Adjusting Boost

[Michael McBroom]

Ed or Jose wrote:

> > Seems to me that the main benefit is that it keeps the wastegate
> > closed longer before opening up.  A regular wastegate using a spring
> > starts to open before the boost is near the desired level so that
> > the wastegate is fully opened by the time (or rather pressure) that the
> > maximum boost is reached.  I don't see that it will add any more
> > top horsepower, but maybe some middle HP after reaching about 1/2 full
> > boost.
> 
>         You're correct. Running an EBC will usually give you more midrange
> power. Also, an advantage with the EBC is the ability to hold a set
> amount of boost without worrying about spiking or overboosting.

Couple of questions, if I may:

Would an electronic pressure bleed-off system (I'm thinking specifically
of the Saab APC) aid in preventing the spring from partially opening
throughout the boost range?

Also, how well would an electronically activated wastegate interface
with a standalone efi/ignition system, like the Motec, if one wanted to
use its boost control?
 
> > What about the difference between high quality vs low quality
> > wastegates?  Do the better ones stay closed longer using a regular
> > pressure regulator?  I am using an HKS racing wastegate now which
> > maintained a very consistent boost on the engine dyno unlike another
> > wastegate I once had.
> 
>         It's usually not the wastegate design that's the problem...it's usually
> the wastegate spring. I had such a problem when dyno testing/tuning a
> project car for Muscle Mustangs and Fast Fords magazine. Boost was
> rather incosistent, and would not go any higher after numerous
> adjustments. After pulling out the spring and replacing it with a new
> one (luckily had a identical wastegate lying around), we were able to
> continue testing/tuning.

Hmmm... with my Garrett, the spring is sealed inside the actuator.  BTW,
the above project car wan't by any chance the SVO Mustang 2.3L turbo in
this month's issue, was it?

-- 
Best,

Michael McBroom

'87 745T 123k w/APC                 Visit the Volvo Performance Site:
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