idea, 4 cylinder to 2 cylinder engine conversion

[aerohead]

Originally Posted by CFECO

True, that is why my original X-Prize car had two, two cylinder outboard powerheads, which would run together or one only depending on load requirements. Think of a gas golf cart, the engine doesn't run until power is required, when you step on the throttle. Mine was to be; Electric to start driving initially, with one or both ICE power plants starting as the throttle was pushed farther down. If the car "Only Needs" 15HP to go 60 MPH, it can be done with a 15HP engine, passing or hills, the HP doubles or more. Harder, in some ways and not as efficient, as making one engine convert from 2 to 4 cylinders.

The Rutan Voyager used a similar strategy,using tractor and pusher powerplants for takeoff and climb,then going to either of the single engines for cruise,which would enable oil changes and servicing of one powerplant as the other just sang along the airways.

[CFECO]

No oil changes while driving for me!

[Frank Lee]

There's a motorcycle tire change while driving on You Tube...

[cRiPpLe_rOoStEr]

If I were going to convert a 4-cylinder engine into a 2-cylinder, I'd probably rather do it in a boxer, either from Volkswagen or Subaru, since they can still remain reasonably balanced with 2 cylinders chopped out. Well, considering that a flat-4 Volkswagen can be safely enlarged to 2600cc, maybe a 1300cc flat-2 could fare better than the stock 1300cc 4-cylinder due to the lower amount of internal frictions and less pumping losses...

[markweatherill]

I just thought, I'm surprised I've never seen anyone suggest a four stroke to two stroke conversion.
And then I looked it up and it appears it's in theory feasible...

[CFECO]

The point is to be able to switch between 4 cylinders and 2, depending on the power required, not just make a big two cylinder engine. I looked at Harley to VW transaxle conversions, but they are fairly expensive, and with most engines, vibrate excessively. I have figured out the major hurdles of making a variable displacement VW engine, just need to get the basic car to get the baseline performance figures.

[davelobi]

apologies up front for not reading all dozen pages so this may have been covered.

I love the idea but don't think you will make it work. First thing that crossed my mind was when you said "My car can apparently generate 115 hp with the 4 cylinder so it would make sense that a 2 cylinder would give 57 hp" With two cyls disabled you would actually make a fair bit less than half the hp because of the other losses of mass, friction, etc.

Best bet I can think of would be to run a cut out switch to the injectors of either 1 & 4 or 2 & 3 and simply flip the switch to shut off fuel to two cylinders once you are up to speed. You could get creative and have two get automatically shut off over a certain rpm if you can do the electronics. You might get a half scale savings in fuel consumption of what you get while under dfco if done this way. Easy enough to try. Love to hear the results.

[CFECO]

I don't know who was talking about the 115HP engine, but if you take a 60HP VW, turn off the fuel injection to two cylinders, and hold the exhaust valve open a little to kill the compression and vacuum cycles, it should easily still make 20 HP. That should be more than enough to maintain highway speed, and with a streamlined body with less weight....I see 100 MPG may be "possible".

[Frank Lee]

Originally Posted by Really really bad idea A

Best bet I can think of would be to run a cut out switch to the injectors of either 1 & 4 or 2 & 3 and simply flip the switch to shut off fuel to two cylinders once you are up to speed. You could get creative and have two get automatically shut off over a certain rpm if you can do the electronics. You might get a half scale savings in fuel consumption of what you get while under dfco if done this way. Easy enough to try. Love to hear the results

Originally Posted by Really really bad idea B

...and hold the exhaust valve open a little to kill the compression and vacuum cycles, it should easily still make 20 HP.

[CFECO]

Frank, why would holding the valve open a little, not make it easier for the "Live" cylinders to spin the "Non-Running" ones? Leave the Exhausts open, have those two pipes into their own collector.