Valve lifters…solid/hydraulic/roller tappet/flat tappet?

[olddog]

Originally Posted by xb-60

Are you serious olddog, or is this like Brent said, tacho wired for a 6cyl?
What's the story?
Cheers,
Glen

To be fair, the head choice in this program I believe to be expert race ported heads. I expect to actually get heads that good would be in the $5000 range or more.

Now most experts (with far more experience than my reading books and playing with computer simulation software) will tell you that large port heads like that will kill the low end torque. Now, I will tell you that if you use a cam to take advantage of those head's top end power potential, they are absolutely right. It will give you a low end dog. However it is my theory that if you give up the top end power and keep the cam mild, the bottom end does not have to suffer.

I look at it this way. With supper good flowing heads, at low rpm the flow will do exactly what the cam tells it to do. If you have over lap, it will suck exhaust back into the intake like there is no tomorrow. If you close the intake valve late, the piston will shove air back into the intake, leaving the cylinder less than full. On the other hand, if you keep the overlap to a minimum and don't leave the intake valve open too long, these supper good flowing heads are going to completely fill the cylinders, giving excellent low end torque. You will give up top end power, but still have decent power due to the flow capability of the heads. From there you play the rob Peter to pay Paul game with the cam to strike the best balance. The heads allow a much milder cam that give a much flatter torque curve.

Buy going all out on the cam, tunnel ram, 1100 cfm, open stepped headers, I can get 900 hp at 11000 rpm, which drops the low end torque to 200 lb-ft. That is how big these heads are. This would be costly and tough to get your hands on. Not to mention trying to keep control of the valves. These are heads that should be on a longer stroke engine to keep the rpm down.