Efficiency/Reliability of Small Light engines

[RiderofBikes]

Sooo... maybe theres a thread or two somewhere about this. Motorcycle/scooters is helpful in that particular category, but i haven't found too much discussion about "regular" 1-2 cylinder gas/diesel engines. Like those that one would use for a Go-cart or (Horizontal shaft) Mowers, and industrial work machines, to use for various projects.

Has anyone done a project from a relatively puney "5HP=196cc Briggs&Stratton" or a larger/similar type engine here?

One thing i do know, is that maintenence is a consistant chore, and the Carburators suck and are utterly poor performers. But what if you were to replace them with better Carbs used from small displacement scooters/motorcycles for better tuning of engine power and fuel performance??

Where would be a good place to purchase these Engines alone? Anyone know of credible/cheap online sources?

[Ryland]

Honda has some better quality small gas engines like their GX line, as small as 25cc and all the way up to 620cc, the 160cc engine is a 5.5hp, so smaller displacement for the same HP, mostly because of improved combustion chamber shape and the over head valves, the classic B&S lawn mower engine doesn't have an oil pump but instead splashes the oil with hopes of it splashing the parts that need constant lube.
Some of the newer lawn mower engines have oil pumps and oil filters on them, this is a drastic improvement an does a lot to extend the engines life.
If you look at B&S engines, their design has not really changed much in the last 100 years and they have floated along by being the standard.
If you are operating at a single RPM then a simple carburetor works quite well, it's when you start to throttle the engine back that you need to get fancy, keeping the engine temp even, the parts lubed and the inside clean, that is what is going to really help make an engine last, over head valves and quality bearings help it use less fuel too.

[RiderofBikes]

yeah, i looked at some of the Honda engines, there quite nice and new models seem to be priced reasonably. Kawasaki as well. The only reason I had mentioned the B&S, was for simplicity, of just buying cheap, and using that particular engine from a riding lawn mower or snow blower specifically(horizontal shaft). I've bought some products before that were cheaper overall, buying the entire product than just a single part.

There's an 11hp 8500Watt Generator (Troy Built brand) for like $550. would be cheaper doing that then buying the engine out-right. 306cc i believe, seems like it might have more use on a home built 4-wheeler or small single-person faired bike type project.

Maybe i'll just have to break down and take a chance on my own project when/if it comes time i have some spare cash.

[oil pan 4]

I dont what you are trying to build or how fast you want to go.
But you are going to need 10 to 12 horsepower on tap just to drive a small car at 55mph.
You will need more than that to get up to speed sometime with in that same day and get over hills.

[niky]

250cc and 15hp to hit 50 mph in a four seat car, given average aero. Probably less if you've got good aero and a small frontal area.

[NeilBlanchard]

You can look at the Edison2 VLC for info on this: a 4 seat, 830 pound curb weight, very low drag (Cd 0.164) had a 250cc turbo charged single cylinder engine. It got ~110MPGe (burning E85) on the EPA Combined test; which is impressive.

The Electric VLC got ~245MPGe with a DC motor, which is even more impressive. It is also a lot quicker and much, much quieter.

[RiderofBikes]

Originally Posted by oil pan 4

I dont what you are trying to build or how fast you want to go.
But you are going to need 10 to 12 horsepower on tap just to drive a small car at 55mph.
You will need more than that to get up to speed sometime with in that same day and get over hills.

I started this http://ecomodder.com/forum/showthrea...ces-23130.html A few days ago, maybe it'll give you an idea.

55mph tops is 1 goal, the other is for more Proof of Concept, Starting easy. Just to see what I can Minimally "real world", get away with.. A standard non tilting 3-wheeler is best, and later if all goes well, i can start to experiment with tilt. Then scale up for the Major build with most of the bugs worked out before hand.

Most of the time it would be used for City Commuting, and short <15mi round trips, and 90% traveling no faster than 45mph. Over relatively flat roads.

I figure for the time being, at most 100lbs for an engine/tranny setup, another 2-400lbs for chassis + driver weight.

EDIT: quick search, best example

[stillsearching]

Small and cheap engines are built to be just that - small and cheap. I can't comment as much about efficiency but I can say something about reliability.

Some rules of thumb based upon when I was researching off grid power and generators... a typical "small gas" engine will last 700-1000hrs before theyre done. It's possible that some maker (maybe Honda if anyone) makes a higher quality longer lasting product, but your typical lawnmower sees such intermittent use (what, 2 hours every week?) that they last for years and give the mistaken impression of being reliable. Try one in commercial service sometime. A 3600rpm gas genset will wear out the engine within just a couple weeks if it's on 24/7.

The high speed 3600rpm diesels are better, but not hugely better. They are made to be cheap again but have to be built heavier due to pressures and such. However because they are more expensive, no more powerful, and usually made by GOOD manufacturers (Yanmar) they will outlast gas engines by maybe several times maybe more. I have the least research information in this category though.

The "medium speed" 1800rpm diesels is where many of your industrial diesels come into play - Hatz, Perkins, etc. This is what you find used in say farm utility tractors, those weighing 5000lbs and meant for heavy duty constant commercial or farm and ranch use. This is not your Sears Gardenmaster (which with its 3600rpm gas engine will die in 700-1000hrs) or whatever, these will still be running after hard use. They cost waaaay more than gas engines of similar power, weigh quite a bit more (they have to make the power at half the rpm) and are made for truly constant use. 10,000hrs of use is probably not unreasonable to expect by what I understand. These actually will run your genset head 24/7 all year if you need it to.


If I wanted to build some small trike or runabout I would probably look at motorcycle gas engines that have a reputation for long life. Yet even those seem lacking compared to many cars.. There are motorcycles that are almost worn out at 10,000 miles and those that will go 100,000 miles. Yet nearly any car will go 100k miles.

I've seen people put single cylinder Hatz industrial diesels (typically 3600rpm types) or Yanmars into motorcycles, I would imagine they would return the longest life and the best economy possible. Were I to build a faired scooter or similar thats what i'd want to put in personally. (and ideally with some kind of hydraulic hybrid using an accumulator since acceleration is where they are a bit deficient)

[Frank Lee]

I wouldn't put all "cheap" small gas engines in the same reliability category. The cheapest of the cheap have aluminum bores and plain crank bushings; as noted, they are good for mowers and such that see minimal hours of use accumulation over time before they wear out and become basically not worth rebuilding. But if a small cheap gas engine has a cast iron bore and ball bearings on one or both ends of the crank, I don't know why it wouldn't be able to live as long as, say, a similar motorcycle engine... or maybe even longer, given the lower rpm operating range. Plus as of recently, we have many OHV choices whereas back in the day small engines were almost all flatheads, which are much less fuel efficient.