454 or 496 V8 How much fuel???

[simon]

Hi all,
Can anyone give me an idea of how much an increase in fuel consumption it is likely be moving from a Ring 21 with Merc Optimax to something like a Ring or Extreme 24 or 26 with a V8 that can push along at 65+mph?

Also are the earlier carbed V8s a lot more thirsty than the newer MPIs etc?

Thanks Simon

[timtap]

All the fuel consumption figures are on the Mercury Marine Boat House bulletin web site.
This site tests all the engines in the range on several types of boat and gives a comprehensive range of info.

[simon]

Originally Posted by timtap

All the fuel consumption figures are on the Mercury Marine Boat House bulletin web site.
This site tests all the engines in the range on several types of boat and gives a comprehensive range of info.

Cheers for that!!! Good bit of info, does anyone know if the earlier carbed v8 are hugely more thirsty?

[motorvator]

About four years ago ran the P18 with 200 2.4 alongside the revenger 27 with 502mpi from Poole to Yarmouth to Bucklers hard in smooth seas running hard and when we fueled at bucklers both took to within a litre of each other!

Ran hard back against wind tide and pestilance and the Phantom used shedloads more fuel than the Revenger as she was cruising whilst the Phantom was finding it hard work.

Both my boats so no axe to grind. Loved 'em both but the phantom finally had to go when I blew the engine to pieces after 1600 hours from new!

So the answer is pretty well the same depending on what your doing but no oil needed on the inboard

[Frenchbruno]

On my RING21E with 250XS average fuel consumption in 70 running hours is 20liters/hours;
Maximum consumption, full rpm is 97liters/hour. Best top speed alone on board with few gear is 80.7 mph gps.
I've installed a 496HO on a 25feet boat and the owner told me that is max fuel consumption was 140l/hour, not checked by myself.

[Tony Davis]

we found that a big block carb motor in one of our 24's uses around 15% more fuel than a similar horse power old type moi motor. the latest generation 496 motors are better still

[blind dog]

our 496ho is unbelievabley good on fuel for a quick boat

[cfun]

Came across an old Motor boats and yachting article the other day testing a load of various manufacturers 200Hp engines back in the late 80's all around 2.5ltr carbed, they bolted them all on too Fletcher 199 sports boats, speed ranged from 53-56mph and GPH were from 16-18 at wide open throttle although the fuel consumption to miles travelled was best around 2/3rds throttle on most engines
Their was also a test on a Sunseeker Mustang 21 a very heavy cuddy cab style day boat with a 330hp inboard 454CUI I think on carb's ran around 60mph and showed wide open throttle at 24GPH again huge savings were to be made in distance covered around 2/3rds throttle

[simon]

Cheers for all replies gents, big help. This is probably gonna be the next step from the old Ring 21c.

Does anyone know how well LPG convertions work with these setups? Cant help but notice not many people use it.

[hunton69]

It don't burn as much as some well known characters on here would belive

[$hooter]

Your 496 BBC might burn less fuel than an older version BBC (454 or 502) but the older version BBC will probably still be running long after the 496 blows itself up. All the late model 496 motors have all cast internal parts...notice...I said "ALL" 496 motors, no matter if it is an HO or not. None of them have forged crank, rods or pistons where as your older and newer 454 & 502 "MAG" motors al have forged internal parts. Also, your fuel consumption will largely depend on how you drive it and what the motor is in. I have a 540 in my boat that I built with 750+ horsepower and the fuel consumption on it is better than the original 454 as long as I keep the rpm below 3500. I know that your fuel prices in the UK are way higher than they are here in Texas, but if you are really concerned...or care about fuel consumption in a performance boat...maybe you should sell whatever it is that you have and get a sail boat...then fuel consumption be damned.

[Fletcher-Andi]

@CFun: do you still got the report of the test?

i am very interested in material about fletcher 199.

My brother has one 199 wit 225 Yam 2.6 and it goes 68 mph

Thanks in advance!

Greetings
Andi