Diesel timing question with turbo + 50/50 water meth inject

Discuss (and cuss) the Nissan LD-series OHC Six diesel engine, popularly available in the US in 1981-83 Datsun/Nissan Maxima Sedans & Wagons.

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TurboKota
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Diesel timing question with turbo + 50/50 water meth inject

#1

Post by TurboKota »

I'm thinking of running a turbocharger with a water / methanol progressive injection system referenced from boost.

My question: If i retarded cam timing a couple of degrees would it allow for a greater percentage of methanol concentration mix in the water as additional fuel as well as cooling the intake charge?

Would it also allow safer operation under boost? I know by retarding the timing I would loose power NA but I would think the benifit of power made up from the extra water/meth dialed in with the progressive controller would yeald greater gains with the extra boost.

Am I looking at this correctly?

This is the system I'm thinking of...

http://www.alcohol-injection.com/forum/ ... -1967.html
diesel-man
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Location: Elkton, MD

#2

Post by diesel-man »

How about a little sniff of propane? Maybe retard injection timing, (w/propane) but retarding cam timing is a bad idea. In the racing world you advance cam timing...specifically longer duration...longer before and after. You need a exhaust temp guage close to an exhaust port.
TurboKota
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#3

Post by TurboKota »

Your right DieselMan I meant IP timing... Too much time with gas motors has me in the habit... :lol:

As far as the Methanol / Ethanol injection here is what I had in mind based off of this study.

http://www.google.com/url?sa=t&source=w ... dNPw1iWKnQ

Image

I wanted to to use the fumigation method described in the study installing 1GPH nozzles into each runner as shown and control the rate and flow to start @ 3-5PSI with full flow at 15PSI. Using a PSI to voltage pump driver I could increase the rate of fuel/water based off of engine load using this http://www.alcohol-injection.com/progre ... er-14.html progressive controller.

Tell me more about Propane and the LD. I know DieselSmoke has mentioned it as well. I've done some reading on it but have no experience with it... How much to use on the LD and what setup is required?


Frank
diesel-man
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#4

Post by diesel-man »

I have never used propane on a diesel...treat it like Nitrous, a little goes a long way...and not for too long!!
windsock
Posts: 144
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#5

Post by windsock »

TurboKota wrote:Tell me more about Propane and the LD. I know DieselSmoke has mentioned it as well. I've done some reading on it but have no experience with it... How much to use on the LD and what setup is required?

Frank
Hi Frank,

A few people I know of are talking LPG (Propane) fumigation into a TDi (Turbo Direct injection) motor so I am not too sure about fume into an indirect injection such as the LD28 is. However, if you are also turboing your motor, I guess you would have a TiDi motor... :) Much is said in the discussions amongst these people I know about detonation and LPG levels. Some say "It doesn't happen at low levels" and others say "How do you know?" etc. I hear enough to be wary of the risk.

I have come across a good website that discusses LPG fuming in some detail here http://www.mrsharkey.com/lpg.htm.
MrSharkey wrote:How it works - Propane by itself resists self-ignition inside a diesel-fuel compression-ignition engine due to it's high flash point and narrow fuel-to-air ratio. During the compression stroke, the air/LPG mixture is compressed and the temperature is raised to about 400°C, not enough to ignite the LPG, which has an ignition temperature of about 500°C. In the small concentrations that LPG fumigation uses, the LPG mixture is not rich enough to be overly flammable and is more difficult to ignite. When the diesel fuel is atomized into the cylinder under high pressure, it immediately self-ignites (diesel ignites at about 385°C.), and causes the LPG to burn as well. Since the LPG is in mixture with the air, the flame front from the diesel spreads more quickly, and more completely, including igniting the air/fuel mixture which is in contact with the cylinder walls, which are cool in comparison to the super-heated air inside the combustion chamber. Much of the cleaner burning of the fuel is attributed to this ignition against the "cooler" components of the engine, and accounts for raising the percentage of combustion from a typical 75% for a well-tuned diesel engine running on pure diesel fuel alone, to 85-90% with the addition of LPG. Obviously, this more complete combustion also gives a nice boost in power, with an accompanying increase in fuel economy and reduction of pollutants.
MrSharkey wrote:What to expect- Normally-aspirated (N/A) engines will realize only a modest gain in power by the use of LPG gas. Displacing 0.5% of the intake air with LPG will result in a small power increase, perhaps 5-8%. Nearly no increase in power will be noted at full throttle, assuming that your injection pump is correctly adjusted already. Attempting to provide more gas to the engine will not increase performance, and will in fact lead to a condition not unlike pre-ignition in a gasoline engine. This has been attributed to excessive peak pressure inside the combustion chamber, and may have a lot to do with the fact that most N/A engines are also IDI (Indirect Injection), which means that the diesel fuel is not injected directly into the combustion cylinder, but instead enters a "swirl chamber" where ignition takes place. The flame front then shoots out of the swirl chamber into the combustion chamber, where it combines with the air (and LPG) to force the piston down in a power stroke. Apparently, these engines have a problem in that the flame front exiting the swirl chamber ignites the LPG/air mixture, all of which burns instantly instead of in a metered, controlled manner as it would during the normal diesel injection window.
I like the idea of a fume button whereby I can induct LPG into the air chamber when required (steep climbs or overtaking) and then revert to normal when cruising. If I was to research more I would look at the auto-ignition temp of LPG and ascertain what if any impact the high compression ratio of the LD28 would have on cylinder temperature. Seems like the high compression (22:1) of the LD motor and the IDI would possibly pose a problem to the fume ignition.

What have you found out since you last posted this?

Cheers,

Phil
Good roads lead to bad fishing.
davehoos
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Location: Karuah Valley,NSW Australia
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#6

Post by davehoos »

Water/methonal question.
methonal was added to improve the water atomisation and blending process for evaporation to reduce intake temps when fuel was very poor quality.i know the chemist here will add that when the mixture burns it improves combustion but i dont think thiis was the original idea when this became the norm post war in the 50's/60's.

my experience with water injection was to clean the engine internals stopping carbon deposit related preignition and reduce decoke labour costs.

controlling oil temps-piston temps is a better dirrection to lock at.
intercoolers and heat exchangers are so cheep and easy these days.
and spray water on to the cooler.


LPG is very common locally with Diesel engines.
mostly trucks and heavy machinery.
your good artical uses 0.5% vaporised LPG to intake air ratio volume.
lpg expand a few hundred times when vaporised so im guessing very little is used.local installers are using 20%+ liquid V diesel.ive seen some that use 50%.these are not like using nitrous.

installing LPG on a modern engine here the installer is require to maintain emision standard-so the install has to be certified.to do this ignition timing etc shouldnt be modified as it alters certification.

plenty of slap it ons,same deal with ignition timing.
so many modified IP and now you got this loverly chip thats easy to reburn.
WCJR31 Skyline.3.0 manual.wagon
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