CMB 45 M-Line fuel consumption question

[Jake Ellwood]

Hello everyone,

In the process of deciding what tank to put in a AC Lazer 40. Got a CMB 45 M-Line going in it

I've got a 16oz Sullivan tank which happens to fit perfectly towards the front of the boat. But I'm curious at what kind of runtime this would give me. I've never run a 45 though.

Anyone have any thoughts/ideas?

The only comparison I've got, is an M-Line 90 which goes through 32oz of nitro in around 6ish minutes. I also tend to run my boats quite rich.

Thanks in advance!

 

[Jeff Barnes]

I had a Phil Thomas sport 40 with a cmb 45 rs evo in it and I had a 14 oz tank in it so I would think 16 would be plenty

 

[Jake Ellwood]

I had a Phil Thomas sport 40 with a cmb 45 rs evo in it and I had a 14 oz tank in it so I would think 16 would be plenty

Hi Jeff

Thanks for your response! Do you know how long a 14oz tank would get you please?

Thanks so much!

 

[Danny King]

Hi Jeff

Thanks for your response! Do you know how long a 14oz tank would get you please?

Thanks so much!

it depends heavily on % of nitro and prop and compression.
I can tell you this. A 45 will use more than half the fuel a 91 does.

 

[Jake Ellwood]

it depends heavily on % of nitro and prop and compression.
I can tell you this. A 45 will use more than half the fuel a 91 does.

Hey Danny

Ok good to know. Prop wise I am gonna start off with an Octura 450/3 and go from there. Using optifuel 16% (thats the maximum legal limit we can get here)

I had a suspision that the 45 might be more juicy than a 91 as I suspect it will rev a bit higher. I'll try the 16oz and see how the runtime goes! Thank you!

 

[Terry Keeley]

Hey Danny

Ok good to know. Prop wise I am gonna start off with an Octura 450/3 and go from there. Using optifuel 16% (thats the maximum legal limit we can get here)

I had a suspision that the 45 might be more juicy than a 91 as I suspect it will rev a bit higher. I'll try the 16oz and see how the runtime goes! Thank you!

Wow, 16%? Whereabouts RU?

 

[Jake Ellwood]

Wow, 16%? Whereabouts RU?

Portugal. It was 30% but changed a couple of years ago, new laws.

 

[Andy Nightingale]

I’ve done extensive testing on 45 mono props on low nitro in the UK and found the 450/3 to be great, but the prop I stuck with was an ABC 1914 15-60, it’s leagues ahead

 

[Jake Ellwood]

I’ve done extensive testing on 45 mono props on low nitro in the UK and found the 450/3 to be great, but the prop I stuck with was an ABC 1914 15-60, it’s leagues ahead

Ooh thanks Andy! What kind of differences were you noticing in particular if you don't mind my asking.

 

[Andy Nightingale]

The main one being that the 1914 is a good amount faster, the engine is under a lot less load on the ABC prop. I also had good results with a 646/3, which was on my boat for a good period of time

 

[Daniel's Racing]

You guy's do not do hopper tanks ? a small 4 oz hopper would give the little bit more you may need one day. For sure it would allow every drop to leave the 16 oz without sucking air and then a bit more.

Running right down close to empty always chance of lean out and suck a plug.

 

[Terry Keeley]

Portugal. It was 30% but changed a couple of years ago, new laws.

I wonder what gubberment pinhead came up with 16% and how he/she/they arrived at that figure?

 

[Andy Nightingale]

In the UK now we can only by up to 25% fuel from the shops. You can buy your own ingredients to make fuel, but you need an Explosives Precursor License to do so ($40 for three years and involves a ‘I promise not to burn down parliament’ quiz). Thing is we don’t get high enough atmospheric temperatures here to burn anything above about 40% anyway, so it doesn’t really matter.

The endurance racers in Europe are now using 12% fuel as a limit, but they’re doing 20-30 minute heats so engine longevity is the name of the game.

People do use hoppers in racing over here, the hydro tanks tend to have them built in and in endurance racing we use float chambers, mostly mounted directly in front of the carb to feed engine from the huge (up to 152oz) tanks

 

[Terry Keeley]

In the UK now we can only by up to 25% fuel from the shops. You can buy your own ingredients to make fuel, but you need an Explosives Precursor License to do so ($40 for three years and involves a ‘I promise not to burn down parliament’ quiz). Thing is we don’t get high enough atmospheric temperatures here to burn anything above about 40% anyway, so it doesn’t really matter.

The endurance racers in Europe are now using 12% fuel as a limit, but they’re doing 20-30 minute heats so engine longevity is the name of the game.

People do use hoppers in racing over here, the hydro tanks tend to have them built in and in endurance racing we use float chambers, mostly mounted directly in front of the carb to feed engine from the huge (up to 152oz) tanks

We have guys here that will mix anything you want but I think 60% is the highest "commercial" fuel available, but at $112/gallon it's more economics here that's pricing high nitro racing out of the market than anything else.

https://vpracingfuels.com/product/60-boat-18-oil/?c=242&
To buy 100% nitro here you need to get a background check by the US Dept. of Homeland Security but that's not a big deal, it costs about $45 a gallon when buying by the drum.

Don't fool yourself though, nitro=horsepower and you can burn it at any temperature, lower temps are more challenging but it can be done.

 

[Jake Ellwood]

You guy's do not do hopper tanks ? a small 4 oz hopper would give the little bit more you may need one day. For sure it would allow every drop to leave the 16 oz without sucking air and then a bit more.

Running right down close to empty always chance of lean out and suck a plug.

Yeah it has been done. Just fooling around changing fuel tanks if needed post build is always so annoying, I'd rather have a bit more from the get go. I'll have a float chamber on it anyway but I can't count on that for more than a few seconds of fuel.

I've messaged Walt (I think hes called Walt) - The Tanks 2 U guy to see if he can make me something