I may still be lost about what plug i need but found a lot of good info on nitrous application plug use.

http://www.spark-plugs.co.uk/pages/t...park-plugs.htm

Good info on this site....

http://www.spark-plugs.co.uk/pages/t..._technical.htm

And an NGK code breakdown...

http://www.spark-plugs.co.uk/pages/technical/ngkjpg.htm.

From a lot of the reading i've been doing, seems for a nitrous or boosted or both type of application, you'd want to shoot for a non-projected tip, short ground electrode, non-resistor type plug with a heat range multiple steps lower then stock. Now to wade through numbers.....

Ken R.

 

http://www.ngk.com/search_char.asp
Build your own.

 

Been all over that site MW. It was very helpful in deciding a few plugs to go with. So assuming I get a non-projected tip with a shorter ground electrode, it seems my only 2 options in a 14mm x .708" taper 5/8" hex is an Autolite or Champion. For Autolite AR474, AR473 and AR472 with heat ranges of 8, 9 and 10 in that order. For Champion, S61C, S59C and S57C with heat ranges of 8, 9, and 10 in that order. Both plugs are non-resistor plugs. Now choosing a heat range. Considering my ride is a 95% street driver, any suggestions on a heat range? Assuming a heat range of 5 for stock, I was thinking an 8 or 9. What do you guys think? I'd have to say that if i compared my spark plug knowledge from this morning vs now, i'm now a spark plug part number expert.

Ken R.

 

Rule of thumb I've heard is drop "1" heat range per 75-100 HP increase.
BTW, why non-resistor plugs? Not planning on using your radio much?

 

As long as you don't get fouling, there is no benefit to a hotter plug and a lot of potential downside. Go with the "10" and see how they work.

Rich

 

I'll give the 10's a shot rich. Joe, i'd prefer a resistor plug, but when you get down to those types of plugs and heat ranges, i've found that resistor types are hard to find. I found a Champion and NGK with all the way down to a 9 heat range, but they were projected tips with a standard length ground electrode, which i believe may be a lot of my problem. We'll see how the non resistors work. It may just be a case of finding a happy medium here. Again, thanks for all the input guys.

Ken R.

 

Won't a non-resistor plug generate enough interference to screw up the sensors and ECU?

 

I guess we'll find out.... My only other option really if I try for a resistor plug is a Champion RSY9C which is 4 ranges colder from stock but the tip is projected. Looks like the ground electrode is shorter then normal though. Thats what I will most likely go to if these non-resistors cause me issues. I went with Autolite AR472's. Other then the Champion resistor option, after that i'd be going backwards in heat ranges and would have to go back to an NGK BR7EF which is non projected, but longer ground electrode and only 2 heat ranges colder then stock. I think i'm pretty much at trial and error time, but i've learned a hell of a lot in the last 2 days about spark plugs.

Ken R.

 

I wondered that myself, but the Champion guys said it should be OK. I've been running the Champion Racing plugs which don't have the resistor and everything works fine. Now, if you then went to solid core wires instead of spiral core supressor types, then you would have a problem on your hands.

And in answer to the question of .708 vs. .750 - .708 is tapered seat and .750 is gasketed. They end up about the same place in the chamber with the appropriate heads, all other things being equal.

 

Thats nice to know about the non-resistor plug Kevin, cause i chickened out after reading Fred's post and ended up going with the NGK BR7EF. Resistor non-projected tip V plug 2 heat ranges colder. I'd like to go colder but but these in for now. I was only 1 heat range colder before and didn't appear to have any issues. Would methanol injection help some if not running a plug as cold as you'd like due to the cooler EGT's? All the plugs looked ok when i pulled them except the one with the cracked one and the other lean looking one because my wire was burnt. Glad i decided to do plugs today. So the wire and the cracked plug must have been my miss (i didn't crack the plug getting it out either). Didn't feel like i had that miss on the dyno but that wire had to have been like that for a while just due to the looks of it and the cracked plug had to have been there too. Might have explained some dyno issues i had. Then during the drive, the car kept dying on me, which has also been an ongoing issue since the dyno. Found a bad MSD to stock harness connection. All in all, it's been a pretty productive and frustrating day.

Ken R.

 

I have also used non resistor plugs in late model computer cars with no apparent ill effects. Don't use solid wire core it don't work it makes the dash look like an emergency in the control room of a nuclear plant.

 

What actual pn are you running? It almost seems like NGK heat ranges are totally inconsistent across plug designs, so one heat range will mean different things with different designs. NGK’s always seem to be a bit of a pain to figure out.

WRT to cold and non resistor plugs… you’d be surprised what you can get away with with a hot enough coil/ignition box. I ran AR12’s (about as cold as you can get in a non resistor autolite) in a very close to stock TPI engine in between power adders for months and never had any problems. Of course:
- tighter gaps make plugs run hotter, they were gapped tight for use with power adders.
- Non resistor plugs supposedly clean themselves better, as do plugs with hard insulators (Autolite’s are about the hardest, NGK the softest).
- That car had a pretty hot ignition to start with (crane hi-6/LX92)

With that you’d think that I was an autolite fan but I’ve always had best luck with AC or NGK plugs. I’ve found autolite resistor plugs very inconsistent and the insulator’s on their plugs in general are very prone to cracking.

 

I work with the NGK guys as well as the Champion guys at work (great guys BTW and free plugs as a bonus ) and they all are sometimes confused about heat ranges, too. They have the plugs rated on a numerical index from hot to cold, but the part numbers do not always represent a full heat range, and some plugs that cross to another brand fall in between the other brands heat range or span more than one heat range. They typically will run the plugs in our engines, then cut them open with a diamond saw to look at the upper part of the insulator and figure out how hot it was running. NGKs have a wide heat range so they cross to a lot of plugs which makes it hard to pick the right one, but also less of a chance picking a wrong one. Also a wide heat range is a good characteristic of extended tip plugs in general.

Now, as to whether meth/h20 injection makes it possible to run projected tips in a nitrous application, I wondered that myself and do not know the answer because there are too many variables there. But conservative is probably the way to go if you are privately funded and have doubts about getting kitchen clearance for another expensive rebuild .

I also run a Crane Hi-6 with a LX-92 coil and I am surprised to see that I can run some pretty cold plugs with no ill effects. Right now I am running Champion C65YC Racing plugs (these are new & no one seems to know the heat range of these), I had some RC9YCs in there a while ago which also worked. I usually cut back the ground electrode to the middle of the center electrode, but the racing plugs come that way already and they haev a heavier shell to prevent any chance of a blowout.

 

I have no trouble with plug fouling and NGK "11" heat range plugs. My ignition is pretty vanilla. Opti, MSD6, MSD replacement coil. If it were a higher revving combo, I'd consider a more exotic ignition. But it works good up to 6,500rpm.

Rich

 

Assuming you're using boost only (12-14lbs.) , no N20, what heat range would you select? One to two ranges hotter? Thanks.