Author Topic: Modifying injection on CS 6 and 8's  (Read 12863 times)

ses

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Modifying injection on CS 6 and 8's
« on: July 26, 2013, 01:22:36 PM »
I'll try to be clear and concise.

Having recently learned about the improved efficiencies with high pressure direct injection automotive diesels (upwards of 20% just on improved atomization alone) I've been forced to wonder about the possibilities of retrofitting the already economical CS model with something comparable.

I thought best to put it out here for all of you with lifetimes of experience beyond mine for some feedback on the variables and implications involved.

Simply put: Why not fit a 2400 bar system (pump, injector and lines) with appropriate simple electronic switches to get one of these beasts ultra-economical?

I understand they aren't direct injection...but is that paramount to the process?
Is the engine otherwise actually in need of the extra lube in the unburnt fuel? What problems would running this much leaner cause?

Thanks in advance!

SES


listard-jp2

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Re: Modifying injection on CS 6 and 8's
« Reply #1 on: July 26, 2013, 03:30:55 PM »
Putting aside the expense verses the fuel savings. It would be easy to convert a genuine Lister CS to direct injection, by substituting the piston, cylinder head, and injector for Indian versions that are specifically made for cloned versions that have been designed to be direct injection.

Now perhaps a more enlightened member could comment upon the complexities involved with converting such an engine to common rail injection.

BruceM

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Re: Modifying injection on CS 6 and 8's
« Reply #2 on: July 26, 2013, 10:35:22 PM »
For the lower speed CS's it's hard imagine much efficiency benefit from direct injection.  They had higher pop pressures easily available then, and they were competent engineers.  Likewise raising compression is often brought up, and again, this is very easily adjusted on the CS's and Lister would certainly have optimized this for the intended speed and loads.

That said it would certainly be fun to read what happens if you do try it!




buickanddeere

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Re: Modifying injection on CS 6 and 8's
« Reply #3 on: July 30, 2013, 06:58:29 PM »
Higher compression ratio does not make an engine more efficient. A higher expansion ratio on the power stroke increases efficiency.
Fuel efficiency ratings would make little difference with 30,000 psi injection vs the factory 2200 or so psi.
The common rail injection if for emissions to reduce soot and allow variable injection timing. Also depending on conditions. The common rail system may inject 2 or 3 times during the compression and power stroke to limit knock and NOX

ses

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Re: Modifying injection on CS 6 and 8's
« Reply #4 on: July 31, 2013, 07:55:36 AM »
Thanks for the feedback gents!

Buickanddeere: What helps a "higher expansion ratio?" By this do you mean how effectively or quickly the fuel is ignited in the cylinder?

I don't have the practical experience, but the literature I read tells me it is all about "the burn." 30k psi helps atomize the fuel and along with multiple stroke injection we get a better burn whilst simultaneously reducing those emissions. Those emissions are unburnt or inefficiently burnt fuel are they not? Increasing compression ratio, or otherwise, can't we see a marked  increase in power and thus efficiency just by handing this beast the modern tools to consume smarter?

Thanks in advance!

SES

listerdiesel

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Re: Modifying injection on CS 6 and 8's
« Reply #5 on: August 05, 2013, 09:52:59 AM »
Lister improved the 6/1 into the 8/1 by using better injectors, higher injection pressure, higher speeds and ali piston.

I can't see any big improvement on the basic 6/1 without spending silly money.

Accept it for what it is, get an 8/1 if you need more power on a genuine Lister engine, but the higher speed might be an issue for some applications.

Peter

millman56

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Re: Modifying injection on CS 6 and 8's
« Reply #6 on: August 06, 2013, 12:42:43 AM »
 Listers design engineers knew what they were doing and had engine test cells to verify this,  a good way to maximise fuel economy is to set the engine up to specifications.                                                                                                                                                                                                                    The scouring effect of water in an engine is pretty well proven, also understandably it lowers combustion temperatures which in a diesel,  I believe,  helps reduce NOX formation.                                                                                                                                                                                                                          Its  a bit difficult for me  to understand how introducing a liquid/vapour that does not burn,  into a combustion chamber where it replaces molecule for molecule a charge that does burn,  can increase performance.       

The cooling effect of adding water in the air filter might increase air density into the engine but  would this be offset by the fact that water wont burn ?

A fair scientific way of measuring the effect on performance would be running my 4 Kva CD powered generator which has accurate digital readouts on volts,amps and frequency,  at a fixed load,  noting the frequency indicated without water addition and then with water addition, a rise in frequency should indicate a power increase irrespective of efficiency.

Mark



































































































                                                   

dieselgman

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Re: Modifying injection on CS 6 and 8's
« Reply #7 on: August 06, 2013, 01:40:37 AM »
Quote
with water addition, a rise in frequency should indicate a power increase irrespective of efficiency.

This sounds like it could work if your governor was also in a fixed position... since it is not, then wouldn't any engine performance (speed) increase also be offset by the governor feathering off the fuel rack position? Perhaps the CD governor is not all that precise? I would think you would need a way to measure the actual fuel consumption to make a real performance measurement.

dieselgman
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millman56

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Re: Modifying injection on CS 6 and 8's
« Reply #8 on: August 06, 2013, 07:21:08 AM »
Dieselgman,  if say for instance  I was pulling 2500 watts from the CD and this load slowed it down to 48 hz from the nominal  unloaded 51.5 hz  and adding water then put it up to 49 hz then this would show an increase in power,   I do know that when running on load on high compression changing over to low compression raises the hz irrespective of the fuel rack position, this is infinately repeatable and works both ways,  up and down, I assume its because of the increased power produced on low compression setting.   This is is reversal of what happens when you apply more load to an engine which is operating at near  its rated output.                                Its easy to lock the rack off and try it this with a fixed fuel amount.   


