What is considered the most powerful and popular engine to replace a 11 hp B&S?

Well everyone i am currently working on a lawn tractor and im torwards the end of tear down and it's getting close to time to put her back together but with a few upgrades . Previously i was going to try to find all the parts to the 11hp briggs & stratton and rebuild it, but then i decided i wanted a litle more power and the 11hp wasnt worth trying to find all the parts for and then rebuilding it . So this is where im at now. Now heres my question whats a good , Popular and Powerfull ( well when it comes to lawn tractors anyway), engine to replace it with? And maybe what the engine comes out of? Sorry for the long intro to question.

The 'bellybutton' (everybody has 'em) choice would be a 28ci (11-13.5hp) Briggs flathead. They aren't power-houses, but they are simple, reliable, and easily found. IMO a good step up would be an opposed twin Briggs. They are just as simple as the single flatties, and make tons of torque. The downside is they are much heavier, and they like to drink...

by popular i mean as in i can buy parts for them like rebuild kits, piston rings, seals that kind of thing.

if you want power and something that has parts that are commonly available then id probably look for a V-Twin briggs engine that is OHV just because they are whats in newer lawn tractors.

im also loking for a pearless transmission any ideas where to find one?

I have a Briggs 17HP OHV single and it does really well. Plenty of power. One downside is they have really high compression, so your starting system needs to be in peak condition. I'd suggest sticking with the good ole Flathead engines as they are much easier to work on. Kohlers are good too. Very reliable. I have yet to see someone swap a Honda twin 20HP engine in a mower.

Tractor Man Jeff wrote:

I have a Briggs 17HP OHV single and it does really well. Plenty of power. One downside is they have really high compression, so your starting system needs to be in peak condition. I'd suggest sticking with the good ole Flathead engines as they are much easier to work on. Kohlers are good too. Very reliable. I have yet to see someone swap a Honda twin 20HP engine in a mower.

Hey im in the middle of reading you build thread and i think im going to take a few ideas from it if you dont mind. It looks like you did awesome work. Hows the engine power wise? Whats the honda twin 20hp engine off of? Is it verticle shaft or a side shaft motor because im in to trying things that arent done alot as long as it has replacement parts i can buy. Not meaning to get off topic here but did you ever figure out your braking system?

For reliabilty and easy to find parts , cant go wrong with a classic flathead briggs - single or twin cylender - most of my flathead motors are almost as old as me, still start and run awsome with no oil burning.

To me OHV motors are sort of annoying - they need regular valve adjustments ( or should get them) , older OHV motors are better because of new EPA laws, they need to be more compliant and run cleaner , which means no carb adjusting - and lower power - swapping the carb would probably help a little.

The only way an OHV could make any serious power to throw a bunch of speed parts into it and ditch all the inferior stock parts - few years back we went to a lawntractor race - the super mod class was using 20 plus HP v twin short blocks , stuffing them full of parts and boring them out to near 80HP - i have to say those things went freaking fast! The bad thing is i bet it wasnt cheep to do that, probably dropped more then $5000 into those motors.

Used to be back in the day, you could find cheep parts tractors on craigslist - heck i got my twin cylender motor tractors for under $50 - one was even free.

One motor had water to the top of the carb , almost thought it was ruined actually - but i cleaned all the water out, sprayed PB blaster in it to free things up, put it all back together and after a few cranks it fired right up - that has to show just how good old twins are.

Recently i picked up a GT murray that has 1" front spindles and 1" transmission axles for $50 plus a ton of ATV wheels - didnt have a motor, but i have some spares around.

Id say scour craigslist for either transmissions or another engine or and old one that has both - just have to be patient is all - or can buy a new motor for around $3000 - northern tools carry them.

I still don't have brakes. I down shift to somewhat slow down, which probably isn't the best thing to do. Honda makes one vertical Vtwin at 20 HP. Very $$$$$. My Briggs has quite a lot of power. Not too much torque, but it does well for me. Pulled some 10'x12' chicken pens easily.

if you want power, you want a twin. My craftsman has a briggs 19 hp opposed twin and i couldnt ask for any more power

I got a opposed twin. It does have alot of torque. It also have a port job on the intake and exhaust ports. Down side is it does drink lots of gas.

I have a v-twin 20hp briggs and I love it.
Parts aren't that expensive and are easily found on partstree.com

All twins are thristy - isnt any getting around it , but for the power - its worth it.
Just bring another gas can along.

