[Epx998]

I am trying to understand the differences between 2 HPTuner tunes. When I open both .hpt tunes via the compare option, this is what it shows me. Main Spark vs. Airmass vs. Open Throttle, High Octane - this is on a 16 SS with a Magnuson, numbers look quite different.

Original tune
https://ibb.co/5WnJpt3

Updated tune
https://ibb.co/yRtPm5h

Differences
https://ibb.co/G55kDky

Can someone maybe explain what the differences would mean?

[TJay74]

Looks like your tuner added some timing in the part throttle area of the table and then took some timing out of the table where the car nears WOT.

[Epx998]

What would taking timing out near WOT do to a car thats supercharged?

[cooper1965]

Originally Posted by Epx998

What would taking timing out near WOT do to a car thats supercharged?

Without a log file and the actual tune, anything said would be pure speculation. If you want real help, you will post both.

[steelheadrob]

The way I look at it to add power on a supercharged car you can either add boost or add timing, but to do either you need the octane to support it among other things. In this case your tuner is reducing timing at the upper rpms at WOT because at the upper boost levels the octane gas you are running cannot support both the boost levels seen at upper rpms and the timing seen at lower rpms.

[TJay74]

Originally Posted by steelheadrob

The way I look at it to add power on a supercharged car you can either add boost or add timing, but to do either you need the octane to support it among other things. In this case your tuner is reducing timing at the upper rpms at WOT because at the upper boost levels the octane gas you are running cannot support both the boost levels seen at upper rpms and the timing seen at lower rpms.

This is spot on and the same way Ted over at Jannetty explained it to me as well. You can have 1 or the other, boost or timing but without the proper fuel system and fuel you cant have both.

Excess timing leads to increase combustion pressure and temps, increase combustion temps that are not kept in check with proper fueling can rise quickly and ring gaps that were once enough run out of room quick and then the next thing you know you have ring gaps touching and broken ring lands on the pistons.

What are your goals for this setup?

[steelheadrob]

Rule of thumb from the procharger website "Higher octane fuel will allow you to run higher boost levels, approximately 1 psi for every 2 points of octane." The other rule of thumb is it takes 1 point of octane for every additional degree of timing.

Based on this, if you are at your octane limit, you will need to remove 2 degrees of timing for every additional 1 pound of boost you add.