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-   -   WI on IDI 1.9 Turbo Diesel (http://www.aquamist.co.uk/forum2/vbulletin/showthread.php?t=1822)

IDI 28-07-2010 12:36 PM

WI on IDI 1.9 Turbo Diesel
Hi, I own a 1.9TD IDI which I run on Straight Vegetable Oil (SVO) and began experimenting with WI as I'd like to tune fuelling system for best power.

On water only I could discern no differences to power, boost or EGT's.

Progressively mixing in more methanol, the results were the same until I got up to 50% which gave a power boost accompanied by a horrible knocking.

I've been told (and several threads on this forum confirm) the knock is either the meth pre-igniting or causing detonation.

Originally, I was advised to use 4gph but with lack of results, I upped this to a total of 7gph which has made a slight noticeable difference.

I can only feel a power improvement with a 40% methanol mix but the knock forces me to turn it off. I also see a rise in boost from 28 to 30psi. There's no change to the EGT readings which peak at 700degrees C.

I would say my fuel system is mildly tuned and the turbo set to it's safe maximum. I make black smoke off-boost which clears to a haze on-boost until I reach the rpms where the governor reduces fuelling dramatically.

More googling research leaves me with the impression I'm flogging a dead horse due to the pre-chamber setup of an IDI diesel yet several posters using the same engine report much better results with no knock - even at 100% methanol.

I've been told this is because I need to add more fuel but I'm loathed to push the EGT's any higher.

Can anyone help me understand what's going on, why the differences in results from the same engine and how I should proceed from here?

IDI 31-07-2010 07:08 PM

Re: WI on IDI 1.9 Turbo Diesel
Is there no-one able to advise me? 20-odd views and no comments?

Richard L 31-07-2010 07:56 PM

Re: WI on IDI 1.9 Turbo Diesel
I will give uit a go...

In general, diesel is excess air system. In order to increase power more fuel has to be supplied. There comes a piont when all air is consummed, more fuel will just create more soot (black smoke). At this point, more air is required. Normally by increasing boost.

By pumping more air and more fuel, the efficiency of the engine is increased due to higher "effective compression ratio". You gas mileage will improve.

Unfortunately, if this contiues, the engine will be under more and more stress due to increase in combustion tempertures and pressures. Knock will rear its ugly head.

This is the only time when water/methanol should be injected or you will loose power. The quantity and ratio of the water/methanol will be determined by the onset of knock. Water slows down flame speed and methanol increases it.

The excessive heat and pressure of combustion is now being utilised to fuel the expansion of steam to perform mechanical work, almost act like a secondary steam engine.

Have a read on this.

IDI 31-07-2010 08:41 PM

Re: WI on IDI 1.9 Turbo Diesel
Hi Richard, I appreciate your response!

So the simple matter is, I'm not pushing the diesel fuelling limits enough? That suits me and my current plans but it won't be happening for the foreseeable future as I need to remove the fuel pump to make the necessary modifications.

But until I get that opportunity, I was under the impression that, with my current state of tune (more fuel and boost than stock) and EGT's peaking at 700C (stock was 500C), I should have seen some benefit, either in power, EGT's or boost when spraying. The fact I need to double the recommended quantity sprayed before I noticed a boost rise had me concerned my kit simply wasn't doing what the sales pitch promised.

I hope I'm understanding you correctly?

Richard L 01-08-2010 12:21 AM

Re: WI on IDI 1.9 Turbo Diesel
what kit do you have ?

I wouldn't believe what people said on face value, ask for real world proof.

IDI 01-08-2010 12:17 PM

Re: WI on IDI 1.9 Turbo Diesel
It's not an aquamist kit. (I'm not sure it's ok to mention other vendors on here?) It consists of a sureflo 8000 series, a check valve and two nozzles/holders. Was described as Universal Diesel and came with 2 x 6gph nozzles after which I bought a 3gph and 1gph nozzle - the recommended size for my engine.

No you're quite right and I don't believe the sales hype straight off. I read as much as I could from varying sources on the 'net and it all seemed to back up what the sellers promise.

Specifically, people that have the very same engine as mine have reported great benefits in both power and EGT reduction. Problem is, they're few and far between and those I've managed to contact, can't or won't give me any specific details of what, if any differences, there are between my state of tune and theirs. Even if they did, nothing I've read explains why I get knock at 40/50% meth when others can run 100% without such problems.

Richard L 01-08-2010 01:02 PM

Re: WI on IDI 1.9 Turbo Diesel
It is Ok to mention Brand names. We only have vendorw on the sponsors section. Anyway, it is not important.

Most diesel power comes for high boost and rich mixtures. Air and fuel produce power, the engine is only an heat exchanger, converting product of the burnt to mechanical work.

