ESE's works engine tuner

[nasone32]

Wobbly can you make a test? I think You can make hcci in engmod by changing from turbulent to prescribed burn rate. From research papers the combustion starts some 2-4 degrees atdc and is completed in just 4-6 degrees. (so you should set advance 0 and delay 4, duration 6)
The combustion efficiency is something like 94% (you could also leave this out, so we appreciate the combustion duration alone?)

I recall once i was using methanol with a 22:1 head (on a 70cc engine) and the kill switch did not kill the engine at all. once warmed up, it was idling at 5000 rpm and it scared the hell out of me. So i removed the spark plug connection to kill it instantly (almost dying from the shock) and the engine continued to work just as normal.
the fool in me thought to drive that thing. with big surprise I could drive it around no problems, it revved like a mad and produced tons of power.
I was sure it was "dieseling" but i was also afraid of killing the engine, plus i could not find suitable crankcase seals that could survive methanol for long, and i had some problems with the carburettor too.
It was many years ago and I was young and i had little money to play with. So after some pistons offered to the gods i left methanol.
I even made a shorter exhaust to compensate for the lower exhaust temperature.
I could not use a dyno at that time but since it was a CVT transmission i can approximate the power gain, I went from 3.8 to 5 grams of centrifugal weight and from 14k rpm on petrol to 15,5k rpm on methanol so there was at least a 40% power gain.
Today I am a CVT transmission developer for a big industry so I am 100% sure of that power increase.
For sure a fraction of that power gain is due to methanol alone, but i don't think you gain 40% of power on methanol alone on a liquid cooled engine.
now I think it was HCCI.

[adegnes]

Wobbly can you make a test? I think You can make hcci in engmod by changing from turbulent to prescribed burn rate. From research papers the combustion starts some 2-4 degrees atdc and is completed in just 4-6 degrees. (so you should set advance 0 and delay 4, duration 6)
The combustion efficiency is something like 94% (you could also leave this out, so we appreciate the combustion duration alone?)

I recall once i was using methanol with a 22:1 head (on a 70cc engine) and the kill switch did not kill the engine at all. So i removed the spark plug connection (almost dying from the shock) and the engine continued to work just as normal. I could drive it around no problems, it revved like a mad and produced tons of power.
I was sure it was "dieseling" but i was also afraid of killing the engine, plus i could not find suitable crankcase seals that could survive methanol for long, and i had some problems with the carburettor too.
It was many years ago and I was young and i had little money to play with. So after some pistons offered to the gods i left methanol.
I even made a shorter exhaust to compensate for the lower exhaust temperature.
I could not use a dyno at that time but since it was a CVT transmission i can approximate the power gain, I went from 3.8 to 5 grams of centrifugal weight and from 14k rpm on petrol to 15,5k rpm on methanol so there was at least a 40% power gain.
Today I am a CVT transmission developer for a big industry so I am 100% sure of that power increase.
For sure a fraction of that power gain is due to methanol alone, but i don't think you gain 40% of power on methanol alone on a liquid cooled engine.
now I think it was HCCI.

Please explain what you base the 40% increase on.
I can't see how you can say anything about power increase from cvt weights and rpm alone.
In my understanding, increased roller weight in the variator would just make it maintain a lower rpm while doing its "thing", regardless of power, and the rpm increase just tells you there was a rpm increase.

[nasone32]

You just see the consequence. let's dive a bit deeper.
a heavier roller weight makes the variator open faster. this is why on the same engine it makes lower rpm with more weight.
also rpm make the vario open faster, because of increased centrifugal force.
so if you both increase the rpm AND roller weight, the variator opens (using above numbers) 10% faster due to rpm, and 31% faster due to more weight.
if the engine is not stalling (i.e. rpm stay steady) it means the power produced can cope with the increased "gear shifting speed".

this is the same reason why a bigger capacity engine requires heavier roller weight. it has more power, thus the variator can shift gear faster, and you accellerate faster as a consequence.

[adegnes]

You just see the consequence. let's dive a bit deeper.
a heavier roller weight makes the variator open faster. this is why on the same engine it makes lower rpm with more weight.
also rpm make the vario open faster, because of increased centrifugal force.
so if you both increase the rpm AND roller weight, the variator opens (using above numbers) 10% faster due to rpm, and 31% faster due to more weight.
if the engine is not stalling (i.e. rpm stay steady) it means the power produced can cope with the increased "gear shifting speed".

this is the same reason why a bigger capacity engine requires heavier roller weight. it has more power, thus the variator can shif gear faster, and you accellerate faster as a consequence.

