Thread: What engine do I have?

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Originally Posted by ocezam

Thanks for the replies. I guess I'm most curious about the compression ratio at this point. Can I just do a compression check to figure out where I'm at? I'm at 6000 ft so I guess any given compression ratio will yield a bit lower actual pressure? Hoe much difference in cylinder pressure is there between say 8:1 and 9:1 ratios?

Depends on the camshaft intake closing point. If the 8.0:1 motor had a short cam and the 9.0:1 motor had a longer cam, the 8.0:1 motor could show more pressure on a compression gauge because the intake valve closed earlier, trapping more mixture in the cylinder. The only way I know to find the static compression ratio of a motor is by using all the data to figure it mathematically. You need 5 values, cylinder volume, combustion chamber volume, piston crown volume, piston deck height volume and head gasket volume.

To begin understanding cams and how they work, start with reading the thoughts of a brilliant cam designer, Dimitri Elgin.....
http://www.crankshaftcoalition.com/w..._Dimitri_Elgin

Here's another wiki article that I wrote that gets into matching up of cams with different static compression ratios....
http://www.crankshaftcoalition.com/w..._compatibility

Another article I wrote deals with properly adjusting the valves....
http://www.crankshaftcoalition.com/w...stment_SBC/BBC

The Victor Jr. intake is rated to operate between 3500 and 8000 rpm's, so it is not the street-friendly intake that you need. Building a motor is a matter of choosing a combination of parts that contribute to a certain end product, so seeing a Victor Jr on a street motor would tell me that the builder had no clue. The other thing that's not helping with horsepower on the street is the shorty headers. Sling that junk over the fence and install a set of equal-length, long-tube headers with an H or X pipe imediately after the collectors.

Now, I'm wonderin' what's inside the motor?
This is the main reason that I will never purchase a motor that is together. In every case, I'll buy parts and engineer the build myself. You may or may not have that expertise, but you can certainly learn.

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