Cam/Intake Question

Hi all,

i come from the VW world so i'm not too familiar with V blocks... here's my question: i've been told that when choosing an intake manifold for a V8, you have to match it to your cam. is this true?

another thing is compression ratio... how is that set? on a flat 4 its a process of flycutting the heads or porting the coumbustion chambers or shimming the barrels to set the desired deck height... its more than just that but is the process on a V8 similar?

thanks fellas

 

With V-8's it's all about combonation. Your compression ratio is determined by both the heads and the pistons. Which intake you choose is determined by cam, heads, exhaust. Which cam you use is determined by what you want to do with the vehicle, etc. If you give some more information we can be more helpful. All of the same priciples apply as your VW's, but some engines may have a much simpler solution.
I hope this is helpful.

 

so pretty much it's all relative... it was a general question. this gives me an idea of what to expect.

thanks,

 

Check out www.speedomotive.com for stock and stroker combos. They list the parts to make the combo from mild to wild and also show a dyno sheet. It will give you an indication.

 

The intake you choose depends a lot on what RPM range the engine is running in. A normal V8 passenger car engine with normal heads running from idle up to only 4,500 rpm would need a dual plane intake with smaller volume runners to be able to run well at the lower rpms for normal cruising. But a drag racing V8 with big valves and free-flowing heads that is meant to run mainly at wide open throttle from say 4,000 to 7,000 rpm, would do a lot better with a single plane manifold with larger volume runners and an open plenum. The cam you pick has a certain rpm range that it's made to run efficiently at and has to match the other components of the engine that you pick out. If you look at a bunch of hi-po camshafts or intake manifolds in a catalog, they'll tell you what rpm range they're made to work best in. All of the parts have to be compatible with each other to work efficiently.

You can up the compression on a low compression V8 that came with dished pistons by putting in "flat top" or "pop-up" pistons which decrease the volume of the compression chamber at TDC, or you can use different heads with different CC combustion chambers, or a combination of both.