Timing adjustment for VO

For discussing the modifications needed for diesel vehicles to run with 2 tank veggie oil conversions.

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Timing adjustment for VO

Postby zoochy » Mon Mar 24, 2008 2:18 pm

With the excellent information brought to light on this forum as of late, it seems as if my VO and the thinners/solvents I use have a higher auto-ignition temperature than D1 or D2. This suggests to me that it might be wise to advance the timing of my engine a bit to compensate for the delay in ignition. Should this be done? Why or why not?

Has anyone adjusted your engine's timing to compensate for the fuel you burn? If so, then by how much?
91 Toyota Hiace 3L engine w/ a 300W ½” heated fuel line, lift pump, additional 10um fuel filter, and a 2nd diesel tank for starting.
>160,000 km on:
88% canola WVO
11% old gasoline
.6% turpentine
.3% acetone
.1% eye of newt
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Postby SunWizard » Mon Mar 24, 2008 2:30 pm

I agree and I think this is one reason why advancing the timing slightly helps. There are many reports of this. I don't know the best way to determine how much to advance. Some do it by sound, (my dad does who is an expert mechanic) but you need experience to know what the different sounds mean, and each engine will differ. The quieter sound that many report on VO is partly (mostly?) due to later combustion which is not a good thing, it should sound as loud a knock as on D2.

Like so many things, it depends on your engine and your fuel mix, no easy answer.

Advancing the start of injection (injecting before the piston reaches TDC) results in higher in-cylinder pressure and temperature, and higher efficiency, but also results in elevated engine noise and increased oxides of nitrogen (NOx) emissions due to higher combustion temperatures. On the other hand, delayed start of injection causes incomplete combustion, reduced fuel efficiency and an increase in black exhaust smoke, containing a considerable amount of particulate matter (PM) and unburned hydrocarbons (HC). From: http://en.wikipedia.org/wiki/Diesel_engine

From http://www.ingentaconnect.com/content/pep/jae/2004/00000218/00000001/art00010:
The engine used in this research follows this technique and had its original injection timing set at 15° before top dead centre (BTDC). With injection timing advanced by 4°, the engine produced better efficiency by 1.6 per cent for WCO and by 1.1 per cent for diesel

If you have access to a dyno and opacity meter, here is the most scientific way to determine the best timing:
Opacity will be at a minimum (least smoke and particulates) at optimized injection timing.
From Yale biofuels study

VO has lower cetane than D2, resulting in ignition delay. Because you are blending with RUG, which lowers cetane further, you have even more ignition delay requiring more advance than V100 or blends with D2. Blending with RUG will also lower your MPG.

From:
Effect of advanced injection timing on the performance of rapeseed oil
The engine has standard injection timing of 30°C BTDC. The injection was first advanced by 5.5°C given injection timing of 35.5°C BTDC. The engine performance was very erratic on this timing. The injection was then advanced by 3.5°C and the effects are presented in this paper. The engine performance was smooth especially at low load levels. The ignition delay was reduced through advanced injection but tended to incur a slight increase in fuel consumption.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
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Postby Cumminscanuck » Mon Mar 24, 2008 5:39 pm

The injection was then advanced by 3.5°C and the effects are presented in this paper. The engine performance was smooth especially at low load levels. The ignition delay was reduced through advanced injection but tended to incur a slight increase in fuel consumption.


I would like to know how this is achieved if one of you "technitions" could explain it simply please. :?
2000 24 VALVE Quad Cab 2500 SLT. Edge Comp. 275 RV's. PDR HX 35/14 hybrid turbo. 4" Diamond Flow Exhaust. Isspro Pyro, Boost, Trans. Temp. Fuel Pressure, Gauges. Turbo Master. Silicone Boot Kit. FASS. BHAF. Running on SVO.
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Postby SunWizard » Mon Mar 24, 2008 7:48 pm

Every engine is different. Yours is a VP44 and the timing is determined by the ECU electronic control unit. You can alter it with chips like:
http://www.thoroughbreddiesel.com/diablo/power-puck.htm
but you may get other side effects like increased fueling since their goal is to increase power. The increased fuel might not be good on VO, but the advanced timing is good.

