STD Tuning Engine Renovation OM 606

Renovation OM 606

Renovation OM 606

 
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XBB240
Naturally-aspirated

18
01-08-2019, 05:23 PM #1
Last year I changed the engine in my boat and I installed an OM 606.962.
The Turbo I mounted then became too big so when the boat is full loaded, it cannot rev up in enough to spin up the turbo.I will now mount a HX 35 turbo instead
I have not been able to measure the exhaust temperature but I think it has been too high because loss of turbo pressure.

The engine could reach max 2800 rpm and the turbo started to build pressure at 3100-3300 rpm.
so it became a slow boat vacation 
I have run the engine like this for about 100 hours 
Before I started to dismantle the engine, I wanted to check the compression and it varied between 6 bar and 31 bar.
When I had disassembled the cylinder head I checked the exhaust valves and all were leaking.
is there anyone here who knows what has happened to them? why do they look like they do?
I also saw that all cylinders except cylinder no. 2 are marked with an X, cylinder no. 2 is marked with an A Why is it like that?
What is recommended that I change now when I have the entire engine dismantle
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XBB240
01-08-2019, 05:23 PM #1

Last year I changed the engine in my boat and I installed an OM 606.962.
The Turbo I mounted then became too big so when the boat is full loaded, it cannot rev up in enough to spin up the turbo.I will now mount a HX 35 turbo instead
I have not been able to measure the exhaust temperature but I think it has been too high because loss of turbo pressure.

The engine could reach max 2800 rpm and the turbo started to build pressure at 3100-3300 rpm.
so it became a slow boat vacation 
I have run the engine like this for about 100 hours 
Before I started to dismantle the engine, I wanted to check the compression and it varied between 6 bar and 31 bar.
When I had disassembled the cylinder head I checked the exhaust valves and all were leaking.
is there anyone here who knows what has happened to them? why do they look like they do?
I also saw that all cylinders except cylinder no. 2 are marked with an X, cylinder no. 2 is marked with an A Why is it like that?
What is recommended that I change now when I have the entire engine dismantle

Attached Files
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XBB240
Naturally-aspirated

18
01-08-2019, 06:20 PM #2
Sorry for the bad picture please right click on the picture and open in a new tab
XBB240
01-08-2019, 06:20 PM #2

Sorry for the bad picture please right click on the picture and open in a new tab

atypicalguy
Holset

555
01-09-2019, 06:14 AM #3
What did you do to the motor other than replace the turbo? Did you increase the fueling level? And are you measuring EGT? How large and heavy is your boat?

In this application you need to pay particular attention to the AFR as the engine will be operating at sustained high power levels. Much different than the burnout, drift and dyno king motors.

Sorry I cannot comment on the valve appearance.
atypicalguy
01-09-2019, 06:14 AM #3

What did you do to the motor other than replace the turbo? Did you increase the fueling level? And are you measuring EGT? How large and heavy is your boat?

In this application you need to pay particular attention to the AFR as the engine will be operating at sustained high power levels. Much different than the burnout, drift and dyno king motors.

Sorry I cannot comment on the valve appearance.

jav1
GT2256V

119
01-09-2019, 08:56 AM #4
I agree with atypicalguy. Marinized engines usually get modifications to deal with the differences of load duty cycles versus on road counterparts. At anything over hull speed, the loads are much higher on the engine and EGT monitoring is especially important. I suspect your EGT's, without the turbo providing additional air were extreme. What type exhaust system did you use? Was it a wet or dry exhaust manifold? Was the Turbo water cooled? Did you use a wet exhaust and did you check exhaust back pressure? Volvo has a very good marine diesel installation manual. I may have it in PDF if it's of interest?

