Petrol to BMW Diesel

[wmcruiser]

Hi
Has anyone done a conversion from VP V8 petrol on 280 drives to bmw td m51 150hp engine?

[Irish rambler]

Hi, BMW did marinise their engines for a while. I had a BM 525 with the 6 cyl turbo diesel and I was very impressed with it, especially after I 'chipped' it. Outdrives legs may not stand the torque so I would chat to someone like Mike Bellamy at Lancing marine, as an ex racer he's a mine of info on marine engines and highly recommended.
I hope this helps.

[goboatingnow]

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I'd start with them

I re-engineered a bayliner 25 years ago to styer( cobra) with its OMC leg . I'd echo the previous poster that it often needs an associated outdrive leg.

Nothing about it makes economic sense by the way. You buy gasoline till your dead with the costs.

Dave

[wmcruiser]

The two vp engines are shot,brought as project boat hence looking at repower with conversion.low cost compaired with new.
Ive done other repowers before just wanted opinion on m51 bmw engine.

[Pete7]

You would be better looking for a Yanmar or Mercruiser diesel with matching stern drive which is likely to be the B2 from Mercruiser. The others like the alpha just won't handle the torque generated. Even the B2s have problems and with big hp get hot enough to scortch the paint so need a shower fitted. this is a water pick up which sprays sea water on the top casing so cooling the top bearing down. One of the other problems with stern drives is the exhaust is often routed through them and out the prop adding to the heat. Also the stern drive design doesn't allow oil from the cooler lower section to mix with the upper section. The one different drive is a sternpowr. I ran 200 hp Mermaid TD Four through mine and it was fine.

Have a good search of this UK site for diesels and stern drives. They are powerboat petrol heads but lots of serious experience.

http://boatmad.com/forum/

[wmcruiser]

Agree but removed v8 volvo unit 200hp looking to replace with 150 hp diesel.torque shouldnt be a problem as they used to run the ad41 on the vp280 legs.
Last conversion i blanked cowhorns and put in though hull exhausts

[Pete7]

I think your problem with the BMWs is there just aren't enough about compared to Volvo, Mercruiser or Yanmar to get a real opinion from users.

Pete

[wmcruiser]

Thanks for your input,was just intetested in rest of world usage.

[wmcruiser]

Any idea where to get fuel/torque curve info for m51 bmw engines.have googled but nothing obvious.?

[Ian_D]

Likewise, im planning on using 2x M51's in my boat (on volvo 270 legs).

Im also struggling to find the curves for the M51 too.

How far have you got with your project so far? and advice etc?

So far, ive only got one engine (from an Omega). Welded together a very rough test frame, and had her up and running for a few mins.

Ian

[wmcruiser]

Yes found company that has been doing for few years a marinisation and adapt to different outdrives,youtube video type in pringlecarl69 and view his channel.
Ebay shop bmwmarine.spoke to him seems very knowledgeable.

Sent from my HTC One S using Cruisers Sailing Forum mobile app

[Ian_D]

Yes I have seen his videos.

Have you bought then complete engine + coupler + bellhousing from him then? or have you fabricated your own?

Ive also found a power curve for the 525tds engine here:

[Edwin73]

Hi,

I'm also preparing a M51 to go into my Bayliner 20,5 ft cuddy cruiser.
It used to be powered by a Mercruiser 4.3 V6, but with the fuelprices over here (Netherlands) and because I was looking for a challenge, I went for a repower.

For cooling I'm going to use a Bowman water/water exchanger and for charge air an aftermarket aluminium water-to-air exchanger which is being anodisised as we speak for better (sea)water resistance.

I will be using the standard Alpha One gen 2 that came with the boat. I was thinking about a speed-up box directly behind the engine to speed up the rpm's before it enters the sterndrive. That way the torque on the drive will be less. Also pitch of the prop can be a bit less then, also better for the drive (less stress)
No sure if it will be able to shift with higher idle rpm's though.

For the engine I will be using an exhaust manifold out of a 524td, because of the higher position of the turbo. That way the riser will be much shorter before it will be wetted. The manifold and the turbo will be isolated, but not wetted.

Just wondering now if I should modify the oil sump. The actual sump is in the front of the engine, while most of the time, (slow cruising speeds in rivers) the engine will be leaning a bit backwards. Also with accelaration it will be harder for the oil to get back to the front of the engine.

What do you guys think of this project?

[Ian_D]

Regarding the sumps, I've also noticed this.

However, if you buy a sump from an M51 which is from a 325tds, the sump is actually at the flywheel end. I assume there was something in the way on the 3-series (maybe subframe / steering or something) hence the different sump.

Also, these engines were fitted to the Range Rover P38 - and they have a completely different sump. I seem to think that these sumps also have a bigger oil capacity, although I could be wrong on that.

Hope that help. Unfortunately, I've been too busy to do any work on my 2x M51's. Maybe I will make more progress next month!

[GordMay]

Greetings and welcome aboard the CF, Ian, and Edwin.