Hey All, Just came across this thread so I figured I would help clear up some confusion and explain why our standard files have reduced output in lower gears and why we then created a "high grip" option.
When we were developing the ECU and TCU tuning for the RS5, we found that it could and would very easily spin all four wheels from a standing launch on the factory tires supplied by Audi, and depending on the road surface, also easily spin higher grip tires like Michelin PS4S and Pilot Sport Cup 2s. Sometimes however it would hook and result in a blisteringly fast acceleration, but it was inconsistent and we found that most customers would be frustrated by the lack of consistency of being able to launch and grip up well.
This led to the decision to reduce the total engine output in 1st and slightly into 2nd gear (it's controlled by wheel speed, not by gear, but I'll simplify here) to allow for the use of launch control to be more consistent across multiple tire compounds and grip conditions. We did NOT do this because there were fears of driveline component failures as we safely and accurately target torque at the axles during a launch event, and can control that value to be within a safe, tested limit. This is the case on our standard and high grip launch files.
I spent about a week with our lead calibrator for the project testing different variations of file changes across a few sets of tires, and we landed on a power reduction amount that still had large improvements on 0-60 times over stock, but was not as touchy as the previous full output files at low wheel speeds. This did mean that in the best case scenarios of high grip tires and a high traction surface, we were leaving some performance on the table. It's a tough game to strike a balance with an OTS file as you're trying to make something that suits the masses in multiple conditions. For OP in this thread, you not seeing gains in 0-60 times over stock likely means that your grip conditions are some of the best case scenarios possible, so having the higher power amount in lower gears would be desirable for your setup.
With time, we then developed the "High Grip" files that still target a specified amount of axle torque when you're on launch control and keep that torque amount safely controlled throughout the launch event, but ramps in the "full" amount of power far earlier in the launch event (I don't have the speeds right in front of me but for examples sake, we change the ramp from full power at something like 45kph to 7kph, so right after the tire has been "struck" and the car has begun moving, the full tuned level of torque is ramped in). The ramp is not a binary amount (once exceeds threshold, jump from 60% to 100%), but a ramp between two points to safely and smoothly increase ther amount of power applied. This torque ramp has been tested repeatedly on Stage 1, 2, and 3 cars on a myriad of tire styles and has been proven to cut consistent 1.4x 60 foot times on the higher fuel octanes and when grip is present. This is a safe and tested file that is available upon request by emailing
[email protected] for any tune stage, though we do recommend at least having Stage 2 TCU tuning. Some may already see the file available in their portal without requesting, as once we port the file for a given ECU box code, we will then turn it on for all to have access to on that box code.
The High Grip file has a higher chance of causing wheelspin after a launch due to the fact it is attempting to apply more power to the tire that may or may not be able to hold it. With some tires (most notably Toyo R888s), this can result in wheel hop. Wheel hop is when the tire effectively spins and catches traction repeatedly, almost "bouncing" up and down. This puts a pretty high amount of shock load through the driveline, which if you stay on the throttle, has the possibility of damaging a component in the drivetrain. We have primarily seen wheel hop break axles. Now, having wheel hop does not always mean you will break something. It is something you can notice pretty immediately, and once you let off the throttle, it goes away.
Not every tire wheel hops when it breaks traction. Most actually have a nice smooth breakaway, and in our case, Michelin tires have been pretty good about having smooth wheelspin if they do spin. There are modifications that help reduce/remove wheel hop (lowering springs, drivetrain mount upgrades, good tires, etc).
So in short, both the standard and High Grip files accurately control and manage power output during a launch event to mitigate driveline damage and have been rigorously tested and proven safe under a wide set of use cases. I tend to steer most folks towards the High Grip files if they have any form of upgraded tire in compound, width, or both. When using the High Grip launch, be mindful of wheel hop and let off of the throttle if you notice it begin to happen. You may never experience wheel hop with your setup, or your set up may be prone to it. This will vary based on tire, suspension, driveline, and traction surface variations that you can optimize for through further modification.
If anyone has further questions about these files, let me know and I'd be happy to clarify further, and as always, don't hesitate to email our support team as well as we're all here to assist (and are not always cruising through random AZ threads).
-Nick@034
Reply With Quote
Originally Posted by RS5IVE
Bookmarks