small engine improvements

using nitrogen scrubbers to increase oxygen content in the intake air

Would it be possible to shave excessive part from the pistons?

You could port it. Pretty straight forward

>>14489644
i actually have an 11 HP honda sitting around that looks like that
need something to put it on maybe a gokart

>>14489650
wut?
That would just decrease the partial pressure of the nitrogen in the air.
You'd have thin air going into the engine it'd be like running it throttled all the time.
Peak cylinder pressure would be down, all the combustion chemistry would be screwed up.
I think that's a bad idea

>>14489689
Would it be possible to shave excessive part from the pistons?
Yes, but it depends on what you mean by excess.

Lets get back to the basics.
Power = Torque (Specific work per cycle) * RPM (engine cycles over time) / 5252 (constant)

Engine tuning is simple, it effectively all comes down to burning more fuel.
Whether you you this by burning more fuel per cycle (increase torque) or running more cycles in a given set of time (increase rpm), the result is the same.

There are two areas where you can make modifications.
Increasing fuel delivery and increasing engine speed. But generally its all a compromise and if you do one you end up doing the other as well.

>>14489644
Supercharge it!

you could try a leafblower to get boost, maybe it works on small engines?

>>14490456

My engine has a fan integrated to it, could nigger rig something to use it as force induction?

supercharger fed by a turbocharger with NOS. That will definitely get the lawn nice and trim.

i think alot about messing with hydrogen. I'd like to make a HHO gen, and run it on my mower, and see what it does. Probably massive killowatt gains

>>14489644
Woodgas.

File: 2016-02-19_15.47.13.jpg (19KB, 250x271px) Image search: [Google]

19KB, 250x271px

>>14490427

Well thanks

I was thinking about something like this.

>>14490704
Well that would defiantly make the piston lighter

>>14490738
probably fucks with the balance in a way you dont want

>>14490481
That could somehow work, but you would loose cooling (or have crappy supercharge-cooler integrated design) and have to modify carb somehow t work with higher intake pressure

>>14490810
If it's 2-stroke it also fucks up port covering and will not work

File: IMG_20140504_200540023~2.jpg (942KB, 2616x2039px) Image search: [Google]

942KB, 2616x2039px

>>14490812
The air box, and the air intake of the fan are both inside the hood, taking hot air in. So I thought making a cold air intake, outside of the hood. So it might make things even.

>>14489644
smog pump supercharger. You get a few PSI of forced induction.

https://www.youtube.com/watch?v=gERfFq8eAK0

>>14490917
It looks very dangerous.
I Like it a lot.

You can jug most 2 stroke engines (change you throttle linkage to allow for a 90* butterfly opening as opposed to 70* like most Briggs engines are set to. Other than that, if its a larger riding mower, look at using a turbo from a vespa welded to the exhaust. Then get a carb adapter to use a 150 CFM single barrel and you have a blow through turbocharger lawn mower, or a Honda Civic with a turbo kit. Both are the same really.

>>14490992

Well, mine is a 4 stroke 16hp briggs, wont do the trick. And the carb already open at 90°. If I sand off one or two millimeters of metals from the heads or the block, it would run a higher compression, right?

John Deere parts rep here.
Briggs and honda actually have aftermarket performance parts out there, just look around. Kawasaki and Tecumseh your only hope is porting and a better carb, unless you want to raise the revs which is usually dangerous because almost all small engines have plastic camshafts

>>14490909
Got any under the hood pics? Judging by what I see its the horizontally opposed briggs twin. Like most engines the cooling fan blows air over the cylinders but also into the airbox, you won't get much colder air making something custom. Your best bet is to bend(shorten) the governor rod just a little to make it rev higher.

I have a Honda gx390, they're 13hp and torquey as fuq stock. I put in a WAY better cam, advanced the ignition, thinner head gasket, and a straight header. Tuned the carb and the thing tears on my go-kart let me tell ya

Also
>AMA

>>14491271
>plastic camshafts
lol, good troll there.
I know for a fact that almost all Honda small engines have metal camshafts. I'd love to see some proof on your claim

>>14491288
>almost all small engines
>almost
Sorry about your dyslexia.

