J-Ru

Great work, @spindlewood !

I have one question; wouldn’t the stock numbers be static between the two charts?

I notice they are slightly higher in the v2 chart and I was wondering why? Thanx for charting this out cuz that really does help to see!

spindlewood

Good eye. When APR released v1, they showed OEM HP at 397. However, Audi listed the car at 354 HP (89% of what APR tested). For my own sense of what was right, I downgraded APR's claims by 89% to match Audi's rated HP with the stock tune and therefore also downgraded APR's claims of what they were delivering from 431 HP to 387 HP with their Stage 1 - 91 octane tune. This seemed more realistic than APR's inflated numbers.

However, when v2 came along, two things changed. With the 2021 year, Audi had downgraded their HP claims to 349 HP (down by 5 HP) and APR completely redid their numbers (including the OEM tune). They now rated the OEM tune at 369 HP (down by 28 HP from v1). Once again, I chose to downgrade APR's inflated numbers (95%) to match Audi's OEM stated claims (I'm off by 1 HP due to a rounding thing). This brought APR's Stage 1 - 91 octane tune down from 411 HP to 391 HP with v2.0.

In my opinion, this was more apples to apples across the board. I could see how much power going from v2 versus v1 was giving. Because Audi also downgraded the OEM HP, it made it additionally confusing as it was a moving target. Given OEM was down 5 HP and APR claimed a bump of 4 HP, v2 looks to give a bump of 9 HP. That is why the max HP/torque numbers I posted in the table don't match APR's dyno graphs - my numbers downgraded theirs.

What these numbers should awaken is the realization that:

• These numbers are a large part hocus pocus - there are so many variables especially the dyno used and the environmental conditions
• APR's claimed HP / Torque are overinflated compared to OEM. They claim you're getting 411 HP with the 91 tune - but this is really 391 HP based on more realistic (OEM) numbers. Same with Torque (APR's 551 ft lbs is really 531 ft lbs)
• The HP and Torque generated are the maximum amounts found in the whole RPM range. A tuner's claims to increased HP and Torque are only the maximum increase - you'll only experience the max at certain RPMs.

Wrapping my head around HP and Torque is always an exercise.

• Torque is easy to understand.
  • It is force generated - like the force generated by pressing on a lever.
  • Engines produce torque - HP is calculated from Torque at each RPM. Due to the math, Torque = HP at 5252 RPM.
    • Horsepower = (Torque x RPMs) / 5252.
  • The goal is to have maximum torque (force) across the whole RPM curve.
  • Past a certain RPM (~4250), the torque starts to decrease.
  • You'll feel more pull at lower rpm. Starting at 2500 rpm, the APR tune increases torque significantly giving this heavy vehicle the much needed grunt to get moving.
• HP is harder to wrap my head around.
  • HP is power generated over time.
  • It relates to acceleration since we're dealing with time.
  • Even though torque is the raw power generated, power over time is measured in HP and delivered through gearing (gear ratios) to the wheel.
  • With more HP, you should have more power climbing hills without slowing and more sustained power passing cars. Not to mention, you'll also have a theoretical higher top speed, that none of us will likely ever experience.

This article gives a good overview of the relationship of both HP and torque to acceleration.

ronsc1985

You are confusing torque with power. Torque is not power. It is simply the ability to twist about a defined axis. Power is energy delivered per unit time. What gets a car or anything else moving is the energy put into the system.

spindlewood

Aside from incorrectly using the word "power" once (I meant to say "force"), can you offer specific corrections where the understanding of torque is incorrect?

MarkP888

I just wanted to add a completely useless comment that as a math nerd myself, I am loving this conversation. Running a 034 stage 1 tune here....

ronsc1985

You interchange torque with force and power. They are not the same. Don't
argue with me, dig up Isaac and tell him his nomenclature was incorrect.

darienal

Had a Stage 1 tune done on my SQ5 a few months ago. The difference that I see is low end. Much harder pulls from 0 at launch and when cruising harder kick downs when punching it to pass., and that's fine for me.. Honestly my biggest beef with my SQ5 is turbo lag while cruising.... (stomp on the gas... watch the boost grow... then it kicks in) and yup that's in S(and yup I'm aware of the discussions about lag).