Suggestions on 200~hp 5krpm+ diesel engine
Discussion
Hi all, I'm Jack from Devon, finally got round to joining the forum!
You seem a knowledgeable bunch, and maybe you can help me. I need an engine for a boat fitted with a jet drive in which I intend to fit a diesel engine for economy. Unlike a boat with a propeller, on which one can easily change diameter/pitch of said prop to compensate for RPM shortcomings, the impeller in the jet drive is limiting my engine choices.
I'm in need of a diesel engine of around 200hp+ potential when tuned that will happily rev over 5k, and be relatively easy to obtain. Unfortunately it needs to have a fully mechanical injection system which rules out most post mid nineties engines.
It also needs to have a reputation for reliability, as running an automotive engine in a marine application, where you are essentially driving flat out up a hill at full revs for long periods at a time is a lot harder on the engine than it's intended use.
Other than a Mercedes OM603/602 I am struggling to think of any which fit the criteria. The 606/605 are semi ecu, and while it is straight forward to swap the pump from an earlier engine, said pumps tend to carry a premium.
The Land Cruiser 4.2, I forget engine number, will happily reach 2-250hp but struggle to rev to what I need, as will most 2.5l+ japanese diesels.
My earlier plan was to use a 1.9td PSA XUD or VW AAZ/ABL, which, with the increased cooling available on a boat, will relatively easily push 110-140hp but have decided that that isn't quite enough power.
There are a few other options I've considered but they all fall short some way or another.
If anyone has any suggestions they would be most appreciated!
Regards, Jack
You seem a knowledgeable bunch, and maybe you can help me. I need an engine for a boat fitted with a jet drive in which I intend to fit a diesel engine for economy. Unlike a boat with a propeller, on which one can easily change diameter/pitch of said prop to compensate for RPM shortcomings, the impeller in the jet drive is limiting my engine choices.
I'm in need of a diesel engine of around 200hp+ potential when tuned that will happily rev over 5k, and be relatively easy to obtain. Unfortunately it needs to have a fully mechanical injection system which rules out most post mid nineties engines.
It also needs to have a reputation for reliability, as running an automotive engine in a marine application, where you are essentially driving flat out up a hill at full revs for long periods at a time is a lot harder on the engine than it's intended use.
Other than a Mercedes OM603/602 I am struggling to think of any which fit the criteria. The 606/605 are semi ecu, and while it is straight forward to swap the pump from an earlier engine, said pumps tend to carry a premium.
The Land Cruiser 4.2, I forget engine number, will happily reach 2-250hp but struggle to rev to what I need, as will most 2.5l+ japanese diesels.
My earlier plan was to use a 1.9td PSA XUD or VW AAZ/ABL, which, with the increased cooling available on a boat, will relatively easily push 110-140hp but have decided that that isn't quite enough power.
There are a few other options I've considered but they all fall short some way or another.
If anyone has any suggestions they would be most appreciated!
Regards, Jack
Most of the OM60x series will rev to 7k with governor mods as will many indirect injection diesels. I only need 5-5500RPM for short bursts, 4500 will suffice for fast cruising. The boat is fitted with a jet drive so has no gearbox, straight from flywheel to drive via double carden.
4/6bt is far too heavy for my boat unfortunately as I am a big fan of this engine.
The engine in the link is an OM606 which is semi ecu, but as I say it is a PoP to swap an earlier pump if one can be found. The 606 or 603 (single cam version of almost the same engine) are what I will likely go for unless I can find anything better.
Thanks guys
4/6bt is far too heavy for my boat unfortunately as I am a big fan of this engine.
The engine in the link is an OM606 which is semi ecu, but as I say it is a PoP to swap an earlier pump if one can be found. The 606 or 603 (single cam version of almost the same engine) are what I will likely go for unless I can find anything better.
Thanks guys
_Neal_ said:
I've no idea on the answer, but interesting question! What's the difference in economy likely to be versus using a petrol engine?
