notstock4long

I have been doing a lot of researching for my next engine build, and I have a rough list made. I am still learning, and some of the basic stuff confuses me.

With heads, if I get AFR 190's, what does the 190cc mean. And what about the intake and exhaust ports and the combustion chamber cc. I would really like to know what these specs mean, and what numbers of each are better. If I got the heads ported more, which seems to be a good idea, would all of these numbers increase?

Also, with cams, I understand lift and everything, but can you explain what the numbers mean. Like the LSA; is a higher lsa better for a nitrous/forced induction application. Thanks guys.

TreySpeed

I'm a bit tipsy so someoen can correct me if i'm off base

::slams bud light down:::

190 is reffering to the runner size in cc's.

combustion chamber size-
this is not "best" you chose the correct size to aquire the desired compression ratio (search dynamic compression in advanced tech to see what your compression ratio should be).

LSA is lobe seperation and is not important when looked at alone.

It is all relative to cam size and cam events.

More lobe seperation means less overlap.


Overlap:
Overlap is when both the intake and exhuast valves "overlap" or are open at the same time. its the only way to get the exhaust gasses out on an NA engine. Think of drainging a coke bottel it chugs when you try to pour it out, but if you had a hole up top and let air in, it wont chug.

Overlap does the same thing. it lets exhaust escape by "cutting a hole." exhuast isn't going to want to leave if its creating a vacuum.

On a blower application, air is forced in there under compression, so it is going to want to leave. its under a LOT of pressure. Picture punching a hole in a baloon. The ballon is under a lot of pressure so all the air shoots out. So overlap is not needed as much in a forced induction motor.

And I'm not sure why I just wrote this all out. Rich Krause (rskrause) does a great job in explaining it in advanced tech. thread title is something like "using LSA to adjust powerband" and he does a great job of explaining why it is wrong to do so (use LSA to adjust the powerband).

rskrause

Trey: thanks for the kudos!

As Trey said, you might want to do a search. In the last 6-12 months there have been some very good cam discussions in "Advanced Tech". It would be difficult and lengthy to rehash all that has been said. But just to get you started, you have to decide a lot of other things before you get specific about the cam.

1. NA vs. SC, turbo, or nitrous
2. type of fuel to be used
3. intended use to optimize for: street, street/strip, track
4. displacement
5. transmission/rear end

Etc.

Rich Krause