Jump to content
SAU Community
  • Welcome to SAU Community

    Welcome to SAU Community, like most online communities you must register to view or post in our community, but don't worry this is a simple free process that requires minimal information for you to signup. Be apart of SAU Community by signing in or creating an account.

    • Start new topics and reply to others
    • Subscribe to topics and forums to get email updates
    • Get your own profile page, build reputation and make new friends
    • Send personal messages to other members.
    • See fewer ads!

    Consider joining our newsletter for the latest content updates

    Click here to register


smadayar

RB25 E85 flex tune spark plugs

Recommended Posts

Hello, had my car tuned on 98  and E85 (470hp 19psi) and want some advise on spark plugs. I currently have BCPR6ES gapped down to 0.6mm  using splitfire coils. This setup has no issue with missfire at full throttle on both fuels. But low load has abit of missfire on E85 and even more on 98 which I believe is due to the gap size. Can anyone confirm and advise on a better spark plug combination of any?

 

Cheers

Link to post
Share on other sites

It's not the plugs you need to change, apart from the gap. And if the Splitfires won't support a larger gap, then you need bigger coils. Small upgrade to Yaris type or large upgrade to R35 type.

Link to post
Share on other sites

At 470hp you shouldn’t be gapping them at all. Could change the plug to R5671A-8. There a ngk race plug that I run, 28psi on 98 with splitfire coils no problems. The plug your using did cause me a misfire up around the 22-25psi but once changed it’s all good.

Link to post
Share on other sites

Do you have a wideband? I wouldn't be surprised if it's a misfire due to a lean condition.

At 1.3bar of boost, 0.6mm gap and Splitfires are a walk in the park. You could run 0.8mm gap and still be fine.

Link to post
Share on other sites

Denso IK01-24 or NGK R7434-8.

best plugs out there and a lot cheaper than a new set of coils. fine tip iridium.

I've had a set for 2 years in an 780hp rb26 and they're still perfect.

  • Like 1
Link to post
Share on other sites
51 minutes ago, burn4005 said:

Denso IK01-24 or NGK R7434-8.

best plugs out there and a lot cheaper than a new set of coils. fine tip iridium.

I've had a set for 2 years in an 780hp rb26 and they're still perfect.

Was curious how much the NGK racing plugs were, I think i may hold off on purchsae

spacer.png

  • Haha 3
Link to post
Share on other sites

They definitely are, but it's really only cost effective bundling with other stuff you order. I run the R7436-8 (53mm old JIS length like bcpr) as it is actually the correct length plug for RB26, not the R7434-8 (50.5mm ISO length like bkr) which is shorter. There's 2.5mm difference in height between them and the old JIS length fits a little better into your coilpacks. Sometimes it's an issue, sometimes not, but the 26 is supposed to have the 53mm length FYI. Fwiw though yeah the R7434/36 is the best plug out there - lowered iridium centre electrode and platinum ground electrode. But at around $50 per unit they'd wanna be...

I've attached the NGK race catalogue for the complete range available, as it's totally separate to the normal NGK site catalogue.

That said, the Op RB25 shouldn't require NGK race plugs though, or a heat range of colder than a 6 or 7 as you don't want be colder than you need to be. Gaps around 0.8mm should be fine too, so maybe 0.6mm is actually a bit small creating a weak spark. Maybe the plugs are just fouled up causing an occasional misfire ?

0.6mm does seems a bit on the small side no ?

NGK_Race_Plugs.pdf

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



×
×
  • Create New...