Anyone familiar with the Dtronic 4.2 motor - 220HP?

O

ontheplane

Well-Known Member
Joined
20 Mar 2004
Messages
2,070
Location
Bristol UK
Visit site
Hi all,

Completed a river trial today on a potential purchase that I am 90% sure I'd like to complete on.

There are however a number of issues which I and the vendor will have to agree.

On the river trial there was the opportunity to open the boat up to full throttle and it's this I wanted to appeal to the collective knowledge of the forum on.

I will start by saying one of the issues was the Tachometer does not work on this boat - so I could not get any RPM readings to back up my gut feelings on this...

So the boat seems to lurch when put into gear by more than I would have expected - however I have only been used to petrol engines, which having a much larger RPM range to run through I suspect are somewhat finer pitched / different drive gear ratios - however it did seem to make manoevering in the marina a little more tricky than I'm used to...

So it runs up the river beautifully - once the motor had warmed up it seemed smooth and quiet enough for a diesel...

I should have measured it properly, but just over tickover I was achieving about 6 knots going with the current and about 5 going against (so I assume about 0.5-1kt of current) based on the sat nav readout. That seemed high for a boat at tickover?

When we got the opportunity to open her up, pushing the throttle to full open produced a slight surge, and the bow lifted slightly... .then not much happened for about 5-6 seconds before the engine started to pick up - "here we go" I thought.... and although the boat picked up a bit, it didn't really seem to do all that much, I'd expected a gradual building surge, some turbo whine, a bit of a delay and then we would start to pick up - but for a long time (20-30 seconds) not a lot happened - the boat appeared to sit on the hump and I began to think the boat wouldn't get on the plane at all.

Then, very slowly, the whistle I'd expected before began to build, and as it built about 5-10 seconds later, the speed began to pick up.... Then with the rising whistle, the boat picked up and properly began to plane, speed rising to 24 knts.

For context, the boat is a 25' (thereabouts) Sea Ray 250 Sundancer with a 220hp Dtronic 4.2 - by my estimations the boat is probably about 2200 - 2500kg or thereabouts - so I'd expected to have pretty good top end - just under 100hp per ton should be pretty decent - I was thinking it would be a 28-30 knot boat at the top end. I didn't expect scintillating acceleration or holeshot - but I was not expecting the incredible delay in pickup - I realise it's not got a supercharger like KAD42 or D4 engine - but a 6 cyl 4.2 litre diesel, I thought would go a bit better.

As I say, no Tacho means that I could not check what the engine topped out at - and this is why I wonder if the boat has been over-propped? If the pitch is too high, then the engine won't spin easily to the boost zone of the turbo, I assume it might therefore hurt the pickup and possibly the top-end as well if it's "overgeared".

On test, the boat was light - it had little fuel in and no water, I assume the holding tank was also empty so I am guessing it was about as light as it could be. Slowing it down, were 4 adults on board and we had the full camper canvas up, but we rolled up all the back and the central section of the front canvas so air could flow through it.

Given I don't have RPM data to help out - does any of this sound about right? Does anyone have a 25' or so American Cruiser with the same engine who get similar performance characteristics from the DTronic 4.2 220HP - (I think the 250HP is rather a different beast). The Tacho needs to be fixed before I commit 100% to buying the boat - so I will get the chance to re-run it to get performance figures.

Now I am looking for a boat that is comfy pottering about, but that can lift it's skirts and go a bit quicker when needed and comfortably plane without having to run the engine ragged.

Assuming a boat like that will plane happily at 20kts - and it does 24 knts that doesn't give a lot of margin once the boat has the usual cruising gear on board....

So does anyone know what the Max RPM of this engine is - and a good estimate what the top speed of an outfit like this should be - as above I thought about 28-30kts should be about right - 24 on a light boat seems a bit low to me.

Thank you
 
ontheplane said:
Hi all,

Completed a river trial today on a potential purchase that I am 90% sure I'd like to complete on.

There are however a number of issues which I and the vendor will have to agree.

On the river trial there was the opportunity to open the boat up to full throttle and it's this I wanted to appeal to the collective knowledge of the forum on.

I will start by saying one of the issues was the Tachometer does not work on this boat - so I could not get any RPM readings to back up my gut feelings on this...

So the boat seems to lurch when put into gear by more than I would have expected - however I have only been used to petrol engines, which having a much larger RPM range to run through I suspect are somewhat finer pitched / different drive gear ratios - however it did seem to make manoevering in the marina a little more tricky than I'm used to...

So it runs up the river beautifully - once the motor had warmed up it seemed smooth and quiet enough for a diesel...

