Slowing down a modern engine....

[cschuerm]

Hey Bio!
Since you've already declared that this is purely for the fun of it, it sounds like a hoot.  I've done a lot of work getting old antique engines to run slowly just for demonstration.  Probably some of the same things that work for those would work for you.  Obviously a large enough flywheel mass to carry you through compression is a must.  Maybe rather than try to get the existing intake to work with a small carburetor, you could remove and abandon the entire manifold and use eight little bitty cabs (lawnmower/gas trimmer type).  You'll need to retard the ignition quite a bit as well.  Probably just around TDC or possibly even slightly after.  Heck, since you know you'll need something totally unavailable for a cam, give up on the central internal cam, run an external gear, and a home-brew overhead cam for each cylinder bank with exposed rockers like the old engines.  Not going to make any power with it, but it could be fun to tinker with.
chris

[Henry W]

There are places to get cams ground. Since you just might want to try it, get in contact with Schneider Racing Cams.

They might be ale to come up with a very mild cam grind.

Henry

[BioHazard]

Hmmm....maybe it would be best to optimize the engine to run around 5-600, since we've already established that the engine can idle there and produce useable power. That's still in listeroid territory. I've got an idea in my head about running a long shaft off the back and use it sort of like a line shaft in my shop.

I'm starting to think maybe I could setup a GM TBI setup to give a more stable idle speed, maybe from something smaller than the 350.

[BioHazard]

OR a truck tire filled with water?  A 24" diameter wheel turning at 500 RPM is the equivelent of 35 MPH...

Anybody else have thoughts on this idea? Would the water work like a flywheel without having compartments inside the tire? That has to be the cheapest "big spinny thing" I can think of that is actually rated to spin....

[Henry W]

There are cams ground for 1000 - 3500 rpm range for the 350. I think you can make a very nice running 350 running @ 1000 rpm easily. The cost of materials would be very little.

Just a thought.

Henry

[Thob]

If the engine is internally balanced (so that the flywheel is balanced on it's own, and doesn't have extra weight on one side to balance the engine) then it seems you could use multiple flywheels.  Just drill out the pressure plate thread holes on the second flywheel and run screws thru them into the first flywheel to couple them together.  You could reverse the second flywheel (such that they are face to face) if that works better.  You might be able to stack several flywheels together if needed, but at some point you get to where you are overloading the rear main bearing.

As far as putting something in a tire on a wheel, I think water would slosh around too much.  Even if you could completely fill the tire, the water is going to be moving back and forth.  You need to fill it with something solid, like concrete.  The problem then is how do you balance it?  Take it to the tire shop and have them add a BUNCH of lead weights?  I think this would make a good "candid camera" scene - you drive up to the tire shop with a tire filled with concrete in the back of your truck - and ask if they can balance it.  Then when the tech goes to pick it up...

Whatever you do, we expect to see video posted online!

I think I'd start with a smaller 4 cylinder engine.  Maybe a John Deere, Kubota, or Yanmar diesel???

[vdubnut62]

I don't know how adventurous you are but I have a 1968 C-50  2 ton with a 327 in it. It has absolutely the smallest venturi's in a  2 bbl carb I have ever seen.  The intake has small runners and  I'm going to assume that the heads and valves are pretty small to keep the velocity of the intake up. It's really got a bunch of low end. And a big ass flywheel. (that's a technical term )

if you could stumble across one like it, all the top end will interchange with a 350.

All the older small block Chevy's are INTERNALLY balanced except for the 400.

I would be scared as hell of a tire and rim filled with anything but air spinning at 600 rpm!! Ever heard the tales of the flywheels coming off old oil field engines, and them being found a half mile away?  And you probably read about cschuerm's Fairbanks-Morse turning at  only 350 rpm.

All the above opinions  are mine alone and do not necessarily reflect the opinions of the management of this forum.
Ron

[admin]

i have in the past considered using a set of duals off a heavy truck or trailer, with a stub shaft from a trailer axle
to mount them.

i standard set comes in at about 750lbs iirc, and that is a lot of rotating mass.

unlike a listeroid flywheel they can be easily balanced and are about as safe as i can imagine, aside from getting caught up between the rubber and the concrete floor of course.

there would be an awesome amount of potential energy available for those hard to start well pumps!

btw, i wouldn't mess with removing pistons/rods and all that. you will end up with balance issues and all sorts of places for oil pressure loss internally.  you might however remove half the spark plugs and let it wheeze? that would reduce pumping losses to some extent, alternatively set the exhaust valves on half the cylinders on the tight side so they leak off compression would work to reduce those loads.  then removing
the compression rings while leaving the oil control rings on the dead cylinders would reduce the friction some more, as would reducing the valve spring pressures by removing the inner coils, which won't be needed for idle speed operation and might provide some level of overspeed protection as the valves would float at a much lower rpm than stock.

bob g

bob g

[BioHazard]

I'm kinda thinking about using at least 2 of the cylinders as an air compressor, rather than belting a compressor to the engine. I was talking to someone on another forum about the possibility of getting a custom cam made that would allow the use of the stock valves for air compression.

Technically speaking it would be a very efficient machine since I can use the heat in my shop. Think of horsepower as an accidental byproduct. Right now I'm using a 125k BTU gas heater @ 80% efficiency, that's about 12 horsepower I'm throwing up the chimney.

[Mad_Labs]

Since efficiency isn't the point, how about a Jake brake on some cylinders? And instead of a cam, electronic ignition?

Jonathan

[cgwymp]

btw, i wouldn't mess with removing pistons/rods and all that. you will end up with balance issues and all sorts of places for oil pressure loss internally.  you might however remove half the spark plugs and let it wheeze? that would reduce pumping losses to some extent, alternatively set the exhaust valves on half the cylinders on the tight side so they leak off compression would work to reduce those loads.  then removing
the compression rings while leaving the oil control rings on the dead cylinders would reduce the friction some more, as would reducing the valve spring pressures by removing the inner coils, which won't be needed for idle speed operation and might provide some level of overspeed protection as the valves would float at a much lower rpm than stock.

By that point wouldn't it have been easier to get a 4 or 6 cyl?

[Derb]

Hi Boss. Like the idea of using some of the cylinders as a compressor. I have seen any number of volkswagen engines configured in this manner and they work real good. At the sort of speeds you are talking of, an SU carby off an early Range Rover 3500 engine should have good airflow and fuel vapourisation. Cheers.

[Ronmar]

I'm kinda thinking about using at least 2 of the cylinders as an air compressor, rather than belting a compressor to the engine. I was talking to someone on another forum about the possibility of getting a custom cam made that would allow the use of the stock valves for air compression.

And a custom manifold that dosn't feed those 2 compressor cylinders with an air-fuel mixture from the carb?

[quinnf]

Imagine feeding a pneumatic impact wrench with an air-fuel mixture from such a compressor, then installing a little ignitor in the motor.  You'd have the first gas turbine powered impact wrench.  The perfect tool for freeing up those REALLY rusty lug nuts!   

Quinn

[Carlb]

blocking off a few runners to prevent fuel from entering the cylinders that are being used as a compressor is not a big deal.  You can cut into the runners after close to the cylinder head to provide air for those cylinders being used as a compressor