Diesel engines in speed boat
02-06-2008, 08:14 PM
#71
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THERUSH, (this is very long & applies to your older engines)
The heat problem the Cummins B has is caused by the fact that the engine oil cooler is mounted onto the side of the block between cyl 1 & 2 and extends into the water jacket. The cooler core comes very close to the cylinders and actually hurts water flow around those two cylinders. Cylinder 1 & 2 will always be the overheated holes under a normal overloaded type of heat failure.
The failure that occurs is a complex failure, you must understand the following first:
- a B engine does not have liners, in normal sleeved engine the sleeve extends above the block deck and the head tightening down on the liner makes a seal. The head gaskets do not seal compression just water and oil passages, they sit around the outside of the liner
- the liners have a sealing ring built in similar to O-ringing the block to cut into the head
- a B engine head gasket is a compression seal gasket where the gasket is squeezed between the head and deck to keep combustion in
- a B engine piston at TDC travels above the deck and into the combustion area created by the head gasket
- look at the attached picture for standard piston and modified/race piston
When the engine is under extreme load cylinders 1 & 2 will run hotter than the others because of the reduced water flow around those cylinders. Since the head gasket is a one size fits all it is larger in diameter than the cylinder bore. When the piston is at TDC the flame travel will go around the sides of the piston and fill the gap created by the oversize head gasket seal ring. The flame/heat will cause the top of the piston to swell and when the psiton shifts to the downward stroke the change in direction will make the piston rock. The swollen top area will hit the cylinder bore as it travels down and scoring will start. It does not take long to wipe out that cylinder.
In the picture you will see we relieved the top area of the piston. If anyone says that is bullsh*t and your hurting the psiton - just tell them look at any liner engine piston, they all have a step and taper in them. It took awhile to realize this because everyone was focused on the cooling issues and thinking the clylinder itself was distorted and so forth. We ran the last engine for 10 minutes under load and then torn it down and seen where and how the failures occured. It was the piston design itself that caused the failures.
To make higher HP on the old 2 valves heads you need to rework the pistons - period - no way around it unless the new replacement pistons already have that cut in.
After all this, don't let anyone tell you that by sleeving the scored cylinder and putting in a standard piston that you helped the balance of the engine. I don't know but I guess you have vibration dampers on those engines, that solves and balance issues. Second by going back to standard bore you didn't help but hurt the problem. The larger pistion had less gap when it clears TDC and would then to expand less beacuse less flame travel in that area.
Wow, that was long. I still need to find pump specs for you.
Your engine suffered the failure above and I think your engine was one of my test engines that we detontated so bad it blew out the freeze plugs because the block was shaking so bad!!!!
If it is one of mine then that tells you how good a Cummins is to still be running all these years later!
Joe Gere, who can't spell groove!
The heat problem the Cummins B has is caused by the fact that the engine oil cooler is mounted onto the side of the block between cyl 1 & 2 and extends into the water jacket. The cooler core comes very close to the cylinders and actually hurts water flow around those two cylinders. Cylinder 1 & 2 will always be the overheated holes under a normal overloaded type of heat failure.
The failure that occurs is a complex failure, you must understand the following first:
- a B engine does not have liners, in normal sleeved engine the sleeve extends above the block deck and the head tightening down on the liner makes a seal. The head gaskets do not seal compression just water and oil passages, they sit around the outside of the liner
- the liners have a sealing ring built in similar to O-ringing the block to cut into the head
- a B engine head gasket is a compression seal gasket where the gasket is squeezed between the head and deck to keep combustion in
- a B engine piston at TDC travels above the deck and into the combustion area created by the head gasket
- look at the attached picture for standard piston and modified/race piston
When the engine is under extreme load cylinders 1 & 2 will run hotter than the others because of the reduced water flow around those cylinders. Since the head gasket is a one size fits all it is larger in diameter than the cylinder bore. When the piston is at TDC the flame travel will go around the sides of the piston and fill the gap created by the oversize head gasket seal ring. The flame/heat will cause the top of the piston to swell and when the psiton shifts to the downward stroke the change in direction will make the piston rock. The swollen top area will hit the cylinder bore as it travels down and scoring will start. It does not take long to wipe out that cylinder.
In the picture you will see we relieved the top area of the piston. If anyone says that is bullsh*t and your hurting the psiton - just tell them look at any liner engine piston, they all have a step and taper in them. It took awhile to realize this because everyone was focused on the cooling issues and thinking the clylinder itself was distorted and so forth. We ran the last engine for 10 minutes under load and then torn it down and seen where and how the failures occured. It was the piston design itself that caused the failures.
To make higher HP on the old 2 valves heads you need to rework the pistons - period - no way around it unless the new replacement pistons already have that cut in.
After all this, don't let anyone tell you that by sleeving the scored cylinder and putting in a standard piston that you helped the balance of the engine. I don't know but I guess you have vibration dampers on those engines, that solves and balance issues. Second by going back to standard bore you didn't help but hurt the problem. The larger pistion had less gap when it clears TDC and would then to expand less beacuse less flame travel in that area.
Wow, that was long. I still need to find pump specs for you.
