Someone will have to help me out here with the cam lobs... that there is a reg grind cam (what ever that is very slow ramps)....then you have the xe cams from comp(more stright up and down)...then there is a more agresive lob then that( or is this the one that is stright up and down) ......so 3 diff types of lobs for (HR) here ...

How do all 3 play a diff part in making power or affect the power band and what parts are need to make things live for street use..

 

Perfect valve events would have the valves open immediately, no ramp or anything. The faster you can open a valve, whether it be intake or exhaust, the better off you are. Closing works the same way, if you can keep all the pressure in the CC instead of it bleeding into the exhaust you are better off. The problem is that if you ramp a valve down that fast you start destroying stuff...ie breaking valve heads off...and your HR lifters wont last ten minutes. That is where solid roller setups make even more power, they can ramp even faster than the fastest HR cam, you still have to slow it down before it closes all the way, but the lifters can handle the extra abuse everywhere else.

So whenever solenoid actuated valve engines come out, they will make more power and be muchhhh more effiecient than any pushrod or OHC engine will ever be.

That should explain your question, to some regards, Im sure if someone like Joe O. got on here he could type you about 200 pages on why for the above, but who wants to hear that

 

Maybe, or maybe not, Jon. You have a good point about mechanical strength of parts. Also consider inertia of the parts... and maybe the air.

"Instantaneous" opening and closing implies infinite loads, since F(load)=m x a(acceleration), so the faster you accelerate a valve the higher the loads, no matter what you are using to do it. Imagne the size of a solenoid that will move a valve, even a titanium one, fully open in about 1 millisecond, or in 40 crank degrees at 6000 if I got the math correct. Todays 19,000 rpm F1 engines get the valves open in about that time if they have 300 degree valve events, and they are still using cams with air springs, as far as they will say.

Even if you open the valve in 40 degrees or 20 or 10, the air mass in the inlet port needs to accelerate, so near-instant opening of the valve should create a strong vacuum because the piston has traveled down the intake stroke before the valve opened, right? Well, the air still needs time to accelerate, so in order to fill the cylinder, we'll still need to open the valve before the intake stroke starts, so there won't be much vacuum until past TDC. Interestingly enough, the piston accelerates gradually as does the air, as does the valve out of mechanical, physical necessity. Maybe they all are really working together.

My point is that I don't think we're going to see a great leap forward with solenoid or any other non-cam actuated valves. Improvement? probably. Revolution? (pun intended!) probably not.

Not trying to flame you, just get you thinking about the big picture.


Schurters LT1, there's a lot to your question, but maybe it comes down to valve event timing and loads. Getting the valves to open and close at the right times with the correct lift controls the engine's output, or torque curve. As Jon said, opening and closing valves quicker can assist in this greatly, but F=Ma, so the loads necessary to quicken the valve opening and closing determine how stong the parts have to be.

The various "types" of lobes are just degrees of the same thing. Quicker opening is "more aggressive", but causes more loads and takes stronger parts and is harder on parts so durability is less.

It's a big circle: more power means more aggressive valve motion, which means bigger loads, which means stronger parts, which usually makes them heavier (or much more expensive if they stay light and strong), which means more loads, etc. Where does it end? How fast do you want to go?

My $.02

 

Ha, I knew one of you guys was gonna come in and make me look like a retard . I guess I was maybe exaggerating a little bit to get the basic point across that faster valve opening and closings make more power, but require stronger parts. I guess even more importantly than that though, valve timing is the most important. Opening the valves at just the right time, and closing them at the correct time. This is something I dont think you can learn from any book or school or teacher, you will get the basics, but until you grind 100s of your own cams you will start to get it right then, that is why most all engine builders or end users will leave it to the cam Experts.