Another fuel consumption question.....

[Damned67]

Hi All,
Reading the other 'fuel consumption thread' got me thinking about my rig....
Typical trip for me and my son is from Manly to Harry's. Probably clock up about 30kms there and back and moving about on the drift etc.
It's a 4.2 Viper with a 30HP Merc, and for our ~30km trip I'd likely use close to 10L of fuel.
Of course, I have no idea of what RPM I'm turning.
On a glass out, she'll hit 45 kph (with a few RPM on the top which doesn't change speed)... and I normally run it at about 40kph, conditions permitting....
I'm wondering if my fuel consumption is about what one would expect, and if I could expect a whole lot better consumption if I dropped my cruise speed to 30-35kph?
Of course, I just love running it as close to WOT as possible. I'm a bit of a hoon, what can I say

[Crocodile]

Hello Damned67 ,

I am assuming that it is the re-badged Tohatsu 2 stroke motor.

Try Seamedia on this link, http://www.seamedia.com.au/sea_libra...nes_drives.php
and follow the prompts.
Boatpoint has this , http://www.boatpoint.com.au/engine-r...ury-30lw-10416

The short answer is there is not much to be gained with your rig.
The Mercury performance bulletin website in the USA has no entries for that horsepower.

[Damned67]

Thanks for that. The Seamedia link doesn't cover the 30, but seems to have a lot of good info anyway.
The boatpoint link was quite informative... and reminds me that I need to take the engine back in for a check. It had it's '20 hour' service and came back in an awesome state of tune. After a month or so, it became quite a bear to start cold at times....

Edit: yes, I believe it's the rebadged tohatsu motor....

[bennyboy]

You fuel consumption goed up enormously after 3/4 throttle. At about 3/4 the consupmtion will be about half of what is it at WOT

[Flex]

I'd take an accurate guess and say a 30hp two stroke burns about 15-17l per hour at WOT. I have run a 30hp Yammy for years and yours wouldn't be to much different.


So if you run at 3/4 throttle(around 30-40km/h) then you would burn about 10l/h I'd say.

To b honest if you have the fuel capacity and its glassed out, Go flat stick.
The 5-7l per hour extra you burn isn't a big expense really. And if you enjoy going flat stick, then why not?

If you know your gunna be traveling long distance in a day and need to preserve fuel then go at 3/4. But honestly with such a small engine, go as fast you as can IMO, heaps more fun!

[Damned67]

But honestly with such a small engine, go as fast you as can IMO, heaps more fun!

Same theory applies with the larger engines!! The car in my avatar has a HUGE engine, and that's certainly much more fun at WOT than any other speed!