Hello Andris, if I calculated correctly, your engine originally had a combustion chamber size of 75 cc (CR 1:17.3), which you increased by 25 cc, so it now has a 100 cc combustion chamber and CR 1:13.3, this will work fine on wood gas, well, only at full load and very calorific gas (a lot of hydrogen and methane), you may detect detonations.
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Tone- I did a bunch of research on compression ratios, flame speeds and detonation for various fuels but especially gasifier fuels.
Gasifier fuel, as supplied to the engine/carburetor is already heavily diluted by unreactive nitrogen. This decreases flame speed and detonation pressures in a given fuel-air charge. This sort of fuel dilution is NOT commonly covered in research papers. Most of them assume undiluted gas or at least much richer gas. Our gasifier fuels give more compression ratio headroom than most reading would suggest.
Based on regular papers and the odd ones that covered dilution… my head space design targeting CRs of 10-12 appeared quite safe from detonation and I didn’t consider much higher because it would be hard to achieve with my base engine.
A CR of 13.3 is starting to get into the “consideration” detonation zone for me, especially if pains are taken to keep the gasifier fuel concentrated. You may have direct experience with higher CRs in gasifier fueled engines. If so I’d take your lived experience over research papers. But what I’ve read suggests safety in that CR range.
Quick example: my propane/NG Generac backup generator is 9.5:1 CR but supposedly the CR limit for that fuel is around 15-16:1 in sparked/carb’d/naturally aspirated engines. I’ve heard undiluted CO/H2 mix is similar to propane? N2 diluted gasifier fuel would be even more detonation remote?
In any case… for a worried soul… just run the engine especially rich or lean (rich better I think) and move the air-fuel mix gradually toward the “Stoch” ratio while looking for signs of knocking in the engine. If it knocks before you get the ideal mix you’ll have to take some material out of the head and try again. No biggie. You could even bleed in some propane or regular petrol into the fuel mix to reverse dilution and see about a margin of safety against knock. I think you’ll find one.
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Anthony, you wrote very well, CR should be between 1: 10 and 1: 12, if we are planning a system that will operate on calorific wood gas. I would also point out another very important factor that affects the CR level, which is the volume of each engine cylinder. If the volume is large, CR should be smaller, because a large cylinder has much less heat loss compared to a smaller one, because the surface area of a large cylinder is smaller in terms of volume than a small cylinder. This means that the gases heat up much more in a large cylinder when compressed, so it should have a smaller CR.
Andis, your engine will be really great for running on wood gas, each cylinder has 1250 cc, combustion chambers in the pistons, … it will easily reach a power of more than 35 kW at 1500 rpm…
You can also fight engine knocking by installing a gas mixer, which has a moving element whose spring presses in the opposite direction of the gas flow, so you always have a slightly muffled engine charge, which reduces CR and mixes the gases well.
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I decided to put it here so everyone will know what has been happening to me. Well to make a long story that is 73 years long in my lifetime short. I found out I have a food intolerance disorder that has been causing all kinds of issues in my body my entire life. I thought the way I feeling in my body was normal. No medical Doctors found the problem. But my Beautiful wife did. She had a test done and found out she was lactose, and sugar/ fruit intolerant. She changed her diet and what a difference it made in her life. Wow amazing. So I saw the change and after much persuading on her behalf I went and was tested. My test came back and showed I too had Sugar/ fruit intolerance also. This means that we cannot mix the two together. They must be 4 hours apart when eating them. I also had another one. Drum roll please…… Potatoes yes the potato family of foods. I have been eating them my whole life. It has been a few months now a what a difference it is hard to believe and it just seems to be getting better every month now. I have more energy now than I ever had in ten years. The every day body pain is going away. And get this it takes about 6 months to a year to see the full results of recovery. All I can say is Thank You Yehovah God for my wife. I can spend days writing what has happened but I will not bore you all. I thought brain fog was normal for me. It is gone. I now can work on more DOW , DOC charcoal projects and do more things now. 73 years old and feeling like I am 10 years younger.
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Thanks for sharing, I never knew either of those even existed.
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That sounds incredible, congratulations Bob, it must be a great feeling to get better day by day.
