moregrip

iTrader: (8)

In terms of 1/4 mile performance, we would usually utilize 3 fwd gears, in 4l60/4l80 land anyway; the goal would be to cross the 1/4 mile towards the top of 3rd gear instead of just after a 2-3 shift. this will allow you to use more of your powerband in each gear to the end of max fwd motion using all 3 gears as much to your advantage as possible. So what rear gear? depends on many things, tire size ( as previously stated ) but also where your powerband lies on the rpm scale.
for instance a vehicle that makes most of its peak power in the 6-7k range, all things equal, would want a lower gear than someone who makes peak power in the 5-6k range.

lots of **** to consider, more than I care to type anyway

CHarris

iTrader: (5)

Yeah... just look at me I'm betting a lot of guys are in similar circumstances though since we are racing vehicles not designed for use as such.

In that video my shift points were all wacked, too. Shifting too early! It'll be better next time.

jimbob

iTrader: (2)

Depends what your willing to live with (as far as rpm's go). If you have enough accelleration to go like 90mph in the quarter mile then you would want to gear to go through traps in 3rd (auto) at your power peak and maybe a few 100rpms' beyond....In reality though, this would be some stiff gears for a truck to do low 90ish mph at say 6k rpms. In most truck combos you see either 33 inch or 35 inch tall factory wheels. So 33 inch with 4.1's would be good compromise between acclleration and mileage...35's need 4.56's or more......This all depends on what rpm through traps you want to go and how much horse power to weight radio.....In your case 4.1 (smaller 33 inch tire) or 4.56's (35 inch would be a great combo)...Now when you make big power like Parrish and turbo who knows what he wants to see rpm wise in quarter mile?


Jimbob

moregrip

iTrader: (8)

all good points, to trap at peak pwr would truly be a nightmare anywhere else except light to light driving, and that could get old soon too.

another thing to consider about the above scenario, could you get a street truck to hook-up out of the hole with gears used to trap at peak power/rpm?
just another consideration........ok......I'm done with this......I'm a terrible typer. you could, but it would require some effort

jimbob

iTrader: (2)

Yep, you make great points (Moregrip)......

Jimbob

htsht

iTrader: (1)

So I am guessing my 2.6 isnt very good then, lol. That is 33" tires and 3.73 gears.

CHarris

iTrader: (5)

Not optimum... no. A 4.10 would help and not hurt you too bad either as long as you stayed at 33 tires. It really helps us out that we have that overdrive gear to keep us from getting too bad of gas mileage.

In my case a gear swap would mean I have to swap the fronts and rears both. It is tempting to do a tire change (to 33's from 35's) to get mine a little better without opening up the diffs. If I did open the diffs I'd need at least a 4.56 gear and should go higher. As it is I only get between 10 and 14 mpg. So you can see my dilemma. In your case a gear change wouldn't affect mileage as dramatically. If I lose even 10% of my mileage I'll really feel it in my wallet

Mr. Sandog

I agree about the need to stay with the taller tires if you decide to swap gears and mileage matters. With 32" tires I felt it (and will continue to feel it) in my wallet, going from 3.73's to 4.10's, as I lost between 2-4 mpg.

CHarris

iTrader: (5)

But 2-4 miles per gallon from what before? If I lost 2-4 miles per gallon from my 10-14 mpg I'd be hurting alot more than a lot of folks out there. If you are getting 15-20 that ain't so bad at all It all comes down to our frame of reference I guess

Mr. Sandog

Simply stated, with my 3.73's I drove 500 miles per week at 19 mpg and used 27 gal of gas. Now I'm getting close to 15 mpg and use 33 gal of gas to cover the same distance, and since gas is $2.49/gal, I'm spending $15 more in gas per week, and $60 more per month. As gas prices rise, this number will get bigger. Granted, $60 isn't everything, but it isn't nothing either. By the time gas is $3.00/gal (which it likely will be by the end of the Summer) that will be an additional $72/month.