Compressed Air Hemi V8

[T Mihelich]

Hey Everyone.

I am finally going to take the plunge into the world of compressed air engines.
Having followed Steve Huck's engine build and Chuck Fellows Opposed, 4 Cylinder compressed engine build for some time now, it has given me great inspiration to tackle one of my own. Thanks Steve and Chuck for your great work!

First comes the design right. 8)
Over the past coupe of weeks I have put together a design which should be somewhat
challenging machining wise without being to over the top. (I hope)
I have chosen to use Chuck's concept which uses compressed air through the cam.
This engine is 1/4 scale in size and roughly based on a Hemi style engine. (I work for Chrysler so it has to be a Hemi right )
It consists of 1 1/4" pistons with a 1 1/4" stroke.

Below is the design which I did up in Solidworks. I just love this program.
I have also animated the crank and pistons just to make sure everything seems to move correctly without interferences and the piston motion in relation to the intake and exhaust ports appears timed correctly.
Most all of the engine will be milled from 6061 aluminum.
If all goes well and this baby actually works as planned, I will add on all of the cosmetic type stuff such as a blower, magnetos etc.
Here are a couple pic's below of the engine design.





I figured I would ease into this beast and start with the oil pan first.
It may be a time killer for some but I have always preferred to mill the
parts first out of wood just to test out the cutter paths before cutting the expensive
aluminum. So being it will be a nice day today in the shop and I am still waiting for the aluminum to arrive, I will do just that.

 

[stevehuckss396]

Looks like a great project. I will be following along the whole way.

Chrysler? Are you in SE Michigan?

 

[T Mihelich]

I am Steve.
Heck I just noticed you are in Sterling heights. I am over here in Troy.

 

[stevehuckss396]

If you need anything or just want to bounce some ideas off someone, let me know.

 

[cfellows]

Great looking drawing! One thing I might suggest is that you make it smaller. An 8 cylinder engine with a bore and stroke that big will require a pretty large air compressor to keep it running. I think a 5/8" bore and stroke would be more practical or at most, 3/4".

My compressor has a 20 gallon tank and it will kick on after running my 4 cylinder horizontal opposed engine for under a minute. The compressor puts out around 6 cfm at 90 PSI and it will build the pressure back up to maximum with the engine running, but it takes a while. I'm dead sure it couldn't keep up with an 8 cylinder engine with a 1.25" bore and stroke.

Best of luck with the build. It should be a very interesting project.

Chuck

 

[Dave G]

Theres nothing like the sound of an injected Hemi, even if it is air injection it will sound good. Looks like a great project. This comes from a guy who has made many quarter mile passes in a Mopar. Tom, I can't wait to see this one built, Dave

 

[kvom]

A quick calculation shows that at 1000 rpm, the engine will use 7 cubic feet of air/minute assuming 2-stroke operation. My 60 gal compressor will handle that, but not too much more.

 

[cfellows]

A quick calculation shows that at 1000 rpm, the engine will use 7 cubic feet of air/minute assuming 2-stroke operation. My 60 gal compressor will handle that, but not too much more.

I expect by the time you consider air leakage and other losses it would require another 25% CFM to keep up.

 

[T Mihelich]

Great news this morning.
Looks like the brown man is going to be paying me a visit
this afternoon bearing gifts of aluminum!

 

[kvom]

It may be a time killer for some but I have always preferred to mill the
parts first out of wood just to test out the cutter paths before cutting the expensive
aluminum. So being it will be a nice day today in the shop and I am still waiting for the aluminum to arrive, I will do just that.

Have you considered machinable wax? You can melt/recast it, and it's easy on tooling.

 

[T Mihelich]

I guess I really never thought about using it for trials.
I always associated it with casting projects but you make a very good point.

 

[T Mihelich]

Well, I am back at this one again after a long break.
Time for some design revisions.

 

[stevehuckss396]

Awesome, glad your back. Have you made any parts yet? Would love to see pics even of the wooden test pieces.

 

[T Mihelich]

Well I finally made some good progress with this engine.
The first shot below is of the CAD assembly and the next two are of the actual
parts completed thus far. Yes..you heard that right. Actual parts.
Now with the foundation of the engine completed and mounted up all nice and sturdy,
I can move on to the crankshaft next.
For size reference those rails on the stand are 9" long.
The bottom end is painted in a nice Hemi Orange but the darn photo did not do it justice.

 

[metalmad]

Looks like a very strong Start.
Looking forward to this one!
Pete

 

[MCRIPPPer]

cool! maybe you need a liquid co2 injection system? ice cold engine.

 

[T Mihelich]

Worked on the upper block section today.
The bearings lined up really nice and the shaft rotates very smoothly.
It will be ready for a touch of Hemi Orange tomorrow.

 

[T Mihelich]

Progress on the dyno is coming along great today.
This can be set up in two different modes.
The first is the flywheel only for recording the motor data while in compressed air mode.
I can then bolt on the electric motor module for testing and break in.
This will also allow me to record data from the flywheel into the Simpledyno program.

 

[idahoan]

Interesting project and it looks very nice so far!

What is the black material the crankcase is machined from?

Dave

 

[T Mihelich]

These parts are machined from blocks of ABS plastic.:hDe: