PROSOUTH

I have found several post relating to the listed camshafts and the best gears or transmission for the car. But for the cruise RPM of these two cams not a real answer.I am wanting to figure the RPM range for the rear gears and transmission. I like a well rounded power range.

I have a chart showing the ratio of Chey's transmissions and it's formula for relating to the total system of Cam RPM, then Transmission gear ratios, in each gear, and the total overdrive if any at the end.

Below is what I have now


Cruising speed= rpm x 60
--------------------------
gear ratio x tire revolutions per mi.


P275-60x15 tire 2500 x 60 = 150.000 = 67.613 mph @2500 rpm
------------------------------
3:08 x 720.29 = 2,218.4932

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Cams I need the Cruise spec's on

Part # 24502586

Duration @ 0.050" Lift: 218 / 228
Lift: 0.525" / 0.525"
Lobe Separation: 112
RPM Range: 1500-6000
Type: Hydraulic roller LT4 Hot Cam

PART# 10185071 ZZ-4 Cam

Hydraulic roller
Lift .47" I, .510" E.
Duration @ .050:208º I, .221º E.Duration @ 0.050" Lift: 208/221
Lift: .474"/.510"
Lobe Separation: 112
RPM Range:
Type: Hydraulic roller tappet

Thanks PROSOUTH



[Modified by PROSOUTH, 2:27 AM 2/23/2002]

PROSOUTH

Trans Ratios

1st gear 2nd gear 3rd gear OD

Turbo 350 2:52 1:52 1:00

Turbo 400 2:48 1:48 1:00

200-4R 2:75 1:57 1:00 0.67

700-R 3:06 1:63 1:00 0.70

Here's the chart


The following equations and rules apply only to four-cycle engines powered by pump gasoline. The equations have been simplified for ease of understanding. Answers will be approximate but generally will be close enough for use as a guideline.

About Mile per Hour and Revolutions per Minute:
First find the vehicle speed, MPH and the consequent engine RPM operating range:
1) MPH = TIRE RADIUS ÷ 168 X ENGINE RPM ÷ GEAR RATIO


Note: Tire Radius is distance, in inches, from center of tire to ground.
Note: Gear Ratio is Rear Axle ratio multiplied by Transmission Gear ratio.
Example: What MPH at 6500 RPM with a 4.9 rear axle and 14 inch radius tire in 4th (1:1) gear?

MPH = 14 ÷ 168 x 6500 ÷ 4.90 ÷ 1 = 111 MPH
Example: in 3rd gear (1.34)?


MPH = 14 ÷ 168 x 6500 ÷ 4.90 ÷ 1.34 = 83 MPH

2) RPM = 168 x GEAR RATIO x MPH ÷ TIRE RADIUS

Example: For the case in #1, what will be the RPM after shift from 3rd to 4th gear at 83 MPH?

RPM = 168 x 4.90 x 83 ÷ 14 = 4880 RPM

3) GEAR RATIO = TIRE RADIUS x RPM ÷ 168 ÷ MPH

Example: For the case in #1, what Gear Ratio is required for 120 MPH at 6500 RPM?

GR = 14 x 6500 ÷ 168 ÷ 120 = 4.51

4) TIRE RADIUS = 168 x MPH x GEAR RATIO ÷ RPM

Example: For the case in #1, what tire radius for 110 MPH but at 6000 RPM with a 4.11 gear?

168 x 110 x 4.11 ÷ 6000 = 12.7 inches
Note: Approximately a 25" diameter tire. Remember that the tire radius will be less during hard acceleration than when the vehicle is standing still. Also, radius will be greater at high speed due to tire expansion from centrifugal force.


WHAT HP & TORQUE is needed: Equations #5, #6, and #7 show how to compute the engine horsepower needed for three different applications.
5) Engine horsepower required to reach MPH in quarter mile (HPq):


HPq = (0.00426 x MPH) x (0.00426 x MPH) x (0.00426 x MPH) x WEIGHT

Note: understates HP required at speeds exceeding 100 MPH.
Note: assumes engine HP must be 2 x the HP required at drive wheels.
Example: What engine HP is required to achieve 110 MPH in a 3200 pound vehicle in 1/4 mile?


HPq = (0.00426 x 110) x (0.00426 x 110) x (0.00426 x 110) x 3200 = 329 engine HP

6) Engine horsepower required to sustain MPH on level ground (HPs):

HPs = (MPH ÷ 3) + (WEIGHT ÷ 1,000 x MPH ÷ 10)
Note: assumes engine HP must be 2 x the HP required at drive wheels
Example: What engine HP is required to sustain 75 MPH in a 3600 pound vehicle?

HPs = 75 ÷ 3 + (3600 ÷ 1,000 x 75 ÷10) = 25 + (3.6 x 7.5) = 52 engine HP

7) Engine horsepower required to sustain MPH up a grade of G% (HPg):

HPg = HPs + (G ÷ 100 x 0.005 x WEIGHT x MPH)
Note: Assumes engine HP must be 2x HP required at drive wheels, calculate HPs with #6.
Example: What HP to sustain 75 MPH up a 6 % grade in a 3600 pound vehicle?

HPg = HPs + (6 ÷ 100 x 0.005 x 3600 x 75) = HPs + 81 = (3600 ÷ 10,000 + 0.33) x 75 + 81 = 52 + 81 = 133 engine HP


8a) Horsepower = TORQUE x RPM ÷ 5252
8b) Torque = HP x 5252 ÷ RPM


Horsepower comes from torque. Torque comes from the pressure of combustion in the cylinder because combustion pressure causes the piston to turn the crankshaft which is measured as torque. The trick is to generate high enough pressure on each stroke and to do it often enough (RPM) to produce the horsepower needed.
Example: What torque is required to generate 329 HP at 6000 RPM?

T = 329 x 5252 ÷ 6000 = 288 foot pounds @ 6000 RPM

Example: What torque is required for 296 HP at 4880 RPM?

T = 296 x 5252 ÷ 4880 = 319 foot pounds @ 4880





[Modified by PROSOUTH, 2:25 AM 2/23/2002]