It's an onan opposed twin with a generator built on.
I did learn there is a GM module with 5 degrees of retard available by grounding the 5th pin. D1941 is the pn.
Spark on dead stroke.
- Thread starter 95 shaw
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I did learn there is a GM module with 5 degrees of retard available by grounding the 5th pin. D1941 is the pn.
scooter_trasher
Member
If Onan doesn't have a split fire ignition, you may do well to check with some bmw r90 guys , they're horizontally opposed twins , if anyone has a hall effect triggered split fire ignition for a opposed twin it will be BMW
scooter_trasher
Member
Even if there is unspent fuel in your exhaust your engine isn't going to make combustion on your exhaust stroke without compression, sounds like your wood gas , (which I'm not familiar with) is the problem, but if your only getting half the power you need , you use it stationary and are stuck with the wood gas, I would use a bigger engine , like a junk yard four banger hooked up with a coupler
The objective of this exercise is for an off grid power supply. Being able to use an already available fuel supply is the idea.
This is an educational project as well.
Also being budget minded.
I purchased this old rv generator for 35 dollars.
I've cleaned it up and have it running on gasoline. I want to run it on wood gas and see what I can do to improve output. This is new to me. But doing some research, I think I can see where it can be improved.
Could run it on gas and be done with it. No need for improvement, but I wouldn't learn anything either.
Again, fun to think about. And tinker with.
Edit
Do you know for a fact that firing the spark plug on the exhaust stroke is not costing you power?
How did you reach this conclusion?
scooter_trasher
Member
(Do you know for a fact that firing the spark plug on the exhaust stroke is not costing you power?
How did you reach this conclusion?)
I've had Harleys for years they have always dry fired on the exhaust stroke , even the evo Harleys and Twin cams with electronic ignition, I have seen guys spend hundreds of dollars back in the early 2000s for split fire ignition with what amounts to zero performance or fuel mileage increase, you need four things to make a combustion explosion, fuel, oxygen, compression and an igniter (spark or flame), on your exhaust stroke your cylinder is full of a burning fuel & oxygen mix (flame) , (put a short straight pipe on and you'll see it),your spark event could not cause combustion ,the flame is already burning and the exhaust valve is open so it couldn't make combustion if it was a fresh oxygen and fuel mix ,it would need COMPRESSION, people who spend a bunch of money are over thinking , trying to divide that electrical spark in an attempt to get a hotter spark on the compression stroke and would be much better off just getting a hotter coil or running duel spark plugs, if you have a slow burning fuel you may help it by advancing your timing .
How did you reach this conclusion?)
I've had Harleys for years they have always dry fired on the exhaust stroke , even the evo Harleys and Twin cams with electronic ignition, I have seen guys spend hundreds of dollars back in the early 2000s for split fire ignition with what amounts to zero performance or fuel mileage increase, you need four things to make a combustion explosion, fuel, oxygen, compression and an igniter (spark or flame), on your exhaust stroke your cylinder is full of a burning fuel & oxygen mix (flame) , (put a short straight pipe on and you'll see it),your spark event could not cause combustion ,the flame is already burning and the exhaust valve is open so it couldn't make combustion if it was a fresh oxygen and fuel mix ,it would need COMPRESSION, people who spend a bunch of money are over thinking , trying to divide that electrical spark in an attempt to get a hotter spark on the compression stroke and would be much better off just getting a hotter coil or running duel spark plugs, if you have a slow burning fuel you may help it by advancing your timing .
So, no empirical evidence?
For an engine running well within its performance envelope, little, on no difference could be visually noted.
Most industrial engines operate with this compromise.
I know advancing the timing is probably the first step to improve performance in this application.
As for the other items you list as must have, comprises are made for each of these.
Extremely lean or rich mixtures can be ignited.
Early ICE engines had very low compression ratios.
Does the spark happen during overlap?
It doesn't have to be a glaring problem to cost power.
Just some thoughts.
scooter_trasher
Member
If you think adding a spark to a cylinder full of exhaust flame and an open valve is going to create noticeable power robbing combustion , run with it and reinvent the wheel, but wrap your head around this , the purpose of a compression release on a small pull start engine is to prevent early 20 to 30 deg advanced spark from causing combustion on a fresh fuel air mixture that would kick back and rip your arm off !
Remove the compression release on any modern 4 cycle industrial engine. Bigger is better.
Leave the spark plug wire disconnected, or ignition turned off.
Rip on that starter rope. And tell me how that treats you.
This whole thread is about trying something different for some small gains.
Ounces make pounds.
Clean up a couple compromises, gain a few watts of power.
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scooter_trasher
Member
Your looking past the obvious problems to try to find a minuscule improvement in performance, if your fuel source lacks the energy to turn the generator at it's engineered optimal 3600 rpm? and your only turning half of that at 1800 ,you need to burn more fuel to make the power needed, ( bigger engine ?) if it has the power but just runs too slow ( like a diesel) you may do well looking into gearing, so that your 1800 rpm engine will turn the generator 3600 rpm, a jackshaft and a pair of pulleys will do that.