I should have measured it properly, but just over tickover I was achieving about 6 knots going with the current and about 5 going against (so I assume about 0.5-1kt of current) based on the sat nav readout. That seemed high for a boat at tickover?

When we got the opportunity to open her up, pushing the throttle to full open produced a slight surge, and the bow lifted slightly... .then not much happened for about 5-6 seconds before the engine started to pick up - "here we go" I thought.... and although the boat picked up a bit, it didn't really seem to do all that much, I'd expected a gradual building surge, some turbo whine, a bit of a delay and then we would start to pick up - but for a long time (20-30 seconds) not a lot happened - the boat appeared to sit on the hump and I began to think the boat wouldn't get on the plane at all.

Then, very slowly, the whistle I'd expected before began to build, and as it built about 5-10 seconds later, the speed began to pick up.... Then with the rising whistle, the boat picked up and properly began to plane, speed rising to 24 knts.

For context, the boat is a 25' (thereabouts) Sea Ray 250 Sundancer with a 220hp Dtronic 4.2 - by my estimations the boat is probably about 2200 - 2500kg or thereabouts - so I'd expected to have pretty good top end - just under 100hp per ton should be pretty decent - I was thinking it would be a 28-30 knot boat at the top end. I didn't expect scintillating acceleration or holeshot - but I was not expecting the incredible delay in pickup - I realise it's not got a supercharger like KAD42 or D4 engine - but a 6 cyl 4.2 litre diesel, I thought would go a bit better.

As I say, no Tacho means that I could not check what the engine topped out at - and this is why I wonder if the boat has been over-propped? If the pitch is too high, then the engine won't spin easily to the boost zone of the turbo, I assume it might therefore hurt the pickup and possibly the top-end as well if it's "overgeared".

On test, the boat was light - it had little fuel in and no water, I assume the holding tank was also empty so I am guessing it was about as light as it could be. Slowing it down, were 4 adults on board and we had the full camper canvas up, but we rolled up all the back and the central section of the front canvas so air could flow through it.

Given I don't have RPM data to help out - does any of this sound about right? Does anyone have a 25' or so American Cruiser with the same engine who get similar performance characteristics from the DTronic 4.2 220HP - (I think the 250HP is rather a different beast). The Tacho needs to be fixed before I commit 100% to buying the boat - so I will get the chance to re-run it to get performance figures.

Now I am looking for a boat that is comfy pottering about, but that can lift it's skirts and go a bit quicker when needed and comfortably plane without having to run the engine ragged.

Assuming a boat like that will plane happily at 20kts - and it does 24 knts that doesn't give a lot of margin once the boat has the usual cruising gear on board....

So does anyone know what the Max RPM of this engine is - and a good estimate what the top speed of an outfit like this should be - as above I thought about 28-30kts should be about right - 24 on a light boat seems a bit low to me.

Thank you
Click to expand...
You need Tom. Tompa marine. https://www.tompamarine.co.uk/maintenance/
He knows Mercruiser inside and out.
 
Is it on a Bravo 2 leg?

If yes, how clean is it (underneath, in general)? Any growth, even seemingly insignificant, will have an effect.

I have the 4.2l 320hp (100hp more) version on my boat (3200kg) and get 26 knots flat out.

Changing the gearset may get me 2-3 knots more as it reaches max RPM very easily, but that sounds maybe a tiny bit slow though within reasonable limits
 
I think it's pretty clean in freshwater at the moment and I can see no real growth (probably has a tiny bit of slime) - it's on a Bravo 3 drive though - props are fairly clean and look undamaged.

I really am not familiar with Diesels - so if 24kts is flat out - but I can cruise at 21 happily then I think I'll be happy with that - I just don't want to be ragging the engine every time we go out. Is it right that with the torque of a good diesel, a boat will often stay happily on the plane at a slightly lower speed - I am used to thinking 24 knts is about the lowest speed to get properly up on and stay on the plane, but with a diesel will it plane happily at lower speeds than that (given it's about 24' waterline length)?

Until the rev counter is working I have no point of reference as to whether the engine is revving out properly.

I have found that the DTronic is allowed to rev out to 3600 so until I can get a Tacho to work, I don't have a point of reference yet - but if it revs to 3200 that would indicate to me I need to drop 1" of pitch on the prop
 
Last edited:
Those laser tacho things are great and don't cost much, a small piece of reflective tape goes on the shaft then the handheld laser instrument will give a reading.

Server Busy

You should be a bit quicker perhaps, maybe a knot or 2, but I don't think that setup would reach 30 knots.

Mine should reach 3900 but gets to 4000 with no issue so I could get some more speed from the boat, but in the end I hit 26 flat out and cruise at 20 which works fine for me.
 
jointventureII said:
Is it on a Bravo 2 leg?

