WasteGate DC Setup 101: Request.

[joey]

Yes, there is, but you're not going to like it. ( http://obdcon.sourceforge.net/2010/06/a ... oad-value/ )

LOAD_ABS = [air mass (g / intake stroke)] / [1.184 (g / intake stroke) * cylinder displacement in litres]
Derivation:

air mass (g / intake stroke) = [total engine air mass (g/sec)] / [rpm (revs/min)* (1 min / 60 sec) * (1/2 # of cylinders (strokes / rev)],
LOAD_ABS = [air mass (g)/intake stroke] / [maximum air mass (g)/intake stroke at WOT@STP at 100% volumetric efficiency]

* 100%. Where:
— STP = Standard Temperature and Pressure = 25 °C, 29.92 in Hg (101.3 kPa) BARO, WOT = wide open throttle.

I mean, there's a formula for the absolute load and based on what you get now and the supporting mods on your car you set your "desired" load targets.

Here's the idea:
- if your wastegate duty cycle values are close you will still hit the load targets because the compensation tables will work for you;
- now, you take those actual BCS DC values you see in the log and overwrite yours from the tune.

There will always be small variations, but as long as your wastegate duty cycle values are close the ECU will need less time to adjust it (+ or -, depending on the weather, and so on).

The ideal way of determining the load values to put in your tune is to take a few logs when the ambient temperature is the average of the year. Where I live we have -35 to +42 Celsius so it's quite hard to do that (I usually consider the average of +10C to be still able to make the car move during hot summers and not to blow the engine during winter), but if the average temps in your area are more persistent over the year then you're lucky.

You also need to take into consideration the flow capabilities of your car in the weather you're using it in most. If you have a stock K04 and you live in South Africa you may never see more than like 235-240g/s (maybe only if you log at night of 2-4 hours before the sun rises). Pushing it too hard in therms of load/boost will not result in more power, because timing is also very important. So if you have a load of, say, 1.9 at 6000rpm but your timing values are around 5... the car will not make power, but will only cook your exhaust side of the engine (vales, cats, and so on).
So load (therefore airflow) is not everything.

I'm from SA, and hit 280g/s with my stock K04. I'm at the Coast and get that anytime of day. Except when its really cold, but then I load my winter tune. Otherwise overboost ftl.

[mituc]

With a 3" SRI it may be possible and easier to accomplish, assuming that your MAF cal is right.

[Kevin]

Im at 5400ft in SA and we get about 230-ish. Obviously with the altitude difference my req load is never = actual load. Is there a way to overcome this baro issue and enable me to hit 1.6 when requesting 1.6 without going BT?

[mituc]

Not really. The load is directly proportional with the air flow. This means that you are limited by the amount of air the turbo can flow, or more specifically you are limited by the volume of air the compressor can push at the maximum turbo RPM. Now, when the barometric pressure decreases you will have less air in the same volume.

If you have the money and want more power stop pushing the limits of the stock K04 and do not be afraid to go big turbo on these engines. Here are a few reasons why:
- at the same boost levels a larger turbo will heat up slower, so the boosted air temperature increase will come only from the pressure increase itself;
- there are a few turbo kits that are direct bolt on. The ATP or ATP-based turbo kits and, even better, the BNR turbo's which even use the stock hot side and can spool almost as fast as the stock turbo (maybe 300-400rpm later) and keep going 2000rpm more than the stock;
- it's torque who's killing these engines, not power (unless you run past the fueling system limits). With the stock K04 you can make huge torque down low (up until about 4500rpm) and then the turbo is out of breath. If you shift the torque curve (or simply make in longer) in the higher RPM range this will result in more power without dramatically increase the torque in the mid range.

To explain it better, here are my dyno charts before and after going big turbo. You will see that the difference in peak torque is minimal:



- so before I was hitting 400Nm around 2900rpm and was starting to decrease below this value around 4300rpm;
- now I hit 400Nm around 3600-3650rpm and on these graphs it doesn't go below 400Nm up until 6100rpm. After a few more timing tweaks I made it to stay above 400Nm up until 6600rpm;
- the peak torque figures difference is minimal (around 420Nm on stock turbo with the Hypertech and 438Nm or so with the GTX - and this 438Nm value I could have obtained even easier with the K04).

...And then you will be able to do this, while on stock turbo it's pointless to go above 120Kmph/6000rpm in 3rd gear, or 160-165Kmph in 4th, or 200-210Kmph in 5th (just listen and keep an eye what happens around 3500rpm when flooring it below that rpm):
http://www.youtube.com/watch?v=XCkqfC8gdC8
http://www.youtube.com/watch?v=DL788W25WZ0