I've been reading all the threads I can find on the t-5 conversion and rear differential ratios to figure out what to put into my '51 1/2 ton at the same time I put the re-built 261 w/M4f, fentons, offy w/2bbl progressives.
It seems like the most common t-5 tranny that bolts right up is the non-world class found in the chevy s-10's (or s-10 blazer) with 4.06/2.37/1.49/1/.86ratios. With 235/75r15 tires the tire height is 28 inches (27.9).
I'm trying to build a daily driver that'll get decent gas milage and be able to move in and out of traffic as necessary in city driving, and still get decent gas milage.
MY QUESTION: With the most common t-5 and 2.73:1 gears am I gonna acheive what I want, or am I missing something?
Here's how I figure it:
Using an RPM calculator it looks like in 5th gear you'd turn about 1,850 rpms at 65, and 2,100 at 75. The M4F is supposed to be good between 2,000 and 4,000, so if you had to pass someone on the freeway you'd be at the start of the powerband and could either downshift from 65 or punch it at 75 and have the 2 second barrels of the progressive 2 barrels open up.
At low speeds, in city traffic for example, with the 4.06 first gear, 2.37 second and 1.49 third, combined with the 2.73 rear end, you'd be doing 25-30 mph at 3,300 rpm in first, 2nd at about 40mph at 3,100; in 3rd at around 60 mph you'd be at 3,000; at 60 in 4th at 2,000 rpms with the powerband ahead of you, at 75 in 5th you'd be at 2100 rpms (or 1,800 at 65), cruising with power to accelerate.
