th400 question
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.
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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:
(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.
Registered User
Joined: Nov 2021
Posts: 3
Likes: 0
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:
(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.
Registered User
Joined: Nov 2021
Posts: 3
Likes: 0
