URLOSN

iTrader: (29)

I have a built LS7 about 12.8:1 compression, TFS 235 heads, Ported fast 90, and a 25x/25x cam. I am going to be running TR6 plugs, i cannot remember the gap i need to set them at? this is a pump gas set up, but 99% track set up.
TIA

JL ws-6

iTrader: (50)

First of all you shouldn't have a #6 plug in that setup, you should have a #7.

The gap, it's not that critical on an n/a car. You can run .035 to .040 and it will be fine... WITH THE RIGHT PLUG.

Not sure who told you a #6 was right for a nearly 13 to 1 motor that should be making over 600 hp at the crank... but they're wrong, very wrong.

tektrans

iTrader: (23)

My N/A LS7 has 13:1cr and I use TR6's gapped at .045
If I drive around the street on those plugs it will run fine but they cannot be raced on again. I drive around on TR55's. I'm well over 700+ at the crank.
Why so cold a plug JL?

robsquikz28

iTrader: (246)

I have no idea why you run on such a hot plug. You can make more power and get a better tune with a colder plug, especially with compr. at 13-1....holy ****.. tr6 or tr55 should be used for cars under 500 horse and lower comp.

URLOSN

iTrader: (29)

Talked to my tuner and he said he could tune a TR6, but he would prefer a TR7IX iridium plug for driveability and they come gapped at 38

WMSuperSport

iTrader: (23)

I run the -7. NGK 5671A-7, or 4091 for Oreillys stock #.

I'm 11.5:1, pump gas

tektrans

iTrader: (23)

My tuner is considered one of the best out there so I'm sure there's a reason for the
TR6's, what the reason is I have no idea. My curiousity is definately spiked though, next time I see him I will ask.

JL ws-6

iTrader: (50)

I'd be curious as to what his reason for that plug is.

tektrans

iTrader: (23)

Spoke to Julio Hormilla today. Basically he said that too cold of a plug will hurt performance because they won't burn hot enough, they get deposits on them, especially with the smaller gaps. That's his experience anyway.
Mike Romaine runs TR7's but he's boosted and runs well into the 8's.
6 sec Pro Mod nitrous car that Julio worked on used TR8's.

I'm not saying you guys are wrong or anything, this is just what Julio used on my car, I guess just use whatever works for you. Obviously whoever is tuning the car should have a preference for a certain plug for a certain combo as well.

JL ws-6

iTrader: (50)

Colder plugs, I agree they foul easier. They also burn colder too.. if you're warming the car on another plug I see no reason not to run the colder plug.

Thing is all the nitrous cars I know that are hitting stuff with alot of power are in the #11 or #10 range, #8 might have been what they ran at one time, but it's not it anymore. One range down on the plug will decrease combustion temps about 100 degrees, doesn't seem like alot, but it can be the difference between hurting something and not. And if you can run the colder plug with no ill effects.... why not?

ATV runs a #11 in his car, I've been running a #9 I'm sure smith and rpm are on #9 or colder as well.

I did try a #8 one day just to see if it would effect anything, and it made absolutely no difference... it was a touch easier to read, other then that the car didn't go any faster, so I just went back to the 9.

If you keep your part throttle and idle timing/fueling in check, you can run the colder plug without too many issues with them fouling out. It takes a little playing with, but it's not that hard. I always load my car in the trailer with a #6 in it to warm the motor on, once it's up to temp, they come out and the #9's go in. I've also, fwiw gapped every plug I run at 35, never any more or less.. that's one thing generally I don't mess with.

robsquikz28

iTrader: (246)

^ sounds about right to me, usually a 8 or higher is recommended for all big shots of nitrous even on the lt1 cars with stock 10.5 compression. You never want to hurt the engine and if you can save the engine from catostrophic damage from a FEW dollar plug, why not. Its safer to know the colder plug can save you in the short run,lol 1/4 mile.

tektrans

iTrader: (23)

I really am kinda out of my realm of understanding here as my knowledge of race motors and "how" they work is limited so bear with me :
If the plug burns colder wouldn't that affect how well the mixture ignites? Flame travel and so on? and subsequently hp made?
The pro mod car I mentioned earlier using the #8 plug, that car is making well over 2000hp, why wouldn't that motor need a #10 or #11 plug? All that nitrous making the mixture so cool that it would take a hotter plug to ignite it?
I would think that the hotter the plug you can use "safely" would make for better combustion of a mixture in a given motor. No?

tektrans

iTrader: (23)

Not disagreeing with you but I'm sure no one here is considering spark plug price as a factor in choosing a plug, so that aside and especially in a N/A motor like mine I would think that spark plug choice is less critical for motor safety yes but indeed critical for performance, even more so than a power adder car.

JL ws-6

iTrader: (50)

The added compression, both static and dynamic increase the burn rate, therefore the plug doesn't need to be as hot to do it's job. One reason you don't run a projected tip plug, the projected tip is to get the plug into the chamber more to ignite a charge that is under a good bit less pressure. Chamber design and plug location also impact this, and when you start getting into the 12.5+ compression, the quench also effects this.

Why you would run a #8 plug in a promod, I can only think of one reason, they were blowing the spark out with the colder plugs, and you can only tighten the gap so far before it's not going to produce a large enough spark to ignite the charge. But, this is usually overcome with a powerful magneto... so again, I'm really at a loss as to why you would run that hot of a plug in that type of engine. I know absolutely nothing about those setups other then they make huge power and they burn parts up faster then you can shake a stick..... that's all I know with promod stuff. That, and it costs about twice what I have into my entire car to build one of those motors... that being said, I really don't even look into that stuff... it's so far out of my reach it's somewhat irrevelant.

URLOSN

iTrader: (29)

Ok, i just got back from the dyno. I ended up putting BR7EF in it gapped at 38 , cause i could not find the TR7IX on short notice. The motor made good power but you could see on the dyno and hear it miss a couple times during the pull. i am going to pull the plugs tuesday when i get home from the Fire Dept and check them out. Is this the wrong #7 to use, would anyone recommend another plug in the #7 range? On a good note it made 527/ 456 SAE through a 5200 stall and a th350 on 28" D/R i think i may pick up a little more after i change plugs, and possibly wires.

KCFormula

iTrader: (4)

With an aluminum block...in cooler weather...I can see using a #6 plug and it being fine. Your static compression isn't all that high and with a hyd. cam you prob. aren't spinning it past 8k.
On a side note I would run at least 100oct though.

tektrans

iTrader: (23)

there ya go, I have a hyd cam and only spinning to 6700 at most and I run 110.

DrkPhx

iTrader: (15)

If we're talking about spark gap and heat range from a pure performance aspect, then you shouldn't guess. Nothing beats good old-fashioned spark reading in this case. For WOT, you need to read them right after WOT to get the most accurate reading. My car is 11.7 static CR and I currently use TR6's gapped bigger than out of the box. There are several articles and opinions how to read and gap plugs, but this is one of my favorites. It's by Larry Meaux of Meaux Racing. I believe he knows something about making horsepower.

http://www.dragstuff.com/techarticle...ead-plugs.html

03 BUSA

iTrader: (25)

TR6's here with 35 gap on a NA 12:5.1 solid roller motor. Pump Gas/100octane at track.

Firehawk441

iTrader: (41)

It's called EXPERIENCE