"no one" wrote in message ...
Yes, you found the website too. I'm looking for good price performance
mods, not a marketing term.

The center-bolt cylinder heads on GM V8's have a large wall in the
intake port. It is easily visible with the intake manifold removed.
This wall improved low end torque and emissions but is a huge
restriction at higher RPM's. The new "Vortec" engines have performance
heads without the intake restrictions and a heart shaped combustion
chamber. I don't know if your motor has Vortec heads or not. I'm
pretty sure the Mercruiser Scorpion engines did. These heads are very
affordable and can make a significant performance improvement. Beware
though, the Vortec intake port is slim and tall and doesn't match up
well to intake manifolds not designed for them.


Anyway, I found out some interesting stuff about MPFI from edlebrock I
should share.

Well, the local FI expert at edlebrock seems to think that since marine
manifolds have dry areas, it's completely feasible (and has been done to
extrodinary success) to place aftermarket MPFI systems on marine engines in
a closed loop configuration - you simply sleeve the waterjacket with a
larger hole down to the manifold itself and drill/tap a smaller hole for the
sensor. An absolutely brilliant solution - Having a sensor looking at only
one side of the motor is a compromise, but only a liability if it's out of
tune in the first place, in which case the sensor's not gonna work or last
in anycase.

Now I got a lot of flak a couple months ago about using O2 sensors in marine
applications ( a statement was made that O2 sensors are only valuable for
emissions and catalyst health - which I personally do not agree with but am
not in a position to argue)

Comments on closed loop aftermarket MPFI marine applications???

Why? What purpose would closed-loop serve?? The computer knows how
much air is entering the engine (displacement x RPM x throttle
openning x temp) it can easily be programmed to supply the correct
amount of fuel without post combustion feedback. The feedback is
neccessary only to trim the fuel to improve catalytic converter
effectiveness. I'll admit some racers are experimenting with wide band
02's but I question why they are neccessary.


"Tom Ruta" wrote in message
...
On Tue, 27 Jan 2004 18:30:58 -0800, "no one"
wrote:

I called summit, they didn't stock anything called vortec...

Vortec is a word GM used to describe a swirling of the intake gasses in
the
cylinder and combustion chamber - what specifically are you talking
about?
The name "Vortec" originated in the 1986 4.3L V-6 engine that used
"vortex technology" to create a vortex inside the combustion chamber.
GM Powertrain engineers incorporated this phenomenon into their
engines to achieve a better air-to-fuel mixture in the combustion
process. The result is what has now developed into Vortec engines --
engines that are designed to deliver plenty of horsepower without
sacrificing fuel efficiency. While the technology has evolved over
time, the design philosophy remains the same. Vortec engines deliver
both power and efficiency, all in a low-maintenance, durable package.