Opinions needed.....colder spark plugs

Methodical · May 12, 2007

I have the NX wet kit. The kit is installed just waiting for the dual window switch from Nitrous Outlet. I plan to work my way up to a 150 shot of N20. Currently I have the autolite 3924s in the car - per AFRs spark plug recommendation. Should I install the 3923s (2 step cold plugs) now or wait until I go over 125 shot? My timing is and will be at 10*. I plan to start with a plug gap of .040 and go to .035 is warranted. My plan is to start with the 50, 75, 100, 125 then 150 shot. Is this a good step plan? Am I working wisely and in the right direction? Also, what affect will the colder plugs have on NA performance - particularly the 3923s.

I appreciate any advice or tips

thumper460 · May 13, 2007

Be safe... get the colder plug when on the bottle..cool??
Just me.............................

Thumper

Methodical · May 14, 2007

Yes for sure. But here's why I ask. I have the Autolite 3924 and 3923s plugs in the wing. Now here's where I get a little confused. The stock GT40 heads (originally in car) required Ford plug AWSF32, which from my research (i.e. Corral sticky "nitrous plugs quick reference guide") is 2 steps colder than the stock GTs. Now that I have the AFR heads, AFR recommends the Autolite 3924s which is 1 step colder but colder than what/which plug . I'm confused because the car already ran colder plugs (i.e. AWSF32). So is the 3923s really only 1 step colder or is it 2 steps colder - see my dilemma. I don't want to put too cold of a plug in the car and have driveability issues.

blksn955.o · May 14, 2007

I would take AFR's recomended plug as not 1, 2, or 40 colder...just what is recomended. I look at it like with the chamber diff. and head meteral diff. you really cannot compare one recomended plug from another...just what is the recomended plug for a given head (assuming they said this plug for N/A use).

With that said I would run a plug at one step colder than the recomended plug for that head if I needed one range colder. If I needed 2 steps colder then I would go 2 steps colder from the plug recomended for that head. I would also rather err on the safer side, and that is what you will be doing at the least from what your saying.

I would start out small, like the 75 shot if I planned to test out things and bigger in steps...I dont think I would really care to run a 50shot that much.

Have you asked around at what people are running with those heads and a bottle? Maybe the heads react weird to a 150 shot and people are running 2 steps colder (from what AFR recomends)?

I didnt notice any power drop from running a colder plug...it might have lost alittle but I didnt feel anything seat of the pants...I also in the end thought "so I loose maybe 5hp with a colder plug, that I can now run 125 MORE saftly on when I need it"...its a nice trade off if you ask me.

Methodical · May 14, 2007

blksn955.o said:
I would take AFR's recomended plug as not 1, 2, or 40 colder...just what is recomended. I look at it like with the chamber diff. and head meteral diff. you really cannot compare one recomended plug from another...just what is the recomended plug for a given head (assuming they said this plug for N/A use)...

Your statement above is right on the money. I spoke with an AFR rep and he stated that the 3924 is what's recommended for NA. They recommend the 3923s for nitrous use,which is one step colder. So I installed the 3923s tonight.

Thanks for the help fellas.

Opinions needed.....colder spark plugs

Methodical

thumper460

Methodical

blksn955.o

Methodical

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