Fuel consumption question on 5.7 4bbl

[stant1man]

Hi folks,

Not yet decided if my new 5.7 v8 is becoming a merc or a Volvo, I have access to parts for both. The engine will have a 4bbl with vacuum secondaries, 330hp im told.

One thing is for sure, it will be a single prop outdrive on merc 23' highfive prop.

I'm trying to establish on our Four Winns Sundowner 205 with me, wife and two small kids and light camping gear what kind of consumption we should expect at -

A- tick over in gear, silent cruising
B- on cruise with smart tabs
C- WOT

Seems like a difficult question to answer but id appreciate if anyone could have a go at it.

Sincere thanks in advance.

Stan

 

[Bt Doctur]

Re: Fuel consumption question on 5.7 4bbl

A under 5 gal/hr
B 12-18 gal.hr
C Up to 28-38 gal/hr
Give or take a few gallons either way

 

[stant1man]

Re: Fuel consumption question on 5.7 4bbl

yowzer! :-S Are those imperial or US gallons? There I thought that nothing could be more gutsy than my previous 1972 Merc 1150....

At 12 imperial gallons (45 litres) per hour assuming im doing around 30mph then it will cost me ?55 to get from one end of the loch to the other (28 miles)...

I used to do that run twice on my merc on 100 litre tank and still have fuel left.... Gutted... I wonder if an LPG conversion can be done on a boat

 

[Bt Doctur]

Re: Fuel consumption question on 5.7 4bbl

US Gal. The better way to determine fuel burn at various setting is to rig your fuel line to accept a remote tank of known volume. shut off the main, turn on the remote, run at a specified rpm untill remote is empty and record the elapsed time.This will give you Gal/hr
My old twin inline 6 ,Edelbrock 4bbl`s 13 -3/4 x /21P props Total fuel burn:
2500 rpm, 32 mph, 7- 1/4 Gal .hr
4950 rpm, trimed out,59 mph, 38 Gal/hr

 

[wire2]

Re: Fuel consumption question on 5.7 4bbl

I have a summer home on Buckhorn Lake, (on the Trent-Severn canal system in Ontario, Canada). I can leave the dock at 08:30, cruise at ~30 mph, go to Kirkfield lift lock & back in 8+ hours, (160 Km return) with maybe 10 min per hour waiting at the locks, so ~7 hrs actual running, with no refueling, (starting with a full tank, 35 US gallons). Works out to ~ 5 gal/hr. Boat is '84 Glastron SX 190, w/ 5.7 4 bbl, alum intake, headers. 4 adults on board.

 

[stant1man]

Re: Fuel consumption question on 5.7 4bbl

I have a summer home on Buckhorn Lake, (on the Trent-Severn canal system in Ontario, Canada). I can leave the dock at 08:30, cruise at ~30 mph, go to Kirkfield lift lock & back in 8+ hours, (160 Km return) with maybe 10 min per hour waiting at the locks, so ~7 hrs actual running, with no refueling, (starting with a full tank, 35 US gallons). Works out to ~ 5 gal/hr. Boat is '84 Glastron SX 190, w/ 5.7 4 bbl, alum intake, headers. 4 adults on board.

That's more what I am hoping for!

I really hope this will be closer to the expected figures but I have at least 1000lbs on you

I would be delighted with a sub 7gph cruise but perhaps this is unrealistic... :-S

Wire, do you find your boat uses a lot just ticking over in gear? This is generally what we do when navigating the islands on the loch...

Thanks again


Stan

 

[krisnowicki]

Re: Fuel consumption question on 5.7 4bbl

I have a flo scan on my 350 vortec but it is a 2bbl.

I get
800 rpms or 4.5-5 mph/1.75 gph
3400 rpms 28-32 mph/11-13 gph depending on load
WOT 46-4800 rpms 41mph ish 22-24 gph

All these numbers are with about 300 lbs of full tank of gas (450 lbs) and 4-6 people