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Cost. By making the engine and transmission one fairly compact unit, the entire driveline can be assembled elsewhere, and then installed with almost no effort and a few bolts.
Any other explanation (FWD is safer, etc.) is bullshit. It all comes down to cost to manufacture.
I'm guessing you guys have heard of Star Citizen..
The latest feature added to the game. Face Over IP. Aka it tracks your eyebrows, eyes, eyelids, nose, mouth etc using your webcam and imitates the movements in the game on your characters face.
Last week, the computers which do the weather graphics both crashed hard just before the 4am start of the morning news.
Responsibility for this falls under my department. It wasn't really any one's fault per se, just a really bizarre set of coincidences.
It took about an hour to restore them. During that time, the news went on, with the weatherwoman using an easel and paper to convey the forecast.
It was sufficiently bizarre that they added a few seconds of it to the latest WGN Morning News promo, so now I get to re-watch that horror multiple times per day.
I'm assuming that the arch in the exhaust is to discourage water from feeding back into it when the engine is not running?
As a kid working on my uncle's boat (dual inboard GM V8, very near, possibly just below the waterline), I never quite fully understood why the exhaust routing was the way it was. It was called a "wet exhaust." Basically, engine exhaust mixed with the raw seawater coming out of the heat exchanger, and the two exited the hull together.
To this day, I still don't understand it. I mean, I understand the advantages. The water cools and quiets the exhaust, and allows for it to be routed through rubber exhaust hose rather than rigid, insulated tube. It just seems like a very complex solution with lots of potential failure points.
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Originally Posted by Joe Perez
I'm assuming that the arch in the exhaust is to discourage water from feeding back into it when the engine is not running?
As a kid working on my uncle's boat (dual inboard GM V8, very near, possibly just below the waterline), I never quite fully understood why the exhaust routing was the way it was. It was called a "wet exhaust." Basically, engine exhaust mixed with the raw seawater coming out of the heat exchanger, and the two exited the hull together.
To this day, I still don't understand it. I mean, I understand the advantages. The water cools and quiets the exhaust, and allows for it to be routed through rubber exhaust hose rather than rigid, insulated tube. It just seems like a very complex solution with lots of potential failure points.
did your uncle's boat have a water jacketed exhaust? In other words, did it have it's own closed loop cooling system? If not, that used water for cooling exits the exhaust. This also keeps things quiet but more importantly you don't have 300+F water spraying out the back above the water level.
That boat pictures above doesn't look to have a cooling system yet and it certainly isn't being routed back through the exhaust. Also custom double wall jacketed exhaust headers are extremely expensive. This is why the exhaust under is stupid. Put it exhaust over like a jet boat should be.
My hydroplane cooling system operates different than anything described above too.
did your uncle's boat have a water jacketed exhaust? In other words, did it have it's own closed loop cooling system? If not, that used water for cooling exits the exhaust.
It's been 30 years since I was down in that engine compartment, so forgive me if I mix up a detail or two.
This was an open-sea vessel, not a lake-duty fishing boat. It's my recollection that each of the two engines did have an automotive style closed-loop cooling system, with an expansion tank and all the stuff you'd expect under a car hood except for the radiator. Instead, the engine coolant, after passing the thermostat, went through a heat exchanger which functioned a bit like an air-water intercooler, but with water in both halves. An auxiliary pump driven by the accessory belt drew raw seawater in from the underside, passed it through the heat-exchanger to draw heat from the engine's primary coolant, and then dumped the warm raw-water output of the exchanger into the exhaust manifold, or a device very near it. A thick rubber hose exiting this then led the seawater / exhaust mix aft past the gearboxes. I do not recall the routing that the hose took on its way to the outlet at the stern, nor whether the exhaust ports themselves were above or below the waterline.
I'm trying to find a picture of a similar engine bay, but Google isn't being my friend. The net effect of being down there was not entirely unlike this, but wider with enough space between and aside the engines for a 10 year old kid to fit into:
Not quite this big, though:
Kind of halfway in between the two, and accessed from the top, by pulling up a couple of large deck panels in the cabin just aft of the galley.
I'm assuming that the arch in the exhaust is to discourage water from feeding back into it when the engine is not running?
Or on a hard-power shutdown. When I worked for MerCruiser, they redesigned the mufflers and exhaust manifolds to prevent water reversion up into the cylinder head. Apparently it was very common for the V8 guys to be running full power down the lake, then just completely slamming the throttle shut and coasting.
My boss sent me down to the lab to replace the manifolds so I could writer a repair procedure for the new manifolds.
10-14-2018, 10:23 AM
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