Basicly Im in the process of converting my lt1 into a 383 stroker, and putting a ysi vortech s/c on it, or a f1 s/c. Im going to get a le3 package with a custom cam, but what my question is, i dont under stand the porting number and etc. What are good flow number on stock casting, and will le do custom porting. Also what does 306cc referr to. I see guys typing that all the time and I dont understand it. Mainly Im more curious about what numbers i should get for my heads and intake. Looking for 700 rwhp (with suporting internals and mods).

 

anyone got anything to say

 

CC306 refers to a particular Comp Cams camshaft. There are other factors expressed in "cc's".

A number like 210cc intake ports means the volume of the head intake runner, after porting, is 210cc's (cubic centimeters). A stock head is 170cc, an LT4 head is 195cc, AFR makes several heads with larger intake runners. Larger volume runners ***MAY*** flow more air, but they may also slow down the air flow to the extent that it is detrimental to combustion chamber turbulence and air/fuel mixing.

Then there's the volume of the head combustion chambers, which is also measured in "cc's".... a stock head is somewhere between 54-58cc, a milled head will have less volume, a head with some attempt to reduce shrouding of large diameter valves may have a larger volume, expressed in cubic centimeters. Combustion chamber volume has a major impact on compression ratio. Since you are looking at a blower application, you're probably going to want a static CR in the 9.0-9.5:1 range, and you can achieve that with a flat top piston and a large combustion chamber, or a stockish combustion chamber with a dished piston.

As far as head flow.... its a little bit of a numbers game, but you need good head flow, express in "CFM" (cubic feet per minute) to achieve high HP. But flow numbers mean little, when compared to the overall picture of matching the flow, velocity and turbulence to the power goals and the "streetability" requirements of the engine.

Best thing you can do is talk to someone like Lloyd or Bret Bauer and ask them for their recommendations in meeting your goals. The head flow and cam requirements for a blower motor will be a bit different than the requirements for a normally aspirated engine. 700rwHP is a lofty goal, and will require a high degree of expertise to arrive at the correct combination of rotating assembly, valve train and head design.