That we had a stock LO3 with 2.73's. Let us further suppose it is running a 16.0 1/4 mile. If we made the following gear changes, what would it run?

2.73's to 3.23's -

2.73's to 3.42's -

2.73's to 3.73's -

2.73's to 4.11's -

Let's hear some opinions.

 

hmmmm...interesting topic...I wouldbe curious about this one too.

 

Bone stock, not a thing done to it, auto or manual?

 

Let's say auto since that is what most people have. And yes, bone stock with nothing done to it.

 

I won't even try to guess on actual et's, but I will say that the fastest will be the gear that lets you cross the traps just past your peak hp in 1:1 gear which is 3rd in the 700r4/4L60. The stock L03 peaks at about 4200 rpm so you will want to shift beyond that to allow you to stay in the meat of your power band. Bone stock I trapped 83 mph in the 1/4 so we can use this to figure out the best gear for the car.

3.23 is gonna cause you to over rev the car in second, but only reach around 3700 or so rpm in 3rd acounting for converter slip.

3.42 will let you trap at around 3900ish in 3rd still acounting for converter slippage.

3.73 will cause you to trap at around 4200ish in 3rd, again, still acounting for slippage.

4.10 will cause you to cross the line at about 4600 or still acounting for the converter slippage.

With a manual the rpm's will be about 2-300 rpm lower at the line. With this information we can see that 4.10's would infact be the best ratio even for a stock L03. Once you start modding and trap speed increases all is thrown out the window though.

 

I would go with 3.42's. It is a great street gear and keeps your power band low where stock TBI motors like best. 4.11's yould put you out of your power band to fast and you would not take the full advantage of the broad curve around 1500 to 3000 rpm. It is too hard to predict ET's but some guys have picked up a half second and gain 1mph.

 

3.73s or 4.11s is your best bet.

 

i love my 3.73s and i wouldnt have it any other way.

 

Id put my vote in for 3.42's. Good middle of the road option. That and tuning should get you into the mid to low 14's.

 

Might get some more answers here....

 

Are those 3.73's streetable though? What kind of RPM do you turn on the highway doin like 80 mph?

 

They are perfectly streetable. With overdrive it's nothing. GM even had 3.73's stock in the L69 cars. I don't know why people don't understand gear ratios. It's very simple to figure out the right ratio for you. All you need is tire size, trap speed, converter slippage if an auto, and desired rpm. From there you can decide yourself.

 

80mph in OD im right at 3000 rpms which is just about the same as driving at 60mph in 3rd (th700). This is my daily driver and i also make a once a month 500 mile round trip when i want to go home from college for the weekend and i still get about 22mpg on the freeway.

 

Thats one thing I never liked about low ratio gears. Gotta buzz the motor to drive fast. With my 2.77s I can fly along at 90+ the whole way and still get good fuel economy.

 

Well I have a T-5, so is Overdrive equivalent to 5th gear?

 

yessir.

 

Get 3.73s, they are great! And they are pretty tame on the street with an overdrive trans too.

 

i have been told that the 3.73's are too low of a gear for an unmodded TPI car, is this true. my car has the over rev problem that was mentioned earlier and it has the factory 3.23's in it.

 

Ok, so its a TPI? Yea, 3.73 might be a bit too short for a TPI motor... 3.42 or so would be the way to go

 

i was referring to my car being the TPI car, i don't know if his is TPI or TBI. thanks for the info though

 

I would go with 3.55 right in the middle I have a t5 with a 5.0 tpi with 3.08 in the rear and I can hit close to 90 in third gear and cruise freeway at 2100 rpm in 5th goin 80 or so. but if it were up to me id throw some 3.55s in her.

 

Oh, well whatever, lol... Just that you don't really wanna use a really short gear set like 3.73 or 4.11 with TPI because the powerband is too short. The engine would just run outta gear too fast.

 

I want to put the 3.73's in, but it will probably be after I convert to the LT1 intake and do my heads and cam. Until then, I may do 3.42's for temporary usage.

 

Just get 4.11's and swap in a T-56

 

i've tried just about all of the changes you're looking into at one time or another. here's my thoughts.

2.73's to 3.23's - .25-.35

2.73's to 3.42's - .30-.40

2.73's to 3.73's - .40-.45

2.73's to 4.11's - .45-50

if you're doing one that you drive alot on the street especially highway, i'd go with the 3.23. if you do alot of city driving, go 4.10 or if performance is the main concern. my recomendation for all around gear is going to be 3.42 also. the best thing i've found to do is spend a bit more on getting a torque converter than gear. i'd say pick the 3.23 or 3.42 gear and get a torque converter for an L35 equipped s10 from a gm dealer or some other type of stall around 2400. going from the stock stall converter to a 2400 will gain you about .3 by itself and keep highway cruise rpm the same.