Cruiser

What are the extra horse power ratings and the cost? I am looking at a 928S4. Thanks,

Tom.

dr bob

Hi Tom:

I have the Autothority chipset in my '89 S4. The peak horsepower number probably hasn't changed much. The most noticeable improvement for me is in low-midrange torque, and the sharper throttle response that's the result of a little extra timing advance.

Downsides:
1) You MUST use a good grade premium, especially in hot weather. I end up using some 104+ on summer days when the AC is on to control detonation. I have a rising-rate adjustable fuel press regulator to go in there one of these days that may help this a bit.

2) The cost. In my opinion, there are better places to find the power. If you don't mind the noise (again, my opinion...) then the RMB would be a much better choice.

3) The car failed California smog on high NOX. NOX is a function of combustion temps too high, typicaly the result of timing advance or a failed cat. I popped the original chips back in, and retested OK. The difference isn't a lot, but was enough to get through the test.


All in all, knowing what I know now after a couple years with them, I probably wouldn't bother with this modification.


Bob

'89 S4, stock again.

Art_Z

I have both the Autothority chips and RMB on my 88 S4, both installed by the PO so I really can't compare them to a stock S4 (its my first 928). What improvement, in terms of power, does the RMB add?

Thanks.