Was there much smoke during those 100 hours? I'd closely inspect the pistons, head and likely replace the valves/seats just to be safe. I'd also mount an EGT gauge straight away when you get it running again.
jav1
01-09-2019, 08:56 AM #4

I agree with atypicalguy. Marinized engines usually get modifications to deal with the differences of load duty cycles versus on road counterparts. At anything over hull speed, the loads are much higher on the engine and EGT monitoring is especially important. I suspect your EGT's, without the turbo providing additional air were extreme. What type exhaust system did you use? Was it a wet or dry exhaust manifold? Was the Turbo water cooled? Did you use a wet exhaust and did you check exhaust back pressure? Volvo has a very good marine diesel installation manual. I may have it in PDF if it's of interest?

Was there much smoke during those 100 hours? I'd closely inspect the pistons, head and likely replace the valves/seats just to be safe. I'd also mount an EGT gauge straight away when you get it running again.

XBB240
Naturally-aspirated

18
01-09-2019, 05:31 PM #5
(01-09-2019, 06:14 AM)atypicalguy What did you do to the motor other than replace the turbo? Did you increase the fueling level? And are you measuring EGT? How large and heavy is your boat?

In this application you need to pay particular attention to the AFR as the engine will be operating at sustained high power levels. Much different than the burnout, drift and dyno king motors.

Sorry I cannot comment on the valve appearance.

I have made a new exhaus manifold that is water cooled after the manifold to the turbo it is just heat isolated. I am runing the engine with Baldurs DLS 1 box and I am using the original fuelpump wit the 6mm original elements 
The boat is a Monteray 250 SEL it is 28 feet long and 9 feet wide and ways about 3000-3200 kg 
EGT is exhaust temperature but What is AFR??
This post was last modified: 01-09-2019, 05:55 PM by XBB240.
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XBB240
01-09-2019, 05:31 PM #5

(01-09-2019, 06:14 AM)atypicalguy What did you do to the motor other than replace the turbo? Did you increase the fueling level? And are you measuring EGT? How large and heavy is your boat?

In this application you need to pay particular attention to the AFR as the engine will be operating at sustained high power levels. Much different than the burnout, drift and dyno king motors.

Sorry I cannot comment on the valve appearance.

I have made a new exhaus manifold that is water cooled after the manifold to the turbo it is just heat isolated. I am runing the engine with Baldurs DLS 1 box and I am using the original fuelpump wit the 6mm original elements 
The boat is a Monteray 250 SEL it is 28 feet long and 9 feet wide and ways about 3000-3200 kg 
EGT is exhaust temperature but What is AFR??

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XBB240
Naturally-aspirated

18
01-09-2019, 05:50 PM #6
(01-09-2019, 08:56 AM)jav1 I agree with atypicalguy.  Marinized engines usually get modifications to deal with the differences of load duty cycles versus on road counterparts.  At anything over hull speed, the loads are much higher on the engine and EGT monitoring is especially important.  I suspect your EGT's, without the turbo providing additional air were extreme.  What type exhaust system did you use?  Was it a wet or dry exhaust manifold?  Was the Turbo water cooled?  Did you use a wet exhaust and did you check exhaust back pressure?  Volvo has a very good marine diesel  installation manual.  I may have it in PDF if it's of interest?  

Was there much smoke during those 100 hours?  I'd closely inspect the pistons, head and likely replace the valves/seats just to be safe.  I'd also mount an EGT gauge straight away when you get it running again.

The exhaust manifold that I have made is a wet manifold, the turbo is just heat isolated after the turbo the exhaust pipe goes up and then turn 180 degree down after that I mix the sea water from the manifold with the exhaust.
the sea water has first went true the intercooler and the heat exchanger and finally the exhaust manifold  
I have not checked the back pressure I can check it between the turbo and where I mix in the water because there the exhaust is dry.
If you can find the PDF from Volvo it would be of big interest.
If I gave it full trotle there came black smoke but as long as I kept it at max 2500 rpm it was fine.
I will mount a gauge for the EGT
This post was last modified: 01-09-2019, 05:59 PM by XBB240.
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XBB240
01-09-2019, 05:50 PM #6

(01-09-2019, 08:56 AM)jav1 I agree with atypicalguy.  Marinized engines usually get modifications to deal with the differences of load duty cycles versus on road counterparts.  At anything over hull speed, the loads are much higher on the engine and EGT monitoring is especially important.  I suspect your EGT's, without the turbo providing additional air were extreme.  What type exhaust system did you use?  Was it a wet or dry exhaust manifold?  Was the Turbo water cooled?  Did you use a wet exhaust and did you check exhaust back pressure?  Volvo has a very good marine diesel  installation manual.  I may have it in PDF if it's of interest?  