Your engine suffered the failure above and I think your engine was one of my test engines that we detontated so bad it blew out the freeze plugs because the block was shaking so bad!!!!
If it is one of mine then that tells you how good a Cummins is to still be running all these years later!
Joe Gere, who can't spell groove!
Last edited by HabanaJoe; 02-06-2008 at 08:31 PM.
02-06-2008, 09:14 PM
#72
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Joe Gere, who can't spell groove,
That was a long read but well worth it in my opinion. Selfish bastard that I am.
You mentioned that the heat in 1 & 2 was generated by the oil cooler. I can understand that but you did not mention if converting the engine to an external oil cooler was something that you tried. Everything you have said makes sense.
Rik,
I think that my slip problem is related to pump settings/engine HP/RPM more than propeller. I have two sets of props 28's & 28.5's. The 28.5's are faster at optimum trim/RPM (2600 tach). If I try to trim down I lose speed /RPM if I trim up I loose speed but do not pick up RPM. I have not no loaded or strobed the engines to verify my tachs or actual RPM. My thought is that I am down on power (less than the 300HP rated) and the only way I am seeing the speeds that I am is by overtrimming the drives to max out the rpm, i.e. slipping the props.
Thanks for any input you can offer guys!
Rich
That was a long read but well worth it in my opinion. Selfish bastard that I am.
You mentioned that the heat in 1 & 2 was generated by the oil cooler. I can understand that but you did not mention if converting the engine to an external oil cooler was something that you tried. Everything you have said makes sense.
Rik,
I think that my slip problem is related to pump settings/engine HP/RPM more than propeller. I have two sets of props 28's & 28.5's. The 28.5's are faster at optimum trim/RPM (2600 tach). If I try to trim down I lose speed /RPM if I trim up I loose speed but do not pick up RPM. I have not no loaded or strobed the engines to verify my tachs or actual RPM. My thought is that I am down on power (less than the 300HP rated) and the only way I am seeing the speeds that I am is by overtrimming the drives to max out the rpm, i.e. slipping the props.
Thanks for any input you can offer guys!
Rich
02-06-2008, 09:49 PM
#73
Registered
The oil cooler is that plate with the filter housing on it. You could remote it, hard, but possible. We found as power went up you needed to fix the pistons anyway, after a certain point they all swell.
Back to the balance thing, when you increase the piston weight the rotating mass still stays the same, it's only reciporcating that you changed, less important to balance.
Don't be afraid to set the pump for 3,000 rpm's, you can prop for 2,800 and you won't be bumping the springs. It will develope more power. Don't forget, as you hit up against the governor the pump will cut fuel back, so you really don't know how much you have left.
Look if I were you this is what I would do. Take off the pumps and send them to a pump shop, set both at 3,000 rpm.
Go and watch them run the pumps on the stand, insist on it! When you set a pump up you can do it a couple ways, one is average the flow on each plunger so the total falls within spec and you get approx HP. Realize the rated Hp is +/- 5% so a 300hp could be really 285hp and still legally be a 300hp engine.
Have the pump guy check what the max spec is for that engine and have him balance all the plungers to put out max rated flow at 2,800 rpm. That way all your cylinders are equal at the rpm you want to run. They will tell you that at lower rpms some cylinders are too high or low - don't worry.
I don't remeber how to balance the Nipondenso's it's been years, the guy that used to flow our pumps is since closed.
Also, check the galley pressure on the fuel pump against spec, too little pressure will cut hp as well. Don't increase fuel galley/housing pressure, that will push the plungers to one side and you'll score the fuel pump, big money - only lost one of those.
This is why people threw projects at us, we played on the dyno and in the field every single day, we had dyno people, machinists, engine builders and people to run the boats daily. We got data quciker than they could. When we moved to the bigger shop in Hillside, NJ there were 8 people on the B engine daily for 1 year
Anyway, this is your starting point to test props. At least you know your at a full 300 - 315 hp that way.
Back to the balance thing, when you increase the piston weight the rotating mass still stays the same, it's only reciporcating that you changed, less important to balance.
Don't be afraid to set the pump for 3,000 rpm's, you can prop for 2,800 and you won't be bumping the springs. It will develope more power. Don't forget, as you hit up against the governor the pump will cut fuel back, so you really don't know how much you have left.
Look if I were you this is what I would do. Take off the pumps and send them to a pump shop, set both at 3,000 rpm.
Go and watch them run the pumps on the stand, insist on it! When you set a pump up you can do it a couple ways, one is average the flow on each plunger so the total falls within spec and you get approx HP. Realize the rated Hp is +/- 5% so a 300hp could be really 285hp and still legally be a 300hp engine.
Have the pump guy check what the max spec is for that engine and have him balance all the plungers to put out max rated flow at 2,800 rpm. That way all your cylinders are equal at the rpm you want to run. They will tell you that at lower rpms some cylinders are too high or low - don't worry.
I don't remeber how to balance the Nipondenso's it's been years, the guy that used to flow our pumps is since closed.
Also, check the galley pressure on the fuel pump against spec, too little pressure will cut hp as well. Don't increase fuel galley/housing pressure, that will push the plungers to one side and you'll score the fuel pump, big money - only lost one of those.
