Knk'in again!

[Xx_R/T_xX]

Had the tune spot on and everything over the summer..26psi 93pump,100meth,30*timing,11.6-11.8afr..come the cold weather 40-50degree,and im see'in 4kr of knock now.Afr is still in the 11's but showing knock.Nothing has changed in the setup

i checked the pump and it is working.grounded the ground wire and it sprays.have full tank of meth,no clogged nozzles or checkvalves

[turbojonsrt4]

I notice knock when the temps outside turn cold too.

[93stang434]

It could simply be the winter blend gasoline.What i can make of it from doing some brief reading is the Reid vapor pressure of the gasoline is different,meaning the winter blend has a higher rate of evaporation which makes it more volatile.Summer blend contains 1.7 percent more energy than winter blend also so not only do we have a greater propensity to knock, we are also making less horsepower.