Depending on the gasket used, 152 cc chambers equals 5.8 in compression ratio.
Now for a few compression ratio facts and a little discussion:
Several years ago (and it has happened more than once) a man called and acted like he wanted to purchase a cylinder head. But his real purpose was to get a cheap thrill out of my reaction. One would think that people would have better things to do. After a short rehearsed sounding conversaton on his part, he said, "I think I'm gonna go with that 6.3 or something head made by ol' so-in-so. It may not beat your B-F Super Heads but it ought to outrun your 5.9! ..... giggle, laugh laugh, smirk felt through the phone, ha, ha, he he."
I thought to myself, "Go ahead Numbnuts... You may be in for a Surprise!"
As far as compression ratios go, it doesn't matter if it's 5.8 or 6.3 or even 7:1.......
Because if the design allows it, a lower compression ratio high comp head can easily outperform another high comp head with a higher ratio. This is true even though a higher compression ratio generally provides some gain in power. It all has to do with the differences in design!
Now compression ratio is a term that sounds very descriptive. BUT, the compression pressure (actual cylinder pressure when the engine is running) is what the engine actually sees. This will vary from one engine to the next depending on the nature of the mods in use.
Now regardless of what I have just stated, most people will continue to think that the ratio number is the definition of power of one high comp head over another. This is simply not so, and is usually only true (but not always) within the SAME manufacturer's cylinder heads. For example, a Brumfield 5.9 as compared to a Brumfield Super Head 7:1.
Of course for some people all this means nothing as long as the performance is an improvement over stock. So for those people, purchase the high comp head of your choice and enjoy it!
Larry B.
