Announcement

Collapse
No announcement yet.

1" Bore x 1" Stroke Vertical i.c. Engine

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • nickel-city-fab
    replied
    Thanks, Brian -- this is exactly what I was wondering. I would probably try to "play it safe" and run iron on iron for a first attempt if I ever get to build one. BTW on a related note -- those crazy guys that are hot-rodding their diesel Dodge pickups nowadays, are using *bronze* pistons (at $140 each...) because the bronze can withstand the higher exhaust gas temps going into the turbo... usually the exhaust valves melt first. Crispy.

    Originally posted by brian Rupnow View Post
    Nickel--there are a lot of differing opinions on this. If you are using an aluminum piston with cast iron rings in a cast iron cylinder, then conventional wisdom is that the outer diameter of the piston should be about .002" less than the bore of the cylinder. This is because aluminum has a different rate of expansion than cast iron, and as the engine heats up, the aluminum piston may "grow" at a rate higher than the cylinder can expand, and the piston may "seize" in the bore. If you are using a cast iron piston in a cast iron bore, then under about 5/8" diameter you don't need any rings.--Just lap the o.d. of the piston into the i.d. of the cylinder---if done correctly, then this gives a practically air tight fit and rings aren't really needed.

    Leave a comment:


  • nickel-city-fab
    replied
    Originally posted by Sparky_NY View Post

    What did they use in the old hit miss engines for pistons and rings? Aluminum against cast of steel must be low friction too, many a briggs type lawnmower engine and similar run the crank directly in the aluminum case. No doubt some aluminum alloys are preferred over others.
    If you look at the old engine restorations and builds on smokstak.com, they were almost always cast iron on cast iron prior to the 1930's.

    Leave a comment:


  • sid pileski
    replied
    My concern would be balancing, or re-balancing in this case.
    Sure, the CI piston will work.
    No problem with exploring for sake of experimentation.

    Sid

    Leave a comment:


  • brian Rupnow
    replied
    Sparky--If you have the article, I would be happy to read it. I have done a lot of reading on the art of making rings this week, but I'm always happy to read more---Brian

    Leave a comment:


  • Sparky_NY
    replied
    Originally posted by brian Rupnow View Post
    I won't be buying any more cast iron rings in future, but will be making my own. I am not going to start machining the new piston until I have the rings here.---Brian
    After that prior engine you used purchased rings on ran so well I am surprised you haven't switched from the O rings for good. I remember you saying you had attempted making rings before but had poor success. With your love of building engines you should nail down the process of making good rings, it will pay off on every engine. I have a excellent article on making rings in a old issue of Strictly IC magazine, I could copy the article for you if you like.

    Leave a comment:


  • brian Rupnow
    replied
    Nickel--there are a lot of differing opinions on this. If you are using an aluminum piston with cast iron rings in a cast iron cylinder, then conventional wisdom is that the outer diameter of the piston should be about .002" less than the bore of the cylinder. This is because aluminum has a different rate of expansion than cast iron, and as the engine heats up, the aluminum piston may "grow" at a rate higher than the cylinder can expand, and the piston may "seize" in the bore. If you are using a cast iron piston in a cast iron bore, then under about 5/8" diameter you don't need any rings.--Just lap the o.d. of the piston into the i.d. of the cylinder---if done correctly, then this gives a practically air tight fit and rings aren't really needed. If you run a cast iron piston with cast iron rings in a cast iron cylinder, then you still try to keep the o.d. of the piston about .002" less than the i.d. of the cylinder and let the cast iron rings provide the almost 100% seal required for the engine to run properly with good compression. You will see that on many of my builds, I lap the aluminum piston into the cylinder bore and use a Viton o-ring on the piston. There is effectively no gap between the cylinder and the piston.----This isn't supposed to work because of the uneven rates of expansion between aluminum and cast iron, but I have never had an engine seize because of that.

