Quieter engine on SVO is not better

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

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Quieter engine on SVO is not better

Postby SunWizard » Fri May 30, 2008 7:49 pm

Quieter isn't better on SVO, it means your timing is retarded. It should have the same loudness of diesel knock as always. When its quieter it means your timing needs to be advanced, until it sounds the same as on Diesel. The extra lubricity of WVO is not making it quieter. The sound of the diesel knock is how the most accurate tuning for the timing of mechanical IP diesel engines is done.

Retarded timing (quieter engine) means you are getting lower power, worse mileage and more emissions. And it burns cooler which leads to more deposits forming. According to Chris at Frybrid, even 2 degrees off causes a large effect:
http://biodiesel.infopop.cc/eve/forums/a/tpc/f/15960555...621026581#7621026581

This is another reason why RUG blending isn't as good as using Kerosene or Diesel.
Lower auto-ignition temps than 410F fuels advance the timing, higher ones retard the timing. Chart here:
http://www.engineeringtoolbox.com/fuels-ignition-temperatures-d_171.html

410F = diesel & kerosene
536F = RUG gasoline
690F = SVO
869F = acetone
1022 = naptha (white gas or spirits)

This is why you will find many references to advancing your timing by 3-4 degrees for best use on SVO.
Last edited by SunWizard on Mon Oct 11, 2010 7:09 pm, edited 2 times in total.
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Re: Quieter engine on VO is not better

Postby coachgeo » Fri May 30, 2008 9:47 pm

SunWizard wrote:....This is another reason why RUG blending isn't as good as using K1 or D2.....
How do you see that. As in if you tune the timing to the fuel... for example fuel blended with RUG.... what is the issue?

Of course there is dimininshig returns...so IMHO the secret would be engine timing tuned to a fuel who's RUG blend ratio thins oil for better combustion, starting etc, yet is not so much that it takes things to within the diminishig returns area.
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Re: Quieter engine on VO is not better

Postby powerstroke73L » Fri May 30, 2008 10:04 pm

SunWizard wrote:Retarded timing (quieter engine) means you are getting lower power, worse mileage and more emissions. And it burns cooler which leads to more deposits forming. According to Chris at Frybrid, even 2 degrees off causes a large effect:
http://biodiesel.infopop.cc/eve/forums/a/tpc/f/15960555...621026581#7621026581

This is why you will find many references to advancing your timing by 3-4 degrees for best use on VO.


Hmmm...I just raised this issue on www.powerstroke.org and asked the guys from DPTuner to weigh in on the issue. They can do profiles (timing, injector pulse width, etc...) for just about anything you want. Maybe they can do a custom WVO profile?
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Re: Quieter engine on VO is not better

Postby SunWizard » Fri May 30, 2008 10:13 pm

coachgeo wrote:
SunWizard wrote:....This is another reason why RUG blending isn't as good as using K1 or D2.....
How do you see that. As in if you tune the timing to the fuel... for example fuel blended with RUG.... what is the issue?

The issue is that RUG makes your timing more retarded than a blend with D2 or K1 in the same %. And most people aren't adjusting their timing, so RUG makes their timing worse.
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Postby hheynow » Fri May 30, 2008 10:44 pm

Well since I'm not touching my timing I decided to blend in some kerosene to see what happens. I added 10% making my blend VO90/K10. Regardless of ample heat (180*F) I always noticed a sluggish go peddle but this blend ROCKS! I've never had so much power and quick throttle response as I did tonight. Yes this is my first experience with solvent thinning and I'm sold EXCEPT that it adds a co$t to running vegoil. But it's not really solvent thinning in this case because viscosity isn't the issue. It's a fine tuning of two different fuels to find the sweet spot ignition temperature....just like blending Merlot with Cabernet. :mrgreen:
Last edited by hheynow on Sat May 31, 2008 1:04 am, edited 3 times in total.
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Postby coachgeo » Fri May 30, 2008 11:29 pm

hheynow wrote:... Regardless of ample heat (180*F) I always noticed a sluggish go peddle but this blend ROCKS!....
Do I read you right your doing normal two tank system with a blend in the WVO tank that gets heated like any other good WVO heated oil system?
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Postby hheynow » Sat May 31, 2008 12:01 am

Yup. Two years, two tanks and 25+K on WVO with the Plant Drive kit. Acceleration from a dead stop has always been sluggish on vegoil regardless of ample heat. Sure heat changes the viscosity but the kerosene advances the timing which was my missing link. I also notice the same sluggishness with B99 compared to #2. Adding some kerosene to my B99 tank advanced the timing and it too ROCKS!
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Postby chasee » Sat May 31, 2008 7:03 am