For complete control of it, use:
http://www.quadzillapower.com/products/adrenaline_98-02.html

More info on VP44:
http://www.dodgeram.org/tech/dsl/ISB/Vp44.htm
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
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Postby Cumminscanuck » Mon Mar 24, 2008 10:21 pm

Thanks Sunwizard, I wasn't sure if "timing" in this context was the same as timing when talking about "chips". I have an Edge Comp on the truck which I usually run on 4/4 which setting gives me best fuel consumption on diesel. I need to check which settings affect just timing and which change the fueling as well. I will experiment with it when running SVO and find the best setting for that fuel. Oh boy! another excuse to play :lol: :lol: :lol:
2000 24 VALVE Quad Cab 2500 SLT. Edge Comp. 275 RV's. PDR HX 35/14 hybrid turbo. 4" Diamond Flow Exhaust. Isspro Pyro, Boost, Trans. Temp. Fuel Pressure, Gauges. Turbo Master. Silicone Boot Kit. FASS. BHAF. Running on SVO.
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Postby VegMeister » Mon Mar 24, 2008 11:49 pm

Thanks for the great info guys (SunWizard). I've been recommended to advance the timing on my truck by a lot of old diesel guys, and now that I've converted to veg, maybe I should.

Apparently with my injection pump you can change the timing with a long hex wrench. In 94 they changed to electronically controlled, so it then required modifying/replacing the computer.
centralvalleybiodiesel CF
1993 GMC Sierra K2500 6.5L + homebuilt veg kit, OEM glowplug failure (update: rebuilt with a 6.2 block, working fine)
1988 Ford 6.9L OEM dual tank, 90+% veg oil blend.
1989 Ford 7.3L, 80+% veg oil blend.
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Postby David » Tue Mar 25, 2008 12:24 am

I tried ramping up the timing on my Merc. Undid the 3 bolts holding the IP in position and heaved on the pump so hard I'm sure I have torn an engine mount from moving everything too far. I only got the IP to move about 1.5 mm. after I did everything back up again, I then discovered there are 4 bolts holding the IP. I think getting at the last one is going to make an easier job overall by just pulling the engine. :x

I couldn't tell any difference to the performance but that was only about 1/3 of what I wanted to advance the timing anyway. I too have heard that when the engine is " on song', the rattle will be louder and sharper which makes sense.

In my testing with WVO/ Bio Blends, I found that a small percent of unleaded, around 5% helped greatly in starting. It is said that in a ULP blend, the oil lights off first. I am very suspicious of this based on experience and theroy.

A petrol engine is lucky to run 12:1 compression before the fuel will light off due to the compression alone. On a petrol engine this is called Knocking.
12:1 on a diesel is so low it may not run at all with 20:1 being a far more common type of compression ratio. Given that petrol is going to light off at much lower compression than Diesel let alone WVO, I can't see it being the last to light off. I also think that the petrol is going to light off the wvo sooner as well and may aid in bringing the timing back to stock.

In looking for performance boosts, I have also read in several places that the great majority of Mechanically injected Diesels are only set to approx 50-75% or their potential power output from the factory.
I have been looking at how to turn the fuel amount up on my car as I am not the slightest bit worried about a bit of black smoke when I want all the power I can get. If anyone were looking to do this, I think it may be wise to set the fuel rate and then do the timing.

It should also be remembered that like petrol engines, the engine is rarely if ever set up for best performance. Emissions, fuel economy, noise and other factors come into play that may not be important to the end user like it was to the factory. As such, stock timing shouldn't be regarded as anything more than a start point at where the engine will run. As such, if tuning the engine by feel ends up being a long way from stock settings, as well as a different fuel, don't forget that the engine may have not been set up for best performance at any time.
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Until then, it's just more endless gloom and doom Veg folk law.
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Postby Burbarian » Sun Mar 30, 2008 1:48 pm

The Stanadyne DB2 has a cold advance solenoid controlled by engine temperature. When energized it advances the timing by 6 degrees. I'm contemplating wiring this through a relay to automatically advance the timing when running vo, then backing off when purging and switching back to d2. Of course, this could be a stupid idea borne of ignorance, so as usual comments and criticism most welcomed.
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Postby VegMeister » Tue Apr 01, 2008 11:52 am

Burbian,

Are you sure this is for all DB2 pumps, or is that just the way it is hooked up on your 'burb?
centralvalleybiodiesel CF
1993 GMC Sierra K2500 6.5L + homebuilt veg kit, OEM glowplug failure (update: rebuilt with a 6.2 block, working fine)
1988 Ford 6.9L OEM dual tank, 90+% veg oil blend.
1989 Ford 7.3L, 80+% veg oil blend.
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Postby Burbarian » Tue Apr 01, 2008 1:07 pm