Hi Neal, fuel consumption for an equivalent(ish) power diesel depending on the engine, should be between 20 and 40% better. Couple that with the price of red diesel (legal for boats) at 59p per litre, the savings are substantial!Jack
engineengineer said:
Hi Neal, fuel consumption for an equivalent(ish) power diesel depending on the engine, should be between 20 and 40% better. Couple that with the price of red diesel (legal for boats) at 59p per litre, the savings are substantial!
Jack
Thanks, that is a substantial saving. Jack
engineengineer said:
Hi Neal, fuel consumption for an equivalent(ish) power diesel depending on the engine, should be between 20 and 40% better. Couple that with the price of red diesel (legal for boats) at 59p per litre, the savings are substantial!
Jack
Red diesel is not legal for propelling pleasure boats, only for heating and cooking.Jack
Edited by AnotherClarkey on Thursday 2nd March 13:50
littleredrooster said:
AnotherClarkey said:
Red diesel is not legal for propelling pleasure boats, only for heating and cooking.
Really? I thought the excise duty applied to diesel was only for road vehicles? Ya live and learn... The only diesel engine i know of that makes peak power at 5krpm is the Audi LeMans racing Tdi engines, and you probably can't afford one of those!
Also, running a diesel at that speed is stupid, it'll have very poor efficiency, make loads of noise and smoke and it'll wear out in no time at all.
What you NEED to do is to get the performance curve for your impeller / water jet, that shows the power it absorbs vs rotational speed, and then choose and engine and step up transmision to drive it properly. The step up could be gears, belts or chains as the load is very smooth (compared to the very jerky load a car puts on its engine for example) A cheap solution would be a nice dual (for redundancy) toothed belt drive system, you'd get a 2:1 step up into a small space and for a low cost that will easily handle 150kW no problems at those sorts of speeds.
Then choose a cheap, big diesel, that makes say 170kW at 3krpm and you're good to go!
Also, running a diesel at that speed is stupid, it'll have very poor efficiency, make loads of noise and smoke and it'll wear out in no time at all.
What you NEED to do is to get the performance curve for your impeller / water jet, that shows the power it absorbs vs rotational speed, and then choose and engine and step up transmision to drive it properly. The step up could be gears, belts or chains as the load is very smooth (compared to the very jerky load a car puts on its engine for example) A cheap solution would be a nice dual (for redundancy) toothed belt drive system, you'd get a 2:1 step up into a small space and for a low cost that will easily handle 150kW no problems at those sorts of speeds.
Then choose a cheap, big diesel, that makes say 170kW at 3krpm and you're good to go!
Use caution on any modern ish diesel road engine in a boat. Get an rpm spike and you might well bounce a valve. Personally I think your only real option is to get a bigger slower jet (if there is such a thing) as there are very few cheap motors which will meet your specs, esp mechanical fuel pump.
If you have space something like an old E290 6 banger would be perfect, you would need to drop the rpms to 3k though and it would run hot at that. Might be 40 year old technology but would run forever.
Perkins do some pretty pokey engines but revs wise you are looking at 4k very max I think. We just sold a machine last year with a great perkins motor, bullet proof but no where near 200bhp.
If you have space something like an old E290 6 banger would be perfect, you would need to drop the rpms to 3k though and it would run hot at that. Might be 40 year old technology but would run forever.
Perkins do some pretty pokey engines but revs wise you are looking at 4k very max I think. We just sold a machine last year with a great perkins motor, bullet proof but no where near 200bhp.
From what I have read about people putting old aero or tank engines into cars they often step up the engine output to get a sensible RPM range for using in a car. Given diesel engines have a fair chunk of torque could you not see what engines fit and work out how much you need to step up the output?
That would give you the output RPM range you need without having to rev the nuts off a diesel. I would stay clear of fancy modern automotive diesels as they are far less tolerant to anything that might get into the fuel whilst operating in a marine environment.
That would give you the output RPM range you need without having to rev the nuts off a diesel. I would stay clear of fancy modern automotive diesels as they are far less tolerant to anything that might get into the fuel whilst operating in a marine environment.
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