Cam, velocity, and flow questions

[jrg77]

On a board to which I suscribe a guy said his ideal cam was 220/230, .600/.600 with a 112 LSA with 1.5 rockers. How would one expect to use this cam? What kind of advertised duration would be good to keep this cam barely in the smog legal range? Could this cam work as a flat tappet grind?

Does it matter if a cam has the exact same specs if it is a roller or flat, hyrdraulic or solid?

Instead of more duration on the exhaust valve could you use more lift? Can you use more lift in general since the exhaust valve is typically smaller?

What controls picking the right size valves? Is there a minimum/maximum ratio difference between intake and exhaust valves?

Is it a safe assumption that larger valves require a larger chamber? Is there a way to quantify the intake runner to chamber ratio? Would it matter?

What dimensions are required to determine the maximum lift you can get out of a cylinder head? How would a head/cam work if the cam was set to give you maximum lift up to about 3500 rpm and tapered down to about 75% of that lift by 6000 rpm? Would you need a big or small intake runner? The lift couldn't be bigger at the end than the beginning could it?

Does a lower head angle (23, 20, 18, 15) work better towards a larger or smaller bore? Does the lower head angle allow for higher or lower lift?

If the intake velocity is as important as the flow, how does one compute it? How do you determine how much flow and at what velocity you need it to accomplish x horsepower or torque?

At 100% volumetric effiency are you getting all of the flow you can out of a head, getting as much flow as the velocity will allow, both or neither?

How do you match the intake manifold to the head to get the right flow/velocity?

[rolling thunder]

Wow lots of questions but good questions ill tell ya what i know. First im not shure what ya mean how this cam could be used but that cam would be good for a street strip motor if thats what you mean. Cams have a code (1,2,or 3) thoes tell you whats smog legal and whats not 1 means completely legal 2 i believe is only illegal in CA and states with there standars for emmisions 3 means it is completely illigal for street use unless its pre emmisions. You could use that cam with solid lifters but it would have to be a solid lifter cam with those specs.
2. It does matter if its solid, hydrolic, hydrolic roller,or solid roller. This is because hydrolic lifters compress which hurts performance and rev limit but its quiet and dont require matinence. Hydrolic roller have roller tips on them so the reduce friction and they allow you to use a steeper cam grind i believe which also means better performance. A solid lifter does no compress so it increases performance and rev limit but it also needs to be adjusted every oil change. A solid roller lifter has the roller tip and does no compress but needs to be adjusted. I would recomend a hydrolic roller cam but there a little expencive especially if you have to retro fit it in.
3. Genrally speaking you want a short duration on th exaust side to increase torque. I have heard of increasing the lift on the exaust side for better performace by useing 1.5 rocker armes on the intake and 1.6 rocker armes on the exaust.
4. Theres really only 2 valve sizes for intake and exaust 1.5 ex and 1.94 int on a stock head and 1.6 ex and 2.02 int on a performance head the smaller valves give more low end torque and the lager valve set gives better high eng horsepower genrally.
5. The chamber size is really mostly for compression ratio. Even in heads with 56cc chamber you can get the larger valves. The intake runner size you need to chose based on the engin size, use, and rpm range.
6. The lift on a cam isnt hindered by any dimention on the head. What limits you is the valve springs the will only allow so much lift befor the spring just cant function proberly or cant compress anymore. The lift will be constant throughout the rev range. Altough if you have a cam that has a big lift and duration you need a head with the larger intake runners so it can flow the amount of air the cams truing to allow.
7. I believe the smaller degree heads genrally flow better in all engin sizes. I could have that backwards though. They also have less of a chance of the piston hitting the valves on a big cam but thats usually not a problem anyways but you can get the same lift out of any of them.
8. Thats a tough one im shure theres a way to calculate it out but i dont know it. You just need to know for example on a head smaller runners will cause a greater velocity wich gives you better torque in the low end but dont have the flow to give high end horse power. It kind of chokes if off. However if you have large runners you dont have as much velocit in the low end so you lose low end torque but you can get higher velocities in the high end because you can flow more so you gain high end hp. I hope that helps.
8. Well i kindof touched on that above its more the amount a head will flow determins where the maximum velocity will be (more flow high end, low flow low end) Higher velocity builds torque in the low rps it shows up as torque and in the high rps it shows up a hp because hp is torque x rpm divided by 5252. And also for some reason torque is always greater than hp below 5252 rpms and vice versa above 5252 rpms odd isnt it. I have no idear why that is but it always is.
9. Well you want the intake to be able to flow as much ar the head so its matched but thats tough unless to have test equipment. However its not really quritical I would chose and intake based on the rpm range you run in.

I hope some of this helped good luck. Little leinghty lol but worth reading.

[NastyZ]

Get a book called Camshafts and valvtranes by David Visard ...it explains ALL of this in alot of detail .