Was there much smoke during those 100 hours?  I'd closely inspect the pistons, head and likely replace the valves/seats just to be safe.  I'd also mount an EGT gauge straight away when you get it running again.

The exhaust manifold that I have made is a wet manifold, the turbo is just heat isolated after the turbo the exhaust pipe goes up and then turn 180 degree down after that I mix the sea water from the manifold with the exhaust.
the sea water has first went true the intercooler and the heat exchanger and finally the exhaust manifold  
I have not checked the back pressure I can check it between the turbo and where I mix in the water because there the exhaust is dry.
If you can find the PDF from Volvo it would be of big interest.
If I gave it full trotle there came black smoke but as long as I kept it at max 2500 rpm it was fine.
I will mount a gauge for the EGT

Attached Files
Image(s)
       

jav1
GT2256V

119
01-10-2019, 08:45 AM #7
I found the manual in .PDF.  Send me your email address and I'll email it to you.  

A few questions.  Are using the boat in fresh or salt water?  If salt, that aluminum exhaust manifold will be very short lived. Also, did you keep the engines cooling separate from the sea water cooling loop? Did you add any sacrificial anodes to the engine?


I don't know what alloy the 606 pistons are but typically marine diesels use hypereutectic pistons since the engine loads tend to produce greater thermal transients than standard pistons can  tolerate- possibly causing clearance/longevity issues.  The thermal loads on marine engines are far greater but are easily dealt with since there is an abundance of cool water around a boat to dissipate the heat.  Heat exchanger design  becomes very important though.  Most (not all) marine turbos are water cooled. Overloading a marine diesel is easy and is the leading cause of premature failure.


There is a great website  - (boatdiesel)-  (I hope this doesn't violate any site rules??) but there is/was a resident expert there named  Tony Athens that is likely the most knowledgeable marine diesel guy I've ever seen.  There is wealth of information on properly setting up a boat and marine engine and I highly recommend a lot of reading before going  too far.  Tony has many articals on the site most dealing with  maintenance, exhaust design and NOT killing a good engine by overloading.  He's a Cummins guy but knows all marine diesel engines and has likely forgotten more than I'll ever know on the subject.
This post was last modified: 01-10-2019, 08:48 AM by jav1.
jav1
01-10-2019, 08:45 AM #7

I found the manual in .PDF.  Send me your email address and I'll email it to you.  

A few questions.  Are using the boat in fresh or salt water?  If salt, that aluminum exhaust manifold will be very short lived. Also, did you keep the engines cooling separate from the sea water cooling loop? Did you add any sacrificial anodes to the engine?


I don't know what alloy the 606 pistons are but typically marine diesels use hypereutectic pistons since the engine loads tend to produce greater thermal transients than standard pistons can  tolerate- possibly causing clearance/longevity issues.  The thermal loads on marine engines are far greater but are easily dealt with since there is an abundance of cool water around a boat to dissipate the heat.  Heat exchanger design  becomes very important though.  Most (not all) marine turbos are water cooled. Overloading a marine diesel is easy and is the leading cause of premature failure.


There is a great website  - (boatdiesel)-  (I hope this doesn't violate any site rules??) but there is/was a resident expert there named  Tony Athens that is likely the most knowledgeable marine diesel guy I've ever seen.  There is wealth of information on properly setting up a boat and marine engine and I highly recommend a lot of reading before going  too far.  Tony has many articals on the site most dealing with  maintenance, exhaust design and NOT killing a good engine by overloading.  He's a Cummins guy but knows all marine diesel engines and has likely forgotten more than I'll ever know on the subject.

