DanaT

I am just trying to solicite some advice from the various tuners as to what
they think is worth the $$ and what isn't.
I currently believe I have a bad head gasket in the 951. Therefore, I have a
few choices:

1) Have the head gasket replaced with a stock one.
2) Have the head gasket relaced with an o-ring head gasket and have the head
machined (i think this is about $250 above the head gasket replacement..but I
could be wrong).
3) Have some extra head work done (i.e. porting, etc). After having looked
at some of the tuners pages I think this is in the '$800 - call for more
info' range.

A little background:
The car has a K27 turbo, APE MAF Stage 2, 1.1 bar 'jet'. It holds boost
quite well to about 6800-6900 rpm.

What I am asking is how much does haveing the head ported really help? Is it
really worth the $$?

Why I ask this because we al know that the more that flows into an engine,
the more power it makes (all other things being equal). One of the ways to
get more air in is through better flow (i.e. less restriction in the intake
system). But, one can also get more flow (ok, maybe not flow but volume) by
increasing the pressure at which the air is flowing through the inatke
system. Well, the 951 does this via a turbo. With this in mind, it is very
easy to crank up a few extra PSI of boost.

Now with this in mind, people will say that I have more of a chance of
blowing stuff up with more boost. I say hogwash to this theory. Damage to
parts (i.e headgaskets, etc) cames not from turbo boost (you wont hurt a damn
thing with 100 psi in your engine..just try a leak down test). What does
damage parts is cylinder pressure (and high cylinder pressure tens to make
high horsepoer). It doesn't matter how I make high cylinder pressure (i.e.
high compression, high boost, nitrous oxide, etc) high cylinder pressure is
what will make power and cause parts to fail.

That said, if I burn X amount of fuel I should make Y amount of cylinder
pressure regardless of how I make that pressure.

Now it is easier for a turbo to make a larger intake volume with less
restriction (no heat from compressing, ultimate airflow capalility of the
turbo, etc).

Now, can see where exhaust port porting would help (i.e. get air out quicker
and spool the turbo quicker), but does the head porting REALLY make a
difference? And at what power level does porting make a difference?

My next question comes to fuel enrichening devices (i.e the ARC-II).

From my experience with EFI (on tuning an EFI motorcycle) what these units do
is typically take in a sensor output (i.e. the MAP sensor) and condidtion it
(i.e with a map sensor it may add some of voltage). This thereby tricks the
computer into thinking it is running at different conditions and compensate
for the false conditions. Is this how these devices work?

If so, why are we still using arcahic devices with ***** to adjust fuel? For
my motorcycle I have a Power Commander II. This has four table that are
programmable in two dimensions. I.E. to adjust fuel you go to the MAP table
and dial in more or less fuel at a specific throttle opening and RPM. In the
same manner timing is adjustable. All this (including the software and null
communication cables, anmd all hook ups to plug and p[lay into the wiring
loom) is under $300. Why is the ARC-II type devices (which I suspect are
nothing more than a few variable resistors (or poteniometers) stuck in a box
to change the voltage so highly priced.

Anyone have any wiring diamgrams for the various pin out and normal ranges
that these sensors operate in on a 951?

Finally, is there a really big difference in the Profec B and AVC-R except
price and looks? I think the AVC-R may be the better product but to be
honest, I cannot stand the ricer-boyz look of the thing. It doesn;t look
right in a Porsche. Analog gauges (and dials) belong in a Porsche.

How does the APE chips compensate for pressures beyond the 1.1 bar?

As you guys can see I have finally gotten serious about building up the 951
(ok..so it has lots of work already) but I want to do it right and once.

So which tuners knwo the most??? No flame wars guys.

BTW tuners, don;t try making me think any of these mods will make my car
'fast'. Even at 600 hp it would be slow. I drive a hayabusa..that isn;t
stock. So I am looking for real answers..

Thanks
-Dana