Re: 200TQ - no overboost

[ikessel@worldnet.att.net]

Charlie Smith wrote:

> Earlier, Phil Payne wrote:

> However - flooring the accelerator at 35mph in third delivers only a
> _slow_ boost accumulation, eventually reaching around 8psi.  The climb
> is the most gradual I have seen on any MC/MB engine.  No overboost at
> all.

You didn't say anything about funny noises, but my guess would be an 
air leak in the pressurized part of the intake system ... like an end 
seal for the intercooler or an intake hose.  It would have to be 
something that's mostly sealed under suction but that opens up under 
pressure.  Do you get a sharp whistle noise when you quickly snap the 
throttle shut?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Charlie is describing _exactly_ what happened to my car a week ago.
The 200 would be s-l-o-w-l-y developing 5psi whereas normally it would
go -WHAM!- to 18 psi.
At the time I removed the dump valve from the Intercooler for testing
and in the absence of said device, after a few abrupt lift-offs under
18psi of boost, the rigid and sleek Si Samco hose slipped off the TB
several millimetres, just enough to start leaking positive pressure
above 5psi but was still sealing the gap at the negative pressures. The
car continued to start reliably which had initially confused me into
thinking that the sys was still airtight.

Like Charlie said, the giveaway was a loud hissing sound under boost -
sounded very intimidating for the surrounding traffic, just did did not
produce the power.

--
Igor Kessel
Two turbo quattros