Turbo
Holset

489
01-10-2019, 09:10 AM #8
what is the waste gate canister hooked up to?
If there is a lot of black smoke something is going hot...AFR will locally be low
AFR short for air fuel ratio
if you use baldur control and it smoke a lot change the map setting
boost pressure?
what turbo and exhaust house you use?
Turbo
01-10-2019, 09:10 AM #8

what is the waste gate canister hooked up to?
If there is a lot of black smoke something is going hot...AFR will locally be low
AFR short for air fuel ratio
if you use baldur control and it smoke a lot change the map setting
boost pressure?
what turbo and exhaust house you use?

XBB240
Naturally-aspirated

18
01-10-2019, 05:09 PM #9
(01-10-2019, 08:45 AM)jav1 I found the manual in .PDF.  Send me your email address and I'll email it to you.  

A few questions.  Are using the boat in fresh or salt water?  If salt, that aluminum exhaust manifold will be very short lived. Also, did you keep the engines cooling separate from the sea water cooling loop? Did you add any sacrificial anodes to the engine?


I don't know what alloy the 606 pistons are but typically marine diesels use hypereutectic pistons since the engine loads tend to produce greater thermal transients than standard pistons can  tolerate- possibly causing clearance/longevity issues.  The thermal loads on marine engines are far greater but are easily dealt with since there is an abundance of cool water around a boat to dissipate the heat.  Heat exchanger design  becomes very important though.  Most (not all) marine turbos are water cooled. Overloading a marine diesel is easy and is the leading cause of premature failure.


There is a great website  - (boatdiesel)-  (I hope this doesn't violate any site rules??) but there is/was a resident expert there named  Tony Athens that is likely the most knowledgeable marine diesel guy I've ever seen.  There is wealth of information on properly setting up a boat and marine engine and I highly recommend a lot of reading before going  too far.  Tony has many articals on the site most dealing with  maintenance, exhaust design and NOT killing a good engine by overloading.  He's a Cummins guy but knows all marine diesel engines and has likely forgotten more than I'll ever know on the subject.

You can email me on vippe100@hotmail.com

I use the boat in both fresh and salt water, the exhaust manifold and everything else on the engine that is in contakt with the sea water is in stanless steel 316L so ther will not be a problem 
The engine has its original cooling system so no sea water in the engine, I have anodes in the intercooler heat exchanger and in the manifold.

I will check the boatdisel site
XBB240
01-10-2019, 05:09 PM #9

(01-10-2019, 08:45 AM)jav1 I found the manual in .PDF.  Send me your email address and I'll email it to you.  

A few questions.  Are using the boat in fresh or salt water?  If salt, that aluminum exhaust manifold will be very short lived. Also, did you keep the engines cooling separate from the sea water cooling loop? Did you add any sacrificial anodes to the engine?


I don't know what alloy the 606 pistons are but typically marine diesels use hypereutectic pistons since the engine loads tend to produce greater thermal transients than standard pistons can  tolerate- possibly causing clearance/longevity issues.  The thermal loads on marine engines are far greater but are easily dealt with since there is an abundance of cool water around a boat to dissipate the heat.  Heat exchanger design  becomes very important though.  Most (not all) marine turbos are water cooled. Overloading a marine diesel is easy and is the leading cause of premature failure.


There is a great website  - (boatdiesel)-  (I hope this doesn't violate any site rules??) but there is/was a resident expert there named  Tony Athens that is likely the most knowledgeable marine diesel guy I've ever seen.  There is wealth of information on properly setting up a boat and marine engine and I highly recommend a lot of reading before going  too far.  Tony has many articals on the site most dealing with  maintenance, exhaust design and NOT killing a good engine by overloading.  He's a Cummins guy but knows all marine diesel engines and has likely forgotten more than I'll ever know on the subject.

You can email me on vippe100@hotmail.com

I use the boat in both fresh and salt water, the exhaust manifold and everything else on the engine that is in contakt with the sea water is in stanless steel 316L so ther will not be a problem 
The engine has its original cooling system so no sea water in the engine, I have anodes in the intercooler heat exchanger and in the manifold.

