NWS4Guy

Lou -

GMG has said specifically that this allows for the use of the stock belt, and additionally, since the one pulley will be larger, rather than making the opposing belt smaller, it will actually prolong the belt life by giving it more surface area to grip with rather than reducing the surface area of pulley surfaces, leading to the same amounts of strain spread across a larger area of belt due to the larger contact patch.

True we don't know for sure, but it's a reasonable guess to say that the ECU only reads and regulates max boost based on:

- dgibbd early VCDS logs on his stock car showing occasional max boost around 12PSI when stock claims 11.7 max (he ran in the fall/winter when weather was colder, thus allowing better IC effeciencies and denser charge air which equates to more power)

- Kevkev has been using water/meth, which does nothing but add some octane, but mainly greatly lower the charge air, as described above lowering the temps makes denser air and more power.

- APR has stated that the dump valve stays closed till around 5K, which could be a hard coded number, but more than likely is tied to monitoring of the amount of boost entering the engine. With so modern a car, and the ECU clearly having the ability read the boost being sent into the manifold, that is the best variable to lock down and track, since as previously stated, atmospheric and elevation and temperature conditions could severly hurt the car's performance if boost bleeds off at a fixed engine RPM but the combination of factors are working against efficient compression.

MadMadS4

I have lots of questions about the new ECU that GMG is planning. Are they truly building their own or licensing/re-selling another product? If building their own, this is a significant undertaking - when did they start brute-force cracking into the ECU? Is it a proper ECU or a piggyback? What will it cost? Will it have multiple programs, etc.

DrVolkl

Good questions... and probably why APR doesn't want anyone to see how they "cracked it"..... could be awhile before we see more options.

I can see myself doing a tune and pulley swap... then waiting to see if/when the B8 RS4 comes out if it's worth trading up to or not... and if not, going with a SC upgrade.

Should be a fun couple years.

Mr_Brown

One point not yet addressed in this thread: What happens to power steering pump, AC compressor and alternator when over-driven by a larger crank pulley?

primetime

It won't as the crank pulley has two separate surfaces, one for the blower belt and one for the accessories belt... later Ron

NWS4Guy

You won't get an honest answer. Anyone who is not doing it themselves in house won't admit to as much until they cannot hide it any further.

Example: If GIAC has a tune they did themselves and Revo decided to use GIAC's, but Revo has to charge more for it to make up the licensing cost and earn a profit, Revo would never admit they are using GIAC and just charging you more for the same thing.

This was addressed literally in the very first sentance in the opening post.