X-TORQ and Water Injection

[Terry Syd]

OK, not water injection, but hear me out. I have a 450e with the X-TORQ system. When I got it I figured that it would never be able to produce as much power as the older style two-stroke engine. The reason? Well, two-strokes are to some extent liquid cooled - the coolant being extra fuel dumped into the engine to flush out the heat. Lean out the mixture and the heat builds up.

The X-TORQ system uses a stratified charge of fresh air coming in the via a piston port controlled by the side of the piston, which then routes it into the top of the transfer port via the transfer port opening. This air does not contain any fuel and thus would not contribute to the extra cooling that an air/fuel mixture would.

Since an air-cooled two-stroke can loose as much as 20% of its power as it heats up, an X-TORQ engine would have a cooling disadvantage that would likely be reflected in a slight loss of power compared to the older style two-stroke.

So, how can an X-TORQ engine be modded to produce more power than the older style two-stroke?

Hmm, I've got a water injection system on my turbo diesel. After playing around with the system I know that water/methanol injection can cool things down. The compressor section on the turbo can be made to operate as if the compressor was running a large wheel using a pre-turbo nozzle. The EGTS can be lowered to keep them in an acceptable range.

Back to the X-TORQ, what if the secondary inlet for the stratified air was modded to provide a metering for water or water/methanol? The water mix would come in and actually hit the piston itself (better cooling), then get sucked down into the top of the transfer port. The water/methanol mix would be the first to flow into the hot cylinder and cool things down - after which it would get pumped out during the normal X-TORQ cycle.

Water has a latent heat of vaporisation of 2259 Kj/Kg
Methanol has a latent heat of vaporisation of 1099 Kg/Kg
Petrol has a latent heat of vaporisation of around 586-628 Kg/Kg.

Perhaps the X-TORQ engine has the potential to out perform the older style two-stroke.

 

[wigglesworth]

?????? I dont see how water is going to help the combustion, which is were the power comes from. Maybe im wrong, but I dont want water in with my bare steel crank rod and bearings.

 

[Justsaws]

HHHMMM, you have hurt my head with hard thinking. I will leave this to wiser people than me and be pleased that the saws are not old enough to fit in my collection yet.

 

[candlerslim]

Water injection, thats crazy!

I have considered water injection my self. I have water injection systems on a '64 Chevy truck, a '80 Chevy truck and an '80 Chevy Monza. In every case the water made a noticeable difference in power. not a ton like nitrous but certainly noticeable. The effect of the water on throttle response was very slight until I advanced the timing a little then it seemed to have a more noticeable effect. The problem that I have had is that if let the water run out while driving you lose your power and after a few miles it can start pinging/knocking on a steep hill. I rigged up a reverse acting solenoid on the carb that keeps the air fuel ratio a little rich unless the water injection is actually injecting. The water injection doesn't turn on until the engine gets warm. Then if you happen to let the water run out int goes back to running rich to keep the engine cool. There is plenty of room for all this junk under the hood of an old truck, but it might be tricky to hang some gizmos on your saw. I thought about if you used a little diaphragm fuel pump from an extra carb to induce the water. you could put a tee in the impulse hose from the head to the carb and run the extra hose to the cannibalized carb whose little fuel pump sent a squirt of water to the intake boot. Then rig it so that when the choke was on, the water was off. Then when the saw got warm and you turned off the choke the water came on. I'm not sure how easy it would be to adjust the timing on a saw. I have only recently became interested in working on saws. If there was a way to adjust it accurately on the fly that would be perfect. Then you would need a little half pint water tank. What do guys think.

 

[Terry Syd]

Leading edge

In automotive science we have often seen the racers leading the way in new technology. I doubt when many of these technologys were first tried that many people thought that such things as double overhead cams, turbocharges, etc. would be found on commuter vehicles in the future.

The X-TORQ concept (or similar stratified charge technology) will likely see more use in the future. How racers begin to modify these engines will be interesting to watch.

Wiggles, the water does not enter the crankcase using X-TORQ. The spray would enter from the side port in the cylinder, into the 'pocket' on the side of the piston and then be inducted into the top part of the transfer port. The 'pocket' never has positive pressure in it, if anything it remains at a lower average pressure than the rest of the crankcase. The pocket may get a slight trickle of oil from the cylinder wall/wristpin when the crankcase is in compression.

The use of another smaller carburetor to meter the water into the 'air' port seems logical. The carburetor would have to be set up so that it would only provide water at WOT.

There is another aspect to tuning these engines that may present problems. The common trick of removing the base gasket to increase compression not only creates a small change in the 'normal' port timings, it also creates a small change in the X-TORQ timing. Whether this increase in air induction is significant and offsets the power increase in compression is something we'll probably find out in the near future.

As the water-cooled two-stroke produces more power than an air-cooled two-stroke (all things being equal), perhaps using the X-TORQ system to ingest water may shift the air-cooled engine's power closer to the output on the water-cooled engine.

 

[Sawdustmaker]

sounds like you are on to something.........

i have spent a good deal of time trying to come up some solutions here and that sounds like it could work. Id hate to have a third tank on my saw though....

 

[Terry Syd]

Using more fuel

For a proof of concept you could just use more fuel from the same fuel tank. Instead of the X-TORQ system creating a 20% saving in fuel economy, it might be using 20-50% MORE! The super rich mixture would hit the side of the piston and then be shot across the piston crown. It would then be vented out the exhaust port so it didn't affect the running mixture.

