Hi,I only discovered this site a couple of days ago and I'm really impressed by the simplicity and effectiveness of grooving.Only trouble is I have a diesel car and I can't find any examples or photos of grooved diesels.I'm very keen to try this on my car but want to make sure I get it right.Is there anyone out there that has grooved a small precombustion chamber diesel engine? Mine is a 1992 Nissan 1680cc not sure of the extact compression ratio but probbabily about 22:1.I think I saw it mentioned that it is best to put the grooves in a diesel engine on the piston top where there is a small "combustion chamber" however it would be easier to groove the cylinder head. I would really appreciate a bit of expert advice here.This could also be a world first for grooving as my engine is modified to run on strait vegetable oil.Thanks alot Dieselveg.
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Re:Grooving a diesel
Date: 2007/07/20 15:01
By: singh
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Karma: 4
Hi Dieselveg,
Many Diesels have successfully been hacked with grooving ! In all probability your 92 Nissan 1680 is a Pre Combustion Chamber design with a heater plug ? Some call it Indirect Diesel Injection ( IDI ) If this is the case there is no place to groove as both the head & piston faces are almost flat ~ The compressing charge is pushed through the " key hole " in the head into the pre combustion chamber and is made to spin while diesel is sprayed into this chamber just before TDC ? Ignition occurs and the expanding flame front alongwith yet to burn fuel jet out of the key hole onto the retreating face of the piston to continue into secondary combustion with the rest of the air in the cylinder ! The Key hole creates enough and more turbulence both ways while the pre combustion chamber gathers the heat for better ignition ? If it is a DI - Direct Injection Diesel, go for the bowl on the piston ! Too many cuts will bring down compression, which intern results in poor burn. Keep Thinking ~ You will find the answer to Hacking Heads ! sing !!!
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Re:Grooving a diesel
Date: 2007/07/22 04:39
By: dieselveg
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Karma: 0
Thank you for the reply,and very gratifing to get one from the master groover himself ! Yes my engine is a precombustion chamber one. I must be misunderstanding something as I thought it was the flat area's on the outer egdes of the combustion chamber that the groves go in.Since there is no real combustion chamber and both the cylinder head part with the valves in it and the piston top inside the cylinder are both flat I assumed that they would be like one big squish area and might benefit from two or three grooves radiating out from where the pre combustion chamber enters the cylinder.Combustion starts at 10 dregrees before tdc.There is first a pilot injection closely followed by the main injection of fuel so the piston is probabily still rising and combustion still happening until maximun pressure at tdc,and for several degrees after.But if others have tried and failed to sucessfully groove an indirect injection diesel then I have more to understand about how grooves work.Do you know if anyone has used grooves in conjuction with a fuel catylst to improve combustion even further?I have a fuel catylst on my car and they do really make the engine run better.So even if grooves won't work on my car I think what you have discovered and are promoting is fantastic and I will enjoy finding out more about grooving.Thank you,dieselveg
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Re:Grooving a diesel
Date: 2007/07/22 04:40
By: dieselveg
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Karma: 0
Thank you for the reply,and very gratifing to get one from the master groover himself ! Yes my engine is a precombustion chamber one. I must be misunderstanding something as I thought it was the flat area's on the outer egdes of the combustion chamber that the groves go in.Since there is no real combustion chamber and both the cylinder head part with the valves in it and the piston top inside the cylinder are both flat I assumed that they would be like one big squish area and might benefit from two or three grooves radiating out from where the pre combustion chamber enters the cylinder.Combustion starts at 10 dregrees before tdc.There is first a pilot injection closely followed by the main injection of fuel so the piston is probabily still rising and combustion still happening until maximun pressure at tdc,and for several degrees after.But if others have tried and failed to sucessfully groove an indirect injection diesel then I have more to understand about how grooves work.Do you know if anyone has used grooves in conjuction with a fuel catylst to improve combustion even further?I have a fuel catylst on my car and they do really make the engine run better.So even if grooves won't work on my car I think what you have discovered and are promoting is fantastic and I will enjoy finding out more about grooving.Thank you,dieselveg
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Re:Grooving a diesel
Date: 2007/07/24 16:22
By: singh
Status:
Karma: 4
Hi Dieselveg ~ Had to say ~ I assumed that they would be like one big squish area and might benefit from two or three grooves radiating out from where the pre combustion chamber enters the cylinder. " You hit the nail on the Head " ! Yes you can have 2 mm straight channels starting from the bore dia slowly tapering deep into the piston crown by about 3 mm and pointing upwards with a curve at the " Key Hole " entry point of the Pre Combustion chamber. What would then happen is on the compressing stroke ~ The air would be guided better into the Key Hole to swirl more vigorously in side the IDI chamber ~ Once ignited the flame / fuel fronts would be guided towards the end of the combustion chamber faster ! Just one channel will not bring down the much needed compression ratio that generates the required heat for proper combustion ~ But 3 channels would definitely do so. The other trick is to offset the gudgeon pin bush and push the piston up by 1/2 mm and hope for the best ! ? All this has been done on primitive IDI's. The engines go smoother and start with little heat in the heater plugs with lesser soot & smoke ! There are no hard and fast rules ~ Just some imaginations of what really could be happening 1/ 2 inch of either side of tdc while the Bang is taking place ! ? sing !!!
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Re:Grooving a diesel
Date: 2007/07/28 09:03
By: dieselveg
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Karma: 0
Excellent ! I definitely want to try this on my engine,however I will have to wait a while as my engine has just been rebuilt and is nor run in yet.Two things I'm wondering 3 grooves would be better than one as far as inducing swirl and directing the flame front to the edges of the cylinder, the only draw back is the loss of compression.Might this be overcome by adding a small low boost turbo charger?The turbo making up for the loss of compression.Also the reason why IDI diesels have a higher compression ratio is to overcome the heat loss caused by the extra surface area of the pre chamber.So if the prechamber, "combustion chamber" and piston were coated with a ceramic heat insulating coating, the drop in heat from a drop in compression ratio could be compenstated for.One other thing that has occurred to me is the less spark or ignition advance you have, the greater the actual compression ration will be at the start of combustion.Since compression ratio is the ratio between the cylinder displacement at the bottom of the stroke and at the top of the stroke.Not the ratio between bottom of the stroke and 10 to 20 degrees {or whatever} before TDC.The most efficient engine would be one that could fire at top dead center throughout its entire rev range.The more I find out about grooving the excited and enthusiastic about it I become.The best solutions are the simplest ones.Thank you Mr Singh.Dieselveg
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Re:Grooving a diesel
Date: 2007/08/01 09:23
By: singh
Status:
Karma: 4
Hello Dieselveg ! The max effects of squish occur closest to tdc ~ Igniting the mixture that close to tdc will further cause a delay in the ignition delay period ? The ideal scenario is to have the shortest ignition delay bring about squirting of flame fronts out of the key hole into the main chamber at ideal crank angles past tdc through the widest operating range. Loss in compression cannot be made up with a turbo ? Means you need sufficient heat out of compression for quick start ups in the cold ! The turbo comes on much later ! i believe In the good old days the Famous London Cabs were left idling all day long ~ As starting these IDIs in the cold was a real slow smoky process ! Ignition delay period goes hand in glove with the generated heat out of compression and the stored heat from the previous power stroke ! Ceramics will be the " Ice-ing " on the cake ! If a little more imagination is applied ~ i am sure you will be able to snap in new ideas to shorten the present ignition delay period my friend ! Keep trying ! Success will follow .... While the Industry is Spending Millions in research to achieve the same ? sing !!!
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