Well I guess no1 on here has an onan.. they (imo of course) are the best engines out there I have a 78 onan twin 18 and that d*m could pull a house down if it had the weight. They are some what heavy, and can suck gas if u take the gov off and rev high.. but if you run it like it should be ran and keep it lubricated up it will last u forevrr. I've sunk mine in water, it now has a bigger briggs 20 carb on it, it has a turbo on it and it just won't die.. it was locked up wen I bought it. Sprayed wd40 in the head where the plugs go, let it sit over night and have been beating on it since..

I have a 20HP onan twin opposed horizontal shaft motor - id put it on my wizard 'go kart' tractor - but thing doesnt have any spark - need to locate a twin wire coil pack ( dont think it has points - its a mid 90's) - im thinking maybe a motorcycle coil pack would work.

The starter mounted solenoid is also screwed - id be able to bypass that with a standard solenoid tho.

Be awsome to run that motor, its the biggest motor i own.

dangeroustoys56 wrote:

I have a 20HP onan twin opposed horizontal shaft motor - id put it on my wizard 'go kart' tractor - but thing doesnt have any spark - need to locate a twin wire coil pack ( dont think it has points - its a mid 90's) - im thinking maybe a motorcycle coil pack would work.

The starter mounted solenoid is also screwed - id be able to bypass that with a standard solenoid tho.

Be awsome to run that motor, its the biggest motor i own.

No Idea what your mean by the "twin wire coil pack" But I have a twin briggs, Just like a champ...when it runs..Hard starts...ANYHOW It just runs 2 magnetos, which is actually pretty simple to wire up, and even mount.

dangeroustoys56 wrote:

im thinking maybe a motorcycle coil pack would work.

Some Victory & Harleys use twin coil packs. I've read that some early Hondas do too, but I'm not sure which models. Also 2 regular 12v auto coils wired in series will work. All of those choices are probably Much cheaper than an OE replacement. Onan parts are way high.

@ Murray modder Onan twins have a double lead coil, looks like a regular 12v auto coil but with 2 plug wires. Briggs also used 2 wire coils on opposed twins.

So are the Coilpack a single magneto that runs to two plugs?

Most older twin and inline 4 motorcycle engines used twin wire coils. 4's used a pair of them.

All you have to worry about is matching the ohms rating. If they don't match you'll eat coils.

79-up CB750's used Dual wire coils with replaceable plug wires and are rated at 3 ohms. Older ones generally have rotten wires, but have a 5 ohm rating.

Canadians can look up cheap universal parts at Motovan.com, and can order them through most repurable motorcycle dealers. Twin pack universal coils should run about 25.00

These are just coils. There is no magneto.

You need to have a system with a seperate magneto, or points.

Most bike engines used a wasted spark system, so one coil would fire both plugs at the same time.


On a 4 banger, they used twin coils

Coils need an electrical signal from a power source (points or CDI) to create the voltage for a spark.

A magneto uses a magnetic impulse to create a spark from a rapidly passing magnet ( flywheel),
The impulse is converted to a spark in the unit itself

Im not to bright on engines, but with engineering I am, so, whats the difference between a coil and a Magneto? (DOnt they both create a spark from highly spinning magnets?)

Murray modder wrote:

So are the Coilpack a single magneto that runs to two plugs?

Yes, they both use a single coil that fires 2 plugs. Briggs used a magneto ignition, and Onan used a 12v powered coil

A magneto ignition (like Briggs uses) generates its own energy, whereas a powered coil runs of an existing electrical system, and fires by either points & condenser or electronic ignition.

SO basicly, one is self supplying and the other one draws energy from the battery? Wouldnt a magneto be better then?

Generally speaking, yes a magneto is better because it is self-sustaining. No points to clean & adjust, and if the charging system dies the engine still runs.
Older engines like early K series Kohlers had no provisions for a magneto. If the starter/generator failed it became a total-loss system, where the coil slowly drains the battery.

Magneto's are superior, a good one puts out a hotter spark, and is self sustained. as AF mentioned. There is a reason that they are used in race cars, extreme performance engines and air craft.

It depends on what your building. If your building a racing or fast mower you should go with a twin or opposed. But if your building and offroad mower it better to have a single, because if you have a lot of weight up front (unless its all wheele drive) the front end will sink in the mud.