performabuilt

iTrader: (25)

While true the 400 is stronger. They can indeed break too, I broke a couple myself in my early years with 5000 lbs cars and big block engines.
As for being cheaper yes but if you drive the car much at all any savings on the build are quickly eaten up by the 30% or more fuel used than you would with the 4l60e and this is only accounting for the ratio difference add in the lack of lockup and a big stall and its will be considerably more.I would never do a 400 swap unless the car was a trailer queen or a weekend track warrior only.
Its like this what if I told you I was gonna build you a 60e really cheap but wanted a $50 dollar a week surcharge forever on it , Would you really come out cheaper? Not to mention your engine is wearing at a 30% greater rate. Alot of people misunderstand that milage is meaning less without other information. A car for intstance with 4.10 will wear the engine at a 30% greater rate than the same car with 2.73 make that a car with a 3 speed auto and now your near 60% .Just and IMO.

382ssz28

iTrader: (24)

I think Z28/2002's chart is accurate. My 70 Nova w/3.73s and a 28" tire w/Muncie 4SD is 2950RPM@60MPH, on an Auto Meter Tach.

HooptyExpress

The formula for RPM to MPH is:
(RPM) ÷ (Trans Gear Ratio) ÷ (Rear Diff Ratio) x (Pi) x (Tire Height) ÷ 63360 x 60 = MPH

For example, here is my C10's speed when running 1500 RPM in first:

1500 ÷ 2.48 ÷ 3.08 x 3.14 x 28.3 ÷ 63360 x 60 = 16.5 MPH

RPM = 1500
Trans Gear Ratio: 2.48 (stock TH400 1st Gear)
Rear Diff = 3.08
Pi = 3.14 (constant)
Tire Height = 28.3" (my tires are 225/75R15)

Assumptions:

• Torque converter is locked, or operating at 1:1 ratio.
• Transmission has zero slip.

HooptyExpress

The formula for MPH to RPM is:
(MPH) ÷ 60*63360 ÷ (Tire Height) ÷ (Pi) x (Rear Diff Ratio) x (Trans Gear Ratio) = RPM

For example, here is my C10's RPM when running 16.5 MPH in first:

16.5 ÷ 60*63360 ÷ 28.3 ÷ 3.14 x 3.08 x 2.48 = 1500 RPM

RPM = 1500
Trans Gear Ratio: 2.48 (stock TH400 1st Gear)
Rear Diff = 3.08
Pi = 3.14 (constant)
Tire Height = 28.3" (my tires are 225/75R15)

Assumptions:

• Torque converter is locked, or operating at 1:1 ratio.
• Transmission has zero slip.

vorteciroc

Looks like the Hoopty Express was not soo express...
about 12-Years not so express!

HooptyExpress

LMAO!!! You’re not wrong.

I figured if I found this thread by searching Google, someone else might too.