Who stole my superchargers ?

Petrolia

Petrolia

Well-Known Member
Joined
24 Sep 2005
Messages
779
Location
Citizen of the world
Visit site
How do Volvo produce 310, 350 & 370hp out of the same D6 block ?

I ask because I used to think the 310 was normally aspirated, the 350 had SC or TC and the 370 had both SC & TC.

But I'm no longer sure. Mine are 370's, or at least the documents say they are, but they have TC's and no SC's.

It's funny because when I went to Volvo for belts to carry as cruising spares they were adament I needed two belts. I told them 100% only one and got funny looks.

Has someone stolen my superchargers /forums/images/graemlins/mad.gif
 
Dude, I love your boat - wanna swap for my girlfriend? /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif
 
The inboard version of the 370 doesn't have an SC. The Sterndrive version does. Both versions have TC's.

I guess that Volvo think you shaftdrive guys don't need the blistering low down acceleration from a Supercharger!

dv.
 
Yes. The sterndrive boat has twin 350's. Mine has 370's.

So how come the sterndrive version has SC's and TC's and only produces 350hp. Mine only has TC's and produces 370.

They must get the extra HP somewhere else ?

So not having SC's at what engine revs will the TC's kick in ?
Again I don't remember seeing it mentioned in the operators manual.
 
OK, so from the same block you get more HP by stuffing more fuel in, in simple terms. The limiting factor on this is that you also need to have enough air to burn the fuel, so you add a turbo and intercooler, which all the D6's have. The different ratings are just determined by the mapping of the fuel injectors. However, different applications tend to need different torque characteristics - lightweight sterndrive sportscruisers want lots of lowdown grunt to give them maximum acceleration, so they get a supercharger which gives boost at low revs where the turbo isn't very effective.

Shaftdrive boats tend to be bigger and heavier, or are otherwise not expected to go like scalded cats, and make do with a different turbo and no supercharger. ISTR Volvo saying that the torque curve of the turbo only shaft drive D6 was exactly where you needed it for the requirements of shafts and props.
 
Top end HP is determined by Turbo and injection map settings.

Supercharger gives more "push" to accelerate onto the plane faster, but drops out at higher revs, where the Turbo has taken over completely.

dv.
 
Thanks chaps I think I've got it.

It's actually a pretty good example of how the outdrives perform v shafts. 40hp less on sterndrive version but goes 3-4 knts faster. Or does same speed using less fuel.

Do I wish I'd got the sterndive version ? Not sure really. Un-usually with the Nova 42 the sterndrive boat is around 20k more expensive than the shaftdrive. That's quite a lot of diesel.
Also I don't have the extra bother/complication of the superchargers. My boat doesn't seem to have to get over a perceivable 'hump' to get on the plane, it's pretty progressive. It's more a case of escaping from the stern wave it's dragging.

He ho. Show me a boat that's not a compromise and I'll buy it.
 
I get it now. No it's diesel. Petrolia doesn't mean petrol engines.

I'm all straight now.

I've got TC's not SC's cos I don't need acceleration. Just a bit of push for those last couple of important knots.

Only thing I don't know now is at what engine speed the TC's kick in at. I guess it wouldn't be good to cruise with the engine speed right at the TC kick in speed ?

I'll have to see if I can find that out.
 
Its easy to see when the turbos kick in, just dial the EVC contol until it displays the turbo pressure on the LCD readout on the rev counter, you will see the boost climb rapidly when the turbo spools up.
 
I assumed the TC's were always spinning as they are powered by exhaust gasses. But is there no 'kicking in' then ? No clutch or anything to kick actual compressor section in & out ?
 
[ QUOTE ]
My kad 44's have both. Lots of belts. Bit of a pain really.

[/ QUOTE ]

So do ALL KAD's

K = Kompressor = Supercharger
AD = Swedish? for Turbo = Turbo


... I think /forums/images/graemlins/blush.gif
 
You must log in or register to reply here.

Share this page

Top