>>14491201

I would get it machined down instead of sanding by hand. If you fuck it up while sanding, your head gasket will have a shitty seal. Also if you take off too much you could run into clearance problems between the valves and piston.

File: thebesticoulddo.png (3MB, 1594x948px)

3MB, 1594x948px

>>14491271

I am pretty sure it's horizontally opposed too. And the cooling fan do comunicate with the airbox, but only through a small hole ( 0.5 x 1.5 inch). So I could maybe open it a little more.

And what about exhaust? I'm thinking there could be some benefits with a dual exhaust system.

>>14491336
Yeah def and you can stick your grinder in there while it's off haha. You'll need to give it more fuel to see any benefits though. If the mower is old enough you can just adjust the carb, if its newer you have to remove the jets and drill them out.

>>14491356

I just freshened up the carb, good deep cleaning, new diaphragm, new gasket and new needles. It's an old ass mower, I can adjust the carb. But I know jack shit on how to do it.

>>14491382
If it's too rich it will stumble under load, if it's too lean it will hunt at higher rpm. You just gotta mess with it.

>>14491446

I will try it again when spring comes back, way too cold right now.
But why do you say an external intake wouldn't do the job? Because right now, it takes it air in an enclosed area, sucking the heat of the engine itself and the muffler

>>14489644

When I was a kid in 4H I did a small engine repair project where I rebuilt the 7.5 hp Briggs in my go kart. I smoothed the con rod out, milled the cylinder head down to up the compression, larger carb, and custom exhaust. Seat of the pants it felt like more power. It pinged if I didn't run 93. That was before pump E85 was common or else I probably would have milled it more and set it up to run E85.

>>14491308

Sorry about your stupidity. Plastic camshafts in the majority of small displacement engines? That's absurd. There's not a poofteenth of proof of this claim.

>>14490823

Not true. Look up 2 stroke piston windows. This is done to increase the amount of charge from the crankcase to the transfer port.

>>14491610

What would be the benefit of smoothing the rods? If I am being gentle, is there any chance I fuck up the balance?

>>14491748
it's pretty common in low end mowers.
I have one but i'd have to rip apart a working lawn mower to show you.

>>14489644

I was looking into modding a Honda clone back when I was building my go kart. It's really easy to remove the governor and get some extra rpm's though the stock flywheel can explode.
There used to be a site dedicated to Honda and clone small engine aftermarket parts. They had flywheels, carb upgrade kits, etc.

File: Camshaft-Plastic-Iron.jpg (271KB, 1202x1602px) Image search: [Google]

271KB, 1202x1602px

>>14491748
You do know most small engines are considered throw away engines right? Why wouldn't they use cheap parts if its going to be thrown away.

File: 09272008-2008-8-9-Jr-Dragster-champion-Mackenzie-Butler-with-family-329.jpg (123KB, 800x554px) Image search: [Google]

123KB, 800x554px

>>14489644
This little fella might have some ideas?

>>14492097

I work on small Honda engines all the time at work. These engines are throw away. A new engine runs us about $600. To rebuild the internals is over $300. So on top of labor and the engine not being used and losing money. (I work at a theme park that has over 60 go karts.) it is most definitely cheaper and easier to replace then rebuild.

>>14492097
>>14492325

But that plastic shit I have not seen except for the governor.

>yfw methanol injected turbo lawnmower

File: best_hho_drycell.jpg (26KB, 537x319px)

26KB, 537x319px

And what about HHO? If I make a generator powerful enough for a car ( usually used to hybrid you car, more mpg and better fuel efficiency), I may be able to have great result. The only problem is electricity, and I dont know the maximum output of my alternator

>>14491774

Removes casting imperfections and inclusions. It can increase strength slightly by removing points that would crack otherwise. I shot peen mine too with a basic Harbor Freight sand blaster unit. I doubt you can mess up the balance unless you do a terrible job,

Some 5 hp based Briggs in junior dragsters make 50 hp.

