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Swapped to BPR7ES from BR7ES ended spark blow out

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turboglenn

15+ Year Contributor
6,375
123
Nov 5, 2007
RIpley, West Virginia
this weekend (friday night) i went to lincoln and visted beanblacktsi to meet him and his friends and check out his car.. I was on BR7ES plugs gapped at .017" and getting blow out past 25psi pretty bad.. Giving some thought to flame propogation and point of origin i decided to buy some BPR7ES plugs before i went (didn't install them until back in omaha today)

While i was there i was amazed to see himpulling 37psi on parts store wires and stock coils and when i got home i text to ask what polugs he was running and he said they were plain BPR7ES gapped at .017 (same as i had been running but i'd been running non projected)

I tossed the plugs in, checked base timing ( was 8* retarded from not re-sync'ing it after retarding the intake gear 4* which = 8* crank retard) The projected plugs did force me to pull timing down a few degrees acorss the board but ended all spark blowout I'd been experiencing. I use to get away with around 17-19* peak timing and 14-16* at torque peak, after the projected plugs i went down to 12* peak torque and 15* peak RPM @ 29psi.

Pull after pull it was clean all the way until redline and this is something i hadn't gotten away wqith on non-projected plugs since puling my MSD box. I'm sure i could have added more timing had i chose to do the common "advance as much as possible before redline" but i stuck with a rather flat curve as usuall and upped the boost and dialed in the AFR"s (i'm running in the 11.9 - 12.2:1 range today) and that's with an ambient temp of 90* and an intake temp of 99- 104*

THese setting yielded almost no knock at all (only when i adanced timing to early did i get timing pulled that wasn't PK)


I've read a lot on projected and non-projected plugs and the concensus is that non projected are less prone toi knock or allow more timing, and i also have foudn that MOST people think they are less prone to blow out, but from my tests and pains of running the plain BR plugs for so long and dealing with blow out only to have it dissapear with nothing more than adding a projected plug i feel that the projection helps start the flame propogation in a better spot to maximizethe burn in the proper way... (although most i read of peoples "thoughts" were that nonprojected were less likely to blo0w out i found tha tmost turbo cars came OEM with projected plugs and there had to be a reason for that and I think i've found out why)

Just thought i'd toss this out there for anyone running BR series plugs and getting blow out but no knock that they may want to try the BPR series and deal with a little less timing and more boost.. after all pure timing numbers don't make power, just enough timing to completethe burn in time does!

happy experimenting everyone!
 
Thanks for posting the info you've found. I'm currently reading up on this cause I'm trying to figure out which would be best for me as well.

Are you gapping both plugs at .017?
 
That's nuts because I've heard the opposite work well because the electrode is protected/surrounded.
 
Thanks! i will test those BPR because i almost had the same problem.
 
I went the opposite, had bad blow out at 6K+ on BPR6ES and went to BR6ES gapped at the same (.025") and it went away completely. Granted this was only at 21psi on a 16g, so maybe cylinder pressure has a large effect on which plug to use.
 
Spark takes the path of least resistance.

Heat, cylinder pressures, etc all factor into it..

Blow out simply means the spark is going to ground someplace other than the spark plug.

Don't blame the plugs, fix the REAL problem.

Hal
 
I have not tried the 7s yet but I had good luck with BPR8s. I have a stock coil pack, ngk 7mm wires, plugs are gaped at .018. I run 34 psi on my HX52 on pump gas with water/meth with out any issues, timing is at 19* at higher rpms to red line. I was considering to try the 7s but since my 8s work fine, I see no reason to fix something that isn't broken :)
 
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