VBOX Testing our 458 ECU flash

Hi guys,
In addition to the restoring the exhaust burbles, I've been working on enhancing engine performance. I'll be posting up dyno graphs documenting the progress thus far. But more importantly, I've been doing a lot of VBOX testing to properly gauge the effects of our tune during real world conditions. For those who don't know, VBOX is a high resolution GPS device used to quantify acceleration/braking/cornering performance. I'm using the new VBOX Sport which samples VBOX data at a very high resolution (100hz). VBOX devices are also used by just about every magazine test so it is as accurate as you can get. The 60-130mph test, in particular, is the king of all acceleration tests. Since it involves a rolling start (in 2nd gear), you don't have to deal with the run to run variance (and abuse) of launching a car from a standstill. And since your all the up to 130mph, you are really testing power and not traction.

The most important part when it comes to VBOX testing is packing a suitable stretch of road. It should be flat and smooth. VBOX results show not only time to distance but also elevation at any given point. So it's easy to determine if the road it flat. "Official" VBOX rules indicate that the maximum allowed downhill slope can be no more than 2.0 deg. That's a pretty significant slope that can reduce 60-130 times by a few tenths of a second. For the sake of this testing, I'm keep things level as possible. According to VBOX data, elevation drops from 519.9' above seal level to 518.8' above sea level over a run distance of ~1200'. So my slope is right around 0%.

All the following VBOX tests were done yesterday evening. Same tank of gas. Same exact stretch of road. The first thing I did was test the stock OEM ECU tune. So essentially a 100% stock vehicle running on CA 91 octane fuel. I ran the car in RACE mode with transmission set to Auto (to reduce driver inconsistently). I did 2 runs (shown below) and logged 60-130mph times of 8.28s and 8.28s. That is as consistent as you can get

Next I flashed the ECU with the tune that I have developed over these past few months. Did 2 runs. First run was a 7.91s. Second run was a 7.95s. A 0.3-0.4s improvement in 60-130 times is very significant. Extrapolated out to 1/4 mile ETs, we are are taking 3/10ths of a reduction (i.e., 11.4 to 11.1s). I am extremely happy with the results. And it was nice to put numbers to what I was easily feeling through the seat of my pants. In the next post, I'll post up data logs that will shed some light upon how this performance was achieved.
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I could only post 4 attachment per post so here are two VBOX time to distance graphs as well as the full detail run of the 7.95s run.
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Here are two datalogs I recorded (with the Openflash Tablet). The first captures the 0-130 run with the stock tune. The second one is with our own performance tune.

Some key differences between the two runs.

With the stock ECU tune, calculated engine road is remains at 95-100% during the entire pull. When calculated engine load reaches 100%, it often induces torque limiting strategies. First comes ignition advance reducing. If that fails, the ECU restores to closing the throttle. Calculated engine load is computed by a number of factors including mass air flow calculations, ambient pressure signal, etc,. With our performance ECU tune, I adjusted the tables that are used to derive Calculated Load. As such, the tuned graph shows Calc Load in the 80-85% range. As such, it doesn't resort to any torque reduction behavior.

With the stock ECU tune, ignition advance falls to 24-25 deg right after each upshift and gradually climbs to 28-29 deg by 9000rpm. With our ECU tune, ignition advance is at 28.5 deg right after the shift and climbs to 30 deg. The extra timing advance just after the upshift results in a very noticeable increase in torque. The engine just feels "meatier".

Air fuel ratio (displayed in Lambda as Equivalency Ratio) also shows some differences between the stock and our performance tune. Stock. AFR stays pegged at a lambda value of .80 (or an AFR of 11.76:1). This is pretty rich for a naturally aspirated engine. With our performance tune, we leaned it out slightly to a lambda of .83 to .84 (AFR of 12.2 to 12.35). Still conservatively rich worth a good bit of power.

Some general observations. In Race/CST mode, the transmission shifts so fast that the brief timing reduction (during the actual shift process) often isn't even captured in the data log which samples at 10hz.

Even with the rev limiter raised to 9300RPM (from 9000RPM) with our performance tune, the transmission still shifts at 9000rpm in auto mode. The shift points are controlled by the TCU (Transmission control unit). I'm currently looking into flashing the TCU to allow for slightly higher shift points since I feel it may result in even quicker acceleration times. One the thing the higher rev limit does does help with is when shifting in manual mode. With the stock limit set to 9000rpm, it's virtually impossible to shift at redline without bumping into the limiter (which adds tenths of seconds to your acceleation times). With the rev limit set to 9300rpm, it's possible to shift consistently at 9000rpm without bumping agains the limiter. Case in point, in manual mode with the performance tune I was able to get my 60-130 times consistenly within 1/10th of a second of my auto times. But with the stock tune, my best manual times ranged anywhere between 2/10th and 3/10ths slower than my auto times. This is only a big deal when you are racing against a stopwatch. But it's still nice to be able to extract close to maximum performance when doing things manually

TOP GRAPH: STOCK TUNE DATALOG
BOTTOM GRAPH: PERFORMANCE TUNE DATALOG
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These are getting installed today. Will re-tune ad re-test ASAP
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They are stainless steel and sold by Agency Power (also sponsors on this site). Not sure on price but they are definitely on the more reasonable side of the spectrum

 

Already done 50+ hrs of development time on the Mustang dyno. Will be going to a Dynojet soon to get some numbers that are comparable to other Dynojet results. But I'll also be posting the Mustang dyno results up next week