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Congrats Bob, I am happy for you and your wife 
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Bob, Great news. Thanks for sharing. That is amazing.
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Great news, Bob! Before we know it you’re younger than all of us and projects will be finished in no time 
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. . . . God is good!
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I had a visit today from Staffan, he has a Peugeot with a gengas unit with a central nozzle, didn’t know that it worked to run with wood and a central nozzle, but it seemed to work well.
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Bob,
I am praising God with you. What a time we live in where we can get this kind of test. Two years ago my PCP made an appointment for me with a dermatologist because of fatigue and severe psoriasis (head to toe). Since my appointment was 6 weeks away I joined an online psoriasis support group and spent many hours on youtube looking for a cure. Many people suggested leaky gut, inflammation, insulin resistance, poor metabolism and food sensitivities as the reasons for a host of ailments. I did a 7 day water fast then eliminated the usual offenders: flour, milk, sugar, seed oils, and high glycemic carbs. My new diet was primarily salad greens with sardines in olive oil, flax meal and balsamic vinegar. By the time of my appointment the psoriasis had cleared significantly and I felt great. The skin Dr. was really easy to talk to but she wanted to prescribe a biologic with side effects a mile long. I showed her pictures of my progress and suggested that I was healing fast. She said "OK come back in a month. It will take about 4 months but I can get this problem under control. One month later I was completely healed. The Dermatologist’s jaw dropped and she exclaimed, “What did you do?” When I told her, she said, “Well good for you, but my patients don’t have the discipline for that and honestly I don’t either.” I have since gradually added carefully to my diet paying attention to my reaction.
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Bruce, your story regarding the doctor wanting to prescribe pills is so typical of today’s doctoring. Doctors are taught in med school all about medicines and precious little about nutrition. The pharmaceutical companies have embedded themselves deeply into our health system. I think their “cures” are worse than the disease.
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Bruce,
I think your doctor revealed why doctors tend to prescribe so much medicine. Their patients want a quick solution which does not involve much effort on their part. The doctors realize that if the solution is involved and takes much effort, their patients are simply not going to do it.
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Quite true SteveB.
In almost any community around me here PNW larger than say 3000 someone trained and skilled as a Nutritionist has set up a shop.
Some of these folks are previous MD and Physicians Assistants. Who the want to actually help people. I know of many whom have been with testing analysis and then individually crafted foods planning . . . AND HAD THE WILL POWER TO STICK WITH IT; been helped greatly.
These provider get almost no Insurance’s payments. They must work in clients cashes.
Ha! My nursing Wife has many times asked me to go to a Nuritionist for my short term memory difficulties.
And I have asked her many times for us to drop all of the monthly pay-out health insurances. That we could cash pay for needs using the prevalent Urgent Care pay-for providers.
And she counters with what about cancer? Long term debilitating conditions?
And I’ll say most in ways are created by the American Lifestyle “I-must” endless pursuits.
We are all going to die someday, anyhow. Let your adopted Lifestyle play out as it will.
Die at home in your own place/space has dignity.
Die’ing in an artificial 21st Century space; plastics isolated from human contact; hooked to machines has very little dignity possible.
That is me countering more than a bit unfair; her being a previous Hospice nurse and now 30 years a Home-Health nurse.
I am trying to shock her away from the industries of implanting and enhancing fears-as-motivations.
We Americans above all insist on Freedom of Choice. And the true of us are willing to carry the consequences of our choices. The good. The bad.
Steve Unruh
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Another reason doctors prescribe so much medicine is because drug reps constantly visit their offices. A nurse posted a video where she disclosed that EVERY day at their practice, a rep shows up with food - donuts, Chinese food etc.
Some pharma companies incentivize docs to give child vaccinations with cash (bribes). If the docs vaccinate a certain percentage of their patients they get $. The higher the percentage, the more money. That’s why you often hear of practices telling parents to take their children elsewhere if they refuse the vaccinations. 
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To all my northern friends, happy solstice. You have entered the summer season and can look forward to glorious warm and long days. For me, the winter solstice means the days finally start getting longer. Granted, by only seconds for a while and they will still be cold and short, but at least the trend is in the right direction. So we all have something to look forward to.
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