Alright , so my gaps were at 2.4 it seemed stock from factory , so i'd suggest adjusting the gap , i'm only after 350 hp max so I'm hoping 3.0 will be good .

I'm curious though , what would the gap on a plug like this equate to on an FD plug without the adjustable gap ? anyone have any idea?

Was that answer meant to my post? :-)

bumping this thread. I was wondering if you get the AR3932 and on a fairly stock setup, should you gap them to the NGK BUR7EQP .056 spec? Not really sure what the gap is on the AR3932. Was thinking the AR3932X would probably be the way to go though. Can anyone chime in on their experience since they started running them.

Also wanted to know. Have a dp exhaust and cai everything else stock. Would the x be fine?

the X should be fine, I ended up getting the 3932's and gapped them to .056, car started up right away and runs nice. I used a bench vise to grip the 3932's while gapping them, makes it a lot easier.

Thanks for the quick response. Will be grabbing these tomorrow

Breaking News:

re AR3932.

last October at the Texas Mile my fuel pump fuse blew. i should have had a 30 A in the system.

as i shifted into 4th i had no motor. approx a month ago i pulled the plugs to find most of the porcelain on L2 was missing. things like that can happen when you go lean w your right foot firmly on the floor. generally, however, we see cracks in the porcelain not the whole piece missing.

yesterday i received an email from someone running one of my engines who had just done a track weekend at flat out Brainerd Int'l Raceway... 2.5 mile road course w a 6000 foot straight and a 90 degree banked turn where you don't have to lift...

so it is a demanding top speed type track.

"The car performed beautifully this weekend at BIR. Only issue I ran into was at around 5-6k rpm the ignition would start to break up. We discovered it was due to the spark plugs, the Autolites. So I swapped out to a new set and still had the issue. Luckily I made some FD friends at the track and he had a used set of NGK race "wire" plugs that we threw in and that solved the issue. Just wanted to let you know and give you an update."

yikes! missing porcelain and running around one bar!

i had happened to be speaking w an Autolite Tech yesterday and mentioned that our motors can make 8.6 flywheel hp per cubic inch... there was a silence and gulp on the other end of the phone.

given the second porcelain issue Autolites will not be going back into my FD. the plugs were originally recommended to me by Lance Nist but it appears that our engines can develop too much Combustion Chamber Pressure/Heat.

i was thinking they would work fine at lower power levels but given the problem at 14/15 PSI E93 i now believe it will be back to NGK for me.

i did run them a fair amount last year w no problems until i blew the pump fuse.

howard

^ Howard, I'm NA so I may still play with them. Be intersting to see how long they last compared to the ngk's. I just now finally installed mine eariler today on my 20b but now my BAC is acting up. I dont know if it's the plugs or not but I will reinstall the ngk's to make sure it's not the plugs causing the BAC to act up. My BAC isn't necessarily programed correctly either.

Well just reinstalled the factory plugs and my BAC is back to normal. Hmmm strange! :confused:

Well, that's a kick in the but. I guess the ngk's are the way to go. Would you recommend running 9's all around vrs the 7 and 9's like factory?

This still for a stockish engine.

I'm just going to keep running the 3932's since I'm basically stock and probably switch back to NGK's later. I'm sure a lot of people are running these now, so hopefully no one else has had problems. Mine are running great though and no issues at stock levels of boost.

I think like all things that these plugs may have there limits and or application specific use. As soon as I sort out my engines problems I will switch back to these and see how they perform on a NA application.

"I think like all things that these plugs may have there limits and or application specific use."

i agree.

i did get off the dyno last wednesday w one of my customer cars/engines. GT4094r, E85, 27 psi and 575 SAE rwhp.

we ran the NGK BR10 EG plugs at .023 (IGN-1A coils at 4.5 mS)

zero misfires in the 10s AFR. the plugs had a light chocolate color.

maybe 40 pulls to the 9000 area.

looking good. i have no problem w the Autolites but given we have had a couple of complete porcelain losses it may be that as t-von states they are a mis-application for our unusual motors at higher power levels.

Lance referred to them as the NASCAR plugs. assuming they are run in the Cup cars... 350 cubic inches and 850 FWhp is 2.42 hp per cubic inch.

2.42 X 80 cubic inches is 193 hp...

at 575 rw X 1.15 = 661 FW hp/80 = 8.26 hp per cubic inch!

obviously HUGE CCP/CCH in our motors and a challenge for any plug before throwing in detonation.

i do speculate that the Autolites are fine IF you have no detonation. they worked fine for me on the dyno at 8950 rpm in fifth gear around 550/575. i do think, however, if you do encounter detonation they add another potential engine killing threat... the porcelain separation.

not to say the BR10EG might have a problem but it is differently configured and i have seen NGK plugs w cracked porcelain which would cause no damage.