This is why people threw projects at us, we played on the dyno and in the field every single day, we had dyno people, machinists, engine builders and people to run the boats daily. We got data quciker than they could. When we moved to the bigger shop in Hillside, NJ there were 8 people on the B engine daily for 1 year
Anyway, this is your starting point to test props. At least you know your at a full 300 - 315 hp that way.
02-07-2008, 07:20 AM
#75
Charter Member #927
Charter Member
TheRush,Rich welcome to OSO. We now have 3 Super Hawaii owners on here. A couple more and we can start lobbying for our own forum. Good luck getting your 40 dialed in.
Joe is being a little modest. He is a wealth of knowledge and a former part owner of SH.
Joe, nice talking with you last week. I am home now and am going to look at those inserts for my transome. Looks like Riches are already installed.
Joe is being a little modest. He is a wealth of knowledge and a former part owner of SH.
Joe, nice talking with you last week. I am home now and am going to look at those inserts for my transome. Looks like Riches are already installed.
02-18-2008, 02:18 PM
#77
Registered
Rush,
230cc @ 2,900 or 1450 pump speed gives you right at 430 hp byt with engine mods as well.
If you do 220cc at the same 2,900/1450 pump should be around 380 hp and that is keeping everthing stock.
Any pump shop can do this for you.
The best thing you could do for those engines is get better aftercoolers. I believe yours are square sheet metal boxes? The newer engines have the cast units. The best would be get a aftercooler off of a "C" series engines like a 450 hp or higher version.
The cooler the air the better it will run. You see pictures of many stock boat diesels where the paint is burned between the turbo and the cooler all that says is intake air is too hot to start with. The after cooler will only have X delta in it. Start with air 20 deg warmer than normal and the air temp after the cooler will be 20 deg higher than expected - therefore the bigger the cooler the more delta and the cooler the air.
If you rip the heads off for some reason, re-work the intake valves, a 3 angle valve job with inner dia cut back flat the unmachined area does wonders!
Allways remember you are moving vastly greater amounts of air than the same size (CUI) gas engine because of the boost. The trick to any of this is very simple - pressure is inverse to flow. For every big gain in pressure the flow does not increase equally.
This dynamic is much different than a naturally aspirated gas engine which needs air velocity to work - we have pressure not suction.
Anything you can do that will decrease restriction which will decrease pressure will increase flow.
Good luck!
230cc @ 2,900 or 1450 pump speed gives you right at 430 hp byt with engine mods as well.
If you do 220cc at the same 2,900/1450 pump should be around 380 hp and that is keeping everthing stock.
Any pump shop can do this for you.
The best thing you could do for those engines is get better aftercoolers. I believe yours are square sheet metal boxes? The newer engines have the cast units. The best would be get a aftercooler off of a "C" series engines like a 450 hp or higher version.
The cooler the air the better it will run. You see pictures of many stock boat diesels where the paint is burned between the turbo and the cooler all that says is intake air is too hot to start with. The after cooler will only have X delta in it. Start with air 20 deg warmer than normal and the air temp after the cooler will be 20 deg higher than expected - therefore the bigger the cooler the more delta and the cooler the air.
If you rip the heads off for some reason, re-work the intake valves, a 3 angle valve job with inner dia cut back flat the unmachined area does wonders!
Allways remember you are moving vastly greater amounts of air than the same size (CUI) gas engine because of the boost. The trick to any of this is very simple - pressure is inverse to flow. For every big gain in pressure the flow does not increase equally.
This dynamic is much different than a naturally aspirated gas engine which needs air velocity to work - we have pressure not suction.
Anything you can do that will decrease restriction which will decrease pressure will increase flow.
Good luck!
02-18-2008, 06:31 PM
#78
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Joe,
Is your 220 cc set up without the piston mods. or should I figure on doing these before I add any more fuel?
When I got the boat the aftercoolers had been updated. I have not checked the P/N but they are the cast variety in lieu of the fabricated tin version. I'll have to take a look at the P/N to see what they cross over to. I agree the cooler the charge the better the durability & HP.
Thanks again for all your input!
Rich
Is your 220 cc set up without the piston mods. or should I figure on doing these before I add any more fuel?
When I got the boat the aftercoolers had been updated. I have not checked the P/N but they are the cast variety in lieu of the fabricated tin version. I'll have to take a look at the P/N to see what they cross over to. I agree the cooler the charge the better the durability & HP.
Thanks again for all your input!
Rich
02-18-2008, 07:00 PM
#79
Charter Member #927
Charter Member
Joe, has the transome of Rich's 40 been changed and a box added? It sort of looks like fullwidth version of the wedges you talked about on my 34. Or were the 40s built like that?
02-18-2008, 08:25 PM
#80
Banned
Rich,
It's about time you got your butt on this site neighbor!! Your still never gonna out run my piston power.........but the diesel boat is cool!! Welcome aboard partner!
Mr.Horsepower
It's about time you got your butt on this site neighbor!! Your still never gonna out run my piston power.........but the diesel boat is cool!! Welcome aboard partner!
Mr.Horsepower
