The Northstar of either the 4.6L or the 4.0 Liter are within 10 pounds in
weight to the LS6, ready to run. Many Northstars are still running with no
visible wear on the cylinders after 150,000 miles. They had a problem the
first three years of porous aluminum castings causing oil leaks that were
replaced by Cadillac with new engines. That problem hasn't been a factor
for quite a while. They had a service bulletin on the oil pump relief valve
sticking as well which was addressed with a new design oil pump in '96.

I don't think you can make the mileage claim of the LS6 over the Northstar
since they were never put in comparably weighted vehicles. I know that the
guys that swap them into Fieros can routinely make well over 30 mpg on the
highway, and the LS6 guys can't do that. But most of the LS6 guys are using
manuals and not the 4T80E that the Northstar was designed to run in front
of.

Both the LS6 and the Northstar/Aurora can supposedly be driven with no
coolant but that's simply a factor of power limiting coming into play in the
PCM. They won't allow them to make enough power to generate enough heat to
cause a catastrophic failure. The other thing is they come standard with an
external engine oil cooler that takes a lot of the coolant load off the
radiator. That doesn't change the complexity of the engine itself. They
use the same sensors and fuel management control. In fact, the LS6 fuel
pressure regulator is a bolt on that the Northstar guys use because there
are adjustable versions of it out there.

There is one major difference in the electronics of a Northstar over a LS6.
The Northstar uses two crankshaft position sensors and a special toothed
segment on the crankshaft which allows the ECM to determine the precise
crank position within 180° of crankshaft rotation. That was incorporated
strictly to make the engine start quickly.

I don't know what you mean by "staying in one piece". The Cadillac is good
to over 7000 rpm on a regular basis with stock rods, crank, and pistons.
The only time they get upgraded by the guys that push them is if they're
boosted over about 7 psi and making more than 525hp. They use the same
powdered metal construction rods the LS6 uses with full floating piston
pins. The engine I'm in the process of building uses turbo cams and springs
from CHRFab that are good to 9,000 rpm. When I called around to some of my
friends that were service managers in Cadillac dealerships to get some
information on rebuilding and weak spots, all of them said they really
didn't know much about it because they'd never had one apart.

John Stricker



clare @ snyder.on .ca wrote in message
...
On Wed, 22 Oct 2003 19:52:03 -0500, "John Stricker"
wrote:

Clare,

The Northstar system is functionally identical to the LS6 with the
exception
of a single crank sensor instead of 2 on the Cadillac.

John Stricker

clare @ snyder.on .ca wrote in message
.. .

The Northstar system is VERY daunting.


The LS6 is lighter, more powerful, and gives better mileage than a
Northstar. It also tends to stay in one peice, and running, much
longer than the Northstar. The LS6 has adaptive shut-down to allow it
to get home without coolant like the Northstar (supposedly) will? ? If
so, I was not aware of it. I thought it was ONLY the northstar and
Aurora engines that had those features.