Spark Plug Gapping Preference for Turbo Build - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

johnowow · 09-29-2019, 01:32 AM

Before I get started, I just wanted to say I've already done my fare share of studying before coming down to actually typing this question out for the past hour or two to no avail - so sorry in advanced if there has already been a definite answer.

It's been a mixture of inconstant answers as to what the best measured gap is for the OEM spark plugs in a turbo charge application.

Build:
2015 FR-S changing spark plugs @ 68k (yes I know its a bit over due lol)
Speed By Design SBD500X turbo that gets around 10PSI max on boost.
Stock injectors with DW300C upgrade fuel pump tuned by Delicious.
Daily Driven - spirited driving - no track.
Bogged a bit once turbo's under boost at around 4k but never got down to the problem as it just went away over time?

So nothing too crazy with the build, pretty average for a turbo set up at best. I've read a mixture of either going colder on a different set of plugs, which I just ended up purchasing the OEM set since they were pretty ideal.

Some say .032" pregapped and leave it at that, while some others are vowing to tighten it due to possibility of blow out and ranges the measurements from .020 like the WRX, .022, .026, .031, etc.

Trying to not waste any more of your time but what gapping have you guys got good results with on a normal set up? Thanks again in advance for any question and I apoligize if this has been over asked since I haven't found a good thread.

86MLR · 09-29-2019, 02:22 AM

Depends, on a few things

You want the biggest gap your ignition system can support.

The bigger the gap, the bigger the spark, the bigger the spark the bigger the flame front, the bigger the flame front the better the burn, hence, more power.

I'm running stock 0.8mm (0.032 "ish") running 8 psi with stock ignition, I have no issues.

I needed to run 0.6 mm (0.023") on my RB running 25 psi with upgraded splitfire coils.

IMO, first point of call would be to check your coils and wiring before touching your plugs.

Unless your plugs are over 50 k, iridium plugs can last longer, but they do lose efficiency over time.

Tonrogs · 09-29-2019, 08:13 AM

I'm currently running oem plugs with stock .032 gap. Running 20psi without any issues. Will be going up before next spring to around 28 psi at which point I may need to revisit this myself.
In my opinion, at your levels, even though you are higher compression than I am, I see no need for you to need to touch anything right now.

DarkPira7e · 09-29-2019, 09:55 AM

Unless you're having spark blowout, I wouldn't worry about it or change it. Good thinking though

johnowow · 09-29-2019, 03:27 PM

Okay perfect, so for anyone currently looking up this same question, final consensus if you’re switching plugs on a turbo application, OEM is fine and stock .032” gap is fine for pretty average turbo set ups around 10 PSI and proven no problem to 20 psi on some. Thank you guys for your time in replying, really helped a lot, and I hope this thread helps people in the future.

Irace86.2.0 · 09-29-2019, 07:19 PM

Quote:

Originally Posted by johnowow

Okay perfect, so for anyone currently looking up this same question, final consensus if you’re switching plugs on a turbo application, OEM is fine and stock .032” gap is fine for pretty average turbo set ups around 10 PSI and proven no problem to 20 psi on some. Thank you guys for your time in replying, really helped a lot, and I hope this thread helps people in the future.

@FRS Justin ...from what I can remember, he is running stock plugs and gap at 700hp.

86MLR · 09-29-2019, 08:06 PM

Quote:

Originally Posted by Irace86.2.0

@FRS Justin ...from what I can remember, he is running stock plugs and gap at 700hp.

What coils?

Irace86.2.0 · 09-29-2019, 09:33 PM

Quote:

Originally Posted by 86MLR

What coils?

I have no idea.

FRS Justin · 10-04-2019, 05:01 PM

Stock plugs and gap with stock coils.

09-29-2019, 01:32 AM	#1
johnowow Member Join Date: Jul 2017 Drives: 2015 Scion FRS Location: Carlsbad, CA Posts: 24 Thanks: 14 Thanked 4 Times in 3 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Spark Plug Gapping Preference for Turbo Build Before I get started, I just wanted to say I've already done my fare share of studying before coming down to actually typing this question out for the past hour or two to no avail - so sorry in advanced if there has already been a definite answer. It's been a mixture of inconstant answers as to what the best measured gap is for the OEM spark plugs in a turbo charge application. Build: 2015 FR-S changing spark plugs @ 68k (yes I know its a bit over due lol) Speed By Design SBD500X turbo that gets around 10PSI max on boost. Stock injectors with DW300C upgrade fuel pump tuned by Delicious. Daily Driven - spirited driving - no track. Bogged a bit once turbo's under boost at around 4k but never got down to the problem as it just went away over time? So nothing too crazy with the build, pretty average for a turbo set up at best. I've read a mixture of either going colder on a different set of plugs, which I just ended up purchasing the OEM set since they were pretty ideal. Some say .032" pregapped and leave it at that, while some others are vowing to tighten it due to possibility of blow out and ranges the measurements from .020 like the WRX, .022, .026, .031, etc. Trying to not waste any more of your time but what gapping have you guys got good results with on a normal set up? Thanks again in advance for any question and I apoligize if this has been over asked since I haven't found a good thread.

