Marinising a 304

[gtrboyy]

Engine is just base model 179kw has no hsv headers or intake/memcal.

Doesn't make much difference once you fit better exhaust/airbox & good memcal tune.

Will run better with airbox as that's where IAT is fitted

Will run no speed sensor but will throw up intermittent fault when at constant cruising rev...speed sensor is bolted up onto extension housing & slip yoke has ring gear on it so might be able to adapt it somehow.

Had similar in torrie no speed sensor.

 

[VK SL 3800]

Engine is just base model 179kw has no hsv headers or intake/memcal.

Doesn't make much difference once you fit better exhaust/airbox & good memcal tune.

Will run better with airbox as that's where IAT is fitted

Will run no speed sensor but will throw up intermittent fault when at constant cruising rev...speed sensor is bolted up onto extension housing & slip yoke has ring gear on it so might be able to adapt it somehow.

Had similar in torrie no speed sensor.

Im just going to plug the speed sensor in and it just wont read anything.

Im not sure if im going to run an air filter, see how much room i have. The IAT i had planned on mounting near the maf. A lot of boats ive looked at dont run a filter and the maf has a screen for big foreign objects so that might be ok.

I got the engine in, just have to wire it all up and sort a few dumb problems.

 

[Bigfella237]

So are you still drawing most of the coolant out the front of the motor through the thermostat housing?

A typical cooling system has coolant going in through the water pump, around the cylinder walls to the back of the block, then up into the cylinder heads and forward around all the valves and exhaust ports, then out through the thermostat at the front.

If you block that off altogether then you won't have any coolant circulating through the cylinder heads where it's needed the most.

All my boats have had heat exchangers, which are a closed system, meaning the sea water is not pumped through the engine at all, well except for the exhaust manifolds.

And how does that drive attach to the front of the crankshaft? Surely it can't rely on the standard woodruff key to transfer the entire engine's power to the prop?

Andrew

 

[VK SL 3800]

The std thermostat port is blanked, ive taped into the discharge at the rear of the heads instead, Im pretty sure the only reason they do this is to stop you getting a big air lock and getting a hot spot at the rear of the heads. I know what your saying, but i dont know whether it will make much difference which end you discharge from as far as the the flow. I was planning on using the heater hose outlet in the front of the manifold as an extra discharge so you get some more flow around that area.

In a car the coolant can get to bore no 1 and then go straight up through the head gasket and then out the front of the head discharge to the thermostat, there nothing that actually makes it go all the way to the rear other then the restriction to flow through the gasket ports.

All other dog clutch setups ive been looking at run the rear discharge system so you would like to think that its cooling the heads sufficiently.

Boats with V drives or Velvet boxes have the engine sit more level so they probably dont need to do that but im no expert.

The drive has a sleeve lightly pressed onto the crank lining up with the original key but then you drill the opposite side and fit a 10mm pin (half drilled the crank and the other half into the sleeve so your crank ends up with a 5mm deep half moon if that makes sense). Then it has a couple of grub screws from the sides.

Seems like you take a lot of meat out of the nose to me but i guess they know what they are doing.

 

[Deuce]

Correction; the block does not have large openings to the head at the front of cyl's 1&2. A few small holes along the way down the block deck face, but 2 large openings at the rear.
So yes, water is forced to 80% go through the block before entering the heads.

 

[Bigfella237]

It was proven over on the Holley forum where somebody fitted two temp sensors to the same cylinder head, one at the front, one at the rear, and the rear sensor read significantly lower than the front (I can't remember the exact figure but it was something like 20°C in a typical closed system).

I know what you're saying about the angle of the engine and I agree that it does need some kind of "air bleed" outlet at the rear to prevent bubbles being trapped there, much like the "steam ports" in an LS motor, but most of the heat in an engine is generated in the cylinder heads so it stands to reason that most of the coolant should flow through them as well?

Andrew

 

[VK SL 3800]

Correction; the block does not have large openings to the head at the front of cyl's 1&2. A few small holes along the way down the block deck face, but 2 large openings at the rear.
So yes, water is forced to 80% go through the block before entering the heads.

Ive never noticed that, so realistically the heads should be removed and the front ports should be enlarged slightly. Not sure how that will effect how it flows overall with large rears as well.

It was proven over on the Holley forum where somebody fitted two temp sensors to the same cylinder head, one at the front, one at the rear, and the rear sensor read significantly lower than the front (I can't remember the exact figure but it was something like 20°C in a typical closed system).

I know what you're saying about the angle of the engine and I agree that it does need some kind of "air bleed" outlet at the rear to prevent bubbles being trapped there, much like the "steam ports" in an LS motor, but most of the heat in an engine is generated in the cylinder heads so it stands to reason that most of the coolant should flow through them as well?

Andrew

This is why i thought i should connect the heater hose discharge under the thermostat to allow more water to flow through the front as it would normally.
From my limited experience with boats, trying to keep the engine warm was a bigger of a challenge then keeping them cool. A lot ive looked at didnt run any sort of thermal control at all so the engine ran at like 50c all the time which is not the best for it.

My temp gauge is still down the front so i should see if the front isnt getting enough cooling first which is a plus.

 

[Bigfella237]

Ive never noticed that, so realistically the heads should be removed and the front ports should be enlarged slightly. Not sure how that will effect how it flows overall with large rears as well.

There are no front ports in the block at all (there are in the heads because they're designed to be a universal fit, left to right). If I remember correctly, on each side of the deck there are three smaller passages between the cylinders and two large slots at the very back of the block.

The problem with changing the factory design is that you create 'short cuts' for the coolant to bypass certain areas of the engine. Water will follow the easiest path, if it can go in the front of the block and then straight up and out the front of the heads it will, leaving the back of the engine with poor to no circulation.

If you were to create front passages, you would have to block off the rear passages, but then you would have to feed water into the engine from the back of the block otherwise the rear-most cylinder walls wouldn't see any coolant flow?

I'm not trying to argue with you, but it seems like you're trying to re-invent the wheel just to save a metre of pipe?

Andrew

 

[VK SL 3800]

Im thinking because the pump is positive displacement it will push water out front and back hoses and give enough flow to keep it all cool, will just see what it does and modify if needed.

Had the engine running, wiring is mostly done. Have to sort out the exhaust and alternator mounting next.
Water pump was the biggest headache so far, it looks simple now but i ended up using the old 308 pulley snout on the crank as it sticks out further and it was just enough to mount the pump with its pulley all the way in, its all very close with the seat back but all fits.

 

[VK SL 3800]

Short little vid of having a fiddle with the coolant lines to find out how to plumb the engine so it gets enough flow out the front and rear discharges.

Worked out if you T both rear head outlets into a single 1/2 line it pushes majority water out the front 5/8 outlet which should cool the heads properly while keeping the rear from getting air locks.

Not much left before a test drive, just have to make the exhaust, mount the thermostat housing and do a little more wiring here and there. But its coming along nicely.