quote:Originally posted by Daniel #9191:
...am I way over thinking this just to go faster...
Yes, you are putting too much mental energy into it. Build the type of engine you want and enjoy it. There are many paths to the same end.
The 3.75" stroke is a good sane stroke for the dimensions of the Cleveland motor. More cubic inches would help the motor run better with 4V heads, but since you're running CHI heads, that's not an issue.
High revs are touger on components than large cubic inches.
Horsepower = (torque x rpm)/5252
Based on that equation, to make the same horsepower at a lower rpm requires more torque, one way to achieve more torque is via more cubic inches. Adding 50 cubic inches lowers the powerband approximately 1000 rpm.
Its wrong to think of torque or horsepower as two separate things, they are inseparable. So its wrong to think torque is more damaging than horsepower.
In my mind, when I am visualizing the performance of a motor, I see the torque curve spread out over the powerband in rpm. The combination of torque & rpm gives you a value we call horsepower. Regardless of how you refer to a motor's output, that output alone does not break components, that output combined with traction breaks components. You are more likely to break components with racing tires than with street tires, street tires are more likely to spin and save the components (or in Doug's case, crumpled sheet metal).
So what kind of powerband works best? In my opinion, for street performance, and for certain types of track racing, a powerband of 2000 to 6000 rpm is ideal. On the other hand, some people, Johnny Woods for example, like high winding motors. Like I wrote earlier, there is more than one path to the same end. Personally, I've had motors with high rpm powerbands, lopey cams and abrupt response, in my opinion motors like that are no fun to drive on the street, not the open road, and especially not in traffic or stop light to stop light. The abruptness of the motor makes finding traction much harder. I admit it, I'm an old fart, I prefer a mellow motor.
If I were to race a car at the 24 hours of LeMans, and I were given the choice of two 500 bhp motors, one a high winding 5 liter motor, the other a mellow 7 liter, I would choose the 7 liter motor, because during the course of the race the 7 liter would be easier to drive fast and tire me out less.
Same thing goes on the street. At a stop light race, you don't rev the motor to 4000 rpm & dump the clutch like you would at a drag race, you leave the stop light at just above idle, motor away a few feet to prevent wheel spin, then nail it. The car that climbs into its powerband fastest from that point will accelerate faster, as long as the power is controllable enough to prevent wheelspin. So the car with the powerband that kicks in at lower rpm has a distinct advantage at a stoplight race. To make more power with a low rpm poweband brings us back to more cubic inches.
cowboy from hell