I will check the boatdisel site

XBB240
Naturally-aspirated

18
01-10-2019, 05:30 PM #10
(01-10-2019, 09:10 AM)Turbo what is the waste gate canister hooked up to?
If there is a lot of black smoke something is going hot...AFR will locally be low
AFR short for air fuel ratio
if you use baldur control and it smoke a lot change the map setting
boost pressure?
what turbo and exhaust house you use?

The wastegate canistor is hooked up to a arm Under the insulation that open the valve in the exhaust house, the hose is conected to the boost preasure in the intercooler, the wastegate open at 1.8 bar but only got 0,9 bar in  because the turbo is too big 
there was only black smoke when I gave the boat full trottle and that is because loss of turbo preasure so yes the AFR was wrong at that time 
the turbo is a Honewell GTC35 with a A/R 0.83 exhaust house
XBB240
01-10-2019, 05:30 PM #10

(01-10-2019, 09:10 AM)Turbo what is the waste gate canister hooked up to?
If there is a lot of black smoke something is going hot...AFR will locally be low
AFR short for air fuel ratio
if you use baldur control and it smoke a lot change the map setting
boost pressure?
what turbo and exhaust house you use?

The wastegate canistor is hooked up to a arm Under the insulation that open the valve in the exhaust house, the hose is conected to the boost preasure in the intercooler, the wastegate open at 1.8 bar but only got 0,9 bar in  because the turbo is too big 
there was only black smoke when I gave the boat full trottle and that is because loss of turbo preasure so yes the AFR was wrong at that time 
the turbo is a Honewell GTC35 with a A/R 0.83 exhaust house

Turbo
Holset

489
01-10-2019, 06:15 PM #11
how much it revs?
Turbo
01-10-2019, 06:15 PM #11

how much it revs?

XBB240
Naturally-aspirated

18
01-11-2019, 05:28 AM #12
(01-10-2019, 06:15 PM)Turbo how much it revs?

The rev limit in the box is set to 5200 Rpm but this summer I could rev max 2800 because the turbo started to give pressure at around 3200 rpm 
When I tested the boat the first time with no furnishing in the boat then it rev about 4800 rpm but now with all the furnishing it is to hevey that is why I put a smalle turbo that give pressure from lower rpm
XBB240
01-11-2019, 05:28 AM #12

(01-10-2019, 06:15 PM)Turbo how much it revs?

The rev limit in the box is set to 5200 Rpm but this summer I could rev max 2800 because the turbo started to give pressure at around 3200 rpm 
When I tested the boat the first time with no furnishing in the boat then it rev about 4800 rpm but now with all the furnishing it is to hevey that is why I put a smalle turbo that give pressure from lower rpm

jav1
GT2256V

119
01-11-2019, 08:02 AM #13
I sent you 2 manuals- the install and exhaust. Sorry I mistook the 316ss for aluminum... good choice!
jav1
01-11-2019, 08:02 AM #13

I sent you 2 manuals- the install and exhaust. Sorry I mistook the 316ss for aluminum... good choice!

Turbo
Holset

489
01-11-2019, 02:37 PM #14
(01-11-2019, 05:28 AM)XBB240
(01-10-2019, 06:15 PM)Turbo how much it revs?

The rev limit in the box is set to 5200 Rpm but this summer I could rev max 2800 because the turbo started to give pressure at around 3200 rpm 
When I tested the boat the first time with no furnishing in the boat then it rev about 4800 rpm but now with all the furnishing it is to hevey that is why I put a smalle turbo that give pressure from lower rpm

To little torque from engine..
GTC35.....
Do wounder what exhaust temperature you have to turbine and pressure losses in intercooler
Turbo
01-11-2019, 02:37 PM #14

(01-11-2019, 05:28 AM)XBB240
(01-10-2019, 06:15 PM)Turbo how much it revs?

