Steve Huck's Demon V8 version 1.5

[cforcht]

I think I am going to have to remake the rockers though. it looks as though Im going to have more lift on the cam than the rockers will allow without binding. not a big deal. but its a step in the wrong direction. at least this new mill can make them faster since I have a much higher spindle speed capacity.

[dynosor]

the big reason small engines can rev higher is less reciprocating mass than its larger counterparts.

Craig, you are right that size and weight of the parts are significant contributors to limiting engine revs. However, for engines with a given displacement and number of cylinders, the shorter the stroke (and larger the bore) the higher the engines can rev.

This is because the forces that the crankshaft and connecting rods have to bear in slinging pistons up and down do not only depend on piston mass, but the linear acceleration and deceleration that occurs to and from TDC and BDC on every revolution. This acceleration is a product of the engine revs and the stroke length of the engine, modified a little by subtitles such as the ratio between rod and stroke length.

As the piston velocity is a function of stroke length at a given engine RPM, and this velocity is reversed at the end of each stroke, the acceleration is also non-linear with peaks around TDC and BDC. Peak acceleration is where the parts are loaded the hardest due to inertia – most likely to fail. Now, peak piston acceleration depends on the square of engine revs, so inertial loads go up exponentially with longer stroke length.

These forces may be reduced by using light pistons or by reducing the piston acceleration by reducing the stroke length. If you want to preserve the displacement, but want to use light pistons running through a short stroke you need to add cylinders.

These pages may add some insight:

Piston Motion: The Obvious and not-so-Obvious, by EPI, Inc.

Piston motion equations - Wikipedia, the free encyclopedia

[cforcht]

ok that made my head hurt after reading it. way more than I need to know for this little hobby engine. however if I were going racing Im sure id want to know this stuff. glad somebody here would be able to contribute to the cause if needed though. might not need it today but you never know what tomorrow will bring. thanks and keep the tech posts coming, we all learn things from them.

[dynosor]

Wow, the SPAMbot is really letting its naughty bits show with two almost parallel post under different new identities! Here today, gone tomorrow...

I have made a little progress. not anything really amounting to much other than buttoning up some of the small things. I got the intake and exhaust ports done in the heads as well as the ports in the intake. engraved the valve covers with the heartbeat logo. got the heads fully assembled aside from the rockers. thats about it for now.

I have made a little progress. not anything really amounting to much other than buttoning up some of the small things. I got the intake and exhaust ports done in the heads as well as the ports in the intake. engraved the valve covers with the heartbeat logo. got the heads fully assembled aside from the rockers. thats about it for now.

[rowbare]

(Looked all over for something to click on so I could get emailed updates on this thread but posting is the only way I know to do it, if anyone knows what to click on PM me the instructions~)

Just for reference:

By posting a reply you have subscribed to the thread. To subscribe without posting (or to unsubscribe) go to the Thread Tools menu in the thread header.

bob

[AMCjeepCJ]

Thanks guys for the PM and the post on where to subscribe... I'm getting the email updates now~

Craig, I have a Mori Seiki lathe also, it's a CL-20 but I don't have live tooling unfortunately. That is why I was looking over how you had your machines laid out in your shop, my main CNC's are literally almost identical in size and weight to yours, it's kind of funny.

Does anyone have any idea what kind of longevity you might expect out of a little engine like this if I were to put it in a very small motorcycle just to putt around under 30mph tops and most likely 5-10mph most of the time?

I make custom wheels amongst other things and that engine would be the coolest thing I've ever seen in a small custom built bike.....and the sound!!!!! My little Honda ZB50 goes about 40mph now with just under 3hp, so power isn't going to be an issue. I just cannot think of a cooler thing to build that a V8 minibike with just about every piece custom made, I might even spin up all the fasteners out of SS just to say I did, lol~

Thanks so much for the writeup on your progress, I'm eagerly awaiting updates and a youtube vid of it running in the future.

[cforcht]

ok your lathe is about the same size but is your mill 30x60 table travels too? my old mill was 16x32. served me very well for the last 10yrs. but decided to upgrade. gotta say I am happy with it. Now that the wire edm is functional again. Its actually cutting a part right now. nothing fancy. just trying to learn how to run it. had a few issues so far but most have been software and figuring out how the control works. needless to say the mits control is far from intuitive. and nothing like a fanuc.

[dstryr]

Lol never heard anyone say a Fanuc is intuitive....that mitsubishi must be a POS.

ok your lathe is about the same size but is your mill 30x60 table travels too? my old mill was 16x32. served me very well for the last 10yrs. but decided to upgrade. gotta say I am happy with it. Now that the wire edm is functional again. Its actually cutting a part right now. nothing fancy. just trying to learn how to run it. had a few issues so far but most have been software and figuring out how the control works. needless to say the mits control is far from intuitive. and nothing like a fanuc.

[cforcht]

The mits is not really a pos. Its just really foreign to me after running fanuc based for 27 plus years

[cforcht]

needless to say the mits control is far from intuitive. and nothing like a fanuc.

nowhere in this statement did I say that the Fanuc was intuitive. Im sure a die hard mits guy would find the Fanuc a PITA, which is how I feel about the Mits control.



on a side note heres the part I cut on the EDM. nothing fancy but it turned out exactly as it should have. pictures kinda crappy though. no its not an engine part. its a sear for a 1911 pistol in O-1 tool steel.

[stumpy1807]

Awesome shop! Engine too!! Ive been waiting a long time and finally starting next month to build my own shop. I've been a machinist over 20 years and would love to get my hands on the engine plans for my first project. Does anyone know how to get in touch with Steve?
Cant wait for more pictures!

[RFB]

Please excuse me! I'm old