If yes, how clean is it (underneath, in general)? Any growth, even seemingly insignificant, will have an effect.

I have the 4.2l 320hp (100hp more) version on my boat (3200kg) and get 26 knots flat out.

Changing the gearset may get me 2-3 knots more as it reaches max RPM very easily, but that sounds maybe a tiny bit slow though within reasonable limits
Click to expand...
Bravo 2 would be unusual on a boat like this. They have a big single prop. Usually for heavier workboats.
A bravo 3 (which is twin prop) is more likely.
 
Elessar said:
Bravo 2 would be unusual on a boat like this. They have a big single prop. Usually for heavier workboats.
A bravo 3 (which is twin prop) is more likely.
Click to expand...
Yes true but the 4.2 Dtronic was supplied with the 2 if I remember correctly (spannerman will know this). The 3 (assuming not the X version) must be right on the torque limits with this engine
 
If it’s still in the water and you have not lifted it to clean the hull or inspect the hull I would do that first , there might be hull growth slowing it down , have the hull surveyed for damp , osmosis, damage etc .
Take a hand held tachometer , I always carry one on sea trials .
If the Rev counter isn’t working then ask the seller to investigate as that may cost you .
You really need to know if it performs or not as there might be underlying problems with the turbo not kicking in when it should do , you described a delay getting on the plane , this could be hull growth, dirty prop etc , as it’s a D tronic there might be electrical issues with the system as the injection pump is governed by a computer which takes information like boost pressure and rpm , load etc . If the rpm sensor has failed then look into it first before you buy .
 
Yes - There is a long list I have told the broker I want fixed before a second trial before I complete - the engine I can't really test without the rev counter working.

Do you have to run with the engine bay open to use the handheld tacho's? I ask because the engine is long so not an excess of space in the engine bay! Not sure I would want to be hanging into the engine bay to get a read whilst someone opens up the taps really!
 
I,m not an expert on the 4.2 but seatrailed a pair of 220hp 4.2 it in a sealine s34 . First - afaik ( but not sure ) the 220 hp is NOT a D-tronic but a pure mechanical version .

The engine itself ( the 220 hp ) is an indirect injection italian VM block . Later versions were direct injection . I can confirm it was matched to a b2 , not b3 . From what i heared the engine itself is pretty durable , the drive may suffer from steering pin leaking.

The engines performed ok without a 20-30 sec delay but were also no match to the bite a volvo KAD has . If everything ia ok and the price is nice i would consider buying it .

The indirect injection version has the reputation to be not very fuel efficient , be aware .
 
Nearly every 4.2 D tronic I have worked on had a Bravo 1 or 3 drive, as only heavy semi displacement boats used the Bravo 2. And a 220hp is well within the torque limits as most use the 320hp 4,2.
If its slow on pickup and the props are correct I would first suspect the boost sensor as the air temp sensor in these often fail, they usually show 90-100C when a diagnostic Rinda tool is plugged which means the ECU drastically cuts back on fuel delivery giving slow accelaration. If this is ok then the wastegate could be sticking open and dumping boost, Mercruiser diesel turbos normally boost from around 1500rpm with associated whistle.
 
aerobat said:
I,m not an expert on the 4.2 but seatrailed a pair of 220hp 4.2 it in a sealine s34 . First - afaik ( but not sure ) the 220 hp is NOT a D-tronic but a pure mechanical version .

The engine itself ( the 220 hp ) is an indirect injection italian VM block . Later versions were direct injection . I can confirm it was matched to a b2 , not b3 . From what i heared the engine itself is pretty durable , the drive may suffer from steering pin leaking.

The engines performed ok without a 20-30 sec delay but were also no match to the bite a volvo KAD has . If everything ia ok and the price is nice i would consider buying it .

The indirect injection version has the reputation to be not very fuel efficient , be aware .
Click to expand...
They do an electronic control version of the older engine .
 
Only from Brokers description which as we all know can be relied on to be 100% accurate lol....

I think he's taken it from the seller - who also told him a ton of stuff was fixed that wasn't so we can't rely on it at all I don't think.

The motor was second hand when installed about 5 years ago I think - although it looks to have been a professional job
 
You must log in or register to reply here.

Other threads that may be of interest

O
General Thoughts on a Crownline 242CR around 2000
Replies
3
Views
315
ontheplane
O
Mr Googler
A rebuild thread to keep you all happy for the long winter
5 6 7
Replies
133
Views
5K
Mr Googler
Mr Googler
J
New small boat
Replies
4
Views
401
Farmer Piles
Farmer Piles
R
Leisure batteries, how to fit? Help!
Replies
10
Views
532
Skipper Felice
Skipper Felice

Share this page

Top