The rev limit in the box is set to 5200 Rpm but this summer I could rev max 2800 because the turbo started to give pressure at around 3200 rpm 
When I tested the boat the first time with no furnishing in the boat then it rev about 4800 rpm but now with all the furnishing it is to hevey that is why I put a smalle turbo that give pressure from lower rpm

To little torque from engine..
GTC35.....
Do wounder what exhaust temperature you have to turbine and pressure losses in intercooler

Anjay1
K26-2

38
01-12-2019, 12:36 PM #15
With cooled exhaust manifold before the turbo it removes heat to drive it. Turbo is a heat driven.
Turbo housing could be water cooled to minimize risk of fire in confine space like under engine cover on the boat. Under heavy engine load for extended time exhaust manifold and turbo may get glowing red hot.
Anjay1
01-12-2019, 12:36 PM #15

With cooled exhaust manifold before the turbo it removes heat to drive it. Turbo is a heat driven.
Turbo housing could be water cooled to minimize risk of fire in confine space like under engine cover on the boat. Under heavy engine load for extended time exhaust manifold and turbo may get glowing red hot.

Turbo
Holset

489
01-13-2019, 06:22 AM #16
red hot in a diesel in a boat, water cooled manifold or not I would say engine would not hold for long...
Have seen hot m,anifold in drag race, one guy he even melted a GTX4202R turbine on one set up...
If it where a twin scroll and right build manifold would have more energy to turbine, in this kind of manifold you will lose the pressure amplitude on exhaust pulse as well.
XBB240 does your name start with M and last name with E?
Turbo
01-13-2019, 06:22 AM #16

red hot in a diesel in a boat, water cooled manifold or not I would say engine would not hold for long...
Have seen hot m,anifold in drag race, one guy he even melted a GTX4202R turbine on one set up...
If it where a twin scroll and right build manifold would have more energy to turbine, in this kind of manifold you will lose the pressure amplitude on exhaust pulse as well.
XBB240 does your name start with M and last name with E?

XBB240
Naturally-aspirated

18
01-13-2019, 06:49 PM #17
(01-13-2019, 06:22 AM)Turbo red hot in a diesel in a boat, water cooled manifold or not I would say engine would not hold for long...
Have seen hot m,anifold in drag race, one guy he even melted a GTX4202R turbine on one set up...
If it where a twin scroll and right build manifold would have more energy to turbine, in this kind of manifold you will lose the pressure amplitude on exhaust pulse as well.
XBB240 does your name start with M and last name with E?

The Turbo I hade on before was a twin scroll kusk like the one I Will mount now 
I Will instal a EGT so I can have it under control 
My name is Andreas and I am from Sweden
XBB240
01-13-2019, 06:49 PM #17

(01-13-2019, 06:22 AM)Turbo red hot in a diesel in a boat, water cooled manifold or not I would say engine would not hold for long...
Have seen hot m,anifold in drag race, one guy he even melted a GTX4202R turbine on one set up...
If it where a twin scroll and right build manifold would have more energy to turbine, in this kind of manifold you will lose the pressure amplitude on exhaust pulse as well.
XBB240 does your name start with M and last name with E?

The Turbo I hade on before was a twin scroll kusk like the one I Will mount now 
I Will instal a EGT so I can have it under control 
My name is Andreas and I am from Sweden

Turbo
Holset

489
01-14-2019, 02:19 AM #18
I was thinking if this was you selling but now I can se there are some difference
https://www.blocket.se/goteborg/Avgaslim...?ca=16&w=3
Turbo
01-14-2019, 02:19 AM #18

I was thinking if this was you selling but now I can se there are some difference
https://www.blocket.se/goteborg/Avgaslim...?ca=16&w=3

XBB240
Naturally-aspirated

18
01-15-2019, 12:06 PM #19
(01-14-2019, 02:19 AM)Turbo I was thinking if this was you selling but now I can se there are some difference
https://www.blocket.se/goteborg/Avgaslim...?ca=16&w=3

I also saw that manifold it is a bit funny that it is just like mine 
maby he have seen my manifold before on Facebook I posten alot of pictures there during the building time
XBB240
01-15-2019, 12:06 PM #19

