has 19mm plug depth in that position.
Washers required.

 

No washers needed. Same thread size and pitch for the plugs.

B

 

Stick them in a spare Renesis rotor housing and verify that. I don't think a washer is needed.

 

Washers are absolutely needed.
THe 13b had 22mm plug holes on the leading and trailing.
The Renesis has a 22mm leading depth and a 19mm trailing depth.
If you try to put a 21.5mm plug in the trailing position, it will bottom out and and eventually distort the housing when it comes to temperature.

 

Ray--i have the IRTO1-31's and 27's denso--tad colder than oem ngk's
OD

 

Again, stick them in a spare rotor housing and verify. Don't know where you came up with this notion of 'housing distortion', either.

B

 

this would be great if this is verified...

if the washers were supposedly not needed, but were used anyways due to not having proof it's needed or not, would that affect anything performance wise? (can anyone follow what i'm saying?)

 

Absolutely, 100% verified.

I am NOT going to waste my time making a video for this one.