Glort,    for a given volume in a combustion chamber,  replacing a percentage of the air charge with water droplets, vapour, or non combustible jellybabies ;D will reduce the available energy produced by the expansion of fuel burning in that space,    cooling the air charge prior to it entering the cylinder will  give more oxygen per unit volume and increase power but how much this will be offset by the water used to cool it being unable to burn, is anyones guess.   
As far as I know simple power in a diesel is dictated by the MEP (mean effective pressure)  which is the difference between the compression pressure at ignition and the average pressure throughout the power stroke,  having said all this, diesels do operate with excess air so there may be a bit of space for some water in there.
Good to discuss this with you.
Mark.


ses

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Re: Modifying injection on CS 6 and 8's
« Reply #9 on: August 12, 2013, 12:48:29 PM »
Listerdiesel...Thanks for this feedback...pray tell what would "silly money" look like? If one had access to salvage high pressure direct injection pumps, injectors, and lines and wanted to adapt some modernity to this beast what would I be bumping my head against...is all I want to know. I am not looking for more HP. I am looking to pull the energy out of the unburnt and exhausted fuel.

Re: water injection...father is a pilot, says water injection goes back many a decade. Specifically, for aircraft it's utilized for extra HP to get off the runway. Prolonged use would inherently lead to premature engine destruction. Water takes up available space of air. Increases compression.

Having said this they are only now starting to certify diesel engines for aircraft and since the diesel already has the higher pressures over the gasoline ICE I haven't the knowledge to understand/determine the implications or diminishing returns of even more compression...beyond bearing in mind material limitations.

What excites me is the apparently new found (irrespective of the 200mpg carb.) methodology for increasing fuel to air ratio via improved vaporization of the fuel. Put a drop of well vaporized gasoline in a can and ignite for a big boom. Fill the same canister up to the rim with liquid gasoline and watch it slowly burn.

Correct me if my final understanding is wrong...HHO, like propane or NG, will help economy by displacing the need for liquid fuel. The injection quantities for a home crafted kit simply do not come close to a quantifiable volume. That or the extra energy necessary to convert electric from your alt to HHO is too inefficient to manifest any net gains....?

millman56

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Re: Modifying injection on CS 6 and 8's
« Reply #10 on: August 13, 2013, 07:58:42 AM »
Near optimum atomisation of diesel fuel  has been around as long as the CS engine and the combustion chamber design of the CS works well on a variety of less than ideal fuels giving a clean exhaust and reasonable economy,     I think that bearing in mind the low working speed of the CS, staged injection would probably be wasted here.
Kubota I believe, manufacture a single cylinder IDI engine with staged injection, the reasons for this are to reduce noise and allow it to conform with euro emissions standards.

Mark.

dieselgman

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Re: Modifying injection on CS 6 and 8's
« Reply #11 on: August 13, 2013, 08:04:41 AM »
Quote
Near optimum atomisation of diesel fuel  has been around as long as the CS engine and the combustion chamber design of the CS works well on a variety of less than ideal fuels giving a clean exhaust and reasonable economy

I wish someone could prove this to our EPA!  :laugh:

dieselgman
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ses

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Re: Modifying injection on CS 6 and 8's
« Reply #12 on: August 13, 2013, 10:30:52 AM »
Thanks again for the valued feedback!

Gary, has no one put an emissions probe on the exhaust manifold of one of these things? If I correctly interpret what Mark says as true then these relics should fly through emissions without effort...Right? Or am I to read between the lines and interpret "near optimal atomization" to mean: low enough tolerances in the injection platform to produce a favorable combination of economy yet still allow for the flexibility to burn a range of fuel stocks?

I can't discern: Is there any debate that atomizing the fuel into ever smaller particles approaching a true vapor increases ability to "unlock" the potential energy of the fuel?

Any resources anyone?

glort: I appreciate what you say about aircraft. I would tend to defer to mark on the scouring effects in the cylinder as reason for limited usage of water...that and the engines aren't built "heavy/strong" enough for the consistent higher compressions.

Would you please elaborate on this, "The fact the fuel goes in as a gas being the holy grail these nutters make it out to be can't even overcome the difference in energy between the fuels tell you what the vaporisation hype is really worth."

I understand the difference in energy potential of NG, LPG and 100LL. Is it only "nutters" who suggest that unburnt fuel goes out the tailpipe (to produce harmful concentrations of exhaust) due to inefficient burn or...otherwise?

millman56

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Re: Modifying injection on CS 6 and 8's
« Reply #13 on: August 13, 2013, 06:43:17 PM »
You don`t have to with proper state of the art 70 years ago English Lister engines ;D

millman56

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Re: Modifying injection on CS 6 and 8's
« Reply #14 on: August 13, 2013, 09:12:30 PM »
Just a couple of clarifications, the scouring effect of water I was thinking of is of scouring deposits from the combustion chamber surfaces, scouring is probably the wrong word, cleaning maybe.                                                                                                                                                                                                                                                                                                                                                                                                                                                                 Optimum atomisation, if you observe the spray of a 1930s  CS injector and compare it with the spray of a 1990s pintle type injector, no tangible difference is apparent.

A clean exhaust in this CS engine context does not imply EPA,  Euro4 or Oz fresh air law compliance. ;D

Mark.