Designing an engine

[Metal_slicer]

Here is the underside of the cylinder head. The chambers are cut 0.1" deep. The intake and exhaust ports are 0.25" O.D. with a 45Deg bevel. Valve stems are cut or I should say will be cut 1/8" The valves will be machined out of free machining T-303 stainless. I was thinking of making the entire head out of brass but I may try to use 6061-t6 instead.

 

[stevehuckss396]

Yes I like the last option also. Steel cylinders, 6061-t6 pistons, and cast iron rings.

I have used both 6061 and 7075

6061 go .001 - .00125 under bore or 1 to 1-1/4

7075 go .00075 - .001 under bore or 3/4 to 1

Cast go .0005 Bob Shutt built his Peewee V4 so tight he still has not put rings in it and it runs great.


This is just what I do and others may advise differently.

 

[stevehuckss396]

Here is the underside of the cylinder head. The chambers are cut 0.1" deep. The intake and exhaust ports are 0.25" O.D. with a 45Deg bevel. Valve stems are cut or I should say will be cut 1/8" The valves will be machined out of free machining T-303 stainless. I was thinking of making the entire head out of brass but I may try to use 6061-t6 instead.

Looks good!

Compression ratio?

 

[Metal_slicer]

Looks good!

Compression ratio?

I don't know ;D I'm using eyeball engineering . I could send you the .igs file if you want to see it. Let me know if you are interested.

 

[stevehuckss396]

I don't know ;D I'm using eyeball engineering . I could send you the .igs file if you want to see it. Let me know if you are interested.

Well your going to want to get that one right or you will cause your self problems. I shoot for 5 to 6 to one. Good idle and easy to turn over to start.

Peewee is 5.25:1

Demon is 5.5:1

If you need help with that one PM me and ill lend a hand. Might want to nail down the CR early because the chamber design will effect the length of the valves and things like that.

 

[Metal_slicer]

Well your going to want to get that one right or you will cause your self problems. I shoot for 5 to 6 to one. Good idle and easy to turn over to start.

Peewee is 5.25:1

Demon is 5.5:1

If you need help with that one PM me and ill lend a hand. Might want to nail down the CR early because the chamber design will effect the length of the valves and things like that.

I found a web calculator that I was able to find out the CR. The current chamber design as it stands right now I am getting 18.5 : 1

CC one cylinder is 0.573

I'm going to need to cut a deeper chamber or dish out the piston.... Working on it now to see if I can get it lower.

 

[Metal_slicer]

Ok I got it down to 6.07 : 1 by leaving the entire chamber cut .1" deep the full diameter of the cylinder. In other words, it will be like a Hemi type combustion chamber. I'm off to bed, got to work tomorrow.

 

[Metal_slicer]

Hello guys,

I want to start machining the engine block but I have a question about the crank journals. Do I drill the hole undersize to ream later? Or do I mill them out using a ball mill? Got any pointers?

 

[stevehuckss396]

Personally I drill under and then finish with a boring head in the mill. You need the bore as straight as it can be.

If your drill wanders the reamer cannot correct it but the boring bar will.

 

[Metal_slicer]

Personally I drill under and then finish with a boring head in the mill. You need the bore as straight as it can be.

If your drill wanders the reamer cannot correct it but the boring bar will.

Thanks, I didnt think about that. Another question I have been wondering about for the past week is do I drill then bore the journals after the main bearings are bolted in place? Because if I do this first then later try to make a matching main bearing, there are going to be issues with roundness.

 

[stevehuckss396]

Thanks, I didnt think about that. Another question I have been wondering about for the past week is do I drill then bore the journals after the main bearings are bolted in place? Because if I do this first then later try to make a matching main bearing, there are going to be issues with roundness.

Nope!

Just bore the block with the caps installed and then make bearings to fit.

 

[Metal_slicer]

Nope!

Just bore the block with the caps installed and then make bearings to fit.

Thanks Steve!

I got some of my material in yesterday, annealed 303 stainless round rod and 6061-t6 round rod for the pistons. I made some practice cuts to test out my setup to get a feel for the material. I'm hoping to start machining the block this weekend if time permits. I fully expect many problems along the way, buy hey, that's ok! I'm doing this project to learn while having fun.

It seems I'm in need of a lot of tools. I need to grind me a tool for the piston ring grooves.

 

[Metal_slicer]

Some pictures to share of my shop, shop dog, tools and equipment...

 

[stevehuckss396]

Nope!

Just bore the block with the caps installed and then make bearings to fit.

Found the pictures. My oil pan also acts as the front and rear cap. Thats why you only see 3 caps.

 

[maki2212]

what all i need have to build v8 ? please

 

[Metal_slicer]

Found the pictures. My oil pan also acts as the front and rear cap. Thats why you only see 3 caps.

My design uses the oil pan as front and rear caps also. Thanks for sharing those images!

 

[mu38&Bg#]

Just a few comments. Just by looking at the image in post 13. The crankpins look small. The small end of the rod has little meat on it. The lower side of the wrist pin hole in the piston has little meat on it. These may or may not be deal breakers, but I would consider increasing crankpin size. It will make for a stronger crank less likely to bend in manufacture, and increase oil film shear for better lubrication. For clearances around things like plugs and valves, you want to be certain before you begin making parts. I can't tel from the image if the hole for the plug is drawn at major or minor diameter. If it's at the minor diameter, make sure it won't break through other features like the valve seats. Actual valve seats should be narrow, .010-.020".

Greg

 

[Metal_slicer]

Just a few comments. Just by looking at the image in post 13. The crankpins look small. The small end of the rod has little meat on it. The lower side of the wrist pin hole in the piston has little meat on it. These may or may not be deal breakers, but I would consider increasing crankpin size. It will make for a stronger crank less likely to bend in manufacture, and increase oil film shear for better lubrication. For clearances around things like plugs and valves, you want to be certain before you begin making parts. I can't tel from the image if the hole for the plug is drawn at major or minor diameter. If it's at the minor diameter, make sure it won't break through other features like the valve seats. Actual valve seats should be narrow, .010-.020".

Greg

Yeah I have the valve seats at .025", the crank pin is at .125" and I agree it is smaller than I would have liked. I would have liked the crank pins to be at least 3/16" I will try to see if I can change this, but it always makes me nervous making changes in CAD and risk loosing countless hours invested. The vale seats, intake, and exhaust ports and bolts are not intersecting. I had to angle the spark plug hole to allow for more valve spring clearance which is not shown in post #13. Another thing I didn't like about this design is the size of the pistons. I feel as though the pistons are to big, but I am not going to change this because it would cause to many changes, and it would be better to just start over.

Today I did a practice cut on a valve and I didn't like the quality of the finish of the valve stem. I am thinking of taking a longer piece long enough for two valves and center cutting the end and making two of the 1/8" stems using the live center in the tail stock and turning them down to .125" , cut them in half and then machine the thicker ends to the dimensions of the valve head for both valves. The problem I was having trying to cut one valve at a time was when the stem became smaller it was deflecting away from the cutter causing a tapered valve stem.

 

[Metal_slicer]

Practice 303 stainless valve I cut today. I did not part it off the bar stock, I just wanted to practice.

 

[stevehuckss396]

It's alot of fun when things go good.

That looks like about a .093 or .125 stem. You can get "E" clips to retain them if your interested. They are tiny so get a few extra. Make a little brass retainer that will hold it on when installed.

This one is .093 stem