Tuning explained?

**SykoraA4** · 04-20-2008 12:53 PM

I've been doing a lot of searching and not really finding much of anything. can anyone explain to me exactly how tuning the car works, or point me to a resource that could explain it too me. I understand the basics. a ko3 chip adds boost, advances timing(?), and ads more fuel. is there anything else? What other adjustments are made to the tune when going Ko4, (what has to be adjusted because of the higher flow?) and are these the same kind of adjustments that are needed for BT set ups, just scaled back? are there any variables i missed?

Sorry for all the questions, TIA!

**djwimbo** · 04-20-2008 01:25 PM

Originally Posted by SykoraA4

I've been doing a lot of searching and not really finding much of anything. can anyone explain to me exactly how tuning the car works, or point me to a resource that could explain it too me. I understand the basics. a ko3 chip adds boost, advances timing(?), and ads more fuel. is there anything else? What other adjustments are made to the tune when going Ko4, (what has to be adjusted because of the higher flow?) and are these the same kind of adjustments that are needed for BT set ups, just scaled back? are there any variables i missed?

Sorry for all the questions, TIA!

Basically what you're gettin with an out of the box tune is a known tune that works on Car A with Turbo A, etc. The tune will #1 increase boost, #2 tweak timing and #3 adjust for fueling demands. The stock programming is designed for longevity of all engine internals, turbo, etc.
If you change the turbo a couple things change. If you're familiar with turbo maps, you're aware of the flow differences of the turbos and efficiency changes.
Just for an example we'll go from one range to another. A K03 will become inefficient past 5500rpm(or less) whereas a GT3071 won't hit full boost/efficiency until 4000+rpm and can carry that until 7000rpm or so. Take that information and apply it to your fueling/VE tables and your ignition curve. As in any application timing will start to be retarded/pulled past 3000rpm to help prevent detonation and spark knock. A larger turbo application will be that much more aggressive at lower rpm to increase the exhaust output that much more to help spool the larger turbo. Higher octane helps take advantage of the aggresive tune as octane is basically how slow or controllable the fuel is.
The fueling is a huge factor as well. Basically a tune has a "reference table" or a Volumetric Efficiency table(VE table). Under WOT the computer recognises the the table and adds that amount of fuel as it's preprogrammed to do so. In a smaller turbo setup (less flow) the fueling requirements are much less. Vacuum assisted fuel pressure regulators also help in these situations. The computer recognizes the fueling needs and therefore adjusts the on/off signal (pulsewidth) to the fuel injectors to add more fuel. There's a couple sensors the ECU also looks at during this process to change the air/fuel ratio. Mainly the Engine Coolant Temp.

The tune, chip, program, etc replaces the VE table, Ignition curve and in our cars the N75 control programming.
hope that helped some. any other specific questions... I just don't want to go too ballz out and bore you or get over my head