Need A Little help Please
Ok put on your thinking hats and help me decide on rear gear. I'm running a 410 W2 race head engine that's been set to run in the higher power band. 6800 to 7200 trouble is I'm going thur the lights just shifting into 3/rd gear, with 727 trans with 5000 stall. Shifting to second at about 330 foot wit 1.4/ 1;5 60 ft. Need gear right? Question is 4:88 or 5:13 I can only afford one new setup. 4:56 in the car now. running 7:10 99 mph. 2800 pound car. New gear I'd hope would get me into the mid 6's
I think that is within reason. So any suggestions will go a long way to helping me. thanks guys
Running through some of your numbers and they make even less sense now. I don't like using 1/8 mile MPH or ET. If you do that, you don't account for half the track.
I have never bought into the idea of gearing for 1/8 mile only. If you do that, you have too much low gear. So I always gear for the 1/4 and let it run what it runs in the 1/8 and then change gears in the transmission if I need more first gear.
Just using your weight and a very safe 550 HP (and if that's all you have, you have some engine issues) and the numbers look like this.
2800 pounds at 550 HP is ~ 9.80ish at 137ish in the 1/4.
If we take those numbers and keep working them, it's easy to see what gear you need. My math says:
137 MPH with your 28 inch tall tire at 7000 RPM says you need a 4.30 gear. It's just simple math.
And that's with a measly 550 HP. On W2 heads that's at a very minimum 50 HP low. At least. 75 HP off wouldn't be a stretch.
If we do the math for 600 HP at the same RPM and tire size you end up with:
9.60ish at about 141 MPH and at 7000 RPM and you'd need a 4.10 gear.
Somewhere you are way, way off.
That's just my 9th grade math. But I'd bet on it if I had to.
