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Author Topic: Direct Injection and Vegetable Oil  (Read 17056 times)

adhall

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Direct Injection and Vegetable Oil
« on: December 23, 2006, 07:30:58 AM »
I see that some of the Listeroids have direct injection.

Any opinions and/or experience to share regarding operating direct injection engines on vegetable oil?

Best regards,
Andy Hall
JKSon 6/1, 5 kW ST Head, 1992 Dodge RAM Cummins 5.9L Turbodiesel, 2001 VW TDI 1.9L Turbodiesel, 2006 Jeep CRD Turbodiesel, Yanmar FX22D Diesel Tractor

Geno

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Re: Direct Injection and Vegetable Oil
« Reply #1 on: December 23, 2006, 11:38:25 AM »
Mine is IDI but there are DI Listeroids running on veggie. I'm pretty sure most of the newer cars have DI as well and there's a lot of them running it too. Just follow the "rules"

Geno

adhall

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Re: Direct Injection and Vegetable Oil
« Reply #2 on: December 23, 2006, 05:52:34 PM »
Yes, I have noticed that various vendors claim success with VO and direct injection, but I am wondering if there are any special pitfalls to be on the lookout for with this arrangement.

Best regards,
Andy Hall
JKSon 6/1, 5 kW ST Head, 1992 Dodge RAM Cummins 5.9L Turbodiesel, 2001 VW TDI 1.9L Turbodiesel, 2006 Jeep CRD Turbodiesel, Yanmar FX22D Diesel Tractor

rcavictim

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Re: Direct Injection and Vegetable Oil
« Reply #3 on: December 23, 2006, 08:27:05 PM »
Yes, I have noticed that various vendors claim success with VO and direct injection, but I am wondering if there are any special pitfalls to be on the lookout for with this arrangement.

Best regards,
Andy Hall

As I understand it the pitfalls include faster and more susceptibility to rink coking.  If injector heat is important in an IDI then it is critical in a DI setup.
-DIY 1.5L NA VW diesel genset - 9 kW 3-phase. Co-gen, dualĀ  fuel
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fattywagonman

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Re: Direct Injection and Vegetable Oil
« Reply #4 on: February 06, 2007, 02:01:09 PM »
I have a burned a lot of  WVO in a DI petteroid... I even start it on WVO...  I heat the injector line and  injector prior to starting... I do modify the piston though... here's a pic.

adhall

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Re: Direct Injection and Vegetable Oil
« Reply #5 on: February 06, 2007, 09:00:26 PM »
fattywagonman:

Thanks for the picture and comments. However, having never seen a standard Petteroid piston crown, I am at a loss to know what modifications you have made. Would you kindly elaberate, please? I would enjoy knowing what you did and what the rational was.

By the way, I decided to play it safe and have purchased an indirect injection engine. I am definitely expecting to run it on WVO.

By the way, if I wanted to try direct injection, could I just change the piston and cylinder head? (My engine is a JKSon 6/1.)

Best regards,
Andy Hall
JKSon 6/1, 5 kW ST Head, 1992 Dodge RAM Cummins 5.9L Turbodiesel, 2001 VW TDI 1.9L Turbodiesel, 2006 Jeep CRD Turbodiesel, Yanmar FX22D Diesel Tractor

tim

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Re: Direct Injection and Vegetable Oil
« Reply #6 on: February 06, 2007, 09:54:49 PM »
Andy you would also have to change wrist pin and bushing as the wrist pin is bigger in the DI engines.

tim

fattywagonman

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Re: Direct Injection and Vegetable Oil
« Reply #7 on: February 08, 2007, 02:12:55 PM »
It's a lister DI not a patter piston but they're pretty much the same...
Here's a link to a photo

http://biodiesel.infopop.cc/eve/forums/a/tpc/f/159605551/m/9111037541?r=2311032641#2311032641

adhall

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Re: Direct Injection and Vegetable Oil
« Reply #8 on: February 08, 2007, 02:53:50 PM »
Fattywagonman:

Thanks for the picture. If I interpret your original picture right, the bowl-shaped cavity in the middle was the original combustion chamber. You must have added the seven radiating channels and the seven dimples. Also, it appears that the dimples have small holes in the center that connect with the original combustion chamber.