The DB2 has 3 solenoids. The low speed idle, the fuel shutoff, and the housing pressure cold advance. It is standard.
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Postby Radrick » Tue Apr 01, 2008 2:05 pm

Burbarian wrote:The Stanadyne DB2 has a cold advance solenoid controlled by engine temperature. When energized it advances the timing by 6 degrees. I'm contemplating wiring this through a relay to automatically advance the timing when running vo, then backing off when purging and switching back to d2. Of course, this could be a stupid idea borne of ignorance, so as usual comments and criticism most welcomed.


After reading the info on the links that Sun posted it sounded like most of the experimenting came up with 3 deg. being the best. I read in a couple of places were 5 and 6 deg. were tried and they ended up back at 3. Of course all engines are different and ours may need more with the indirect injection. It wasn't clear if the engines they were talking about were direct or indirect. Just thinking with my fingers :roll:
1995 Chevy K1500 6.5 TD not on WVO yet but soon.
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Postby Burbarian » Wed Apr 02, 2008 4:45 pm

After doing some more research, it appears that the DB2 is very flexible in timing adjustment.

Here's a page with good info:
http://rubiconautoparts.com/wst_page7.html

It appears that dynamic and tunable advance can be achieved with the use of backpressure regulation on the return fitting and the internal transfer pump pressure test fitting. Even dynamic on-the-fly timing adjustment by the use of a servo slaved to a pressure regulator.


This is an excerpt:

There are three timing advance mechanisms on the fuel injection pump:

1. An automatic advance system
2. A mechanical light load advance
3. The housing pressure cold advance (HPCA) solenoid.

The automatic advance mechanism advances and retards the start of fuel delivery. This mechanism starts working as the engine speed increases to ensure that the injector nozzle opens just before the piston reaches top dead center, when compression is at its highest point. Otherwise fuel wouldn't be injected before the piston had started moving downward on it’s power stroke.

The mechanism comprises a power piston, servo valve, servo spring, servo piston and a cam advance pin. The cam advance pin connects the advance mechanism to the cam ring. When the power piston moves, it rotates the cam ring so that fuel is delivered earlier.

Housing pressure and transfer pump pressure behind the power piston influence the action of the servo piston. When the engine is cranking, the fuel behind the servo piston is at housing pressure, and the power piston is seated against the housing. As the engine speed increases, transfer pressure rises and the subsequent increase in transfer pump pressure forces fuel into a chamber behind the power piston.

When transfer pressure in chamber behind the power piston exceeds housing pressure, the servo piston acts against the servo spring, and the power piston pushes the cam advance pin which rotates the cam ring in the opposite direction to the distributor rotor’s rotation and so the rollers contact the cam lobes earlier and injection timing is advanced.

When engine speed decreases, transfer pressure drops, the cam ring rotates in the other direction retarding injection timing.

A light load advance mechanism provides advance when the engine is operating at low speed or under light load, when the transfer pressure is too low to move the advance piston.

The light load advance is actuated by an external face cam and rocker lever assembly when the throttle shaft rotates (on the 6.2L and 6.5L engines, this mechanism is on the passenger side of the pump). The lower end of the rocker lever pushes on the end of the servo advance plunger.

As the throttle shaft rotates, the face cam pushes on the rocker lever using a “see-saw” action, which depresses the servo plunger and advances the timing through the power plunger’s linkage to the cam ring. At a predetermined angle, the face cam flattens out, so that additional throttle movement does not affect the servo.

After the light load advance mechanism ceases to act on the servo plunger, advance action is regulated by transfer pump pressure.

The housing pressure cold advance

(HPCA)

solenoid is one of three solenoids that affect the operation of the injection pump. The (HPCA) solenoid makes it easier to start a cold engine by reducing housing fuel pressure in the advance mechanism.

The (HPCA) solenoid is located under the fuel return outlet, under the pump housing cover. It is activated by the coolant temperature switch, which is mounted on the rear of the passenger side cylinder head. When coolant temperature is low the temperature switch is closed, energizing the (HPCA) solenoid (rear pump terminal connected with a green wire), which lifts the check ball off its seat in the return outlet. This reduces housing pressure to near zero, so that the transfer pump pressure behind the power advance piston can easily advance the cam ring.
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