cylinder head flow vs cam lift

I am staring to gather more info since I am getting into trying to understand cams a lot more. Lets say a cylinder head flows it's peak at .600 lift and you put a cam that yelds a .700 lift with the rockers. How much degrading will it do to performance? Does it really start to slow the air on the intake? What would it do to the exhaust? I have researched and all I come up with is high flowing heads with small camshafts.

it will not degrade performance.

dfree383 wrote:it will not degrade performance.

X2 ... you can overlift the valve past the point of max flow about 15% and still make gains. After that point, it may stay the same or hurt a little.

Hows that? So I would benifit from having more lift than where my heads peak on air flow? I am not knocking you Dave I am trying to fully understand this.

Gotcha Randy.

Not Dave but, it's simply about the amount of time the valve will spend at the point of maximum flow; (unless the whole combination is not matched and "out to lunch").

Tennessee Bullitt wrote:Hows that? So I would benifit from having more lift than where my heads peak on air flow? I am not knocking you Dave I am trying to fully understand this.

Flow data typicaly is on a dry bench with only 28" and with no charge movement... a running engine is way Different than a bench. Thier is alot more going on then a steady flow.

rmcomprandy wrote:Not Dave but, it's simply about the amount of time the valve will spend at the point of maximum flow; (unless the whole combination is not matched and "out to lunch").

and alot depends on the head itself allong with the operating peramiters of the engine. Super stock engines are a good example...... they lift the valve way past the typical peak flow..... and the cars go faster....

Average flow. If you lift the valve slightly passed .600 lift, you stay in the peak flow area longer.

Thanks for all the info guys. Now I can keep notes and records on what is what. I love learning and it is also great to have inteligent people who teach others.

Also keep in mind most people do not flow heads with the intake attached. So if a given head peaks at .600, it will likely not stall as low with the intake attached simply because the intake will probably cut the flow by a fair margine. In other words the intake will reduce the overall flow at the same .600. I've seen heads that stall at given lifts, not stall for another .050 or more lift with the intake attached. Add that to what the others said about what the engine sees and maybe this will help you understand.

Bret

I'm far from being any sort of expert on this, but I can tell you real world that flow bench numbers are great to get you going but dyno tuning is where you see real results! My little 466 with Freelander ported D0VE-C heads peaked out on the bench at .700 I 327/E 186 and my cam is a solid roller 110lsa 268/277 @ .050 750/760 lift. When we put it on the dyno, the last pull peaked the tqe at 529.3@5200 dropped a point then came back up to peak again at 530.2@6000. So knowing that my cam opens way more than where my peak flow numbers are, it doesn't hurt at all! BTW, the pill was set at 7500 on the dyno on the stock crank.

Long story short, if these guys say don't sweat the flow bench numbers, listen to them!