Volvo D4 EGT

[GusC@AK]

I repowered my boat with a pair of new D4 240s (replacing the old D4s). Additionally, I installed a pair of ISSPRO pyros at the NPT port on the turbo. However, I am getting high temp readings during sea trials (1100-1150 F). I am able to achieve WOT with no lag (load seems fine), new air filters, raw water circulation is great. Is it time to look at my exhaust elbows for carbon occlusion? Muffler? Etc? Stumped.

 

[Portofino]

590 to 625 Celsius .
Seems pretty ball park at WOT or there about ?

What rpm and cruise speed are theses occurring?
Weight / displacement they are trying to move ?
What killed the previous engines , how many hrs ?
Have you got access to load data at those EGT s ?


I never really go over 600 Celsius , but running @80 % load all day ( I set the cruise speed based on load ) then on the same screen can see the EGTs which are a bit lower 575 ....maybe a bit higher if the props are fouled or boat fully loaded up .Gives around 30 knots or just under ish .

 

[kashurst]

1100 Farenheit is about 600 Celcius.
I would check with Volvo what they would expect and check the calibration/location on your temp measuring system to how Volvo would do it.
If you can acheive max RPM with a loaded boat you are probably fine.

 

[julians]

Have a look at this spec sheet for a d4 300, it says that the EGT at exhaust pipe connecting flange after the turbo charger was 1040F or 560C at 3500 rpm

http://www.darthaven.co.uk/userfiles/products/files/Technical data D4-300A.pdf

 

[Portofino]

1200 F is 645 C ......Aluminium starts to melt at this temp as a reference .Sure there’s a lot of alloys with higher melting points in the cylinder and it’s surrounds but it’s just to show how hot it gets inside a fully functioning turbo diesel and how little headroom there is to play with .
Its the exhaust valves that get it first when consistent elevated EGTs are allowed.They mushroom , and loose seal .
This is not a binary ....bang ....or a light bulb on / off fail .
It creeps up insidiously.

As a bit of afterthought for those with older set ups .......I noticed a 10-20 drop down in EGTs after adjustment of the tappets ( valve clearance ) ....like for like rpm etc .This is because due to the high pressures the final ends of the valve closure / opening timing is crucial in terms of Hp generation . A significantly loss of power occurs if the timing is out even by a small margin from wider valve clearance gaps .

Of course returning to the Op we don’t know the boat , it’s weight , it’s performance, etc and if it’s correctly propped .
Over propping , over loading , fouling all will elevate the EGTs .
Lets assume the engines being out of the box are correctly set up .

Slightly lower pitched prop ( and speed reduction ) will lower the EGTs .

A lot of variables and as I said it’s only slightly up if that’s WOT ?

 

[GusC@AK]

Thanks for the input everyone. I wasn't specific in my original question. I am getting those temps at much lower RPMs (under 2000rpm). Load, props, fouling are not the issue.

 

[Portofino]

Load and EGT s are linked ...
Can you answer the other 3 Q out of 4 I asked in post #2 ps .

A screen should show load in % terms up to a 100 , once over a 100 % EGT s rocket .

What EGT readings are you getting @ WOT and say a suggested ( by many WOT less 10% rpm ) 3-3200 cruise ?

 

[julians]

It could be that the pyros and or guages are not accurate, a quick Google suggests that those isspro pyros can be a bit inaccurate.

I guess you'd need to test them on a known good engine to determine this.

 

[volvopaul]

I repowered my boat with a pair of new D4 240s (replacing the old D4s). Additionally, I installed a pair of ISSPRO pyros at the NPT port on the turbo. However, I am getting high temp readings during sea trials (1100-1150 F). I am able to achieve WOT with no lag (load seems fine), new air filters, raw water circulation is great. Is it time to look at my exhaust elbows for carbon occlusion? Muffler? Etc? Stumped.

You have not said if it’s shaft or stern drive ?

 

[GusC@AK]

Portofino, the boat is 18k lbs w/ duel and water. Performance: cruise at 2900 at 21knts and burning 1:1 (21 gph). It is a v-drive/reverse gear. And the pyros are installed pre-turbo...

 

[Portofino]

8 to 9 tons depending on units that’s heavy for 240 s imho
What killed the last set of engines ?
Whats the EGT at your 2900 cruise and WOT , you said it achieves WOT ?
Name of boat modal would help ?
Where are you getting “ load “ from .

Theres not enough info from the op to make a meaningful diagnosis......and thus propose a treatment plan .

 

[Portofino]

Above the load 81%

General with the coolant pump pressure the impeller pump .

EGT 586 Celsius, + turbo boost P 1.91bar ....I,am happy with that @30 knots cruise .


EGT fall straight away as soon as you throttle down and the turbos drop off .

Thing is the engines + props + hull ( displacement 17 tons ) are beautifully balanced .
They say optimum EGT s in terms of minimal agglomeration is between 550 and 600 Celsius.
Agglomeration in Diesel engines is something you are gonna have to google .....basically it abrasive soot formation .
Operating outside theses temps for excessive periods wears your bores and rings out prematurely.

In terms of practically for most on here nothing much as an engine knackering @2000 hrs or lower , for most does not matter as if It would have lasted to 6000 hrs spending its life running between 550/600 C EGT .

It a case of informed choice.

 

[GusC@AK]

Awesome info. I’ve scheduled a load test/diagnostic seatrial with a local dealer. Meanwhile, I’m moving my pyro probes to read post-turbo temps to make sure I’m pulling accurate data. I wish my engines had all the read outs as yours!