Rodbolt ... running my 50hp yamaha on meths ..

[deejaycee_2000]

Hey rodbolt I need some advice, I've been working on this motor of mine for over a year now, it is a 2004 50hp yamaha 2-stroke, that was made race ready but never raced, blueprinted and fully modified by our racing standards (oversized pistons, racing gearbox, head, flywheel, fuel system etc. etc., .. I am trying to get it to run on methanol 130 octane, I changed the compression ratio to 14:1, and changed all the rubber pipes to custom made stainless steel piping, cause I know the methanol will melt the rubber pipes, but still worrying about the fuel diaphram and fuel filter, otherwise everything has been changed to stainless ..... will the meths melt PVC or polyurathane? ...... as the motor is now I can get about 70hp out of it and should get about 90hp out of it with the meths, now I haven't tried it yet, but I wanto ask you if I should try and run it on the meths or rather jetfuel which is 110 octane, cause I am not sure if the 2-stroke will mix with the methanol, but I know it should mix with the jetfuel ..... and if I get it to run like hell on the meths how long should the motor last? The motor is now totally complete and I wanto try it but just need a opinion from you ... what do you think?

 

[rodbolt]

Re: Rodbolt ... running my 50hp yamaha on meths ..

never tried running one on a fuel such as JP5.
our dewatering pumps in the USN started on propane and ran on jp5 and they used 2cyl omc 55 looper powerplants.
I dont deal with racing 2 strokes but some friends have, most ran castoroil and methanol.
for methanol you will most likly have to make your own main jetting as it takes roughly twice as much meth as gasoline to run. actually most alchohol based fuels are actually about 100 octane or so but they lend themselves well to nitro methane. nitro methane is simply an oxygen bearing liquid that allows extra oxygen to be introduced in the fuel stream.
Methanol Ethanol Unleaded Gasoline
RON 106 107 92 - 98
MON 92 89 80 - 90
Heat of Vaporisation (MJ/kg) 1.154 0.913 0.3044
Nett Heating Value (MJ/kg) 19.95 26.68 42 - 44
Vapour Pressure @ 38C (kPa) 31.9 16.0 48 - 108
Flame Temperature ( C ) 1870 1920 2030
Stoich. Flame Speed. ( m/s ) 0.43 - 0.34
Minimum Ignition Energy ( mJ ) 0.14 - 0.29
Lower Flammable Limit ( vol% ) 6.7 3.3 1.3
Upper Flammable Limit ( vol% ) 36.0 19.0 7.1
Autoignition Temperature ( C ) 460 360 260 - 460
Flash Point ( C ) 11 13 -43 - -39

a little chart showing a few fuel characteristics.
to actually gain anything with alchohol fuels you MUST extensively modify the crankcase volume by stuffing it to make it smaller and modify the exhaust to allow 2 times the gas to escape.Nitromethane ( CH3NO2) - usually used as a mixture with methanol to reduce
peak flame temperatures - also provides excellent increases in volumetric
efficiency of IC engines - in part because of the lower stoichiometric
air-fuel ratio (1.7:1 for CH3NO2) and relatively high heats of vaporisation
( 0.56 MJ/kg for CH3NO2) result in dramatic cooling of the incoming charge.

4CH3NO2 + 3O2 -> 4CO2 + 6H20 + 2N2

The nitromethane Specific Energy at stoichiometric ( heat of combustion
divided by air-fuel ratio ) of 6.6, compared to 2.9 for iso-octane,
indicates that the fuel energy delivered to the combustion chamber is
2.3 times that of iso-octane for the same mass of air. Coupled with
the higher flame temperature ( 2400C ), and flame speed (0.5 m/s), it has
been shown that a 50% blend in methanol will increase the power output by
45% over pure methanol, however knock also increased [28].

while using methanol as a fuel can be fun it gets expensive as you get to be the engineer.
we ran a 427 chevy in a 67 camero for a bit on a methanol-nitromethane mix.
was fun but took about 2 years to make it work better than gasoline.

http://www.hydroracer.net/forums/showthread.php?t=5233
a pic of an old konig alky motor .

 

[Ray Neudecker]

Re: Rodbolt ... running my 50hp yamaha on meths ..