09-29-2019, 02:22 AM	#2
86MLR Senior Member Join Date: Aug 2018 Drives: 2002 VX Commodore SS LS1 Auto Location: Sydney Posts: 2,203 Thanks: 500 Thanked 2,185 Times in 1,111 Posts Mentioned: 13 Post(s) Tagged: 0 Thread(s)	Depends, on a few things You want the biggest gap your ignition system can support. The bigger the gap, the bigger the spark, the bigger the spark the bigger the flame front, the bigger the flame front the better the burn, hence, more power. I'm running stock 0.8mm (0.032 "ish") running 8 psi with stock ignition, I have no issues. I needed to run 0.6 mm (0.023") on my RB running 25 psi with upgraded splitfire coils. IMO, first point of call would be to check your coils and wiring before touching your plugs. Unless your plugs are over 50 k, iridium plugs can last longer, but they do lose efficiency over time. __________________ Disclaimer: This post represents the official views of the voices in my head at the time of posting. http://www.ft86club.com/forums/showthread.php?t=133311 I'm only here for the biscuits

09-29-2019, 08:13 AM	#3
Tonrogs Senior Member Join Date: Apr 2018 Drives: 2014 BRZ Limited, Satin White Pearl Location: WI, 53593 Posts: 106 Thanks: 10 Thanked 40 Times in 30 Posts Mentioned: 3 Post(s) Tagged: 0 Thread(s)	I'm currently running oem plugs with stock .032 gap. Running 20psi without any issues. Will be going up before next spring to around 28 psi at which point I may need to revisit this myself. In my opinion, at your levels, even though you are higher compression than I am, I see no need for you to need to touch anything right now. __________________ '14 SWP BRZ 6MT \| FBM built 9:1cr engine w/ GTX3076R Turbo \| Mazworx CD009 trans swap \| EcuTek \| Jackson Racing Dual Oil Cooler/Radiator \| SPAL fans \| JDL 3" Dual Resonated OP/FP \| Perrin 3" \| Radium Dual Cans \| 18" Rota Titans \| M85 3.73 diff \| DSS 1k axles \| And more....too much more....ugh.

10-04-2019, 05:01 PM	#9
FRS Justin Senior Member Join Date: May 2014 Drives: 2013 Asphalt FRS Location: San Antonio Posts: 994 Thanks: 693 Thanked 695 Times in 417 Posts Mentioned: 22 Post(s) Tagged: 1 Thread(s)	Stock plugs and gap with stock coils. __________________ Instagram FT86PROJECT9S Facebook FT86PROJECT9S 710whp

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
SPARK PLUG GUiDE!	Kojiap1	Engine, Exhaust, Transmission	15	04-13-2022 01:30 PM
Spark Plug Options?	BRZach	Mechanical Maintenance (Oil, Fluids, Break-In, Servicing)	27	08-18-2017 12:14 AM
Spark Plug Replacement	Dacfrs	Rocky Mountains / Great Plains	4	03-21-2017 12:16 AM
P0351 bad spark plug...	Jaden	Engine, Exhaust, Transmission	3	01-02-2016 10:19 AM
Spark Plug Time !!!!	RFB	Scion FR-S / Toyota 86 GT86 General Forum	26	11-24-2014 07:46 PM

09-29-2019, 09:55 AM	#4
DarkPira7e Rust bucket enthusiast Join Date: Feb 2017 Drives: 2013 Turbo Firestorm FRS Location: Vermont Posts: 3,932 Thanks: 3,199 Thanked 4,095 Times in 2,045 Posts Mentioned: 31 Post(s) Tagged: 0 Thread(s)	Unless you're having spark blowout, I wouldn't worry about it or change it. Good thinking though

09-29-2019, 03:27 PM	#5
johnowow Member Join Date: Jul 2017 Drives: 2015 Scion FRS Location: Carlsbad, CA Posts: 24 Thanks: 14 Thanked 4 Times in 3 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Okay perfect, so for anyone currently looking up this same question, final consensus if you’re switching plugs on a turbo application, OEM is fine and stock .032” gap is fine for pretty average turbo set ups around 10 PSI and proven no problem to 20 psi on some. Thank you guys for your time in replying, really helped a lot, and I hope this thread helps people in the future.

User Name		Remember Me?
Password