Without a gas break down one can only guess what the change in BTU of the fuel is with the water gas.
Hydrogen burns fast and at atmospheric pressures the lower and upper flammability range is between 4% and 75%.
Its also requires less spark energy to ignite.
( source Wikipedia )
This is exactly what you want to counter act the effects of Nitrogen dilution that tends to slow the speed of combustion, cool combustion and makes ignition harder.
Carbon Monoxide has an upper and lower ignition of 12% and 74%.
This is also very good auto ignition temperature of 1148f at atmospheric.
But not much information on how it behaves in an engine.
From the gasifiacation archive there seems to be some discussion that CO will decompose easily under heat ( so we must cool producer gas quickly after it evolves )
But little info in how this effects it as fuel.
Conclusions:
The hydrogen will push the excess of the CO diluted with N down to range of performance we would expect of a low BTU High octane fuel with good ignition properties.
This might explain how some folks run a wider range of lean fuel air mixtures than you might expect to work well.
Gasoline works best slightly rich of its ideal mix
Hi Wallace,
The main advantage from the hydrogen mixed with CO is the flame speed … hence the mere presence of hydrogen above a certain % makes it un-necessairy to advance the ignition timing even must be retarded…
The second advantage is the ability to run on higher RPM’s since the CO flamespeed is to slow for short stroke engines above 3000 - 3800 RPM
I think in the library section are some case study’s about this, if not i will upload some…
Anyway… its a joy to have this topic and your knowledge about those sweet engines / honda clones…
Yes Jeff your right.
There is probably an optimal rpm for the fuel…
You want slow enough to take full advantage of the gas pressure and expansion ( not outrunning the the speed the fuel burns at.)
You go too slow you start to loose heat to the cylinder liner.
You want an ideal piston linear motion and I do not know how to calculate that.
Its quite observable though.
100LL tends to burn slower than Mogas and its more than just octane.
the slow turning speed and large bores of air craft engines need a different kind of fuel than cars.
anyway, imo, the longer burning time from the mixture, CO only, is in favor for small bore , long stroke, same goes for most slow fuels and especially when high torque at low rpm is desired
If the engine is running fast and the gas not finished burning/expanding when the piston gets back up…
Hi koen, the flame front could spread across a small diameter piston faster than a larger diameter piston. At least right after the spark. There is a lot to learn out there. We’re lucky that this stuff works without us not understanding exactly why…
That’s why i do the “step by step” approach… with the engines i mean…
1: stripped the carburator, who need that restriction anyway…
2: tooked a GX200 to do the job of a 160, (some advice from SU i picked up on the fly…)
The 200 has the same bore but a longer stroke
3: finally advanced the timing…
I can not prove it, but I suspect based on a conversation with my cam grinder that the OEM Honda GX160 cam might have a profile that works better for this aplication.
Koen:
Tips and tricks for you now.
If you are have the opportunity to strip a 160 now use the head and piston if it has a short skirt and flat top.
If it does not you could cut the skirt by hand to fit I have done this and it works.
If you bolt on the Honda GX160 flywheel it has the extra timing already built it and you will not need to check with a timing light.
This is Z8H I hand cut this with a dye grinder.
This is Z4M
1310X-Z4M-000
You have to look close too see but look at the wrist pin hole.
The piston ring should have a gap less than .012 inch but more than about .005.
I should provide metric for you, but for fine tolerances I have never made the switch
To help with breaking in an engine has anybody used a motor or engine to turn over the engine being broke in…? I know that it was common practice back in the day.
I turn them over first…
Literally upside down and get the oil to coat everything.
Start, warm up check for leaks tune as required shut down after warmed up.
Drain oil, check for metal, re torque look for issues and then refill.
Second start put a moderate load on it for half an hour use it carefully and shut down again
Check everything again, adjust valves if required.
Change oil again ( oil is cheap ).
Third run at operating rpm and load.
Run for a tank of fuel.
Drain oil CAREFULLY check for metal or issues.
Put motor into service ( ready for the track )
Yes I used 2 litres of oil without ever doing anything but its better to be careful and sure.
