E85 + Boost, what plugs?

-
subcom

subcom

FABO Gold Member
FABO Gold Member
Joined
Sep 17, 2010
Messages
1,968
Reaction score
1,356
Location
South Florida
What spark plug would you guys recommend? I've read a few threads on the turbo forums and YB. Lots of folks recommend NGK and a non-projecting tip in a heat range between 7-10, 10 being the coldest. Anybody have a part # they've had good luck with? Mine is an iron headed 5.9 magnum, stock compression, E85 and about 8psi max. Also, what gap? I currently have an HEI ready-to-run setup and have my Autolite 3924s gapped pretty wide at ".045"
Thanks!
 
I was currently running these https://www.summitracing.com/parts/ngk-4091/overview/ with about 10psi of boost. Then a very reputable performance shop said I should be running at least a 9 heat range if I'm boosted with a carburetor. I need to do some more research about heat range with carbs vs FI before I make the switch. And yes, that is way too much gap for forced induction. Tighten that up to .030-.032.
 
chargd72 said:
I was currently running these https://www.summitracing.com/parts/ngk-4091/overview/ with about 10psi of boost. Then a very reputable performance shop said I should be running at least a 9 heat range if I'm boosted with a carburetor. I need to do some more research about heat range with carbs vs FI before I make the switch. And yes, that is way too much gap for forced induction. Tighten that up to .030-.032.
Click to expand...
Thanks for the feedback. That NGK you use is specd very similar to the one I chose, so hopefully I'm on the right track. Mine have resistors though. Didn't want to risk ECU interference from a non-resistor plug. I think 7 heat range is a good starting point for a car that gets some street mileage also.
 
How did those plugs work out? I have a very similar setup only FItech EFI on a W2 iron headed LA motor. I'll be starting out with somewhere between 5-8PSI (guess work based on the s/c pulley).
 
I ended up going with a colder Autolite. 3922 I think? Gapped at 0.030. The original one in my first post was too wide to fit in the socket well if my heads.
 
You must log in or register to reply here.
-

Back
Top