12mm Spark Plugs for a Race Engine
 

What 12mm spark plugs are you folks using in race engines with either one or two 12mm spark plugs in each head? My specific application is a 3.6L engine with ITBs revving to 8000 RPM.

Thanks.

I am running NGK D6EA, not because I knew something, but that was a suggestion and the engine makes good HP. Another plug I have heard about and might be pricey, XR2CS Bosch. In a second motor I have DCPR7E. I have looked up info on compatibility with compression and made decisions accordingly. The plug people will talk to you, and I would get multiple opinions. Bob

The Bosch XR2CS is a plug that someone knowledgeable recommended. The pricing is no issue but I am a little worried about the durability of the silver center electrode.

I am going with the Bosch XR2CS plugs......

http://forums.pelicanparts.com/uploa...1578781777.jpg
http://forums.pelicanparts.com/uploa...1578781777.jpg

Maybe look into Brisk plugs? They make them for Porsche Cup car motors like the above. Perhaps they have an application suitable for your needs.

I looked into Brisk. The pricing seems high and their plugs don't seem to offer anything the Bosch XR2CS plug doesn't.

Obviously applications are varied. I use the W3CS and F3CS in 2.0 twin plug 46mm carb, 8k application.

I just found out that the Bosch XR2CS has been on backorder for 6 months. They won't say they have been discontinued, but that is effectively the case as of now.

More searching.....

I really want a Bosch in the 2 heat range or an NGK in the 9 heat range.

Plugs need to be chosen not just by heat range but by firing end type. NA engines will run more extended open firing ends as long as you have piston clearance. The more extended the "hotter" the plug runs even at its stated heat range.

Assuming you need 14.00mm x 3/4" reach.

NGK offer both 'production" plug or a race plug. Race plugs are a lot more expensive.

Do you need a non resistor plug? PM me and I can help with plug choice and supply. We have several in stock in 9 heat range.

I need 12mm plugs....I sent you a PM.

Bill Roth is ultimately the bosch supplier to the Motorsports market in America
He has pretty much every plug used by every Motorsports entity in the country
Also if you wish to find a NGK Monarch Distributing in the Inland Empire is the equivalent for NGK
Mech Tronic
Phone: (631) 423-0523

I emailed Bill last night and he responded today telling me that Bosch stopped making the XR2CS plug as of 09/2017.

It looks like I will be going with an NGK iridium plug......I am not sure which one yet.

https://www.summitracing.com/parts/ngk-6681/overview/
the NGK DR8ES is crossreferenced to the XR2CS
so the heat range is 8 try the DR8EIX/6681 which is a 12mm x 19 reach with a resistor.
Most supped up Porsche will run a NGK 8 bp or es
regards

Keep in mind that that plug needs a 5/8 wrench size on a 3.6 head also in my case none resistor plugs caused a lot of electrical interference causing starting problems

I am looking in the NGK 9 heat range. I am looking at the DCPR9EIX and the KR9CI. Both are 5/8" and both are resistor plugs.

Is there a reason that resistor plugs are preferred, or is that just what's available?

Race cars get interference with the telemetry and 2 way comms, Street cars Stereo
Bosch also uses that to keep energy high....

Porsche sparkplug connectors have resistors, and of course many performance sparkplug wires are resistor type as well. I've assumed that given one or both of those in use, resistor-type plugs are not required?

The advance in Ecu controls and sensor technology have sensitized signal processing.
Predominantly Porsche Historic racecars don't have a resistor wires and or plugs sometimes these things raise hell with engine dyno control, just ask PMNA, the plugs do the trick on radios the wires have to be used with dyno control and modern ecus.
This is rather Esoteric and you never have to deal with it but when for whatever reason when you need a clear signal and uninterrupted comms you do what you have to do....

My engine uses a MoTec M130 ECU and the WeaponX "coil on plug" setup. With the plethora of electronics on and around this engine, resistor plugs are the way to go.