Effects of camshaft timing on turbo spool-up

[Jörgen Karlsson]

Hi,

I guess that your turbo is shot, most stock audis have boost at 2700rpm but
most US models have a smaller exhaust turbine and should have full boost at
around 2000rpm.

When you say that you have retarded the cam I think that you mean that the
valves opens a bit later in the stroke then they did before, but other
things in your explaination lead me to think that you have advanced the
cam(the valves open earlier in the stroke then before). The later will
release hotter exhaust gas to the turbo and it will spool quicker and at a
lower rpm.

But you should check your cam timing! I don't think that your car is
performing very good if you have retarded the timing 16º from the stock
setting. It will probably not work very well if it is 16ºadvanced either.

If your car is a 5000series turbo then you could experience very late
ignition as some of the 83-84 models use the distributor for ignition
timing. That will ,definately let turbo spool quicker, but it will cost you
huge amounts of power and will most likely damage a thing or two if you give
it the time. If it is an URQ I am pretty sure that the ignition timing will
not be affected by cam timing, I think that even the '83 URQs take the
ignition timing from the crank.

Anyway, set the cam timing and ignition timing to factory specs and if the
turbo does not provide boost at 3000 then you should look into getting a
replacement turbo. BTW, it is VERY important that you don't have a leaky
exhaust manifold. Turbo Audis are extremely sensitive to this.

Please let me know the model of the car.

Jörgen Karlsson
Gothenburg, Sweden.
3 AWD turbo Audis and counting...


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