what are the diffrences of 185 cc runners comparred to maybe 230 runner?


Is it more for power up top

 

Yes, the larger runners will allow a lot better air flow at high rpm regions. You have to be careful, though, that your camshaft and the rest of your intake are all chosen with that same optimum operating range in mind. A set of large runner heads (230 for example) stabbed onto an otherwise bone stock motor wouldn't do jack for making power. Combine that with a much better camshaft, though, with an improved upper intake tract, and the net result will be significantly better.

If you are considering buying a better set of heads, first you need to do some research on other proven combinations out there. Find out what sort of cam/head combo truly works for other people. And remember: talk is cheap. The web is filled with thousands of people who have assembled the best combo in the world (according to them), and it will soon get them into the 11 second range, but right now something isn't right and they can't break out of the 13s. Look for proof of success. Listen to the guy who says "here's my combo, here's why I did it, and HERE'S MY FRIGGIN TIMESLIP."

 

If you are asking about the intake port runner size in the heads, the volume is an indication of the head's ability to flow without restriction. Obviously, ports with more volume are larger, and can therefore flow more air (theoretically). The higher flows will support more engine RPM without starvation, as long as the rest of the system can support the flow as well.

The other effect of larger ports is that since the area is larger, the flow velocity at a given RPM is lower. This tends to reduce the charging effect at lower RPMs, contributing to a loss of low-end torque. The TPI system, and to some extent the CFI system were dependent on higher flow velocities at lower RPMs to enhance cylinder charging at lower RPMs, making great torque from small valves and small displacements. Larger ports would negate this effect, and should therefore be considered carefully for any TPI or other long-tube intake system.

Larger ports on a carbureted, DFI, an LT1 or Mini- or Super-Ram type induction system would probably be a good thing, since these systems are already designed for larger flow volumes and lower flow velocities. With the LT1 and later designs, the fuel delivery systems can also support higher RPMs since the PCM has no practical limit of intake flow, unlike the MAF type TPI engines.

The head port volume is just another factor to consider when designing the engine you want to build. Depending on your intended operation of the engine, larger intake ports could be a good or bad thing. If you plan to do most of your driving in 1700' trips with the pedal on the floor, large ports can be good. If you are planning on a daily driver, larger ports can help to some extent, but the size should be limited to some degree to maintain good flow velocity at street RPM ranges.