Buzzed engineer here, with some light experience.

>B&S
These are hard to get anything out of without major modification. Usually, you can help the top end of these by messing with the governor to cut off at a higher speed, and messing with the exhaust. Fun fact: most B&S have National-Pipe-Threads for their exhaust, so you can easily make your own exhaust system.

SAE Mini-Baja races run these engines, so there is some information on how to mod them on the interwebs.

I tried shaving the deck in a 5hp horizontal shaft to get better compression with no noticeable result (except it hated ethanol blended fuel when that came out). Guessing I just fucked something up.

>Tecumseh
Pretty much the same as B&S. Governor is set WAY too low on these. Hard to get any decent power out of them. Go karts I've messed with responded well to air-box modifications (uni air filters) or just removing the air filter all together, if you're brave.

>Yanmar Diesel
Ran a '5hp equivalent' engine in the Shell Eco Marathon in Houston. Got 683 mpgs in the diesel category. Impressive engine. Ended up removing the resonator/exhaust system halfway through the competition and just straight piped it. Made no difference in the low end torque, but definitely helped in the upper end. Ran best on off-road diesel; noticeable difference between #2 and off-road.

>>14492776 cont.
>Honda
Usually the best out-of-the-box for small engines, IMO. V-twins and larger single cylinders respond well to exhaust upgrades. Hard to do anything to lawn mowers, though.

Have a 1978 XL350 motorcycle that loves the uni air filter and straight pipe. Have a 350X engine in a go kart that I made custom dual exhaust (single cylinder, dual exhaust valves) for, and that thing now revs until the valves float. Custom CDI boxes make a hell of difference on these.

>Kawasaki
Had a KX125 2-stroke for a while. Finicky as shit carb. After owning that, I can't imagine needing any more power out of a 2-stroke. Learned there is a big difference between 2-stroke oils, with Klotz being the best brand I ever ran. Also learned that reed valves make a big difference in power band.

rebuilt a briggs & stratton 5 horse in high school. Sanded the head down for higher compression. One guy in the class put his in a mini bike, and it had insane amounts of torque.

>>14492784 cont.

>>14492448
Made a few 'large-scale' hydrogen generators for a couple of large V8's (in an effort to help MPGs back when gas was 4$ a gallon). Had this awesome 2 gallon one that would make up to 50 liters per minute.

Short and long of it, hooked it up to a carburated AMC 258 ci straight six. Mixture was so far off on the carb, couldn't keep it runing under a few lpm. Output of the generator wasn't consistent enough to re-jet the carb to get it to run. Ran like shit always with the hydro on. Scrapped that one and put a different system on a Ford pickup with a 351 windsor with fuel injection. Fuel injection would throw a check engine light and run weird, but improved his milage from 11.8 to 13.2 (if memory serves right. It was about a 1.5 mpg increase). After tallying up all the expenses, we figured it would take about 30,000 miles to break even for the cost of materials.

Scrapped that one and closed the book on hydrogen generators. It wasn't worth it.

IIRC, the 50 LPM generator would draw around 15A. Unless you're running an older shitbox, your alternator should be able to handle it.

Explosive shit. Be careful with that stuff. Had a prototype blow up on us (because we were lighting off the vapors and thought a cigarette butt stuck in the outlet was a sufficient 'spark-arrestor'). The blast was so loud we had two different roommates run into the garage with 911 ready to dial. Found a couple of pieces of the generator housing in the neighbor's driveway.

>>14492820

And how did you do it? I read somewhere that you could glue sandpaper on a piece of glass, so you know it is perfectly flat. I know it's the poorfag way, but whatever.

>>14492858
Why would it explode? Where you trying to contain it? Because that could be dangerous. If there is one thing important that i've read about this, it's that you use a bubbler, so if something blow up, online the line and the couples cm3 in the bubbler would ignite.

