Ambient temperature

[JDClubsi]

It has been getting warmer here in California. My question is does anyone go to a larger jet for warmer outside temps?
I am currently running one 0.7 and one 0.8 jet on a WRX. I am getting an occasional knock that I wasn't getting when it was cooler out. I am thinking about upping the 0.7 to a 0.8.

[Charged Performance]

This may seem at first to appear to be the proper response but more diagnosis is really necessary.

Besides temperature is there anything else that could be different? Eliminate things like your timing having moved or a change in fuel blends, etc. If you have narrowed it down to the intake temp difference has surpassed your previous knock suppression then the increase in jet size may be the likely answer. You may or may not need to retune for the effect of the additional water mixture.

[dsmtuned]

I've found that when the system starts to not work quite as well for knock supression, I need to clean out my nozzles.

Try that first.

[JDClubsi]

The Jets are clean. I was wondering this because I went from Orange County (by the beach) to Fontana (Inland) there was about a 20F change in outside temp plus a lot of stop and go driving.

[Charged Performance]

I may have been running some extra overhead in mine. But going from NJ to CO last year the only time I changed jets was when I ran out of states that sold 94 and was getting 91 octane. Upped it one size just from caution, no det.

Try the larger jet and see, though I wouldn't have expected a 20* difference to require it. Maybe you were on the border of too small a jet to begin with.

If you aren't running max pressure (a 2c or 2d at factory pressure setting) you could up the pressure of the system as well.

[dc96819]

I would up the jet size

[JDClubsi]

Originally Posted by Charged Performance

I may have been running some extra overhead in mine. But going from NJ to CO last year the only time I changed jets was when I ran out of states that sold 94 and was getting 91 octane. Upped it one size just from caution, no det.

Try the larger jet and see, though I wouldn't have expected a 20* difference to require it. Maybe you were on the border of too small a jet to begin with.

If you aren't running max pressure (a 2c or 2d at factory pressure setting) you could up the pressure of the system as well.

I have a 2d running at the factory set pressure.

[Charged Performance]

You could increase the jet size as you have been considering or increase the pressure on the manifold switch to see if that addresses the effect you have been experiencing.

[JDClubsi]

More pressure is clockwise or counter?

[Charged Performance]

It is a normally open switch that closes with pressure. When it closes the pump stops.

To increase the pressure required before it closes and turns off the pump, turn the screw clockwise.