Reving volvo Edc engines in neutral

[nfluester]

i was told the turbo doesn't come in unless under load surely it would be able to rev to 3900 unloaded without the need of the turbo?

 

[Portofino]

i was told the turbo doesn't come in unless under load surely it would be able to rev to 3900 unloaded without the need of the turbo?

That’s rubbish .
Exhaust gas can,t go through it without spinning it up .The boost pressure may be a bit lower but it will still spin up to 3900 or what ever .
Try it on your car in N .

When I WOT my engines in N at the dock and can hear the turbos spool up In the normal way ( starts at 1400 rpm )

It’s just the EGT ,s due to lack of load that don’t come up and the L/hr is lower as there’s no props spinning demanding more fuel .
But they still rev up and the turbos spool up .


With outdrive boats I think there’s a reliance on Fwds water pressure on the gills in front of the leg .
So eventually without said fwd motion they I suspect would be starved of water .Thats why they probably reach 84 or what ever at the dock in N because the water flow is basically restricted.Even though the EGT s are a fraction than @ cruising - spinning the props .Might be why they don’t want you WOT ing then in N .....for too long as the water cooling cant cope .Fine fir short tests I would have thought .

If It was to have full flow in N at the dock due to low load , low EGT s they will take ages to warm up and struggle to reach 60 degrees .Which is what I see with a shaft drive set up .
Its load from the prop demand asking for more from the injector ( more fuel = more Hp ) that raises the EGT s and soon after the water jacket temps . Obviously that load is not there in N @ the dock .

EGT ....Exhaust Gas Temperature.
Idle under 200 with F engaged 1st click....bit of load 20 % or so pushes it @7 knots .
Idle @ dock in N 100.....single digit load .....one gear box disc spinning and the fly wheel .
585 cruising .
300- 350 @ displacement speeds .
600-650 with fouled stern gear .

EGT @ the dock In N @ WOT , turbos well spooled up is under 300 !

 

[jrudge]

Get the local dealer to put a vodia on it and take it out.

that will show you all sorts including the boost pressures.

it could be all sorts and there is little point in going on a wild goose chase.

vodia wont give an absolute answer but it will tell you where to look.

 

[nfluester]

yes he has one booked in for early july but it's on the river and not easy to get out to the estuary to be able to perform a WOT test hence trying to do it in neutral at the marina i am trying to help him out and trying to rule out some things

 

[jon and michie]

Have a look around the flange outlet of the supercharger near where the black air pipe comes out - it could be leaking air from that joint causing lack of rpm happened on my kad 300 the other year.
Easy fix just remove the black pipe and the green plastic cover off the supercharger - remove old sealant and put new sealant on - rebuild.

 

[vas]

cannot help re your particular engines, just note that in neutral you can rev the engines to your heart's content but you wont get any serious boost from the turbocharger. I mean you may get 2bar at WOT boat moving/gear engaged, but I doubt you're going to get more than 1-2psi out of gear. Yes, turbo blades will be spinning but it wont be doing anything serious.
I did a lot of testing when I bought my boat and port engine wouldn't rev so boat couldn't plane. Turbo stuck solid, engine would rev to 2.7krpm out of gear no problems...

V.