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Old 15-09-2020, 12:59   #1
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Possible to convert turbo D2-75 to non-turbo D2-55?

Hi, my Hanse 505 came with a Volvo penta D2-75. In
my opinion the boat is overpowered, and as a result, my options are to cruise at 1600 rpm and deal with carbon build up in the turbo and elsewhere, or to run harder, but burn excess fuel. Right now my strategy is to run hard for 15 minutes every watch, then cruise at 1800 RPM, which is 200 RPM higher than I even want.

The boat is new to me, and I suspect the previous owner never ran the engine hard. As a result my exhaust elbow is carboned up, turbo needs to be rebuilt, wastegate is stuck, and lots of oil is leaking from the intercooler, probably oil that gets past the turbo seal. Iím looking at a $5000 repair. This for a turbo that I donít even want or think is necessary on my boat. Iíd love the pitch the turbo in the trash.

Does anyone know whether other parts on the engine are different between the D2-75 and the D2-55 other than the exhaust plumbing? Electronics? Mechanical fuel pump? Injectors? Pistons? I suppose Iíd have to reprop.

Thoughts and opinions welcome.
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Old 15-09-2020, 15:09   #2
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Re: Possible to convert turbo D2-75 to non-turbo D2-55?

Quote:
Originally Posted by ohthetrees View Post
Hi, my Hanse 505 came with a Volvo penta D2-75. In
my opinion the boat is overpowered, and as a result, my options are to cruise at 1600 rpm and deal with carbon build up in the turbo and elsewhere, or to run harder, but burn excess fuel. Right now my strategy is to run hard for 15 minutes every watch, then cruise at 1800 RPM, which is 200 RPM higher than I even want.

The boat is new to me, and I suspect the previous owner never ran the engine hard. As a result, my exhaust elbow is carboned up, turbo needs to be rebuilt, wastegate is stuck, and lots of oil is leaking from the intercooler, probably oil that gets past the turbo seal. I’m looking at a $5000 repair. This for a turbo that I don’t even want or think is necessary on my boat. I’d love the pitch the turbo in the trash.

Does anyone know whether other parts on the engine are different between the D2-75 and the D2-55 other than the exhaust plumbing? Electronics? Mechanical fuel pump? Injectors? Pistons? I suppose I’d have to reprop.

Thoughts and opinions welcome.
you need this SS https://hdimarine.net/product/v55-st...l-exhaust-kit/
or bay Perkins in steel price is 270€ and be carefule whit bolts
But Hanse 505 75 hp is underpowered and your engine must work minimum 2000-2200 rpm read user manual
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Old 15-09-2020, 18:04   #3
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Re: Possible to convert turbo D2-75 to non-turbo D2-55?

I have more power than I want or need with the D2-75. Do you think the part you linked is all that’s needed? Or would other modifications to the engine be required?
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Old 15-09-2020, 18:20   #4
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Re: Possible to convert turbo D2-75 to non-turbo D2-55?

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Originally Posted by ohthetrees View Post
I have more power than I want or need with the D2-75. Do you think the part you linked is all thatís needed? Or would other modifications to the engine be required?
maybe you mast change propeller, somebody mast Calculate propeller load .use online or profesional service. https://www.ecalc.ch/motorcalc.php
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Old 15-09-2020, 18:30   #5
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Re: Possible to convert turbo D2-75 to non-turbo D2-55?

I’m not familiar with that engine, but a regular mechanical injection Diesel it’s not hard to remove the turbo, it’s just plumbing and rescheduling the fuel, often this means a new injection pump and injectors.
It’s foolish to do so though, there is no reason at all that a turbo motor can’t be run at low power settings. You need to fix what you have and enjoy it, so long as you run it hard enough to reach full operating temps and blow it out once in a while, like a 5 min run at the end of the day, it will give you years of good service.

Just because you have the power does not mean it has to be used, that’s an old wives tale. Wife’s car is over 500 HP, likely we rarely use over 50 or so.
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Old 16-09-2020, 15:17   #6
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Re: Possible to convert turbo D2-75 to non-turbo D2-55?

Normally aspirated Diesels have higher compression ratios than Turbo models. Turbo models are still restricted by the same peak pressure.
Its the lower pressure at low load that determines consequence of splashed Luboil, that often gunks up the piston rings. Turbo models are effected more by the poor combustion at reduced load.
I would think that Compression ratio needs to be increased, maybe the cam timing is also effected, but perhaps can be ignored. I wonder if the ring stack is exactly the same.