Ah... I see.
With my reasoning any engine, 10 or 1000hp, with the same exact cvt configuration would maintain the same rpm regardles of power, which of course doesn't make sense...
Thanks for enlightening me!
Feeling stupid...

[MotleyCrue]

Please explain what you base the 40% increase on.
I can't see how you can say anything about power increase from cvt weights and rpm alone.
In my understanding, increased roller weight in the variator would just make it maintain a lower rpm while doing its "thing", regardless of power, and the rpm increase just tells you there was a rpm increase.

A power change on a CVT is a common thing to figure out, almost like a mini dyno except it only runs one engine speed at a time without stopping and changing stuff (weights) to look at another speed. Unless something else like ramp changes were done to the CVT between the gas and methanol tests then the weight change and rpm change Nasone mentioned would indicate at least 40% more power.

Anybody that ever ran a carb dry on methanol on idle before shutting the engine off knows how it loves to rev very high just before the fuel is all gone, but racing lean methanol I don't think is possible or else it would be a commonplace thing to do.

[adegnes]

A power change on a CVT is a common thing to figure out, almost like a mini dyno except it only runs one engine speed at a time without stopping and changing stuff (weights) to look at another speed. Unless something else like ramp changes were done to the CVT between the gas and methanol tests then the weight change and rpm change Nasone mentioned would indicate at least 40% more power.
.

Thanks for explaining!
I've built and tuned more than a few cvt bikes, can't believe I've never thought of this relationship.

[MotleyCrue]

Thanks for explaining!
I've built and tuned more than a few cvt bikes, can't believe I've never thought of this relationship.

Probably a lot of people never thought of it, but I bet the wheels are turning in your head now about how to use it, now that you know.

[nasone32]

thumb rule for power gain, supposing the engine stays steady (and stayed steady before)

{[ (new weight * new rpm) / (old weight * old rpm) ] -1} *100 = %power gained

of course there's always some belt slipping involved, so... thumb rule.
also centrifugal force goes linear with weight, but with speed squared, so it's an approximation for small variations in rpm. but proved reliable in practice.

[Frits Overmars]

For sure a fraction of that power gain is due to methanol alone, but i don't think you gain 40% of power on methanol alone on a liquid cooled engine. now I think it was HCCI.

If you wish to keep the same Lambda-value for methanol that you used for petrol, you will need 2,265 kg of methanol for each kg of petrol.
Methanol has only 2/3 the net heating value of petrol but since the engines passes so much more methanol, it should give a 50% power gain, all other things being equal (which of course they never are).
I think it is very likely that you also experienced HCCI. Then the power gain should be even bigger than 50% , if it were not for the lower exhaust gas temperature probably messing up the pipe resonance.

[MotleyCrue]

Pretty sure methanol is only half, or a smidge less than half, the heating value of gasoline. Racecars around here gain very little if any peak HP over race gas, bit more peak torque though on the methanol.

[Frits Overmars]

Pretty sure methanol is only half, or a smidge less than half, the heating value of gasoline. Racecars around here gain very little if any peak HP over race gas, bit more peak torque though on the methanol.

That will teach me to rely on wikipedia. I can't even find it back where it said 2/3. You're absolutely right Motley.

[nasone32]

when i used to play with methanol i estimated about a 20% gain, by a slight increased heat output (should be 10% more when corrected for AFR), intake charge cooling (air density) and raised compression ratio.
I made a shorter pipe aswell. the engine on methanol pipe had max power around 15,5k, with the standard pipe on methanol around 11,5k.

I went straight from 14,7:1 to 22,4:1. I also made a 20,5:1 head but never tried that.
The engine worked reliably somewhat, but something in the fuel line could not cope with the fuel consumption and the carb dried out and became lean after a while.
now I know i should have used a fuel pump or a pressurized fuel tank.

with methanol, viton seals swell and become twice as big, while NBR seals wear in no time because the seal lip becomes too soft.
this led to numerous pistons on the sacrifical shelf.

I thought to build my own metal/ptfe seals but eventually i left.

