rojizostang

Starting a separate thread from my drag wheel set up thread

So some are suggesting 4.10's will be too low for my roush supercharged '13 f150.

The goal is to reach sub 12 second quarter mile times. I'm currently running 3.73's with mt 3574's which have netted 1.85 sixty foot times and pretty much dead hooking. I think perhaps with a stall converter 4.10's might be too low, but I don't have one.

Give me some insight here as to whether I should or shouldn't swap to 4.10's, thanks.

rojizostang

Bueller....Bueller.....Bueller.....

BareBonesXL

You should be looking at your data logs from your runs and seeing if you need more RPM or less. Then choose gearing accordingly. I think that's how the pros do it.

w00t692

Do either/or.

Either a stall OR 4.10's. Don't do both. With a stall you definitely won't need 4.10's

First thing you need to do is plug your tire size and gear ratios into a calculator and see where you'll be at mph wise and make sure you aren't going to end up needing to shift to another gear.

rojizostang

oh trust me I've used the ratio/rpm calculator extensively. the thing is though mt advertises the tires as "high growth" tires, so even though they're only 28.5 inches tall, I don't really have an idea of how tall they are at speed.

thank you also for confirming my thoughts about the stall converter. I will also check with a couple of the local shops I deal with for their ideas on the subject.

edit: using the rpm calculator, the 4.10's at 109 mph will net 6006 rpm in 4th gear. it certainly seems that it wouldn't be too much gear

BadCon

If you are already running 3.73's with a 28" tall tire, I just don't see the benefit. Gearing of the 6r80 doesn't lend itself you 4.10's with that size tire. Have you had your truck on the dyno, and do you know the weight? Your MPH seems kinda low for what I would expect you'd be making power wise.

rojizostang

No it hasn't been on the dyno. I'm just running an email tune from 5 star, but a dyno run with datalog is on the list of things to do.
I don't know the weight of the truck either.

Judging from past experience...I ran 4.56's in my 07 mustang gt with a 275/40/17 drag tire (at the track only) which was a much lighter vehicle and that was pretty much a perfect gear. It would do 1.6 60ft times and trap 113 mph. This was just a bolt on car but ran pretty well. My thought process is since I'm running a taller tire on a heavier vehicle, it seems I could easily benefit from a 4.10 gear. The truck makes a lot more power though....but the mustang got out of the hole pretty well.

blue5.0

First gear in the t-3650 was around 3.38. First gear in the 6r80 is around 4.17. Not apples to apples. I have 4.10s myself and love them for stop light to stop light and daily driving. It definitely feels faster if that makes sense. But that has not been true at the track.

BadCon

I'd get it on the dyno and perhaps seek a different tune. Before I spent the money on gears I'd go for more power, as your trap speed is a bit low at 109mph. I'm also curious what your truck weighs, as weight reduction could help if possible.

Spooled

Converter > gears