Author Topic: Petteroids on veg oil?  (Read 9212 times)

Spacehog

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Petteroids on veg oil?
« on: September 24, 2006, 11:04:52 AM »
Hi again, is anyone running a petteroid on veg oil?
How hard are they to start on veg oil?

  Cheers
            Spacehog

Doug

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Re: Petteroids on veg oil?
« Reply #1 on: September 24, 2006, 10:45:49 PM »
Probaly a bad Idea......

Most likely it will coke up in a hurry. DI engines aren't the lest choice, the real experts around here with veg run precup engines and still spend a little time clearing the coke out....

Doug


FYI: I have a big Petteroid and have looked over the engine stripped bits and pieces and read a little on the subject of VEG. I don't think this is the best use of these motors....
« Last Edit: September 24, 2006, 10:49:37 PM by Doug »

Spacehog

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Re: Petteroids on veg oil?
« Reply #2 on: September 25, 2006, 08:01:46 PM »
Do you think it would coke up even if working to full capacity on a generator?

Doug

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Re: Petteroids on veg oil?
« Reply #3 on: September 26, 2006, 12:15:51 AM »
I can't answere that, I don't know how long a slow turning DI motor will run before coking and fouling becomes an issue. The fact that some of the Listeroid owners have to remove their heads and scrap them out or use some other methods like propane injection hours makes me think you may not be able to go half the 200-500 they do with the precups.

Do you have a Petteroid yet?
Odds are they will perform better in Waste oils mixed with fuel oil than veg. On the other hand the DI engine lends itsself better to dual fuel opperation. Maybe a Veg ignited producer gas engine Petteroid is better option.

I'm months away from have any answeres for you.....

Doug

mjn

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Re: Petteroids on veg oil?
« Reply #4 on: September 26, 2006, 12:34:00 AM »
I don't have a Petteroid, but I can offer some insight into VO conversions in general.
Hi again, is anyone running a petteroid on veg oil?
In the early days of VO conversions, direct injection engines had significant problems with ring coking because the VO was not being heated enough, or the oil was injected while the engine was still cool.  Indirect Injection engines were more successful because the ignition chamber in the head made it harder for the unburned oil to work its way into the rings.

The current thought regarding VO in direct injection engines is that as long as the VO is heated sufficiently and is injected into a hot engine, you won't have problems.  If you inject cold (less than 160ºF) VO or your engine is not up to temperature the oil will end up in the rings and eventually lead to coking.

The trend in VO conversions on DI engines is to use heaters on the injector lines to heat the oil to between 200º to 250º.  At this temperature, the viscosity of VO is nearly the same as diesel.
Quote
How hard are they to start on veg oil?
I have started my Changfa on cold VO (~70ºF) and it is something I don't want to do twice.  I cranked for about 30 seconds before I started getting any form of firing.  Eventually it started popping, with lots of white smoke, but not enough to keep running.  I kept cranking for another 10 or 20 seconds before it finally started to run. 

Once the VO and engine are up to temperature, I can shut down on VO and restart within a minute or two without any problems.  It starts up just like it does on diesel.

Trying to start a cold engine on VO is asking for trouble because all of that cranking is pouring cold oil into the cylinder which  will get into the rings and turn to carbon.  (There are people who do it all the time, but I'm not aware of anybody with a direct injection engine doing so).

The real answer to how hard is it to start on veg oil is "you don't start on veg oil".  Start on diesel. Once the engine is up to temperature, and your VO is hot, the switch to VO is totally seamless.  The only clue you have that you are running on VO is the exhaust does not stink as badly.

Changfa 195 7.5 kw ST.  WVO conversion http://martin.nile.googlepages.com/
Metro 6/1 DI Listeroid. Pumping water for fire control.
1933 Stover CT-1 hit and miss
1936 Farmall F-12 -- unrestored, still used to mow the field

Doug

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Re: Petteroids on veg oil?
« Reply #5 on: September 26, 2006, 01:12:34 AM »
There you go and answere spacehog....
Yes but heat the hell out of.

Doug


mjn

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Re: Petteroids on veg oil?
« Reply #6 on: September 26, 2006, 03:14:43 AM »
By the way, I was referring to "coking" as meaning when unburned fuel gets into the rings, and eventually turns to carbon which freezes the rings in the grooves.  This often leads to scoring of the cylinder and often ruins the engine.

