[Stan Weiss]

Originally Posted by 455-4+1

I think a really important part is being missed here when comparisons are being made on the dyno.
Unfortunately due to pretty poor processing power, and sampling rates, the industry (Superflow? ) settled on 300 rpm / sec as the default test rate.
This is extremely slow and does not compare to actual acceleration rates in vehicle. Often these are thousands of rpm per second, and an engine will respond very differently under these conditions.
If the intake CL remain nearly the same, and volume goes up, so must CSA.
Often cylinder filling with larger CSA heads can be less effective at low rpm, but the slow rate of acceleration on the dyno allows this to "recover" somewhat.
At the track the lack of bottom end, may be made up for with increased performance in the higher ranges, resulting in similar ET. (mph may be a good judge of this?)
I would like to see the tests carried out at higher rates, ie 900 rpm / sec and 1500 rpm / sec, but alot of dyno setups probably couldn't maintain that?

The rate of RPM Change will not only change from 1 gear to the next but vary in each gear. The rate will increase as you go up to peak torque and then will decrease after peak torque. The 300 and 600 RM per second ranges are what many may see in high gear.

Stan

This is from some years ago on the Bo Laws Inertia engine dyno.


__Weight_(or_Req._Inertia)_=_335.0#____Radius_=_12 .0_Inches____Rear_Gear_Ratio_=_1.0

____________________________Rear_____Aero_____Roll ing____________Rear_W__Accele___Time___Rate
__RPM______MPH___Velocity___Wheel___dynamic___Resi st.__Elapsed____Horse__ration__Differ_Rev_Per
__________________ft/sec___Torque__Drag_-_HP____HP______Time______Power__in_G's__ential___S ec
Inerata
_5000.0_356.999__523.599____0.000______.000____.00 0____.0000_______0.00__0.0000__0.0000_____0.0
_5100.0_364.139__534.071___832.33______.000____.00 0____.1310_____808.24__2.4846__0.1310___763.4
_5200.0_371.279__544.543___832.33______.000____.00 0____.2620_____824.09__2.4846__0.1310___763.4
_5300.0_378.419__555.015___838.73______.000____.00 0____.3920_____846.40__2.5037__0.1300___769.2
_5400.0_385.559__565.487___832.33______.000____.00 0____.5230_____855.79__2.4846__0.1310___763.4
_5500.0_392.699__575.959___832.33______.000____.00 0____.6540_____871.63__2.4846__0.1310___763.4
_5600.0_399.839__586.431___832.33______.000____.00 0____.7850_____887.48__2.4846__0.1310___763.4
_5700.0_406.979__596.903___826.03______.000____.00 0____.9170_____896.49__2.4657__0.1320___757.6
_5800.0_414.119__607.375___832.33______.000____.00 0___1.0480_____919.18__2.4846__0.1310___763.4
_5900.0_421.259__617.847___838.73______.000____.00 0___1.1780_____942.22__2.5037__0.1300___769.2
_6000.0_428.399__628.319___845.24______.000____.00 0___1.3070_____965.62__2.5231__0.1290___775.2
_6100.0_435.539__638.791___851.84______.000____.00 0___1.4350_____989.38__2.5428__0.1280___781.2
_6200.0_442.679__649.262___851.84______.000____.00 0___1.5630____1005.60__2.5428__0.1280___781.3
_6300.0_449.819__659.734___851.84______.000____.00 0___1.6910____1021.82__2.5428__0.1280___781.2
_6400.0_456.959__670.206___845.24______.000____.00 0___1.8200____1029.99__2.5231__0.1290___775.2
_6500.0_464.099__680.678___838.73______.000____.00 0___1.9500____1038.04__2.5037__0.1300___769.2
_6600.0_471.239__691.150___838.73______.000____.00 0___2.0800____1054.01__2.5037__0.1300___769.2
_6700.0_478.379__701.622___832.33______.000____.00 0___2.2110____1061.81__2.4846__0.1310___763.4
_6800.0_485.519__712.094___826.03______.000____.00 0___2.3430____1069.49__2.4657__0.1320___757.6
_6900.0_492.659__722.566___826.03______.000____.00 0___2.4750____1085.22__2.4657__0.1320___757.6
_7000.0_499.799__733.038___813.70______.000____.00 0___2.6090____1084.52__2.4289__0.1340___746.3
_7100.0_506.939__743.510___807.67______.000____.00 0___2.7440____1091.86__2.4110__0.1350___740.7
_7200.0_514.079__753.982___790.11______.000____.00 0___2.8820____1083.17__2.3585__0.1380___724.6
_7300.0_521.219__764.454___784.43______.000____.00 0___3.0210____1090.31__2.3416__0.1390___719.4
_7400.0_528.359__774.926___767.86______.000____.00 0___3.1630____1081.90__2.2921__0.1420___704.2
_7500.0_535.499__785.398___746.82______.000____.00 0___3.3090____1066.48__2.2293__0.1460___684.9
_7600.0_542.639__795.870___736.73______.000____.00 0___3.4570____1066.09__2.1992__0.1480___675.7
_7700.0_549.779__806.342___717.34______.000____.00 0___3.6090____1051.70__2.1413__0.1520___657.9
_7800.0_556.919__816.814___698.95______.000____.00 0___3.7650____1038.04__2.0864__0.1560___641.0
_7900.0_564.059__827.286___681.47______.000____.00 0___3.9250____1025.06__2.0342__0.1600___625.0
_8000.0_571.199__837.758___664.85______.000____.00 0___4.0890____1012.72__1.9846__0.1640___609.8

_Averages__________________803.84_________________ _______________995.48__________0.1363__737.2

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