Ask for the boost and fuel they puttting in. Knock occurs when the ratio of methanol is too high vs water or fuel. I suggest run pure water for a while and rid of all the carbon which can cause pre-ignition.


IDI 01-08-2010 04:55 PM

Re: WI on IDI 1.9 Turbo Diesel
There shouldn't be any carbon to worry about as it was all cleaned up when the HG was replaced a few thousand miles back at which point I also blocked off the EGR after seeing/cleaning all the goo smothering my intake manifold...

Perhaps this is why I'm not seeing the "improvements" others boast?

A couple of hundred miles back, after upping the fuel and boost, I began using 100% water but with no noticeable difference. As previously explained, with ever increasing ratios of meth, still no results until 50% where I get power but then knock.

Oh well, I'll just have to wait until I can mod my fuel pump and start the experiments again.

Richard L 15-08-2010 01:52 PM

Re: WI on IDI 1.9 Turbo Diesel
Well, you can see a large of power increase if you allow more boost and fuel into the engine, diesel loves boost and fuel.

This can continue until your egt become excessive, at this point water is necessary to keep the engine together.

Have a look at this project how water helps to increase the power to the diesel engine.

nutron 18-08-2010 05:37 AM

Re: WI on IDI 1.9 Turbo Diesel
I found on mine that below 50% methanol I lost power aswell. Running 100% water seem clean up smoke though, which I did not expect from my research. Possibly because with the reduced cylinder temps, the unburn fuel doesn't carbonise as it would in the absense of oxygen in a normal heat cycle.

Methanol obviously burns hotter and faster than diesel and there is only a limited amount of oxygen available in the cyclinders as has been said. As you pump in more and more methanol, it will burn in preference to the diesel. This is because it burns faster and because you can burn twice as much methanol in the same amount of oxygen as you can diesel. So as the smoke increases from adding more methanol, it's the diesel that isn't burning on the whole that is producing the smoke, not the methanol.

The burn temp of diesel under atmospheric condictions is about 800 Deg C, where as Methanol burns around 1200 Deg C. As you increase the pressure, these burn temps increase and the thermal energy has to be disapated before the next burn or it will build up. In my experiments, I found that 70% methanol gave virtually the same if not slightly lower EGTs than just adding more diesel until I hit max power. So i would recomend you start at 50:50 and go no higher than 70:30 methanol:water mix. Getting the right mix for your engine will be trial and error using measuring equipment to avoid damage. methanol burns hotter and faster, water retards the auto ignition point because it cools the mix

I would retard the amount of diesel you are adding and add more water/methanol as you can get more torque for the same power this way. The water expanding into steam obviously creates alot more pressure than just heating the air in the cylinders. the amount you are injecting is tiny to be honnest. You are using american gallons per hour (gph) (American gallons too which are about 3.79ltr) nossels which are based on 100psi of relative pressure at the nossel into atmosphere pressure. Without testing the pump pressure and a graph from the supplier such as Aquamist can supply for their nossels, of flow over pressure for a given nossel; you have no way of knowing what amount of water you are actually delivering to the engine.

I currently inject about 1.135 ltrs per minute into my 1.9 common rail turbo diesel. That would be about 68.1 ltr/hour or 18gph to compare to your nossel markings. So I'm not supprised that you are seeing very little chages with your small nossels.

One thing I am interested by is the knock, as the auto ignition point of methanol is significantly higher than that of diesel (diesel = 210 C, methanol = 470 C). So in order for the methanol to be pre-igniting, you would have to have unthinkably high cylinder pressures, that would without a doubt be giving massive rises in EGTs if the engine was actually capable of withstanding them (which I find implausable at best). So I think you need to look to a different reason for this knocking sound, which may well be the methanol but not as you think. The specific heat capacity of water of massive, that's why we use it for cooling, fighting fires, e.c.t. Methanol however isn't as good and as though it would cool the intake charge, on it's own it could expand and create higher cylinder pressures and temps (this is only a theory). If you have a non-dirrect diesel injection with a pre-ignition chamber, the diesel might be igniting at the wrong point, or it might be igniting, and creating a sufficiently high temp to then ignite the methanol in the cylinder before the flame wall reaches it. With a direct injection engine, the fuel is injected at the point it is supposed to ignite and that would remove the possibility I would have though.

Knock occurs in a spark ignition engine when the pressure and temp are so high that you get compression ignition, independant of the spark. you can get pockets of fuel igniting beyond the flame wall, sending multiple flame walls across the cylinder, causing shock waves which you hear as knock. A diesel engine does this normally anyway.

Without knowing more about the sound, vibrations, boost, I don't think anyone can give sound advice on what your problem is. I would try reducing the amount of diesel, replacing it with a 50:50 mix of water:methanol, increasing the amount you inject and see how you go.

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