I also noted it was totally insensitive to ignition advance, at this point it could have been due to HCCI?

[wobbly]

When using methanol in karting before it was banned, I used it with bigger compression ( up to 18 from 15.5 ) and the exact same ignition and pipe designs.
We used to run AvGas at around 1280*F and this was the egt for best power.
When changing to Methanol I found that the best power with that com was had at around 1000*F, but that with the same pipe it would rev even harder.
This was due to the carbs natural tendency to richen up, over the top of the power band and is why solenoid powerjets work so well when using petrol.
Unlike petrol that drops off the power rapidly when going richer than about 10% under stochiometric ,this makes no difference to methanol power at all.
In fact going over 20% rich you can make more power with even more com and kill any tendency to deto by simply drowning the combustion in unburt fuel.
But this drops the egt too much, and you then need to shorten the pipe.
That setup had less mid, more peak, but less overev, and was simply not as fast on track as the lower com version.
I found that the stock pipe length made more mid and the high com gave better peak, then the fuels natural A/F characteristics giving better overev.
Using this setup we could get mid 70RWHp from a 250MX engine that made mid 60s on Avgas, about a 15% increase.
The way to stop seal issues ( and stop moisture in the methanol from rusting all the steel wear surfaces ) was to flush thru the engine on petrol/oil for a few spluttering minutes after every race meeting.

[adegnes]

Probably a lot of people never thought of it, but I bet the wheels are turning in your head now about how to use it, now that you know.

You bet!

thumb rule for power gain, supposing the engine stays steady (and stayed steady before)

{[ (new weight * new rpm) / (old weight * old rpm) ] -1} *100 = %power gained

of course there's always some belt slipping involved, so... thumb rule.
also centrifugal force goes linear with weight, but with speed squared, so it's an approximation for small variations in rpm. but proved reliable in practice.

Thanks for posting the equation and thumbs-up for different-brackets-use!

when i used to play with methanol i estimated about a 20% gain, by a slight increased heat output (should be 10% more when corrected for AFR), intake charge cooling (air density) and raised compression ratio.
I made a shorter pipe aswell. the engine on methanol pipe had max power around 15,5k, with the standard pipe on methanol around 11,5k.

I went straight from 14,7:1 to 22,4:1. I also made a 20,5:1 head but never tried that.
The engine worked reliably somewhat, but something in the fuel line could not cope with the fuel consumption and the carb dried out and became lean after a while.
now I know i should have used a fuel pump or a pressurized fuel tank.

with methanol, viton seals swell and become twice as big, while NBR seals wear in no time because the seal lip becomes too soft.
this led to numerous pistons on the sacrifical shelf.

I thought to build my own metal/ptfe seals but eventually i left.

I also noted it was totally insensitive to ignition advance, at this point it could have been due to HCCI?

When using methanol in karting before it was banned, I used it with bigger compression ( up to 18 from 15.5 ) and the exact same ignition and pipe designs.
We used to run AvGas at around 1280*F and this was the egt for best power.
When changing to Methanol I found that the best power with that com was had at around 1000*F, but that with the same pipe it would rev even harder.
This was due to the carbs natural tendency to richen up, over the top of the power band and is why solenoid powerjets work so well when using petrol.
Unlike petrol that drops off the power rapidly when going richer than about 10% under stochiometric ,this makes no difference to methanol power at all.
In fact going over 20% rich you can make more power with even more com and kill any tendency to deto by simply drowning the combustion in unburt fuel.
But this drops the egt too much, and you then need to shorten the pipe.
That setup had less mid, more peak, but less overev, and was simply not as fast on track as the lower com version.
I found that the stock pipe length made more mid and the high com gave better peak, then the fuels natural A/F characteristics giving better overev.
Using this setup we could get mid 70RWHp from a 250MX engine that made mid 60s on Avgas, about a 15% increase.
The way to stop seal issues ( and stop moisture in the methanol from rusting all the steel wear surfaces ) was to flush thru the engine on petrol/oil for a few spluttering minutes after every race meeting.

There's no regulations for me to follow, just building stuff for fun, I must admit I'm getting increasingly tempted to give the jungle juice a go...

Is there any commercialy available seals that can withstand it? Is the "purging" people do enough to keep the seals living a few hours of runtime?

[speedpro]

Check the chart that Frits posted - What is "Still Gas"?