am i incorrectly seeing knock? 2015 SC f-150

[txcharlie]

^^^ funny how all the fails knock goes away with e85.

I ran tested 87% Ethanol with stock Roush spark tables and got knock. It's a real thing with the Roush blower.

[LastPlace]

I ran tested 87% Ethanol with stock Roush spark tables and got knock. It's a real thing with the Roush blower.

Definitely, and you tested it correctly to determine and rule out without damaging the engine.

[dperformance]

Hi guys,

I was reading about this issue because I think I'm in a similar position.

My car (Whipple SC in a 16' Mustang GT) was making 780WHP with only E20 and nothing of knock. Now, I stroked it to 5.4L and add a +20% balancer with a 3'' SC pulley.

First, I reduced 10 degrees just to be sure for the borderline table and I?m using E85 but still car is pulling 10 degrees and was making like 550WHP, I limit the knock retard to 5 degrees, and it gets to 650WHP with 10 degrees of timing I think is too low.

Because of my new pistons and crankshaft, I know knock sensitivity changed so I removed 20% of all KNOCK SENSOR GAIN which says, ?This defines the sensitivity of the knock sensor, higher values are more sensitive.? But nothing changed. I don?t think there is detonation with 10 degrees and E85, specially because I?m 7800 feet over sea level so compression inside cylinder is lower.

What do you guys think?

[engineermike]

dperformance are you running global or per cyl retard? If per cyl, I would suggest logging the kr for all 8 at a high data rate and few other pid?s to see what each cylinder is doing.