i have a ride on mower with a 16hp briggs and stratton,v twin engine hohc vanguard,great engine,but,the starter motors are so expensive,has anyone ever converted one into a hand recoil start,the mower is old but it seems a shame to scrap it when there might be a way of starting it.i have seen video of starting one with a electric drill and a socket on the flywheel but the thought of a socketectomy is a tad offputting,many thanks for all advice,oh!,and happy christmas all
Or even based on piston area - iirc. I suppose in the dim and distant there was a correlation of engine piston area to HP, but that got left behind quite rapidly from the 30s onward.
piston area..which as another poster points out leads to long stroke engines of 'low' horsepower but high displacement and quite decent brake horse power.
Example: BMC A series 948cc engine works out as just under 10HP but actually developed a massive 30bhp in its typical stock single SU configuration..
Thats a long stroke. You might have more HP for the same displacement with a shiortyer stroke.
A typical BHP range is somewhere between 30bhp per litre (VERY stock basic 4 stroke engine), up to 100bhp per liter for a tuned 4 stroke..or up to 300 bhp per litre or more if you can turbo charge it or get the revs up.
I.e a 1 liter normally aspirated engine produces more or less the same peak torque no matter what it is, but if you can get the revs from a morris minor 2500, 30 bhp to something say in the 5500 class. as - say - a twin SU midget had, you were up to nearer 65bhp and with balancing and tuning you might take that to 7500, and get 80-990 bhp..whereas an F1 engine limited to 18,000 rpm gets around 850bhp from 3.0 liters: That's nearly 300bhp per liter, but with peak torque at nearly peak RPM.
Essentially power is all down to BMEP X Piston AREA X RPM and BMEP is fixed with a given fuel and compression ratio to more or less the same thing
You can do a but with higher compression and higher octane fuel..but that's its. the rest has to come from higher RPM.
In principle the formula 1 engine is a simple beast: its an engine strong enough to do 18,000 RPM coupled to a cylinder head with valves big enough to suck a full charge of air at 18,0000 RPM and able to ignite the specified fuel at 18,000 RPM at the highest compression ratio that fuel will run at.
The rests is about making it strong and light...and able to deliver something decent at less RPM than that..
Are the starters the same as used on their older, single-cylinder engines? The latter seem quite readily available still, and it wouldn't surprise me if B&S didn't retain the same starter for the twins.
Another approach might be to buy the starting gear assembly and adapt a different starter motor for use with the engine.
I've seen recoil starters on their old 8HP single-cylinders, but never on anything bigger.
I wouldn't recommend that, at least not without something to guarantee disconnection when the engine does fire!
You are. ;-) The Ford Anglia 105E was just under 1000cc but had an RAC rating of over 20 HP, IIRC. But that engine was designed long after the RAC rating ceased being used.
Engines of those days were generally as long stroke as they could make them.
Right - so the smaller engine had likely a much larger RAC rating than I gave.
The beauty of a very oversquare design is it allows much bigger valves - on an inline valve setup like most basic pushrod engines had. Of course these days twin OHC and 4 valves per cylinder allows more valve area on a smaller piston - and very oversquare designs went out of fashion due to emission regs.
You trade a very good low down torque on a long stroke engine with the ability to rev higher and breathe better at high rpm on a shorter stroke..the problem with a short stroke screamer is there is very little at low RPM at all..
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