Thread: Making Combustion Chamber Bigger

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Originally Posted by FAYLUR

Thanks guys. So there are many variables,both externally and internally that come into play here when talking dynamic compression ratio and combustion pressures. Sounds like an area that just one spec out of a dozen or so could be out and cost an engine.
This is a tough one to find alot of info. on (I'm trying to learn) because of evidently, those many variables. As one motor with 9:1 SCR and 200+ cranking pressure may require a certain high octane, another motor built the exact way except with a different cam,may have 9:1 SCR and 180- cranking pressure because of it's intake valve closing point being higher than the first motors,and run fine on a lower octane,yet be faster?
I was hopeing for a 'rule of thumb' figure that would link Dynamic compression ratio with a certain or 'required' octane but it looks like an "inexact" science.
Mr. Ericson and Mr. McCarthy have quite a bit of experience in this I would suppose, would you guys,or anyone else chime in?

Like you said it is an "inexact" science.
Many years ago when we built "hobby stock","stock car engines" we use to try and cheat by installing a cam that was cut on a tighter l/s.
This would allow us to run a little higher comp. ratio and not get caught.
There are so many differnent variables.
Even something as simple as "spark plug reach" will affect it.
There is no " magic number".
If you can get "dyno time" this is the only true way to find this out I.M.O.

Originally Posted by DennyW

If a newby looks at that piston, and can't tell the difference, that means he surely wouldn't understand the things you discribe in detail some times. And, it he can't tell the center is lower than the edge, he has a second problem.

And, When something you post gets corrected by me personally, I always have to prove my point. I think 35 years of building all kinds of motors, and working in general on all parts of a car, qualifies me for not having to prove things to a book guy as yourself. You are very good on the Tech end, but many times, I can tell you really do not have the hands on experience like some of the other guys on here.

My self, I'm not right up to par on the latest and greatest things out, but, I will tell you, if you want it to run a certain way, or speed, or pull, I can get er done.

By the way, for the newby's, here's a 10cc piston domed piston. High domed, Sticks up, instead of down in. I hope you can really see the + up, and in the other photo above, the - Down.

Now boys can't we just get along?
You both know I am the one people don't like because I am a smart a$$.

Denny, my apologies to you and to anyone else on this board for anything I've said to upset them.

You're correct about my passing information to members of this board on which I have no hands-on experience. I'm a hobbyist and while I've done many of the things of which I speak, other information has come from working around drag strips and talking with drag racers and professional builders for the last 49 years about what works and what doesn't. I don't own a flow bench or dynomometer, but I get to talk with fellows regularly who do.

Again, my apologies.

Relax Denny, I won't be responding to your posts anymore. Have a great day

Originally Posted by DennyW

:

Everything is fine though. I have taken my meds, and feel much more mellow now. Have a great day everyone.

You taking those little blue pills as well as me now Denney ?

Originally Posted by DennyW

I take orange, white, off white, and a pinkish color one with flowers on it, looks like to me. Oh, and I can't forget the big green one every other day.

Lets see........

3 oranges, 3 blues, 1 red, 3 oils daily

AAAAHHHHH MMMAAANNNN,,,,,,Denny and Techinspector1,,,you are two of the main reasons I,and many others I'm sure,turn to this very website for advice and instruction.
If either of you were not here,,,it just wouldn't be the same.
And for what its worth,,,there are about a half dozen knowledgable guys 'like yourselves' here and I can't seriously say that any particular one is better than the others.
ANYWAYYYYYY,,,,,,I had understood the dish/dome explanations and my apologies if starting this thread or anything I said offended anyone.
If that was my fault then heres how I feel-
"Thats it Moma,,,they oughta write across my forehead in big bold letters, F-A-Y-L-U-R,,," Quote from Eunice ( Carol Burnette ).

Originally Posted by DennyW

Erik, your going to get into trouble with Tech.

we use to try and cheat by installing a cam that was cut on a ((tighter l/s.))

You did not say what this is, or stood for, and a newbie will not know what this means. Can you explain it please ??

Oh Tech, Erik made a boo-boo here.

Denny,I am the smart a$$.
Don't you think we might be blowing this out of proportion a little bit?
There is still plenty of room in the sand box for everyone.