How Strict is a Cam’s “Operating RPM Range” Relative to Being Out of the Range?

[aPOS]

Specifically, what can one expect for performance below a given “Basic Operating RPM Range” for a certain cam?

For example, the FP2 (272/272) cam gives a basic operating range of 2400 RPM to 7200 RPM. In contrast, the Crower 272/272 cam gives a basic operating range of 1000 RPM to 8000 RPM. Do these different ranges mean that the FP2 cam would provide less (worse) performance below 2400 RPMs than the Crower, and compared to stock cams would there be noticeably poor performance from idle to 2400 RPM when using the FP2 cam?

Another general question about the basic operating range of a cam concerns how one would describe the way the higher RPM ranged FP2 cam would perform from idle to 2400 RPMs. Is there inherently a noticeable sacrifice of operating (driving) performance from idle to 2400 RPMs when swapping from stock cams to the FP2 cams? Equally, does the more narrow range given for the FP2 indicate that below 2400 RPMs the cam lacks something regarding how performance is developed at idle? Lastly, do different given operating RPM ranges for different variations of a “272/272” cam relate to an intended design of each cam to only operate well within the given specific range, or are the ranges expressed quite differently among cam companies?

This useful discussion (http://www.dsmtuners.com/forums/articles-engine-fuel/221200-cam-basics.html) helps me recognize how the VE changes at different RPMs for certain duration cams, but I am unsure about how this might relate to my "Operating RPM Range" confusion.

 

[viperlp01]

Generally speaking. The more aggressive the cam the further up the rpm range the power is going to be made. Lift and duration are the major factors in this. IF you see a ton of lift and a aggressive duration then the cam will make power much higher in the RPM range. This generally means a loss of spool and a loss in torque down low.

 

[jmartinez1228]

Generally speaking. The more aggressive the cam the further up the rpm range the power is going to be made. Lift and duration are the major factors in this. IF you see a ton of lift and a aggressive duration then the cam will make power much higher in the RPM range. This generally means a loss of spool and a loss in torque down low.

Is that why strokers are blowing up? As in very popular right now?
The stoker setup makes up for the loss of tq? Just curious.

 

[canada4g63]

Stroker's aren't made to rev high. They make more torque down low, i would think over revving would be a key factor to them blowing up.

 

[EclipseOwner95]

I think he was referring to "blowing up" as in gaining extreme popularity, not physically blowing up.

 

[viperlp01]

Strokers don't rev very high because of the sub par rod angle and loading on the side wall of the piston along with the extreme piston speeds they see.
I would love to rev higher. I have to shift into OD at the track and that would not be an issue if I could rev to 9k.

A stroker has more displacement that adds to the torque down low. Its effectively still moving the power band around. I run Kelford 272s and make more power down low than a 2.0L running Kelfords but I would loose steam up top(if I could rev that high) vs. a 2.0L up top. If that makes any sense.

A stroker is a great choice. Most guys don't have the money to build a head to rev and make power to 9.5k. So we make our power from 4k-8k while they make power from 5k-9.5k.

 

[jmartinez1228]

Thank you Eclipse. Wow even after I made that statement clear people still don't understand. I was simply stating that strokers are gaining much popularity nowadays and was wondering if that was the reason.
People get big cams, lose bottom end power on a 2.0L so they stroke the motor out to gain that tq they lost. That was all i asked about.

Also never mentioned about revving high but that could be for aPOS

 

[aPOS]

Generally speaking. The more aggressive the cam the further up the rpm range the power is going to be made. This generally means a loss of spool and a loss in torque down low.

Thanks for the information about the power band changes and its effect on torque/power/spool.

I guess my main question relates to this power band change since I would like to gain a better understanding how (or whether) the moving of the "power band" higher in the RPM range actually corresponds to a "loss" of torque/power in the lower RPM range compared to the amount of torque/power of the stock configuration cams. Or, does it mean that there is not truly a loss of torque/power at lower RPMs, but that there is no torque/power "gains" (like at the specified "Operating RPM Range" RPMs, or its designated "power band") at the lower RPMs using the higher performance cams (FP2). I am trying to figure out whether the performance cams (FP2) elevate performance to some extent over the entire RPM range, compared to a stock configuration, yet not as much at the lower RPMs as at the changed "power band" RPM range. Basically, my confusion lies in understanding that whether the "loss in spool and torque" is a "loss" described as "compared to stock cam low RPM characteristics," or if it means describing "less gains" as "compared to the FP2's gains at its Operating RPM Range."

Coincidentally, I have no need for high RPM revving.

 

[viperlp01]

Think of Vtec(I know right)... Low lift and duration down low and when it reaches a higher RPM the head switches to a high lift longer duration profile to "make more power"