GM turbo Diesel 6.5 V8

[Jon Fuller]

Originally posted by Admiral P. Brain
our sunseeker tomahawk mk2, twin kad42, total 460hp, runs 42-44mph.

yeah, 36-37 knts, so 50 knts with that power is rather optomistic.

[Jon Fuller]

Originally posted by Scand
Are you running two of these in the Phantom?
May I be as bold as to ask how much these cost to build?
I was wondering about replacing my twin 5.7 MFI V8 petrol’s with something that’s a bit cheaper to run.

It aint cheap.

reckon I spent about the same as buying Yanmar 315 hp packages in the end, so back then (2000) about 30k for the pair. And that was doing it all myself, and sourcing the drives/gimbles at very good prices.

new engine/drive pachages are the way to go really.

Remember also, that the Alpha drive (if that's what you have) won't take that much torque, so you'd have to upgrade to Bravo.

[Scand]

Ouch, that’s over my pain threshold. Always thought that as the base engine is so cheap that this could a beneficial option, but suppose when you add all the bits all up…
I am running bravo3’s and getting 48 knot at the moment.
Thanks for your replay.

[Jon Fuller]

In 2000, the bare long motors (blocks, heads, cranks, pistons etc, inc turbochargers, injectors and injector pumps) were about 6-1/2 K each, so 13k before I even started the marinizing, and transmission side of things.

By splitting new Petrol V8 packages (selling off the V8, keeping Drive, Gimble, Trim pump etc) each 'Transmission assy' cost me about 4k.

So 13 + 8 for the basics, then all the cooling system, heat exchangers, raw water pumps, chargecoolers. All the motor anciliaries, Exhaust manifolding (big headache), oodles of powdercoating, stainless fasteners etc. it adds up fkkn quick.

[Matt]

For comparison sake, how much is a the similar petrol package?

[Jon Fuller]

feck off

[Matt]

I was being serious nobba - working out how much fuel you'd have to burn for the diesel motor to be ahead on the game with and without tax on the diesel.

[Scand]

Mine cost £18.5K (in 2000) for 2x5.7’s with bravo3’s including installation and props.

[Matt]

So you need to gain back 14K in fuel & resale to justify it in a build. Resale is difficult to gauge, but 14K of petrol in a twin 330hp boat wouldn't take that long for the diesel to be ahead - 3 seasons maybe?

[Jon Fuller]

Originally posted by Scand
Mine cost £18.5K (in 2000) for 2x5.7’s with bravo3’s including installation and props.

What HP?

[Jon Fuller]

Originally posted by Matt
So you need to gain back 14K in fuel & resale to justify it in a build. Resale is difficult to gauge, but 14K of petrol in a twin 330hp boat wouldn't take that long for the diesel to be ahead - 3 seasons maybe?

I make that 11.5k

[Matt]

Yeah Yeah.
I took a bit off for installation and props - since I guessed those weren't in your 30K estimate.

[Matt]

Or maybe I can't count.

[Scand]

Mine engine gives 260hp on the prop, so about 275hp on the flywheel.

[Scand]

And externally:

[verytricky]

Odd?

The Volvo penta 5.7 generates 320hp. Why does the Mercury ones only produce 275????

[Scand]

Mercruiser makes numerous versions of the 5.7, I think there used to be 330 hp Mag, at moment the 300 hp is max.

[Lars T]

Originally posted by verytricky
Odd?

The Volvo penta 5.7 generates 320hp. Why does the Mercury ones only produce 275????

They do?!?!?

Merc have 5.7 from 250hp (90-96) from 96-03 5.7 MPI 260hp (now replaced by the 5.0MPI)
350mag (5.7) does 300hp and the new one 6.2 does 320hp...

Funny reading
http://www.mercurymarine.com/mercruiser_volvo
http://www.mercurymarine.com/uploads...BeatsVolvo.pdf

[Lars T]

BTW - i though they were of the same engineblock??

[Scand]

Both based on the same GM block.