Diesel Engine Swap

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I intend to swap my Mercruiser 5.7 V8 petrol engine, driving an Alpha 1 leg, for a GMC 6.5 V8 Diesel (easy out, easy in). I have read most of the previous posts on the subject, but didn't see any from anyone who had first hand experience of such a swap. Is there anybody who can point out the problems I'm likely to encounter, apart from a light wallet.
 
Oh dear, here we go again.

Have performed "the swap" on a couple of occasions, it isn't that difficult to do, depending on engine source.

Question 1.
Where are you getting the engine from?
Question 2.
What drive are you intending to use?
Question 3.
What boat are you fitting in?
Question 4.
Are you Mechanically minded?
 
Be carefull on this, if the diesel is a turbo the alpha leg won't take the torque and even with a non turbo it will go bang fairly quickly, also you can't swop an alpha for a bravo drive because the transon holes are different.
 
Thanks, 1) I have info on engines from Lancing Marine, Samurai and Marine Diesel,
all GMC 6.5 V8.
2) I thought I might get away with using the Alpha drive provided I used
a non super/turbo charged engine. Andrewa's thoughts seem to accord
with my doubts.
3) Bayliner 2755 Cierra (about 3 tons).
4) Yes!
 
I thought all of the 2755 model Bays came with Bravo drives. I was looking at that model but in the end went for a 1993 Sea Ray 270, you mention lancing marine, they have a 300hp Merc D-tronic with a blown turbo and Bravo 3 which they will rebuild and fix for £10k plus the VAT may be worth a look, I was going to buy it but its to long for my engine compartment.
 
This site may be of interest, its in the states but talks about changing the alpha to a bravo its quite a common question, don't look at the prices though you will feel ill.
 
Went through this process a few years ago and eventually decided to go for it. Things to consider:
1. Alpha drive not suitable due to increased torque - info from Mercury marine in UK and US.

2. Be careful where you source your GM engine - have heard of problems relating to claimed hp and actual - get tested.

3.Go for Bravo 3 if you can.

Eventually went for Yanmar/Mercruiser package - good deals around and got part ex for my 5.7litre V8, in Bayliner 2655 (wide body). Yanmar 240hp 4cylinder now gets 31/32 knots WOT and cruising at 2800/2900 21/22knots @ around 6-8gph on 24inch pitch B3 set.

If there is space in your compartment, the Lancing marine deal sounds good - plenty of places in US to get cheap parts. If memory serves me right Peninsular Marine use GM blocks and Star Power same as Mercruiser (7.3l).
 
Do you have some outline pricing for this Yanmar package or a web site etc?

Regards

Jim
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Sorry for the delay, been away.

Samurai supply what seem to be ex US military/US salvaged Chevy V8's, some good, some crap.You are very much left on your own when it comes to any help.

Lancing Marine would probably steer you in the direction of the 7.3 litre v8, nice engine, used by Mercruiser bit expensive.

Marine Diesel, same base engine as Samurai, but the are a new motor, supercharged and can be bought as a package. Prices seem to be similar to Yanmar, but in theory should be a better performer(no turbo lag) and I'm sure will run much cleaner.

Although most people refer to the 6.2 & 6.5 litre V8's as chevy, they are actually produced by a company in the USA called AM General, who also build the Hummer which uses this motor. They bought the rights to the motor from Chevrolet a couple of years ago, and their version is considered to be the best having improved the castings. Their web site is www.amgmil.com, where you will see details of their marine diesels.

The Alpha is a no no, it would have to be a Bravo or a Volvo.

If you go Bravo, you would also need to change your transom assembly, and depending on how you sourced the motor, you would also need all or some of the following.
Drive plate, Flywheel cover, Engine legs & mounts, Water pump, Alternator, Exhaust, shift bracket. The list goes on but those are the most expensive. You could rob most of these parts off your existing motor, but you would then reduce its value.

The other thing to consider when going the Bravo route is ratios. Most petrol Bravo 1's are 1.5:1, which in your size boat would probably be fine, if you went Bravo 3, you would need to do some calculations as there are loads of different ratio's available. You can sometimes get around the problem with propeller choice, but on a B3 you have a pair, and they are not cheap.
 
Bravo 3X leg on my package has 1.8 ratio with 24" pitch propset. Weight of boat around 3.2 tonnes.

Only real difference with transom cutout is that 2 extra hole have to be drilled out to accomodate Bravo transomshield.

Contact on e-mail for further details if required: robinsimps@yahoo.co.uk or call me on 07768-825617
 
Thanks for all the replies to my question, I can see that it's ALL out and All in, engine and sterndrive complete. Balancing the cost is going to be the biggest problem, anyone want to buy a single engined aeroplane?
 
Retail price for a 300 yanmar on Bravo is around £21,500 + vat. I believe you can buy the same package from Dave Crawford in Lymington for approx £14,500 + vat. Its a mad world isn't it.

Also, the list price for a petrol 8.1 litre Mercruiser on a bravo is £21,695 + vat in England, in Italy its 27,900 euros, which is approx £16,740 + vat. And we thought cars were a rip off here!!!
 
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