Colder plug vs Meth inj

hoffit · 09-06-2006, 12:26 PM

If both colder plugs and meth injection both drop combustion chamber temps, I was wondering why would someone go with meth inj vs going to colder plugs. It seems as if a lot of people say to go 1 step colder and then later to go with meth inj but say that 2 step colder plugs are overkill. If they both accomplish the same thing then why go meth? Is it because colder plugs will cause you to run rich if not boosting all the time vs meth will be added as needed? Can someone explain to me why 2 step colder plugs isn't the next logical choice?

P.S. Mods I have don't matter right now, it's for future reference.

Flycaster · 09-06-2006, 12:44 PM

First, the evaporative cooling effects of injection will greatly exceed any combustion chamber temperature change caused by going to a colder plug. Second, going 2 steps colder will make starting more difficult, the plugs will have a tendancy to load up, and you may actually suffer a performance decrease...unless you're building a 600whp monster that requires every thing you can throw at it to keep from detonating.

As an example, I'm using a GT30R on a built block that is right at 400whp. When I informed the engine builder (Cobb) that I was going to use 50/50 injection for additional safety and a little more torque, he advised me to use the standard range plug. His opinion is that a colder plug would be ill-advised in my case, and that I would be much more likely to have fouling issues, especially in the fall-winter-spring. In fact, he sugggested that I might want to either turn the injection off or go to a warmer plug in the middle of winter in order to avoid fouling and drivability issues.

**Interior Flaire** · 09-06-2006, 12:55 PM

Well said Fly. I do not see where meth=colder plugs no matter how many steps down you go. I am running both-meth + 1 step colder and my reason is that I live in Texas and am trying to make consistent, reliable power througout the year.

CB

hoffit · 09-06-2006, 03:12 PM

Thanks for the responses. Makes sense. Just wanted to make sure that I wasn't missing something.

***VSGTS14*** · 09-06-2006, 05:15 PM

yea meth gives you a lot more power than colder plugs...lol.

09-06-2006, 12:26 PM	#1
hoffit Professional STI Racer Car: 04 Subaru WRX STi Fav Mod: Carlabs X-brace & RPM brace Location: MN Posts: 640 Join Date: Oct 2005 Trader Rating: (8)	Colder plug vs Meth inj If both colder plugs and meth injection both drop combustion chamber temps, I was wondering why would someone go with meth inj vs going to colder plugs. It seems as if a lot of people say to go 1 step colder and then later to go with meth inj but say that 2 step colder plugs are overkill. If they both accomplish the same thing then why go meth? Is it because colder plugs will cause you to run rich if not boosting all the time vs meth will be added as needed? Can someone explain to me why 2 step colder plugs isn't the next logical choice? P.S. Mods I have don't matter right now, it's for future reference. This ad is not endorsed by this member. Please register or login to hide this ad.

09-06-2006, 12:44 PM	#2
Flycaster S204 Racer Posts: 3,008 Join Date: Apr 2004 Trader Rating: (0)	First, the evaporative cooling effects of injection will greatly exceed any combustion chamber temperature change caused by going to a colder plug. Second, going 2 steps colder will make starting more difficult, the plugs will have a tendancy to load up, and you may actually suffer a performance decrease...unless you're building a 600whp monster that requires every thing you can throw at it to keep from detonating. As an example, I'm using a GT30R on a built block that is right at 400whp. When I informed the engine builder (Cobb) that I was going to use 50/50 injection for additional safety and a little more torque, he advised me to use the standard range plug. His opinion is that a colder plug would be ill-advised in my case, and that I would be much more likely to have fouling issues, especially in the fall-winter-spring. In fact, he sugggested that I might want to either turn the injection off or go to a warmer plug in the middle of winter in order to avoid fouling and drivability issues. Last edited by Flycaster : 09-06-2006 at 12:47 PM.

09-06-2006, 05:15 PM	#5
*VSGTS14* Muller Chevrolet Car: 08 Chevy 2500HD Fav Mod: a new 08 STi Location: Milford, NJ Posts: 9,984 Join Date: Oct 2004 Trader Rating: (11)	yea meth gives you a lot more power than colder plugs...lol. This ad is not endorsed by this member. Please register or login to hide this ad.

09-06-2006, 12:55 PM	#3
Interior Flaire Authorized Vendor Car: 05 PSM Stage 4 Fav Mod: Pro-Tune Location: Big D Posts: 1,745 Join Date: Apr 2005 Trader Rating: (16)	Well said Fly. I do not see where meth=colder plugs no matter how many steps down you go. I am running both-meth + 1 step colder and my reason is that I live in Texas and am trying to make consistent, reliable power througout the year. CB

09-06-2006, 03:12 PM	#4
hoffit Professional STI Racer Car: 04 Subaru WRX STi Fav Mod: Carlabs X-brace & RPM brace Location: MN Posts: 640 Join Date: Oct 2005 Trader Rating: (8)	Thanks for the responses. Makes sense. Just wanted to make sure that I wasn't missing something.