I'm pretty sure that, at least in my PD engine, timing adjusts based on fuel temp. This can be problematic due to the high temps we WANT our fuel to be at. I know that the Elsbett kit for my car does not include new injectors since PD injectors are a whole different animal, but it does remap the ECU. So at least one company is aware of the timing issues.
2005 Golf GLS PD-TDI, 5-speed. Grease Car kit installed right off the lot when brand new. Running on WVO about 85% of the time.
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Postby roverhybrids » Sat May 31, 2008 1:39 pm

I think there is more to it then just the auto-ignition temp(AIT)

The flash point is more indicative to the burn in an engine due to the fuel being injected as a vapor(hopefully)

The flash point of gasoline is -45F where kerosene is 100F and diesel is 125F
http://www.burnandfireprevention.org/new_page_3.htm

So if my logic is working then adding RUG will lower the flash point. Following this logic adding RUG to diesel as suggested by Mecedes for winter climates would lower the flash point allowing easier starts in colder temperatures.
This would also apply to other fuels like VO. I don't know the VO flash point but would guess it is very high. The addition of RUG lowers the flash point therefore allowing the combustion to start sooner combined with the lower burn of VO equalling more power??????????
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Postby SunWizard » Sat May 31, 2008 1:50 pm

The flash point has no effect on a diesel engine since it relys on compression igniton. Flash point is where it ignites in presence of a flame or spark. The RUG and anything else doesn't ignite until it reaches its AIT in a diesel since there is no spark. So D2 or K1 will auto-ignite sooner than RUG.

Diesel is required to have a high flash point and a low autoignition temperature, the opposite of RUG, see:
http://en.wikipedia.org/wiki/Flash_point#Examples_of_fuel_flash_points
YVORMV - Your veg. oil results may vary.
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Postby roverhybrids » Sat May 31, 2008 3:21 pm

but the AIT of RUG is not that far off of diesel, especially when compared to VO or your blend of VO/kero/dino.

Does not RUG in a diesel cause knocking?
Following only the AIT logic it would not?

Isn't this knocking pre-ignition?
Caused by the RUG combusting to soon(advanced timing)

Flash point is the "point" based on temp where a gas can be ignited. Ignition can come from a spark or flame as well as a high heat source(which in our application is hot air from compression)
Flash point is based off of vaporization, which RUG does at much lower temps than diesel.

So as my brain is trying to logicise, the low flash point of RUG allows it to further vaporize reaching the point of AIT sooner than diesel, even given diesels lower AIT??
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Postby SunWizard » Sat May 31, 2008 3:43 pm

roverhybrids wrote:Flash point is the "point" based on temp where a gas can be ignited. Ignition can come from a spark or flame as well as a high heat source(which in our application is hot air from compression)
Flash point is based off of vaporization, which RUG does at much lower temps than diesel.

So as my brain is trying to logicise, the low flash point of RUG allows it to further vaporize reaching the point of AIT sooner than diesel, even given diesels lower AIT??

No, study flash point further, even stated at the link I gave above. It requires a flame or spark to ignite. Hot air won't do it. This is why there are different figures for flash point and AIT. If what you are saying is true, then the AIT would always equal the flash point (if the flash point were lower.)

All of the fuels vaporize long before they auto-ignite. AIT is igniting vapors always.

RUG causes knocking but only because it explodes rather than the slower, more powerful burn you get from VO or D2. But the explosion and knocking from RUG which can damage your engine occurs later (more retarded) than the same amount of D2 in a blend.

But this is not the main point of this thread, which is that VO retards your timing, making a quieter engine. Adding RUG causes a whole different knock, so the sound is no longer an indicator of whether your timing is retarded.
YVORMV - Your veg. oil results may vary.
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Postby Jake Palmer » Sat May 31, 2008 6:34 pm

Great thread!

I saw a youtube video the other day where someone was showing off their mercedes 300sd conversion:

"The car runs WAAAY better on vegetable oil than on diesel! Hear how much quieter it is?! And plus, there is no more black smore, just white smoke, look!" [points to white smoke at idle]

classic!
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Postby hheynow » Sat May 31, 2008 7:18 pm

My truck is retarded on vegoil...but I'm dealing with it. :mrgreen:
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Postby David » Sat May 31, 2008 8:44 pm

I have a lot of reservations about this theory that RUG ignites after Veg when blended in a diesel engine. The very description of it causeing knocking is evidence of it burning before the veg, not after.