I don't know about a Petteroid, but people with Lister engines routinely (every thousand hours or so) pull the head and scrape the carbon buildup.  I would consider this a normal sort of activity like changing the oil.  As long as it is not let to go too far, it does not damage the engine.
Changfa 195 7.5 kw ST.  WVO conversion http://martin.nile.googlepages.com/
Metro 6/1 DI Listeroid. Pumping water for fire control.
1933 Stover CT-1 hit and miss
1936 Farmall F-12 -- unrestored, still used to mow the field

Doug

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Re: Petteroids on veg oil?
« Reply #7 on: September 26, 2006, 03:35:15 AM »
I was under the impression the injector would coke up and the unburned combustion products would cause missing and smoke long beofre the engine was damaged. Are you saying RVO can ruin a DI engine without you even noticing?

Doug

Spacehog

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Re: Petteroids on veg oil?
« Reply #8 on: September 26, 2006, 07:29:59 PM »
Thanks chaps, plenty to think about, i'm about to order a little 2.5kw genset.

mjn

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Re: Petteroids on veg oil?
« Reply #9 on: September 26, 2006, 07:40:21 PM »
I was under the impression the injector would coke up and the unburned combustion products would cause missing and smoke long beofre the engine was damaged. Are you saying RVO can ruin a DI engine without you even noticing?
Doug

Most of us on this forum would notice the symptoms and pull the head and clean the carbon. The problem is that if you pull the head and scrape the carbon off, you still have carbon in the rings.  If unburned fuel is getting to the rings, then eventually the rings will freeze in their grooves and stop sealing.  Loss of compression is the first symptom of ring coking.  If caught early, then the piston can be pulled and the rings freed up, but if left unattended the cylinder will be scored.

The studies which were done in the '80s with unheated vegetable oil all noted that IDI and DI engines encountered ring coking in a rather short amount of time (usually in 50 hours or less).   IDI engines were less susceptible to coking.  Since that time it has been demonstrated that heating the VO prevents ring coking on IDI engines.  In the last few years as the DI engines came off warranty and a few brave people risked their expensive engine, it has also been shown that DI engines are also capable of running on VO without damage as long as the engine is hot and the oil is hot.

My personal experience is rather limited.   My Changfa engine is IDI, but I still heat the VO to around  200º.  I have 160 hours on my engine.  I ran a compression test on the engine when new, and again at 100 hours.  There was a slight increase in compression at 100 hours (probably due to the rings seating).  I plan on doing a compression test every 100 hours of operation.

Thanks chaps, plenty to think about, i'm about to order a little 2.5kw genset.
Be sure to let us know how it goes.

Changfa 195 7.5 kw ST.  WVO conversion http://martin.nile.googlepages.com/
Metro 6/1 DI Listeroid. Pumping water for fire control.
1933 Stover CT-1 hit and miss
1936 Farmall F-12 -- unrestored, still used to mow the field

buickanddeere

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Re: Petteroids on veg oil?
« Reply #10 on: October 05, 2006, 04:18:24 AM »
  As previously stated high temps are required.
 Reverse flow cooling helps and coolant temps of 220 F are not unreasonable. Pre-heated fuel is vital. 200F is good, 300F is better.
 High rpms and max HP loads also run hotter.

fattywagonman

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Re: Petteroids on veg oil?
« Reply #11 on: November 09, 2006, 03:04:01 AM »
I run them on VO but I do modify the piston top... heating the injector line will help keep the injector from fouling... they do start a little harder on VO but will start at temps in the 50's and 60's

diyer

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Re: Petteroids on veg oil?
« Reply #12 on: February 20, 2007, 01:19:28 PM »
I don't own a Petteroid (yet).  I do have a Mercedes 240D on WVO.  My take on it is that the engine must be started and stopped on diesel.  The most important is the stopping on diesel.  If you allow WVO to stay on the hot engine as it cools, you will be doing the same thing as "seasoning" a frying pan.  The hot oil will drip down the head and rest on the rings.  As it cools, it will become solid.

If you shutdown on diesel, you will not have the diesel solidify.    I disagree about the heating of the oil.  It has to be hot enough to flow through fiters and your IP. 

If you calculate the specific heat of the amount of fluid being sprayed into the engine with the engine head temperatures, you will realize that the oil will be the same temp as your cylinder head (most likely above your water temp).  You have a several hundred pound engine that has to heat up 5-10 gallons per day.   This is no problem for it.

diyer

Hoke

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Re: Petteroids on veg oil?
« Reply #13 on: July 25, 2007, 11:57:59 PM »
I recently ran my Petteroid on WVO with no ill effect.  I started and stopped on diesel and the WVO was initially heated to 100deg F.  I loaded the generator to about 7.0kw and it seemed to work fine.

Doug

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Re: Petteroids on veg oil?
« Reply #14 on: July 26, 2007, 01:44:06 AM »
What size Petteroid do you have?

Doug
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