RE: Boost controllers: A very positive data point (long)

["Geoff Jenkins" <jenkinsg@pilot.msu.edu>]

Frank Amoroso wrote:
> What is the collective wisdom regarding electronic boost controllers? A
> decidedly Japanese Turbo car kind of a thing, I know, but what the hell.

I was going to hold off on a post on this until the installation is exactly
as I'd like, but as the subject has come up... I have an HKS EVC IV
installed (by Graydon Stuckey) in the S4 (BTW, Frank, at altitude,
logically, shouldn't you want the "EVC IV atm" with an atmospheric pressure
adjuster?).

What it does is replaces the wastegate frequency valve (WGFV) with a fast
and powerful valve actuator run off a separate boost controller. It learns
how to sense how much boost the turbo can handle, and holds the wastegate
shut until max boost (specified by the driver) is reached, and then only
opens the wastegate enough to bleed off the _excess_ air. If boost starts to
fall, it re-shuts the wastegate to try to maintain maximum boost.

Q: "Doesn't the WGFV do the same thing?"
A: "Essentially, yes, but less powerfully, less swiftly, and with no
user-control"

The result is that boost should come on sooner, and remain stronger across a
much wider rev-range. So far, we've got this working at higher revs (3000+),
and are working on a better pressure source for the valve controller when
the revs are low (the stock WGFV has only a low-pressure source). We expect
this to be finished soon, and when it is, I'll post a detailed description
of its installation and effects.

For the moment, even just above 3000rpm, the effect is incredible. The sheer
pull of the car is now phenomenal (and I had the TAP stage 1
chip/exhaust/K&N filter beforehand) and very smoothe. The old "lump" of
power at 3200 rpm is now smoothed out, and power is retained _far_ better up
the RPM scale.

Qualitative Improvements: (UD=user definable)
=========================
1) Boost at part throttle about 3000rpm is _instantaneous_. No lag. This was
particularly noticeable when driving my car against Chuck Price's S6, back
to back.

2) Boost is cockpit-controlled: The EVC has two stored boost settings (UD),
high and low, which can be alternated at the flip of a switch. I currently
run 1.25 bar+ and 0.6 bar+ (as a "valet mode")

3) Overboost is replaced by "scramble mode" which adds, when you push the
scramble button, for a period of time (UD) an increased (UD) level of boost.
If, during scramble or normal operation, the EVC detects excessive (UD)
boost levels, it warns you. I have yet to see it overshoot the mark I've set
by more than 1-2%.

4) Digital boost guage... I need to re-mount this where I can see it,
because currently testing this thing is a 2 person job.

Quantitative Improvements:
==========================

Boost:
(comparing guage readings to a chipped & stock S4 at Scott Mockry's site)

*(note: I may be slighly mis-reading Scott's graph, as the X-axis isn't
marked)

		Stock		Chipped	Chip+EVC
4000rpm	2.00		2.20		2.25
5000rpm	1.97		2.18		2.15
6000rpm	1.90		2.02		2.05
7000rpm	1.80		1.90		1.97

So, while the chipped car suffers a 0.28 bar drop between 5,000 and redline,
I only see my pressure fall by .18 over the same range.

HP at the wheels :
(Gtech-Pro, side-by-side testing, peak measurements at upper end of 2nd
gear)

Chuck's S6 (Hoppen chips, 3.0 bar sensor, RS2 manifold, Abt exhaust):
248HP to 255HP at the wheels

My S4 (now fairly idle TAP chip, 2.5 bar sensor, Scorpion exhaust, EVC IV):
268HP to 272HP at the wheels

I'd say that I was on the power sooner, and that at 5,000, our readings were
almost identical (which makes sense, as that's when the WGFV should be doing
as well as it can), but his didn't climb as fast or stay as high above
5,000.

Overall Conclusion:
===================

Even as it is, without the modified pressure feed to get quicker boost below
3,000, this is without doubt the best bang for the buck I've yet seen for a
turbo engine.

I'd suggest contacting Graydon Stuckey [graydon@apollo.kettering.edu] about
all this. I'm no engineer, YMMV, etc., but I _am_ a very happy EVC user.

Geoff

...whose S4 finally has something cool _before_ Frank Amoroso buys it! :-)