As rodbolt says, you will need to rejet considerably to run methonal. I would also suggest an electric alcohol fuel pump in place of the fuel pump. I doubt the current pump would carry the volume needed.
Since the mix is going into the crank and other bearing surfaces, the engine will have to be flushed by running regular fuel after every use or the bearings will become instant junk.
Racing fuel with additives would be a lot more practical and able to produce close to the same HP without the disadvantages to the methonal of eating up the motor.

 

[deejaycee_2000]

Re: Rodbolt ... running my 50hp yamaha on meths ..

mmmm very interesting, thanx for the info ..... the crankcase volume and exaust are allready fully modified with different jets and boysen reeds .... so maybe I should just mix the meths with my current fuel as you said, unless I can actually get an electric fuel pump to handle the meths, but how would I implement the electric fuel pump and make it work on this motor .... but now the bearings are bothering me ...... I don't want this motor to burn with the first try, I basically want to only run this motor once just to say I did it, then have it on show as it alreally looks funky with all the stainless steel (bling bling) on a "pimp-my-boat" inflatable I am working on with wicked graphics on the sides ... nice motor rodbolt ... I love the exausts, looks funky ...

here is a pic of my normal racing 50hp modified to the max, I have the same carbs on this motor as on the ones on the pic .....

 

[rodbolt]

Re: Rodbolt ... running my 50hp yamaha on meths ..

that motor is not modified much at all.
here in the states we make our own echaust ploates and use tuneable,movable, exhaust expansion pipes.
next time I am at at Rons marine I will see if I can get some pics of his 3cyl 75 jonny.
home made gearcase,home made midsection. custom ign system, custom flywheel,home made as well.
on a plywood, if ya wanna call it that, 12ft hydro.
and it ran a home made "hot" head .
but like I say. I dont mess with racing anymore.
I did for a while but gave it up.
but when we say different jets its way different.
it takes roughly twice the volume of alchohol to air as gasoline to air.
on is roughly 14/1 and the other about 7/1.
dont use most 2 stroke oils with methanol as they tend to fight each other.
on the 427 we were playing with we also had to change to steel tipped larger diameter needle valves with larger diameter seats for the needed extra fuel.
I forget the name of the dye but make sure you add it to the methanol as methanol burns with a colorless flame.
the dye will add color to the flame so you can be seen when your on fire.
methanol was fun t run, was expensive to dial in.
wont do it again.
no sense in mixing the meth with gas, will create more issues.

 

[deejaycee_2000]

Re: Rodbolt ... running my 50hp yamaha on meths ..

yes please try to get pics, would love to see it .... sounds interesting ... I now see what you mean with the jets, thanx on the tip about the dye, very good thinking ..... i will see if I can maybe change te carbs for the meths, changing the neddle and seat etc, like you said ..... how would I implement the electric fuel pump and would the meths not distroy it? Wonder how tough PVC or polyurathane is against meths?

 

[rodbolt]

Re: Rodbolt ... running my 50hp yamaha on meths ..

like Ray says an electric alky pump with an approved alky pressure regulator will be needed, I dont know if that stock pulse pump is capeable of feeding an alky motor at 6000 RPM.
remember with alky your GOING to move at least twice the fuel volume of gasoline.
leanouts with alky do the same damage as gas.

 

[Ray Neudecker]

Re: Rodbolt ... running my 50hp yamaha on meths ..

Also even with the alky fuel pump, you will have to flush it out with non alcohol fuel to keep it from locking up after running. Put it on the bottle for real performance. Nitrous oxide will light a fire for sure.

 

[deejaycee_2000]

Re: Rodbolt ... running my 50hp yamaha on meths ..

Thanx guys, I appreciate the info ..... I thought about adding some NOS .... have you done that yet Ray, what would I need to do to run a bit of NOS, I am not familiar with that kind of modification .....

 

[Ray Neudecker]

Re: Rodbolt ... running my 50hp yamaha on meths ..

Best source for outboarders has been Chuck Goodman at Hydro Dynamics for nitrous set ups. He does the intake as well as sells the products needed.

 

[deejaycee_2000]

Re: Rodbolt ... running my 50hp yamaha on meths ..

Thanx Ray, I think I should try it .... allready checking their website ....