Damn Wallace
I stripped a brand new GX200 to see the diffrence between the 160 clone and the Honda 200…
summary:
160 = bore 68mm stroke 45mm (162 cc)
piston reaches above the cylinder wall 0.1mm
Piston face cavity has 3cc
Original headgasket is 1mm thicknes = 3,6 cc
cyl head cavity is 14 cc
Camshaft and toothwheel are plastic
actual physical CR: 162 cc to 20 cc (14 from Cyl head + 3 from gasket + 3 piston )
Please correct me if i am wrong here
should i take displacement + cavity’s as start volume to be compressed into cavity volume, then i have 182 to 20 or about 9:1
effective CR: (displacement @ WOT * 0.7) to 20=
162*0.7=113cc to 20 = 5.6:1
Now the Honda 200:
bore 68mm stroke 54mm (196 cc)
Piston stays below cylinder wall for 1mm
Piston face cavity about 2 cc
headgasket 0.15 mm = 0.54cc
cyl head cavity = 20 cc
actual physical CR: 196 cc to 26 cc (3.6 from piston to cylinder wall, 2 piston face, 0.54 from gasket, 20 from cyl head.)
so: 222 to 26 = 8.5:1
effective CR: (displacement @ WOT * 0.7) to 26=
196*0.7=137cc to 26 = 5.2:1
will post some pictures today, later on…
Things i want to try:
Flatten the 160 piston so its equal to the cylinder wall, even might flatten the cylinder walls as well
This will reduce the cylinder cavity to 2 cc
using the thin gasket from the 200, reducing from 3.6 to 0.5 cc
gain: 4.1 cc
This would raise the physical CR to: 162 +16.5 to 16.5
178.5 to 16.5 = 10.8:1
Effective CR @ WOT:
6.9:1
There are as many idea’s about breaking as there are mechanics. I have come to believe you should break in the same way you are going to run it.
It can be clearly understood that the parts will move and wear in differently when under combustion pressure than free spinning.
Here is my reasons.
On these engines with the new 1mm ring set you have less material to work with.
You have a less time to seal up.
SO I suggest you do the warm up and tune part first checking for leaks and such and shut down.
Sometimes ( especially when yo mix and match parts like I do ) things go wrong.
A leak, over heating and scuffing I oil control rings jammed up because you screwed up on install yes it happens to everyone on at least one engines ).
The second and third steps I suggest are more about watching the oil and looking to see its shedding the right particle size.
But this is also a brief period and we are under a clock.
Third run up we are sure everything is OK.
We want to get some pressure on the rings and load up the engine so those skinny rings seat well.
I do whats called a Plateau finish on my cylinder so my rings have very little time to bite.
My engine is machined and ground and assembled to be as close to broken in as possible from the start.
I expect to see very little metal in the oil.
You might not go as far as me.
You will see more or less metal depending on how well you machine and hone and how tight your tolerances are.
But I am anal about this ( on race motors at least )
I also built some awful dogs out of scrap parts.
these dogs shed a lot of metal and ran hot.
But they settled down.
My suggestion is you make sure you build your engines as clean and tight as practical.
Run them up with the three step I suggested and get a load on them within that half hour ( but not a stupid load, work up too a rated load ).
The tighter and cleaner you are ( on spec good finish clean as a surgical ward ) the less metal you shed.
You see shed metal is wear, wear is life and the less life shed in your oil the longer they engine lasts and more power it can make.
Leave the oil sender or remove its up too you.
Just make sure the oil is on the dip stick where it is supposed to be.
Never run less than 600ml of oil ( unless you racing where less means more power and less foamy oil )
Koen:
I am not familiar with the current crop of GX series engines.
I suspected there was something like you said about piston pop up on the 160 looking at the new series of heads.
I suspect its the piston that is different and I suggest the ZH8 or Z4M as an alternative ( it will fit trust me )
In Thailand these pistons are about 10 USD at the dealer.
You are in he right place to find clones too, that is a very competitive area for engines and parts.
My suggestion is strip every blown engine you can find and look at it.
Also:
Most engines fail because of lack of oil.
but these are not always a right off.
If you put the crank shaft of one of those engines in bath of KOH ( caustic soda + water ) this solution will eat the aluminum off.
they you polish the crank with some 400 grit, them 600 grit in a cross cross pattern to make it shiny again ( very hard to make out of round if you count the number of strokes and move often )
You max clearance on the rod is .005.
you can cheat and sand .002 off a rod cap but more than this will cause trouble.
These are some of my dog motor tricks for making scrap run.
In conclusion Koen you want to find a head that has a small chamber and looks like this
You would be better to chose a piston that does not pop up above the deck as you have found in the new engine you opened up ( still a good engine but you must be careful about gaskets ).
You want to measure from the top of the piston to the flat part of the head squish area about .030 minimum space to make sure the piston will not contact the head.
more clearance is safer from a piston strike, but tighter makes for better performing engines
Some pictures of battleground Honda… and clones…
will make some pictures tomorrow from the cylinderheads 200 and 160
The 160 pops above the deck and the 200 stays below (to much )
Hi Koen, I think I’ve read that if you remove material from opposite the lobe and readjust valve train you end up with more lift. But I’m not sure about that.
i should have left “short” out
