Looking at some information from last year it looks that I may need some -7 plugs for nitrous. The motor setup:
TEA S2 12.2:1
150+ nitrous
Big cam

Anyone have the P/N to a good "7" nitrous plug?
Phil

 

Try an autolite 472 R plug.
It's a very cold, nonresistor, short-tip plug.
They survive the nitrous very well.

 

NGK # BP7EFS

 

That's a number 9 plug. Little more than he needs.

 

you mean the equivalent of an NGK #9 ?

 

Yes. That's a very cold plug, especially just for a 150 hit.

 

Yes but that is still a projected style tip...You really want a non-projected tip when spraying...its good for a few more ponies on the jug.

R5672A-7
" -8
" -9
R5672A-10

Any of these will be good for nitrous.

I use R5724-8 for NA use in my car. I run the 9's for the gas. Dry kit, with a .082 jet single nozzle Made right at 150hp at the wheels last time on the dyno. Had some fueling issues and havent gone back to check the power level now. But i know it hits harder then it did then..

Mike

 

I disagree!

 

You're not gonna lose anything with that cold of a plug gapped at .030. If anything you'll make more power because its cooler in the chambers with it.

Mike

 

He will be fouling those out constantly. He won't be making enough heat to justify going that cold IMO. He doesn't have a 706 with 3 systems!

 

I run a TR8 and moving to a 10 soon...

 

My testing supports what you say. If you can tune a little leaner with the cold plugs the power does increase a bit. The short tips seem to have fewer misfires at WOT from what I've seen on my vehicles.

Yes the cold plugs will foul if you run rich. Cold start can be a problem unless you take steps to prevent it... like tuning leaner.
In cases when you shut the engine off only seconds after a cold-start, the plugs will be wet with fuel and refuse to fire. EFI runs pig-rich on cold-starts and that is the cause. None of my carbureted engines EVER fouled one of these cold plugs, because they don't have cold-start enrichment or a choke for that matter. Adjust the PCM and you shouldn't have a fouling problem.

 

Neither do I....One its added safety for less or no detonation, and When you tighten the gap up on a colder plug it brings a little bit of the "heat range" back so to speak. Dont knock it til you try it. Hell do some back to back testing at the track. Change plugs out there and make a pass, see what you pick up with the colder non-projected style tips.

Mike

 

My car has never once tried to foul the plugs out with the 42lb injectors and I know my tune isnt right on. When I fire my car the voltage, sits over past 15 and its dumping fuel....But i hold er steady for about 5 seconds shortly after start up to help rid of the extra fuel being dumped in, then it idles decent after that.

Mike

 

Have you tried the TR6 plugs? I run the TR6's gapped at .035 on a 20 shot with no problems....

Tried the -8 plugs, but they were too cold and didn't like anything above the 150 sot on the chassis dyno. They fouled out easily on teh street too...

I recommend trying the TR6's for th 150 shot and start there, then try the TR7's...

 

I think the 5724-8 will work nicely in his combo personally. I ran them on the street for a few months and several 175-200 passes and no problems at all. But thats the fun thing about all of us here, each specific combo may react differently! Good luck Phil and lets know how well whichever plug works out.

Charlie

 

If you are tuning it leaner, then I can see your point. But that pretty much defeats the purpose of going to a colder plug in my book. I mean, you could go down all the way to an 11 plug, and lean the **** out of your setup. Is that any safer? Not in my book. He may as well stick to a 7 or 8, and keep his setup where it's at.

 

The way I look at it, blasting N2O into your engine isn't what I'd call safe in the first place. I spray to push the limits of the engine and see how much power output I can get and it still hold together... not a very safe thing to do.
Tuning the N2O leaner will indeed get more power, so that is the purpose of running the cold plugs.
That's what I do because I have no intention of doing what's safe for the engine. I just want to avoid major engine damage due to a stupid plug failure. I'd rather see something else break besides something due to a plug failure... that's just me.

I've never cared for running any resistor-type plug while spraying, so a lot of those plugs you are talking about, I'd never even try myself.

 

Fix your tune! Nuff said Cant just swap plugs and expect them to work correctly. You have to tune the engine for those plugs...Id bet you pick up some power too.

Mike

 

I dont consider mine leaner...I start the AF at say 12.5 at 2500 and lean it out progressively till peak HP then leave it at 12.9-13.0:1 at peak HP NA. Cruise around town is about 15:1

Mike