Nitro V8

[michaelj199]

i believe the effective volume of the crank case will stay the same. while one piston is going up another is going down. the crank case pressure will only get as high as boost pressure and cylinder pressure will always be greater then or equal to boost pressure. therefor there should not be much if any air/fuel pushed up past the rings. there is only one point in time that the crank pressure could be higher then cylinder pressure and that's with the exhaust valve open right before the intake port is uncovered but that would be for only a very short period. with this V8 design and an open crank case ( not divided) there will always be an intake port open to the intake valley. so pressure increases caused by blow by of the rings will vent back into the intake valley. so there's no reason the crank case should become excessively pressurized.

i plan on running around 6-7 psi. this is a calculated figure so most likely closer to 5psi. my initial compression ratio is ~8 to 1 and after boost my effective compression ratio will be around 9 to 1. i plan on using brass chim stock for head gaskets so i can adjust compression ratio at will. timing can be controlled by the heat of the plug. i will start out with a medium and work from there.
~.78ci engine
~.88ci per rev supercharger
1.25 overdrive on pulleys
=~6-7 psi boost

 

[trumpy81]

That all sounds good Michael. I hope it all goes to plan for you.

When do you plan to start building it?

 

[michaelj199]

school starts the 27th. I've got to batten down and double check all my parts. it's going slow considering i just started quitting smoking. my brains all fuzzy lol. every time i try concentrating i unconsciously get up and head out for a smoke. It's hell but it needs doing. lol

 

[vcutajar]

Good luck with the build. If you post it here I will surely be following.

Vince

 

[trumpy81]

school starts the 27th. I've got to batten down and double check all my parts. it's going slow considering i just started quitting smoking. my brains all fuzzy lol. every time i try concentrating i unconsciously get up and head out for a smoke. It's hell but it needs doing. lol

Well I wish you luck re: smoking. I wish I could give it up, but I lack the will power to even try ... lol

Right now I'm re-working my own V8 project. I found a few items that weren't quite finished and I decided to make some changes, so I know what your going through right now.

I hope you will keep us posted on your progress. This is an interesting project simply because it is a two stroke and there is not too many examples of multi-cylinder two strokes out there.

 

[michaelj199]

sorry for no updates between learning matercam and sharing machine time with other students things provided slower then expected. i was so caught up in trying to get parts done i didn't take picks. now that the semester is over i took some of what i got done

the engine block was made using the 4th axis so it would be easer to set up the part. ie. not needing clever ways to set my part zeros. the first block was made in wax to verify tool paths. the second block was in aluminum and i had an oops when i forgot to update both banks bolt pattern when i made a change. the third was a success.

the oil pan was cut out of the center of a piece of stock. pocketing out the inside then flipping it and contouring and parting it off.

the heads were also cut out of the center of the stock. top side first then bottom. then i used a radius tool down the sides of the top getting ride of the tabs for a bonus. then i stuck it in the vise on the side and did the exhaust side.

and some shots of what i have assembled

 

[agmachado]

Very, very nice...

Congratulations!!!

Cheers,

Alexandre

 

[stevehuckss396]

I love it!!

 

[trumpy81]

Michael, that's looking really nice. I can't wait to see the finished article.

 

[michaelj199]

unfortunately i do not know when i will be able to work on it again. i do not own my own my own machines. and im finished with school.

 

[trumpy81]

Sorry to hear that Michael. If you were in my neck of the woods you'd be welcome to use my machines. I'm assuming that you are in the US?

I read, quite some time ago now, that there were places that you could hire certain amounts of time in an entire workshop. I don't know if these places exist or still exist but worth looking into?

Another possibility, a school workshop (community college I think they are sometimes called), with permission of course Maybe you could approach the staff/administration at the school where you started the project?

Or post an ad in your local newspaper requesting the use of someones workshop, for a small fee of course. I'd hate to see this project go unfinished.

Anyhow, I wish you all the best with this project and I would like to extend the Seasons Greetings to you and I trust you will have a Happy New Year.

 

[Herbiev]

I'm sorry to hear that too. If you are in South Australia you are welcome to use my facilities. Whatever you do dont go back on the cigarettes. I gave up 21 months ago but too late. 18 months ago I was diagnosed with emphysema, put on oxygen 24/7 and suffered 4 bouts of pneumonia. If only I could turn back time

 

[michaelj199]

thanks you guys. im in the process of applying and interviewing for jobs. after everything is settled down i have my eye on getting an sieg x3 mill. then hopefully work on getting the parts to cnc it. and since most of the stuff i work on is small i was contemplating building a jig to allow me to use the mill as a lath until i can afford one. thats my plan anyway will see how it goes