Andertusa
Full Access Member
Anyone know the differences between the regular IDI and the marine version? Yes, this was inspired-by fordgirl4by4 's thread.
7.3IDI -VS- 7.3Marine IDI
- Thread starter Andertusa
- Start date
perhaps better injectors & IP
exhaust manifolds have water ports in them.
im not sure with the ones we saw had heat exchangers,
either coolant or water, i would think coolant, and then the salt water cools the exchanger.
The Warden shall chime in tonight, he's the OB Pirate! ARRRRR.
exhaust manifolds have water ports in them.
im not sure with the ones we saw had heat exchangers,
either coolant or water, i would think coolant, and then the salt water cools the exchanger.
The Warden shall chime in tonight, he's the OB Pirate! ARRRRR.
Andertusa
Full Access Member
Not to sound like a COMPLETE nut-job, but if it were only a few 'simple-ish' things, maybe we could be making these beasts more 'competitive'. 
The big difference in Marine applications vs non-marine applications for the engine (gas or diesel) is cooling capacity.
In a non-marine applications the engine has some kind of closed self contained cooling system. The system has a finite capacity. The coolant (normally some type of water/antifreeze mixture) can only collect and shed so much heat. Then the system used to shed this heat is a relatively inefficient one. (yes it does work, but only to a point, ask the guys in the mountains) An air to liquid cooler can only transfer heat from the coolant to the air at a certain rate. The larger the cooler, the more it can dissipate at a time. Like the difference in the radiator in a Ford IDI vs and IH Truck IDI, same basic engine, but the IH radiator is HUGE in comparison. Plus ambient temperature gets involved in the transfer, as hot air can only absorb so much heat vs cooler air.
In a marine application, your radiator is the size of the body of water in which you are floating. In an open cooling system, "cold" (ambient lake water temperature) is drawn into the engine, pumped through the block (just like in a non-marine application) then this water is jettisoned overboard. So the coolant path is, body of water, intake to boat, through engine and water pump, and back put of the boat. So your coolant is always cool, it doesn't heat soak and maintain a set temp, it gets new water. In a closed system, there is coolant in the engine, just like non-marine applications, but the "radiator" is a liquid to liquid heat exchanger. A liquid to liquid exchange is much more efficient that air to liquid. So it can move more heat out of the coolant to the lake water than a radiator to air can...... Same reason when you add a auxiliary transmission cooler, you leave the factory radiator cooler connected, it transfers heat better.
This is one of the big things that make a "marine-ized" engine, plus the more moisture resistant electrical on the engine, plus they have a "Backfire Flame Arrestor" rather than an air filter, since there isn't much dust on the water.
This is how on my Dad's last boat, it had a MerCruiser Sterndrive in it with a marine-ized 350 Chevy. It was a carbed 350 that was rated at either 275 or 295 horse......... His was an open cooling system, which used lake water in the block for cooling,which means here up north you have to winterize the boat..... since there is just plain water in the water jacket......
In a non-marine applications the engine has some kind of closed self contained cooling system. The system has a finite capacity. The coolant (normally some type of water/antifreeze mixture) can only collect and shed so much heat. Then the system used to shed this heat is a relatively inefficient one. (yes it does work, but only to a point, ask the guys in the mountains) An air to liquid cooler can only transfer heat from the coolant to the air at a certain rate. The larger the cooler, the more it can dissipate at a time. Like the difference in the radiator in a Ford IDI vs and IH Truck IDI, same basic engine, but the IH radiator is HUGE in comparison. Plus ambient temperature gets involved in the transfer, as hot air can only absorb so much heat vs cooler air.
In a marine application, your radiator is the size of the body of water in which you are floating. In an open cooling system, "cold" (ambient lake water temperature) is drawn into the engine, pumped through the block (just like in a non-marine application) then this water is jettisoned overboard. So the coolant path is, body of water, intake to boat, through engine and water pump, and back put of the boat. So your coolant is always cool, it doesn't heat soak and maintain a set temp, it gets new water. In a closed system, there is coolant in the engine, just like non-marine applications, but the "radiator" is a liquid to liquid heat exchanger. A liquid to liquid exchange is much more efficient that air to liquid. So it can move more heat out of the coolant to the lake water than a radiator to air can...... Same reason when you add a auxiliary transmission cooler, you leave the factory radiator cooler connected, it transfers heat better.
This is one of the big things that make a "marine-ized" engine, plus the more moisture resistant electrical on the engine, plus they have a "Backfire Flame Arrestor" rather than an air filter, since there isn't much dust on the water.
This is how on my Dad's last boat, it had a MerCruiser Sterndrive in it with a marine-ized 350 Chevy. It was a carbed 350 that was rated at either 275 or 295 horse......... His was an open cooling system, which used lake water in the block for cooling,which means here up north you have to winterize the boat..... since there is just plain water in the water jacket......
BioFarmer93
OPEC Hater
If that is the case, then why do we have 205° thermostats? Do we actually want our engines to run at a temp lower than this? I don't understand...
fsmyth
Full Access Member
Complicated answer. In general:
Gasoline (and gaseous - propane and natural gas) engines like to run at 185-200.
Diesels like to be a bit warmer, but have a hard time getting there without a load.
At those temps, all the iron is at it's design dimensions, the oil is thin enough to
circulate, and the hot areas are cooled by the water jacket and oil, the water
condensates are evaporated (hopefully) by the few hot areas.
Running closed systems at 230 degrees is much preferable to cycling from cold
to hot to cold.
Now, all that said, you can turn up the fuel, run hotter cams. longer dwells
and generally all the stuff that race cars use, IF you can keep it cool.
More power means more heat (see above about unloaded diesels).
icanfixall
Official GMM hand model
The idi does not have a 205 thermostat. We only use the factory 192 degrees thermostat. We sure can buy others but.. They are not the right fit and will cause issues. They can't flow enough coolant to keep things cool.
Sorry, I guess I did oversimplify it.....
The marine engines do have a thermostat and run at a specific temp. Just like your truck, it is maintained at the temp specified by the thermostat, in the Ford trucks, that is ~195 degrees. It's been awhile since I was out on Dad's boat, but I do remember there was a temperature gauge in the dash of the boat, and it ran a similar temp that I would expect if it were in a vehicle. The difference is, the liquid doing the cooling, in this case "lake" water, is always cool when it enters the system. In a vehicle, the coolant that is entering the engine that is cooling the engine is already carrying left over heat from the last time it was in the engine, that was not shed in the cooler (radiator). In the marine system, this cooling water, is "lake" temp when it enters the cooling system (yes it mixes with the water that is already in the block and is brought up to temp so there is not a shock to the block, same idea as adding coolant to a warm vehicle engine while it is running so the new cool coolant mixes with the warm coolant, rather than having a "cold spot" when the new coolant hits the system). Even in the closed system, the water coming into the heat exchanger is cool lake water, that is constantly being replaced. So the contained coolant in the engine is being cooled in the exchanger by this constantly cool water.
Sorry for the confusion.... I guess I left a few pieces out, being familiar with a marine cooling system, that left out some important pieces.
The main thing is, the cooling system can remove more heat in a marine application due to the source of the cooling liquid, than in a non-marine application. When you have "unlimited" cool water to run through the engine (even in a really warm body of water, in the 80 degree range), it can pull more heat from the block, than a cooling liquid that is already 150+ degrees because it has already been warmed the last time through.
in a open marine system, such as my 17' v-drive flatbottom,
the water pump picks up the lake water, feed around the exhaust manifolds to heat the water up,
into the block to cool the engine, out of the thermostat housing area(no thermostat)
T's off 2 ways.
1) exits through the exhaust to comply with waterway regulations,
2) exits through a weep hole to evacuate the used water.
both exits have ball valves.
to hold the water in the engine longer to reach desired temp.
the water pump picks up the lake water, feed around the exhaust manifolds to heat the water up,
into the block to cool the engine, out of the thermostat housing area(no thermostat)
T's off 2 ways.
1) exits through the exhaust to comply with waterway regulations,
2) exits through a weep hole to evacuate the used water.
both exits have ball valves.
to hold the water in the engine longer to reach desired temp.
I would assume the 275 hp on the marine engine is gross hp at the flywheel, willing to bet it is not wheel hp. Convert the 275 to wheel hp and it is not that high of number for a turbocharged idi.
that depends if the boats on a trailer or not?
89Laredo
Underemployed
Compared to a stock turbo idi that makes 190 bhp, it's quite a difference...
larson
Full Access Member
Line your truck beds with plastic sheeting fill with water hook up heat exchanger. There ya go marine idi in said truck.
Might want to up the boost a little bit more due to added water weight. Lol I'm just bullshiting.
Might want to up the boost a little bit more due to added water weight. Lol I'm just bullshiting.
BioFarmer93
OPEC Hater
Duh! I knew that- brain fart, sorry.. 205 is where my engine typically runs unless it's 96 in the shade and I'm pushing it hard, then it will go all the way to 210-215..
Black dawg
Registered User
dont know what rpm this hp level is at either.
