| For some of you,
this is nothing new and you've seen or done it all before, but we thought this might be
interesting for a few folks out there who haven't had the opportunity to disassemble one
of these engines Photo 1 shows a complete '96 & newer
L67 (GM 3800 Supercharged engine developed by GM Powertrain Flint Engineering group,
formerly known as Buick) with the Eaton M90 supercharger already removed. This
particular engine is a salvage one that already had the blower removed. (Shucks!)
Visible is the lower intake and the square hole is what the blower forces intake air
through. The smaller round hole to the right is the bypass (wastegate if will,
although technically only turbos have wastegates) and the one more to the right and
forward is where the coolent thermostat sits.
Removal of the lower intake reveals the balance shaft as shown in Photo
2 & 3. (This is a 90 degree V6 and hence requires a balance shaft to smooth out
annoying harmonics.) Photo 2 is with the intake gaskets still attached and in Photo
3 the gasket (and valve covers) are removed.
Photo 4 shows a closeup of the rockers still in the heads. Photo 5
has the rocker removed, and clearly visible are the needle bearings - very trick high
performance stuff! Also visible are the lifters still in their bores.
Since the lifters are hydraulic rollers, there must be a guide plate
installed to keep them from spinning in their bores. This guide plate is plastic,
and shown in Photo 6 (it's removed and laid there for photo purposes). There's
another rocker lying there too.
A closeup of the lifter is shown in Photo 7. You can readily see
the roller on the bottom where it contacts the cam lobe, and the oil hole in the
side. Again, very high tech stuff previously only seen on serious high dollar racing
engines.
Photo 8 is the "short block" with heads removed, balance shaft
visible. Photo 9 is the #1 cylinder bore with the dished piston top fully visible,
and Photo 10 is the complete head assembly with valves in place and the intake ports in
full view. Note that the injectors are mounted into the head on a
supercharged 3800 (L67) whereas a naturally aspirated 3800 (L36) doesn't have these holes
tapped for the injector bosses. This is because the width of the
supercharger makes it impossible to locate the injectors in the intake manifold and still
get the proper injector targeting.
Photo 11 & 12 are closeups of a combustion chamber, and visible are
the intake (large) and exhaust valve (small). Notice how much hotter the exhaust
valve gets from its coloration. For those of you not experienced in seeing this,
this coloration is typical of all 4 stroke internal combustion engines. Photo 11
shows a cylinder that is oil fouled due to some abnormality, and Photo 12 shows a normal,
clean chamber.
Photo 13 is the timing chain cover (which the water pump mounts in) with
the built-in oil pump, shown in closeup in Photo 14. This oil pump is turned by the
crankshaft directly, unlike "conventional" ones driven off the distributor
shaft. (What distributor shaft you say - that's right, there isn't one!) So,
don't let anyone try to sell you a hi volume/pressure oil pump for these engines - they're
not needed and don't exist!
Photo 15 is the timing chain. See its all steel gears - no nylon
covered teeth in this engine. Visible also is the famous tensioner present in all
Buick V6s, so the dreaded problem other engines have of skipping a tooth when the chain
stretches under high mileage is eliminated! What's that gear above and behind the
timing chain cam gear? That's right - the balance shaft.
Photo 16 is the camshaft. Yep - it's billet steel. Note the
complete absence of a distributor gear! So if anyone mentions a distributor gear on
a 3800 cam, you know they're never actually seen one!
The main caps on this block are cross bolted! This makes an
extremely strong and rigid block - cross bolting is typically only seen on extreme
competition engines! These cross bolts are visible in Photos 17 & 18, in 18 they
are unbolted and slid out for better visibility. So, if you're trying to remove the
main caps and you smack them with a hammer and pry with a cold chisel and they still won't
budge, and you're thinking "Geez, these things are wedged in there tight!",
well, now you know what the problem is! (Now we sure do!)
A piston is shown in Photo 19. Note the extremely short skirt, and
how they're graphite impregnated. The piston, wrist pin and connecting
rod are what differ between a normally aspirated 3800 (L36) and the supercharged short
block (L67), as the supercharged ones are much heavier and stronger. The
resulting compression ratio subsequently differs between the L36 (9.4:1) and the L67
(8.5:1) That's right, you can't just bolt a blower on a naturally aspirated 3800 and
expect to get a L67! Heads, rods, and pistons (including wrist pins) need to be
changed.
Photo 20 is a closeup shot of the piston to reveal its low tension rings
to reduce internal engine friction. Look how thin they are! Truly state of the
art.
Lastly, Photo 21 is of course the crank shaft. |