On large bore diesel engines was easy for us to do ring inspections and regulate the lubrication of ring stack.
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Old 16-09-2020, 16:01   #7
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Re: Possible to convert turbo D2-75 to non-turbo D2-55?

Your confusing gasoline engines with Diesels, turbo diesels have high compression , if they didn’t. They wouldn’t start.
But even gasoline engines can have their turbos removed, they will still run, and can be run on much lower octane fuel too.

As a general rule though if you remove a turbo from a motor, it will become a real dog compared to its turbo version, often meaning it has to be run at much higher RPM to make acceptable power.

Making power is real simple. All it is is more air and more fuel, fuel is easy, just install bigger injectors, air is hard, that’s where polished ports, performance camshafts, larger valves or forced induction comes in.
If you remove the forced induction, that’s removing a lot of air, so a lot of fuel has to be reduced and that means lower power
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Old 16-09-2020, 16:17   #8
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Re: Possible to convert turbo D2-75 to non-turbo D2-55?

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Originally Posted by Oceanride007 View Post
Normally aspirated Diesels have higher compression ratios than Turbo models. Turbo models are still restricted by the same peak pressure.
.
false for answer boat engine 404-22 & 404-22T have Compression Ratio 23.3:1
only different is turbo have bigger Maximum Torque and Power and some engine (depend factory,year) have BCD bost compensation device for preventing overfueling and black smoke in aclereration from low idle.
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Old 16-09-2020, 16:45   #9
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Re: Possible to convert turbo D2-75 to non-turbo D2-55?

My wanting to get rid of the turbo is kind of a product of frustration that I’m having expensive trouble with a part that gives me more power than I need, with expensive downsides. In reality, I’m not seriously considering the conversion. I’ll fix it, keep after the wastegate, and make sure to run it hard for a few minutes each watch.


The Volvo mechanic managed to clean up the waste gate valve, and he feels that will fix our oil leak, which he said is from oil being forced into the intercooler and out the intercooler weep-hole by over pressure, and not a leak in the turbo itself. I’m not so sure about that.
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Old 17-09-2020, 02:49   #10
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Re: Possible to convert turbo D2-75 to non-turbo D2-55?

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Originally Posted by ohthetrees View Post
My wanting to get rid of the turbo is kind of a product of frustration that Iím having expensive trouble with a part that gives me more power than I need, with expensive downsides. In reality, Iím not seriously considering the conversion. Iíll fix it, keep after the wastegate, and make sure to run it hard for a few minutes each watch.


The Volvo mechanic managed to clean up the waste gate valve, and he feels that will fix our oil leak, which he said is from oil being forced into the intercooler and out the intercooler weep-hole by over pressure, and not a leak in the turbo itself. Iím not so sure about that.
this is not expensive malufuction, any generic turbo specialist easy and cheap can repack your turbo. next time you sail with your boat do not use engine under 1800-2000 rpm
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Old 17-09-2020, 04:38   #11
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Re: Possible to convert turbo D2-75 to non-turbo D2-55?

Hi,

I don't know about the Volvo but I did exactly that to a Yanmar 77hp 4JH DT.

I removed the intercooler, removed the turpo impeller and blanked the side off so the turbo body could be used to connect the exhaust to.

The engine performance is the same to about 2000 rpm but beyond that it runs out of grunt and smokes. It does need the pitch reduced. (Maxprop)

The reason - Engine access is limited and with the intercooler and turbo in place, there was no access to the starter motor or some of the cooling water hoses. No way was I going to sea like that.

A friend did the same to his Yanmar and also had no problems.

I shall look into an electric blower for extra boost for the odd occasions it may be needed.

The Yanmar has no computer so that probably helped. I have not needed to change the injectors or timing.

Bob
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Old 17-09-2020, 07:52   #12
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Re: Possible to convert turbo D2-75 to non-turbo D2-55?

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I shall look into an electric blower for extra boost for the odd occasions it may be needed.
Don't waste your time on an electric blower, it's not going to develop even close to enough PSI to make any difference at all unless it's a real e-supercharger which is a significant piece of equipment. Keep in mind it takes 6-7 bhp for every psi of boost your typical supercharger produces. Convert that to the size and amps you'd need from an electric motor and it just isn't terribly practical for a boat.
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Old 17-09-2020, 08:20   #13
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Re: Possible to convert turbo D2-75 to non-turbo D2-55?