The onan generator is designed to run at 1800 rpm.
Already direct connected.
Budget says make use of what you have.
Time, like I spend here, has little effect on my bottom line.
Except maybe I learn how to learn.
I already know the sky is not falling, and am pretty sure the earth is not flat.
Value, like beauty is in the eye of the beerholder, oops, I mean beholder.
Lol
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I worked on and occasionally drag raced turbo v6 Buicks. The stock ignition is a waste spark system (3 coils, 6 cylinders, each fires on every stroke. Stock ignition and ECMs were raced down into the 10 second range. If there was horsepower to be gained, the Buick engineers of that era (very interesting history) and the aftermarket would have ditched it.
That being said, if it was a 1hp difference, it wouldn’t be much percentage wise on a 700 HP engine, but in your application 1hp is huge.
I agree, it’s a cool thought exercise. I don’t let anyone dissuade me from my ideas, neither should you. Post some pics if you can. Good luck!!
That being said, if it was a 1hp difference, it wouldn’t be much percentage wise on a 700 HP engine, but in your application 1hp is huge.
I agree, it’s a cool thought exercise. I don’t let anyone dissuade me from my ideas, neither should you. Post some pics if you can. Good luck!!
https://www.offshoreonly.com/forums/general-q/268503-delco-voyager-est-igniton.html
Found this marine hei ignition with an advance curve built in.
Just got to figure if it sets total advance, then drops back for idle retard, or vice versa.
Instructions use a timing plug to set initial timing.
I read that some of the computer controlled ignitions look at base timing(mechanical timing) and advance to fire the next event. Makes so you could actually set at any zero and move timing a predetermined amount before the next timing event.
Not sure this will do that.
Still working on the wasted spark thing.
Found this marine hei ignition with an advance curve built in.
Just got to figure if it sets total advance, then drops back for idle retard, or vice versa.
Instructions use a timing plug to set initial timing.
I read that some of the computer controlled ignitions look at base timing(mechanical timing) and advance to fire the next event. Makes so you could actually set at any zero and move timing a predetermined amount before the next timing event.
Not sure this will do that.
Still working on the wasted spark thing.
I saw a video where the guy used a generator like mine, and set a separate timing wheel. The adjusted with an arduino for timing advance.
My programming skills not that advanced.
Haven't pursued to see if there is an open source sketch for that application.
If could calculate for advance from previous series of sparks, could use breaker points for base timing, and advance from there.
And maybe cover wasted spark also.
MSD used to make a manual “timing computer” back in the day before aftermarket EFI units came to market. Not sure if they still do or if you could find an old one.
Speaking of MSD - Multiple Spark Discharge - used to fire for about 30 degrees at low rpm with the concept that it continued to ignite the mixture for better combustion (at higher RPM, it just became one fat spark).
Speaking of MSD - Multiple Spark Discharge - used to fire for about 30 degrees at low rpm with the concept that it continued to ignite the mixture for better combustion (at higher RPM, it just became one fat spark).
Not all of them were belt driven.........
Shaw, I haven't completely read this thread, but you mentioned a post I made about ignitions. So let me see if I can clarify it. The post I made was for a completely different objective. We were trying to gain a faster discharging coil on a single cylinder engine and found that if you use a twin lead coil (we used a Honda CB72 coil) and ground the unused spark plug lead straight to the frame, it produced a slightly higher voltage spark on the other used lead. This was because the coil was getting the benefit of the lead that did not have to jump to ground. This also produced a coil that would operate at a slightly hotter temperature (never gave us a problem, but???).
Now, it appears that you are just trying to not fire the sparkplug during the overlap cycle. If this is true, I would try to use an older two cylinder Wico Magneto and just grind off the distributor part for the second cylinder. The Wico mag has an automotive type distributor attached to the end of the rotor to determine which cylinder fires. If you have multiple cylinders, use a mag with 4 spark leads and grind away. Look on EBAY and you will find bunches of different Wico mags and configurations and some are fairly inexpensive. They were/are used on quite a few different engine types. Don't worry about parts for them because they are almost identical to a Fairbanks Morris mag (they may be the same company, I dunno???). There are bunches of different new and used ones on EBAY. Some may look bad but I have never seen one that would not work.
Anyway, Hope this helps. Good Luck.
Now, it appears that you are just trying to not fire the sparkplug during the overlap cycle. If this is true, I would try to use an older two cylinder Wico Magneto and just grind off the distributor part for the second cylinder. The Wico mag has an automotive type distributor attached to the end of the rotor to determine which cylinder fires. If you have multiple cylinders, use a mag with 4 spark leads and grind away. Look on EBAY and you will find bunches of different Wico mags and configurations and some are fairly inexpensive. They were/are used on quite a few different engine types. Don't worry about parts for them because they are almost identical to a Fairbanks Morris mag (they may be the same company, I dunno???). There are bunches of different new and used ones on EBAY. Some may look bad but I have never seen one that would not work.
Anyway, Hope this helps. Good Luck.