Update April 2008: GTQuattro has several Do It Yourself Performance Kits now available for the earlier Quattro's. New kits continue to be added to provide easy and inexpensive modifications by providing instructions and components in a "DIY" Do It Yourself Kit.
In addition to the expanded GTQChip offerings, I still have QLCC Chips for '85-88 Turbo/Quattro available. I will still ship a set with chip and PROM socket and instructions for installation for $67 anywhere in the Continental US. A kit including Wastegate spring, chip and instructions is $115 including shipping.
Here is a quick summary of the differences in the QLCC chip and the MAC11C code:
1. The overboost shutdown is raised to 1.95 bar(just below the 2 Bar rating of the pressure transducer in the ECU.
2. The WGFV target boost tables are modified to leave the WGFV open longer until the boost gets up to the 1.7-1.8 bar level.
3. Timing and fuel values remapped to accomodate higher boost settings.
Although the chip will allow you to obtain boost to around 1.8 by itself by regulating the frequency valve and raising the overboost protection, obviously a stiffer WG spring and/or pressure regulator mod will help get boost sooner at lower RPM and maintain the boost longer.
This chip may allow approaching the level at which the engine can detonate if the knock sensor system is not working properly, and using low octane gas, as some of the knock protection built into the MAC-11 is by limiting the boost to 1.5Bar. It is however a far more sane approach than other mods (eg. R/Z or those that attempt to bypass the fuel pump overprotection).
A bypass valve is a good addition to this setup as it prevents pressure spikes and helps keep the turbo spooled up between shifts.
I have some other chipsets available for the later 200 Turbo quattros and possibly othere, so enquire about these if you are interested. See GTQkits
.
