No, propane provides extra oxygen by having an abundence of the O2 molecule in it's structure. The atom readlity breaks of providing the extra oxygen to burn the remaining fuel.

The propane doesn't burn at the pressure it is injected into cylinder.

Turbocharged Diesel Power | Banks Power: Propane and the Turbo Diesel by C.J. Baker

Incorrect - you are talking about NOS, not Propane. Totally different. Works different too for that matter

I wasn't but edited to remove the erronous comments about nitrogen, still works the same ish

LPG (Propane) Fumigation for Diesel Engines

Anyway back to the aquamist...... going on about the last link says, reducing the temp of the egt will have an ill effect on performance

not if the EGT is way too high and knackering the turbo etc though.

Which based on burnt out exhaust valves appears to be the case :(

For absolute power I'd certainly go for NOS, but progressive NOS only I suppose.

In my case there is a definite increase in power you can notice when I turn it on

I can't see that water injection is going to help really...

You add the LPG to increase the the cylinder pressures and to burn up "stubborn" spots of diesel near the cylinder walls. Surely water will just knock back the benefits of having the propane.

Due to the way diesel + LPG seems to work, I think most of the problems will manifest themselves at higher revs where there's less time to complete the burn in the cylinder. Maybe reduce the percentage of gas added at higher RPMs?

I think your plan to monitor EGTs is a good starting point.

J.

My understanding of water injection comes from the world of gas turbine engines (the rolls royce pagasus engine in the harrier). It's employed to reduce heat soak into the turbine blades when hovering for prolonged periods, otherwise they'd melt! The expansion of the water as it absorbs the heat and turns into steam also helps to marginally increase thrust.

I know a VAG PD engine is an entirely different entity but i think the losses people are talking about might not be as pronounced. The expansion of the fuel air mixture may be reduced by the drop in temperature, but that could be countered by the expansion of the water. OK it might not be exactly equal but it can only be a plus, right??!!!

Exactly - although I doubt it will solve all heat-related problems, I'm pushing it enough to make me want to look into 'every little helps' solutions that overall might just keep the engine alive

few misapprehensions here...

WI isn't used in Subarus, water spray is used, because of their placement of the TMIC.

WI will slow flame front speed. Can't think of anything worse to put in a diesel engine.

WI is only a useful tool in petrol cars if you take advantage of it by mapping. You can typically get another couple of degrees ignition with it, which more than compensates for the power you lose from slower flame. It does also mean that you can't run without it then, if your bottle empties, the car will det. Using WI to cover det in a road car is stupid, it's masking a problem, not correcting it.

I can however take advantage of it, remember I have propane which has a different flame front, and I can hook up the water fail safe to the propane so the propane comes off when the water runs out/fails to inject etc.

Also the kind of injection system I'd go for is mappable based on injector pulses, boost and some other parameters

My understanding of water injection comes from the world of gas turbine engines (the rolls royce pagasus engine in the harrier). It's employed to reduce heat soak into the turbine blades when hovering for prolonged periods, otherwise they'd melt! The expansion of the water as it absorbs the heat and turns into steam also helps to marginally increase thrust.

I thought the water was only injected to keep the ducting at a servicable temperature post drive turbine blades? Or is there a seperate injection system for the turbine as well?

Chris

An extract from TURBOKART

The Pegasus is normally equipped with water injection, to allow it to attain its peak thrust rating even on hot days or at high altitude.

Not how i remember it from training (but that was 6years ago and i've not touched a harrier since!!)

An extract from TURBOKART

The Pegasus is normally equipped with water injection, to allow it to attain its peak thrust rating even on hot days or at high altitude.

Not how i remember it from training (but that was 6years ago and i've not touched a harrier since!!)

Having a phone round, it appears that the water injection is to keep the JPT down to below a pre defined limit that varies depending on engine variant to preserve hot end turbine blades. It may or may not also add to mass flow, thus increasing thrust. Basically it is cooling water that boils away, so must increase expansion more than heating gas, kind of like reheat without fuel and taking heat out:confused:

Chris

Having a think about the way the diesel works, I can sort of see that no one seems to understand the way propane injection works. The idea that unburnt diesel is burnt from the cylinder walls is a bit unlikely. Diesel in wet state is unlikely to burn if it is wet on a cylinder wall as the wall will drop the temperature.

My take on the way it may work is thus: When the diesel injector fires, what you effectively have is a stratified charge. Areas away from the charge will have less or no fuel to combine with the air in the cylinder. Adding more diesel late in the combustion cycle will result in less good combustion as the oxygen remaining is a long way from the injector. If you put some propane in, you are effectively using up the lean areas in the stratified charge.

Could be wrong, but much of what I have read on the subject has flawed reasoning.

Dont konw if it will reduce smoke by burning up carbon deposits (I think that the LPG will maintain a higher tempreature for longer in the combustion chamber than diesel alone which peaks and cools quickly) or by reducing the carbon content of the overall burn (LPG has a much higher Hydrogen content than diesel so will reduce the amount of soot that way).

All conjecture, but food for thought.

Chris

It is weird though, as there is definitely a difference in the power delivery throughout the rev range on mine, and it appears to be 'more' with propane enabled.

That said I am extremely interested in the RR outcome at JKM for this reason alone, I really want to see 'where' it does something in the graph.

At the moment I am not quite as interested in the absolute figures, as the car isn't tuned properly for the hardware that's fitted. If I do manage to achieve that before the RR day it would be quite amazing

More of a response to ChrisGB.

If the propane burns longer, as well as hotter, I can see that that will affect (raise) the EGTs.

I feel it's revs related too, though. As with no ignition to advance, adding gas higher in the rev range is more likely to eject still burning mixture out of the exhaust ports.

I don't think PD engine exhaust valves are cutting edge technology. Maybe a material upgrade and/or look at the valve guides. Have to take the engine apart for that though...

J.

It's been to bits - trust me. I'm just trying to work out how to pay for this, the total cost is about 2500 now including labour and a few minor tweaks, 60k service included too in that.

There is more to come though which won't be too great for my bank account, really need to knock this one on the head asap now :(

More of a response to ChrisGB.

If the propane burns longer, as well as hotter, I can see that that will affect (raise) the EGTs.

My main concern would be for a standard turbo as they are (so I have read) not happy with high EGTs. A petrol engine produces longer lower pressure burn and as a result, higher EGTs than a diesel. Something that could be logged with a pyrometer in the system somewhere.

Chris

Hopefully my EGR stuff will arrive soon

How would fuel additives effect the EGT situation?? (I'm thinking vegetable oil here. Before you say it, i know it effects the fuel filter!!)

It might do - not 100% sure at the moment.

I've also spoken with a tuner about this and his words were along these lines (not verbatim so won't mention the tuner).

1. Aquamist or similar water injection systems work on petrols/turbo petrols in particular

2. There is generally not enough heat to cause the need for this on a turbodiesel, unless (and this is where I might end up needing it) you end up with very high EGTs. Oddly that is exactly why I consider this option

As it stands it is unlikely I will get to that stage for a while, so it will not be installed just yet

A mate at work has water injection fitted in the intake on his turbo diesel Toyota Hilux Surf, & he says it makes a difference to the inlet temps.

However, his doesn't have an intercooler.

I think a remapped TDI would benefit from water injection to drop the temps & sustain boost. On the same lines as a FMIC would.