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Originally Posted by a64pilot View Post
. . . It’s foolish to do so though, there is no reason at all that a turbo motor can’t be run at low power settings. You need to fix what you have and enjoy it, so long as you run it hard enough to reach full operating temps and blow it out once in a while, like a 5 min run at the end of the day, it will give you years of good service.

Just because you have the power does not mean it has to be used, that’s an old wives tale. Wife’s car is over 500 HP, likely we rarely use over 50 or so.
I agree.

Removing the turbo will not change the minimum power setting, where wet stacking or other unhealthy consequences start. It will merely cut off the top of the power curve.

I would fix it so that it works right, and leave it. Turbochargers are very reliable devices. I have put about 3000 hours on my Yanmar 4JH3HTE for a total of nearly 4000, without the slightest such problems. I often run it at 1600-1700 RPM (out of 3900 redline) and as long as I follow the Yanmar manual and operate at high power periodically, there is never a problem.

Having a turbocharger actually REDUCES the % of full power you can operate at and still be healthy, compared to a naturally aspirated engine of the same power. Because a turbo engine can be smaller displacement, which pulls less air through at a given RPM (when off boost).

So my 2000cc 4JH3 pulls through less than half of the air at 1200RPM, as a 4400cc Perkins M92 does. Guess which one is healthier to run at 1200RPM?

Lastly: Do you really think 75hp makes a 50 foot boat "overpowered"? Just because you need only a fraction of max while motoring slowly in calm weather, doesn't mean you don't need more. I would surely not want less than my 100hp in my 54' boat. The requirement for power goes up exponentially when you are trying to get up against strong headwinds and/or seas. You might not need to do that often, but as they say, when you do need to, you will REALLY need to.
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Old 17-09-2020, 08:57   #14
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Re: Possible to convert turbo D2-75 to non-turbo D2-55?

I thought about removing my turbo on my 42ft boat. I've got a Yanmar 4JH2-UTE. The turbo was seized after 500 hours. Turns out sea water in a turbo isn't a good thing.

I personally think one is better without a turbo, but the added HP is welcome because there is times where the added boost is needed.

I decided against removing the turbo and instead rebuilding it(along with custom exhaust) for the sole fact that having the extra HP and an engine that's not modded to hell to 'work without turbo' doesn't make sense.

Learn to maintain the system and when it comes time to replace the engine, replace with a non turbo if at the end of the period you don't like it
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Old 18-09-2020, 03:20   #15
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Re: Possible to convert turbo D2-75 to non-turbo D2-55?

We have exactly the same Motor Same problems. Our engine is now 4 years old and has 700 hours. The waste gate was stuck within the first year. Poor design. Which then pushed the hose clamp on the 2” rubber hose of and released the extra pressure this way. Everything was ok I just got only 2700 rpm instead of 2800 when the wastegate still worked. We like mothering at 1800 and make 6.5 to 7 knots. Also we Motor sail on longer upwind trips at 1600. If we would have to motor sail at 2200 we would slam In to the waves At 8 knots .
This year we only got 2500 at full throttle still doing more than 8 knots and not smoking. When I removed the exhaust elbow two of the fife Screws where just about rusted in place. So it’s a good idea to take them out and lube them with high temp Neverseeze. The elbow was heavily corroded on the inside and the turbo was stuck in soot. Regardless of us running the engine at full throttle every 10 hours as by Volvo recommendation. I freed up the turbo and installed a new Stainless St. Elbow. No chance to get the wastegate to run free and smooth.
I installed a pressure sensor after the turbo to see what’s happening.
The charge pressure only kicks in at 1800 at 1 psi. 2000 3psi. 2200 5 psi. 2400 7psi. 2600 10psi. If I go higher the hose between the turbo and engine starts to balloon. The official Volvo number for the wastegate to open is around 10 psi.
So for now I will run the engine more often at 2200 and put up with the noice and higher fuel consumption . But if the turbo dies I will remove it and run whiteout at 2500 (whiteout the restriction of a stuck turbo 2600) and hopefully no more babying needed. Would I have known about the tour I problems I would not have ordered the 75 hp upgrade. Not worth it. We got plenty off power with a stuck turbo.
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