(01-14-2019, 02:19 AM)Turbo I was thinking if this was you selling but now I can se there are some difference
https://www.blocket.se/goteborg/Avgaslim...?ca=16&w=3

I also saw that manifold it is a bit funny that it is just like mine 
maby he have seen my manifold before on Facebook I posten alot of pictures there during the building time

Turbo
Holset

489
01-16-2019, 02:30 AM #20
Intressant, har du en länk till din facebook sida? skall byta motor i min egen båt. Har du mätt tryckfallet över intercoolern?, där av min fråga tidigare do jag tog det som en vatten kylare, är det titan växlare typ de man hittaar på alibaba som de brukar sälja för pooler?
Skulle precist köpt ett drev men en kille köpte det bokstavligen mitt framför näsan på mig, satt ett bravo ett orginal och v8 men någon snodde drevet och får det blev helombyggnad.
Turbo
01-16-2019, 02:30 AM #20

Intressant, har du en länk till din facebook sida? skall byta motor i min egen båt. Har du mätt tryckfallet över intercoolern?, där av min fråga tidigare do jag tog det som en vatten kylare, är det titan växlare typ de man hittaar på alibaba som de brukar sälja för pooler?
Skulle precist köpt ett drev men en kille köpte det bokstavligen mitt framför näsan på mig, satt ett bravo ett orginal och v8 men någon snodde drevet och får det blev helombyggnad.

atypicalguy
Holset

555
02-06-2019, 04:44 AM #21
An easy thing to try would be a smaller diameter prop. By increasing the propeller "slip" (difference btw theoretical speed from prop rpm/pitch and the actual speed of the boat) you can get the motor into higher rpm and onto boost. This needs to be done for your typical running condition, so the weight of the boat fully loaded for worst case scenario. Essentially, you are looking for gearing (transmission and prop) that allows the motor to achieve full target rpm when fully loaded. This avoids "lugging" the motor and killing it prematurely.

I have a 4500lb RIB with a cummins 6bt, non-intercooled. With an 18" prop, I could not get it to target rpm. Shifting to a 17" solved all my problems, due to increased slip allowing the motor to run at full rpm.

You can find slip calculators on the internet. Boatdiesel has one also. Boatdiesel is worth the small subscription price. There are some very experienced people there on the forums who can help you think your problems through.

If that exhaust manifold is stainless, I salute your welder. But I also agree that what you want is a water jacketed turbo, instead of a water jacketed exhaust manifold. That way the turbine sees the full exhaust temp and energy, before dumping gas into a water jacketed elbow, then out the wet exhaust. So your seawater runs through a water to water heat exchanger to cool the internal motor cooling loop, then dumps its water into the exhaust elbow.
atypicalguy
02-06-2019, 04:44 AM #21

An easy thing to try would be a smaller diameter prop. By increasing the propeller "slip" (difference btw theoretical speed from prop rpm/pitch and the actual speed of the boat) you can get the motor into higher rpm and onto boost. This needs to be done for your typical running condition, so the weight of the boat fully loaded for worst case scenario. Essentially, you are looking for gearing (transmission and prop) that allows the motor to achieve full target rpm when fully loaded. This avoids "lugging" the motor and killing it prematurely.

I have a 4500lb RIB with a cummins 6bt, non-intercooled. With an 18" prop, I could not get it to target rpm. Shifting to a 17" solved all my problems, due to increased slip allowing the motor to run at full rpm.

You can find slip calculators on the internet. Boatdiesel has one also. Boatdiesel is worth the small subscription price. There are some very experienced people there on the forums who can help you think your problems through.

If that exhaust manifold is stainless, I salute your welder. But I also agree that what you want is a water jacketed turbo, instead of a water jacketed exhaust manifold. That way the turbine sees the full exhaust temp and energy, before dumping gas into a water jacketed elbow, then out the wet exhaust. So your seawater runs through a water to water heat exchanger to cool the internal motor cooling loop, then dumps its water into the exhaust elbow.

 
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