The AIT of VO is listed at 365oC whereas the AIT of RUG is listed at 246oC. Obviously out of the 2, the RUG will light off much sooner than the Veg and once it lights, it will light off the veg as there is now a flame front present in the cylinder and the flash point of the veg will have been long past allowing it to burn as well.

In a petrol engine, it is rare to see compression ratios over 12:1 due to the problem of the petrol self igniting in an untimed manner.
In high compression engines, this is always pre ignition which mean the fuel burns in the compression stroke earlier than it should and causes engine damaging knock. Even modern computer controlled petrol engines using comp ratios above 10:1 would be doing it on Premium fuel only otherwise the knock sensors would tell the engine management computer to RETARD the timing which eliminates the knocking and the engine runs at reduced power due to the reduction in advance of the timing.

Many high performance engines both past and present have used things like water injection to control this pre-ignition and allow these more efficient high compression ratios to be used in petrol engines without the engine self destructing.

A LOW compression Diesel engine will run 16:1 compression and most run higher than that, some engines at the high comp end are running 30:1.
The 16:1 compression of a diesel engine is magnitudes above even what a very high compression petrol engine would run at 12:1 and there wouldn't be many gas engines doing that. Typically most modern engines running on Regular unleaded fuel are using compression ratios of around 9:1.

If RUG will light off at say 13:1 compression, ( and most times well below that!) how could it possibly light off after a non aromatic and far less flammable fuel at compression ratios of 16:1 or Higher?
To me that makes no sense.

I don't see that mixing with WVO would change anything because the droplets of RUG when sprayed into a diesel engine would still be exposed to the heat and compression of the engine which would make them combust just the same.

Most tellingly, Knocking ( or Nailing as it is called in a diesel engine) is a sign of PRE-IGNITION or ADVANCED timing, not retarded. Knocking occurs because the piston basically collides with the pressure wave of the fuels combustion because the fuel lit off too early in the pistons upward travel on the compression stroke and is trying to work against it, rather than in normal combustion, the peak cylinder pressure is reached when the piston has started its downward decent in the bore on the power stroke.

The fuel in an engine does not explode, it burns in a very rapid but controlled fashion at a very specific point in time. The burning flame front of the fuel when it combusts in a cylinder is designed to move in a specific direction so as to actually push on the piston, not to smack it. It is the effect of bad timing that gives the knocking or nailing effect, not any fuel exploding. It should also be remembered that in a diesel engine, the "mixture" isn't compressed like in a gas engine, fuel is sprayed into a compressed atmosphere.

Normally with a diesel engine running Diesel fuel, the fuel is injected before the air temp has reached the diesel fuels AIT and when it does light, there is an amount of fuel present that burns very quickly which is what gives diesels their characteristic Knocking sound. The fuel continues to be injected after this initial ignition and the extended burning event is what also helps give diesel engines greater torque than petrol engines.

If RUG was slower to burn, either the veg would light off first which would ignite the RUG ( having a lower flashpoint that the veg) at the same time and no nailing would occur,
OR,
if the RUG caused the Diesel fuel component to be delayed in it's ignition, then late timing would occur which doesn't cause nailing or knocking, Advanced timing or ignition does that.

It s my belief that the RUG advances the combustion timing which offsets the delayed timing of the Veg igniting. If adding RUG to a diesel restored some of it's previous clatter, that would be a good thing.
Having done all this mental arithmetic, I think I should go back to adding a percentage of RUG to my oil when I want to restore some power that the delayed timing of veg creates!

It is against physic's, logic and engine design principles to say that a fuel that burns slower is causing knocking in an engine... They are opposite effects.
It is the same as saying house wives are burning their hands doing the washing up because the hot water coming out of the tap is freezing cold. :?

The reason why people want ( should) advance their timing when Using WVO because it burns slower, is so the ignition of the fuel occurs when the peak pressure of the cylinder acts on the piston so as to basically give it the greatest push possible. Retarded timing is when this point has passed and the piston is already on its way down the bore. The amount of time the pressure wave has to act on the piston and the initial push it gives it is reduced and there is less time available for the pressure wave to act on the piston before the exhaust valve opens and all the pressure is lost.

For these reasons, it is my belief that the theory of RUG causing delayed burning of Veg in a diesel by burning after the veg lights off,
and at the same time causing nailing which is a symptom of pre-ignition which is the complete opposite of delayed ignition, are flawed and don't stand up to the physics and design operation of Internal combustion engines no matter what fuel type they are.
Last edited by David on Sun Jun 01, 2008 6:50 am, edited 1 time in total.
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