>>14492917
Our bench tester was a modified 10 gallon acrylic fish tank. We used it to test different plate materials, voltages, AC vs DC current, number of plates, etc. This allowed us to tune it pretty well. We cut out a piece of acrylic for the top that the components would bolt to and then drop in from the top. Nylon fasteners and washers would hold the plates together, and they would seal it to the top. It had a 1/4" or 3/8" outlet for the gas, with about 18" of hose. We would seal the edge and clamp it down so we could measure how much LPM it would produce through the outlet by positive displacement (a 2L filled with water would fill in X amount of seconds).

So, I guess to answer your question, it was a semi-sealed aquarium with about 5 gallons of pure hydrogen and oxygen gas, yes.

The "bubbler" kept the flame from propagating to the tank, (we just stuck the outlet tube in a glass full of water), but that wouldn't work in the field. We needed a dry spark arrestor that wouldn't impede too much flow and work in the conditions of a vehicle. So we tried cotton stuffed in the tube, stainless steel wool (we ultimately settled on this), unused fuel filters, and a cigarette butt. We didn't think it would detonate the aquarium, but it did.

>>14493032

And so, what was the best material? I tried copper, and it turn the water brown. I tried alluminium, and there white stuff polluting the water again. I will try galvanized steel (road sign) in a dry cell. And I read the best plate layout was 5 neutral, 1 positive, 5 neutral, 1 negative.....

>>14493068
It varied based on current/voltage. For 12VDC, we found nickel was the longest lasting. It wouldn't corrode like the other metals, and would consistently put out the same flow rate over a thousand miles. I think we got some from a Home Depot for a restaurant swing-style-door kickplate, but was virtually unobtainable at a reasonable cost.. Unfortunately, we didn't get much tesing out of this because it was so damn expensive (Poor college student at the time).

316 stainless was a close second. It would obviously corrode and needed replacement after a few thousand miles (around every oil change) but could be bought at any home improvement store. We did the bulk of our testing with this.

304 stainless, and regular steel would corrode and pit pretty fast. It wasn't economical.

We tried aluminum flat plate and expanded-metal-foil (ECF). Flat plate would work only for a few hundred milesbefore corrosion would pit it so bad it would fall apart . Aluminum ECF would put out insane flow rates, but would only last for about a hundred miles, if that. We suspected that because the surface area of the foil was so much more than the plate it just worked better, and the aluminum would corrode until it wouldn't generate hydrogen anymore.

Aluminum in general we would just use until the plates didn't exist anymore, and then change them out. Like you said, it always left the water whitish with a lot of contamination.

I'm not sure why you'd orient any neutral plates. That defeats the purpose of electrolysis. For best output/maximum current draw, we always ran 1/1 alternating (+-+- etc). If we wanted a lower output, we would just remove plates. We messed around with some wider spreads (+++- - -) and it prolonged plate life at the cost of much less output. Ultimately, we wanted a small package under the hood and ran a few plates in a +-+- stainless steel configuration and changed the fluid and plates frequently.

>>14493192

I'll take that into consideration. What did you end up using it for? Because I know you can make a high temp torch, mostly for jeweller

Last bump

>>14496766
Wroooooong

>>14498607
What have you done?

Run it on e85, increase timing

how to tune the shit out of a 50cc engine.

Buy/make a new, more aggressive cam
Buy new valve springs
find max valve lift of new cam
Mill head / deck block till youre within 0.1" of that (safe limit for valve clearance)
(if you want to go crazy you can also flycut the pistons and mill the head further.
Port and polish
ensure you re-grind oilways (since we're going well below spec on the head here)
balance engine

You could look at also regrinding the head and fitting larger valves.

our 50cc quad engine is a de-stroked high compression 75cc scooter engine that i attacked with a CNC mill

Air cooled with a 12:1 compression running water injection

>>14500954
>0.1"
You mean 0.040" right, 1mm.