After lots of R&D into Barra tuning, our first Barra customer has been successfully tuned through our "Beta Tune Testers" program (Something we will talk about soon in another blog post).
Tuning the so called Bogan Banana proved initially somewhat of a challenge given the customers goals, but through some tricky workarounds, we were able to get things how the customer wanted. So, without further ranting, let's get into how we got the Bogan Banana firing off its legendary 1m+ fireworks and well outpacing its factory tune in performance.
What is the Bogan Banana?
The Bogan Banana is an affectionately named Bright Yellow BF Falcon that you probably saw on our home page. It's equipped with the legendary Barra engine, mated to a 6HP 6-Speed Transmission sending power to the factory 3.45 limited slip differential, creating a punchy combo that is respectably quick.
As far as the 6 Cylinder B series falcon models are concerned, we consider the Bogan Banana to have the best Stock Driveline available. The 6 Speed Automatic Gearbox provides a great set of ratios and strong acceleration, especially paired with the 3.45 Limited rear end.
As far as mods are concerned, the customer was running a generic set of 4495 clones with a high flow cat and a near straight through cat-back system. This gave the Barra a very loud exhaust note, but also enabled much better exhaust flow, which is a common mod to apply to the Ford 4L platforms, given the factory systems reasonable amount of restriction.
Tuning the Banana, an interesting first hiccup
Initially, we had hoped the Banana was going to be straightforward in the tuning department, but it didn't take long for us to see someone else had already tuned this car to an unknown extent, which raised our first issue.
The existing tune on the car was generated with PCMtec, using there "CustomOS" tool to enable features like launch on cruse controls. At the time of tuning the Banana however, we were using the HP Tuners VCM suite of tools, and had no idea if the two different pieces of software were going to play nicely. But the customer had asked to try and preserve the existing Launch Control System, so we decided to see if we could continue anyway.
Thankfully, HP was still able to read the car, and even work around the Custom OS, as if it wasn't there at all. This enabled us to continue forward with the Barra tune, modifying it to suit the customers' requests.
The Goals for the Bogan Banana
The goals of the customer were largely fairly straightforward.
See if there is any additional performance on the table
Get the car shooting flames. BIG flames to be exact.
Goal one was something we had seen before, and right away there was plenty of room to enhance the map applied to the car.
To kick off our enhancements, we went right ahead with modifying the stock fueling of the Barra, which from the factory is very rich for the cars Naturally aspirated configuration. For those not in the know, factory Barras normally aim for as low as 0.82 Lambda in the AFR department, which for N/A is far too rich to make meaningful power in most cases. To fix this, we took the AFR target up to 0.87 Lambda which is a much more ideal AFR to run N/A.
You might also see the massively rich commanded AFR on Deceleration, but we will get to why that is soon.
The next big table to calibrate for power was the Spark BDLN or Borderline Knock Table. This table defines a maximum spark advance before we expect to see knock occur. In the factory calibration, its values are incredibly lenient and forgiving, which makes for an issue, as under full throttle conditions, this tables spark advance values are followed until just after the barra's natural knock plateau / valley which is around 3800-4000rpm. After this point the EEC will begin to lean toward the MBT values until knock is observed.
This means a large amount of low-end power is lost, which hurts the performance and drivability of an otherwise very big engine. So, we went ahead and bumped the values and smoothed the dips somewhat to improve the power and smoothness of the engine.
Making the Banana shoot flames
The last step of our tuning was to get the banana shooting flames. This proved a little more challenging, as the approach of just taking timing out on decel as per what most tuners do to get flames happening wasn't going to work, due to an annoying limitation; The Factory tune limits negative spark to -15 Degrees (And HPT doesn't support changing that value).
Thankfully, one lesser-known trick is to instead apply more airflow through the engine on Decel, which enables the same amount of spark retard to even less effectively combust the Air Fuel Mixture, moving more unburned mixture into the exhaust. Combining this with the very rich AFR shown above, we were able to get much more unburned mixture past the engine, leading to these results:
Wrapping up
After it was all said and done, it was safe to say the customer was very pleased with the results of our work, a few hours later we were sent the above, now legendary photo of our work in action, which we decided to plop right on home page, just because of how cool that photo turned out.
Hopefully soon we will have Barra tuning live for everyone, but for now we are still keeping it as a Beta, just to ensure we iron out any issues.
Happy Tuning Everyone!
-Rob
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