Howard

I don't know much about the topic, but is this porcelain issue only present with the AR3932 (non x) rather than the AR3932X? Looking at the X version it appears the porcelain is shielded more from the direct flame front by the ground straps themselves in comparison to the single strap - much like the ngk which don't seem to have porcelain breakage issues as bad. Am I off base in my thinking that the X version may still be a go?

the AR3932X worked fine for me until we were in the 500 area. at that point they exhibited some misfires at higher rpms. i assume it is due to the wider gap.

we switched to the AR3932 gapped at .023 and all was fine.

i like both plugs, however, if you encounter detonation i think the NGKs present less risk of alot of ceramics going thru your motor and turbine wheel.

i do think you are correct that the X should be less likely to pass ceramic pieces due to the 4 ground straps presenting a barrier.

HC

From Howard's first post....if you look at picture of the AR3932X plug.... we had aircraft plugs that used a gapper that incorporated a knurled headed bolt to adjust the gap? The plug was first installed into a metal boss and
each spoke (ground leg) could be adjusted accurately.

We also had a pressure tester that could bring the pressure up while firing the plug. The gap was critical as the pressure rose. Howard is right about .023" for 25 psi. I think .020" might be appropriate for 35 psi boost.
Keep testing.

Barry

Like this.

Barry has all the cool tools:)

FWIW, i finally had a chance to disassemble my motor after i lost the fuel pump fuse at the Texas Mile. i could go in to details re the motor but since this is a spark plug thread i do want to share the relevant info.

as you may know, the entire ceramic insert was missing from L1. i assume detonation was the cause as the motor leaned around 550 hp in third. of course i was expecting an unhappy interior. the rear rotor and housings were fine except for pancake flat corner seals.

my pulse rose as i removed the mid iron to take a look...

pretty much nothing! what happened to the missing piece from the plug? i will resurface the two rotor housings but they look good.

thanks Goopy for your apex seals. big time detonation and no broken seals. a bit flatted on the shoulders. i will check them for straightness tomorrow but they won't be going back in the motor.

Job One for apex seals is:

don't break.

the GT4094r turbine wheel is also in excellent condition.

maybe Autolite porcelain vaporizes.

BTW, w re to the BR10EG............

there are two flavors so be aware.

product code 3993 is what you want as it has a solid outer tip

product code 3830 has a screw on tip.

successfully registered for the Oct Texas Mile today.

howard

hey howard, pretty informative thread as usual! thanks for all the information, i always learn something new about our engines when you post topics. anyway i have a question regarding the choice of spark plug i am using.

i have a single turbo FD with LS3 coils using NGK heat range 9 platinums while running methanol injection. i believe i read somewhere that platinum plugs dont mesh too well with the kind of A.I. i am running.

im wondering more about this because after running a couple autoX's the porcelain on one of my spark plugs was cracked. im going to look into getting heat range 10 plugs since my engine is currently about to undergo a rebuild (it blew under regular driving....how ironic). does nickel mix well with m1 non-lubricated methanol? thanks!

"read somewhere that platinum plugs don't mesh too well with...." methanol

you did indeed read that on the site. i believe it was a Honda research paper. they referred to it as a "chemical reaction."

i was running pump and a lot (3000 CC) of meth and had two instances where out of the blue i had an instance of detonation. i had been fine for 3 years starting at about 1200 cc and slowly increasing the meth.

sure don't know for sure but when i switched to inductive ignition/E85 i also switched to nickel copper plugs which have served me well around 550.

i do think 9s are too hot and will result in spark plug mountain. take a look at your rotor housings when your motor is apart.

a colder plug will help lower SPM.

i do still love pump and meth AI...

howard

thank you! i just read that when platinum gets too hot it can become the catalyst to turn methanol into formaldehyde, yikes lol. that will cause the detonation you have mentioned and thus lead to engine failure.

im starting to believe this may have definitely been a cause for the engine going out on me recently. while its apart ill be sure to check out housings, im expecting to see the wings there for sure.

ill stick to NGK plugs but will look into nickel and copper. those will surely be better than what i had been running for a long time.

edit: my single turbo set up is currently tuned on a haltech platinum sport 1000. im running 15psi boost

Failed NGK BR10EG
 

Has anyone ever had this happen? anyone knows what could have caused it?

Cracked porcelain = detonation