whats going on up top??

[siceclipse]

i used to be able to get 19* advance at 7000rpm on 20psi


last night i did a log and got 14-15??

knock?
boost leak??

what the hell???

for right now i turned the boost down to 15psi and im back to 18* again at 7000rpm

thanks in advance.

 

[olmytsi]

It's most likely knock.

 

[siceclipse]

well shit im stumped

i have a Big T-28 thats SUPPOSED to be at 22psi and a giant FMIC and now i have knok that its getting colder??

thats so ####ed!

i have no idea what i should do besides turn the boost down

is this something that happens when it get really cold outside in winter.

the air becomes so dense that i cant supply enuff fuel and knock is reached?

 

[bfdahl]

It could also be that your gas stations have changed to a "winter" blend of gas that has a little different aditives in the mix.

 

[olmytsi]

Just raise the boost slowly 'til you get less than the normal advance and back it up 1 psi and that's your sweet spot. Or, leave the boost at the higher psi you want and tune for the timing advance (get rid of knock). I'm assuming you have some kind of tuning tool.

 

[siceclipse]

just an SAFC and a logger

I raised it from 15-18psi and saw creep ip to 21.

i got 18* timing do im okay for right now.
still keeping an eye on it tho.

 

[daren_p]

Does sound like knock but could be several things. Have you done the std boost leak test? You may have answered your own question though, nice & cold ambient air temps, if you were on the edge of out running your fuel supply before, this may be enough to put you over the top.

 

[siceclipse]

the dyno will reveal all soon enuff.

thanks for the help