Timing Curve
- Thread starter TurfBurn
- Start date
Kooldino said:
but is it wow... we have no idea what you are at at 10 psi with the MPI... the MPI's have put down better numbers than other EMS's to date for the most part.. and I believe that is due to timing. For all we know you are running 40 degrees at 10 psi... but no one knows for sure.
I did some poking around.. the most info I could find was on the SRT-4 forums... they have a longer stroke than us (101 mm I guess versus our 92mm), but roughly speaking they find that they run as much as 32 degrees of advance under 22 psi of boost... and their ratio is 8.1:1 best I can tell... at partial throttle and vaccum they get as high as 50 degrees of timing... so needless to say my timing values from before were not unreasonable. Time to trust the JandS 
They apparently start out around 26 to 28 in their midrange under full boost, and build up to the 30s with rpm's... if it knocks it pulls out about 10-20 degrees...
They apparently start out around 26 to 28 in their midrange under full boost, and build up to the 30s with rpm's... if it knocks it pulls out about 10-20 degrees...
Last edited:
Wow... car hauls ass now with the timing adjustments... The JandS would show some mild activity once in a while, but i'd adjust timing in those spots and it would go away... So good in that department overall. Still some more timing that I can add in some spots to try and eek out more power as the JandS would never indicate.
But anyway.. roughly speaking... the car under 10 psi of boost from 3,000 rpm's to 6600 rpm's will creep from 26 degrees advance to 31 degrees of advance. The critical range where detonation would start to show was between 4500 and 5500. Most specifically a narrow range of about 4900 to 5200 was where I'd see the most intensity. So I'm running about 3-4 degrees less in that range than elsewhere and that took care of the issue.
I can't hear any detonation on my listening device (amplified knock sensor) and the JandS is cranked for sensitivity (about 90% of the way up I believe) and it has been content.
But anyway.. roughly speaking... the car under 10 psi of boost from 3,000 rpm's to 6600 rpm's will creep from 26 degrees advance to 31 degrees of advance. The critical range where detonation would start to show was between 4500 and 5500. Most specifically a narrow range of about 4900 to 5200 was where I'd see the most intensity. So I'm running about 3-4 degrees less in that range than elsewhere and that took care of the issue.
I can't hear any detonation on my listening device (amplified knock sensor) and the JandS is cranked for sensitivity (about 90% of the way up I believe) and it has been content.
I dont know hows the J&S display but on the MSD knock monitor it says that it should show "medium" Amber area, when on boost but no knock and Red when ping/knock happens.
Maybe its normal to see some activity on the J&S when configured to be very sensitive and not being knock but normal loud combustion that could mean aggressive timing without knock.???
Only thoughts?
Maybe its normal to see some activity on the J&S when configured to be very sensitive and not being knock but normal loud combustion that could mean aggressive timing without knock.???
Only thoughts?
The JandS will only display on the monitor when it pulls timing. The number of LED's it shows indicates how much timing it pulled out. In my case I'd see a max of what would indicate 6 degrees of timing being removed... it'd do that for about 300-400 rpm's and then clean out... It may be hearing very very high level light knock and thus indicates even though I can't hear it with the microphone or the like... It gives it credence that it only showed it right around the torque peak, which is where you'd expect to see knock come up, and when I adjusted the timing it went away.. so I think it was doing it's job.. my only concern at any point is having it not sensitive enough to hear knock in other places... hence I have kept increasing and increasing the sensitivity to see if I can start getting obviously false triggers (where retarding/advancing timing makes no difference). Based off that I have a good indicator as to how things are doing... at this point I think it is working well. My timing values make sense, it seemed to behave the way it should... and everything was happy during the drive.
The MPI does not show the total timing as you are running. When you add or remove timing, as you know, it does it in full degree increments off of stock. So unless you know what stock is, you can't tell with the MPI, only tell how many degree's off stock you are.