Have I got that right?

Can you tell me what these modifications accomplish? And how did you adjust the compression ratio after removing that material from the piston crown? (or did you even have to?)

Best regards,
Andy Hall
« Last Edit: February 08, 2007, 02:56:28 PM by adhall »
JKSon 6/1, 5 kW ST Head, 1992 Dodge RAM Cummins 5.9L Turbodiesel, 2001 VW TDI 1.9L Turbodiesel, 2006 Jeep CRD Turbodiesel, Yanmar FX22D Diesel Tractor

Doug

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Re: Direct Injection and Vegetable Oil
« Reply #9 on: February 09, 2007, 04:40:23 AM »
Here's the stock Piston....

http://www.putfile.com/pic.php?img=4206636

Whats the bore on that modified Petter fattywagonman ?

Looks smaller than my 102....

fattywagonman

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Re: Direct Injection and Vegetable Oil
« Reply #10 on: February 09, 2007, 01:27:58 PM »
Hi Andy, Doug,

The channels create a vertical swirl when the piston reaches TDC. The vertical swirl helps mix the air / fuel better since the injector nozzle has only 3 holes and sprays fuel radially.

Removing material from the piston does lower the compression slightly but I have noticed the engine starts better that it does with the higher compression / stock piston. It defiantly make less smoke which generally means better combustion.. I believe it also burns slightly less fuel when compared to the stock config but I haven't fully documented this.

I did this to help with burning veg oil... more complete combustion is important so there is less residue from the unburned fuel.

I think this is an 87mm bore

blacksea7

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Re: Direct Injection and Vegetable Oil
« Reply #11 on: June 11, 2008, 12:03:35 PM »
Gentlemen,

The difference in DI and IDI is staggering. IDI's have a habit of being able to run a slightly lower quality of fuel while DI's have a thrist for a more refined fuel. IDI's have by their nature, burn slower, somewhat cooler and have slightly greater backup torque.. DI's burn faster and hotter... it's their nature. IDI's are always pintle injection whereas, DI's can be multi-hole or pintle... each having an advantage over the other. If you tamper with the piston in a DI engine you've done more damage than good. The combustion bowl in the piston was engineered for maximum swirl of the air so more of the air becomes intimate with the misted or atomized fuel being injected. Narrowing the bump clearance (distance from piston to head) is self defeating as you've managed to stop the flame front from propagating across the entire piston (the flame front will not propagate through a narrow slot.. you need to have at least .035 for the flame front to move freely across the piston). In other words, clever maching of the piston is needless and self defeating. Compression heat destabilizes the fuel. Think of it this way. From the piston pin down, engines are pretty much the same. From the piston pin up is where corporations spend substantial amounts of cash to make the enigne efficient... ie. piston, head, runners, valves, etc. all to get the maximum amount of swirl into the chamber... squeezing the charge doesn't do it all... it simply augments the swirl of the incoming charge.
In order to burn heavy fuel, you need to atomize the fuel... the heavier the fuel the higher the injection pressure you need to run. The pressure is nearly linear to the viscosity of the fuel. Makes sense, doesn't it? Next you need to heat the fuel before it gets to the pump.
Heavy fuel or alternative fuel engines are generally more robust to tolerate the longer burn time of a less refined fuel. Other issues are in the ring pack as fuel impingement is nearly impossible to stop in a heavy fuel engine (unburned, slightly burned fuel coming in contact with the cylinder walls). You'll also see a marked change in the power output. Something to remember, in a gas engine the fuel mingles intimately with the air thereby defining the engine as homogenous... naturally aspirated diesels manage to consume about 80% of the oxygen in the intake charge of air... the heavier the fuel, the less the oxygen it will react with.. the molecules are heavy.. they need to be destabilized through heat... a lot of heat. 

sodbust

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Re: Direct Injection and Vegetable Oil
« Reply #12 on: November 20, 2008, 05:00:51 PM »
I cover my thinking about veg oil and diesel engines in my web site,, www.oilcrusher.5u.com under "testing"

Engines with a pre chamber are able to eat allot of poor veg fuel better than one that shoots the fuel into or at the piston. The pre chamber catches most of anything that will damage a DI engine better..

sodbust