I don't think this is exactly what the EPA had in mind, but it feels right for me.

 

[candlerslim]

To imagine how water might improve combustion, consider when your saw is about to run out of gas. Your thinking "any time now" and then the saw start running real strong and revving up right before it dies from lack of fuel. In those few moments the saw is running real lean. the lean mix has lots more Pop per charge of air/fuel but if you ran the saw like that for more than a moment you would cook off the valves and stuff. The extra fuel in the normal fuel/air mix actually quenches the fire. Only the fuel that is a vapor/gas at the moment of ignition pops. The extra fuel is mostly liquid at the moment of ignition. This extra fuel, in liquid form, evaporates a moment/millisecond later then starts to burn on its way out the exaust. The extra fuel absorbs some of the heat from the initial Pop and actually cools down the combustion chamber temperature and protects the piston and exhaust side of the head. The working theory of water injection, is to try to replace that extra, liquid fuel, with water, which is free and it also keeps the inside of the combustion chamber nice and clean. The other advantage is that when the extra fuel is burnt on its way out there is not enough oxygen left in the mix so the exhaust is very sooty. That soot is what actually wears out the saw. The tiny carbon particles make a great polishing compound that just polishes away the rings, bearing surfaces, etc.

 

[scotclayshooter]

For a proof of concept you could just use more fuel from the same fuel tank. Instead of the X-TORQ system creating a 20% saving in fuel economy, it might be using 20-50% MORE! The super rich mixture would hit the side of the piston and then be shot across the piston crown. It would then be vented out the exhaust port so it didn't affect the running mixture.

I don't think this is exactly what the EPA had in mind, but it feels right for me.

Adam Clarke modded a Stihl MS441 to use the strato port to put more fuel in.
He used a reed system, But I think the reeds failed but he said it was a good runner before that happened. It proved the concept was sound.

The thread is not on this forum BTW!

 

[Taxmantoo]

That mix going through the cylinder in your normal piston port engine is 12-14 parts air and one part fuel by weight. That air being used to scavenge your stratocharged engine is all air, but there's probably a lot more of it.

I think the general premise of this thread is barking up the wrong tree.

 

[Sawdustmaker]

Adam Clarke modded a Stihl MS441 to use the strato port to put more fuel in.
He used a reed system, But I think the reeds failed but he said it was a good runner before that happened. It proved the concept was sound.

The thread is not on this forum BTW!

You have to be kidding.... you mean the AS is not the only saw forum out there???

LMAO :jawdrop::hmm3grin2orange::hmm3grin2orange:

 

[jeeptj19992001]

OK, not water injection, but hear me out. I have a 450e with the X-TORQ system. When I got it I figured that it would never be able to produce as much power as the older style two-stroke engine. The reason? Well, two-strokes are to some extent liquid cooled - the coolant being extra fuel dumped into the engine to flush out the heat. Lean out the mixture and the heat builds up.

The X-TORQ system uses a stratified charge of fresh air coming in the via a piston port controlled by the side of the piston, which then routes it into the top of the transfer port via the transfer port opening. This air does not contain any fuel and thus would not contribute to the extra cooling that an air/fuel mixture would.

Since an air-cooled two-stroke can loose as much as 20% of its power as it heats up, an X-TORQ engine would have a cooling disadvantage that would likely be reflected in a slight loss of power compared to the older style two-stroke.

So, how can an X-TORQ engine be modded to produce more power than the older style two-stroke?

Hmm, I've got a water injection system on my turbo diesel. After playing around with the system I know that water/methanol injection can cool things down. The compressor section on the turbo can be made to operate as if the compressor was running a large wheel using a pre-turbo nozzle. The EGTS can be lowered to keep them in an acceptable range.

Back to the X-TORQ, what if the secondary inlet for the stratified air was modded to provide a metering for water or water/methanol? The water mix would come in and actually hit the piston itself (better cooling), then get sucked down into the top of the transfer port. The water/methanol mix would be the first to flow into the hot cylinder and cool things down - after which it would get pumped out during the normal X-TORQ cycle.

Water has a latent heat of vaporisation of 2259 Kj/Kg
Methanol has a latent heat of vaporisation of 1099 Kg/Kg
Petrol has a latent heat of vaporisation of around 586-628 Kg/Kg.

Perhaps the X-TORQ engine has the potential to out perform the older style two-stroke.

crack does not smoke it's self.............

 

[scotclayshooter]

You have to be kidding.... you mean the AS is not the only saw forum out there???

LMAO :jawdrop::hmm3grin2orange::hmm3grin2orange:

From what im told AS didnt start off as a "saw" forum the clue is in the name
Just that the chainsaw part is the biggest now.

 

[Terry Syd]

Stoichiometric

Generally, when we lean out a two-stoke it really isn't going 'lean'. What is happening is we are eliminating the excess fuel used for cooling (making it less rich) and moving the mixture closer to the stoichiometric ratio. That results in a better (and hotter) combustion, but it also sets up the engine to start building up heat.

If we were using the 'Strato Port' or 'X-TORQ' system to assist in cooling, then we should be able to lean out the actual combustion mixture as it wouldn't need to be as rich. That in itself should contribute to an increase in power.

I couldn't find the other thread on the MS441 using Google, does anybody have a link?