    Leave a comment:


  • Sparky_NY
    replied
    Originally posted by brian Rupnow View Post
    Sid--From all I have read, an aluminum piston is better for a high speed engine because of less reciprocating mass, and consequently less forces on the rod and crankshaft. Cast iron piston is better on slow running "work" engines because it has a high concentration of free graphite, which makes it slide in the cast iron bore with less friction, and since the engine is not intended to run at high rpm, the weight factor isn't nearly so important. .
    What did they use in the old hit miss engines for pistons and rings? Aluminum against cast of steel must be low friction too, many a briggs type lawnmower engine and similar run the crank directly in the aluminum case. No doubt some aluminum alloys are preferred over others.

    Leave a comment:


  • nickel-city-fab
    replied
    Brian, -
    one thing I have wondered for a long time. Could you educate me regarding how you determine the proper piston clearance to the cylinder? I mean, if you have different materials, you have to know the expansion, etc, right? To get the running clearance. I'm thinking of trying an engine someday, mostly just for my own education. I'm interested in making a model of the old hot-bulb ignition engines by DeLaVergne and Muncie from around 1910.

    Leave a comment:


  • brian Rupnow
    replied
    Sid--From all I have read, an aluminum piston is better for a high speed engine because of less reciprocating mass, and consequently less forces on the rod and crankshaft. Cast iron piston is better on slow running "work" engines because it has a high concentration of free graphite, which makes it slide in the cast iron bore with less friction, and since the engine is not intended to run at high rpm, the weight factor isn't nearly so important. .

    Leave a comment:


  • MikeWI
    replied
    Originally posted by sid pileski View Post
    Brian- curious as to why you are going to make a cast iron piston? Why not stay with aluminum?

    Sid
    He did say that he was "bored doing nothing" After all, in this hobby if we needed a good reason for what we're doing would we be able to justify it (or the cost)?

    Leave a comment:


  • sid pileski
    replied
    Brian- curious as to why you are going to make a cast iron piston? Why not stay with aluminum?

    Sid

    Leave a comment:


  • brian Rupnow
    replied
    Now we are going to try something a little different. The engine runs well as is, with a Viton o-ring on it, but I'm bored doing nothing, so now we are going to see how it runs with cast iron rings. If you are one of the people who purchased plans for this engine, fear not--the new piston drawing and anything relevant to it will be posted here. This morning I purchased a foot of 1 1/4" diameter grey cast iron from my local vendor for $40.(He didn't have any 1" cast.) That seems like a lot, but then there should be enough material there to build about 10 pistons. I have ordered a set of two compression rings from Debolt The price was shocking, at $52 Canadian funds, but that is $10 American for each of the rings and $20 American for shipping. The top of the new piston will be about 0.080" taller from the wrist pin, to give the engine a bit more compression. I won't be buying any more cast iron rings in future, but will be making my own. I am not going to start machining the new piston until I have the rings here.---Brian

    Leave a comment:


  • brian Rupnow
    replied
    Today I made an "add on" for the gear cover. It's not so much a safety thing as a noise reducer. Yes, if you were careless enough to stick your finger in there while the engine was running, it would probably give you a very quick manicure. The spur gears which drive the camshaft are noisy little devils. The 0.100" thick piece of aluminum I added to the gear case will fill up the gap and cut down on the noise. I find it almost impossible to add on a piece like this without screwing up the paint on the part I'm adding to, so it was simpler to give it a five minute soak in laquer thinners, wipe off any remaining paint, and then repaint the entire thing.
    Last edited by brian Rupnow; 04-14-2021, 10:10 AM.

    Leave a comment:


  • brian Rupnow
    replied

    Leave a comment:


  • brian Rupnow
    replied
    I have been asked about gaskets on this engine. There is a gasket 0.030" thick between the bottom of the cylinder and the crankcase. The head gasket is 0.030" thick. There is a gasket 0.015" thick between the two sides of the crankcase. These are simply standard utility grade gaskets, cut from rolls of automotive gasket material. Same material as would be used for fuel pumps, waterpumps, etcetera. I do not use a special grade of head gasket material anywhere on the engine.

    Leave a comment:

Working...
X