I hit a curb last night, the rear end is bend up, so I'll be putting in a new one, I'm not sure about insurance yet, I might end up doing this with my 350 (unless, I need the money, and keep the LO3 in there)

355, L98 heads, 9.3:1 compression

I don't drive the car that often, I was thinking 3.73 or 4.10, I just want this car a lot quicker!!!!

BTW, what about if I keep the LO3? what do you recommend then?

 

Your gear selection will depend on numerous factors.

Gas mileage?
Do you visit the strip a lot? (may or may not need that extra shift at the line)
What kinda of power curve does your combo make?

Most people go with 3.42's or 3.73's and are happy with all of the above listed concerns.

 

gas mileage isn't much of a concern, don't drive car much, love the drag strip, takes an hour to get there.

basically I want the fastest I can get, I've read about TBIs not doing good with really low gears.

 

You probably wouldnt notice much difference at the track with the higher gearset unless your motor was out of its powerband when you launch.

The key thing to remember about gears is that they dont make the power, they just transmit the power at varying ammounts of torque multiplication. The only real need for a low gear ratio is if the motor is way out of its powerband when your starting off and it can rev high enough to take advantage of the lower gears.

Too numerically high (low gear ratio) of a gearset may slow the car down as there will be losses from having to accelerate teh rotating assembly as well as time delays from shifting. Id say that 3.42's would probably be a good all-around ratio.

 

gears are where it's at!!!!
the ideal gear set fo rthe track will allow you to run past the rpm of your peak HP just before the traps.
gains from going to 3,73's or 4.10's are most often in the .5 sec or a little more range.
i recomend the 4.10's with the 305 or a mild 350. they do not have a dramamtic effect on mileage, but the performance gain is amazing.

later
tim

 

4.10s are way too much for a TBI car period really

why would you want the car to rev like that considering if its a 305. 305 makes bottom end TORQUE i went with 3.42s from an 85 2.8 Camaro. but in my opinion and experience with my car LO3s run best with like a 3.42-3.55 gear

just check my sign

 

.

 

I have 3.42's and an Eaton Posi.

There is more to consider than just RPM at the traps. what you really want, is to have the revs drop from the HP peak to the torque peak when shifting. if you go to high (numericly low) gears like a 2.73, when you shift, your revs drop to below the toque peak, so you don't have as much power as you could. if you go too steep (numericly high), you are not utalising the torque the engine produces, you are also having to shift more frequently, and losing a little bit there also.

 

sorry, but you are completely wrong. you don't match gears to a low end power or where you are of the line. gears have to be picked for use down track, so that the entire power band is used through every gear you see during the run.
the ideal gear set will bring you past your peak HP just before you get to the traps. ie: if you make peak power at 5k rpm you want a gear that you will exit the traps at 5300-5500 rpm.
gears are a way to take advantage of ALL of your engines power, not just part of it. try it, you'll love it.

later
tim

 

Really more then anything else its about matching the engines powerband to the cars operating range. Take a look at how fast you plan to trap or what kind of usage itll see, what the motors powerband looks like, and use that to determine what gear ratio looks the best. Ideally you want to make sure your fully utilizing the powerband the whole way down the track. Depending on your car 4.10s might be just right or you may want a different gear. It all depends on the car. Also keep in mind that youll only realistically have 1-3 with a 700-R4 so dont count on overdrive at WOT if the trans is still stock.

 

I second what nj and dimented stated

Since it is mainly a drag stip car with a not to modded LO3, 4.10 will yield the best times, as 60's will be better and he will cross at the end of 3rd gear.

In respects to swapping in an L98 and assuming it will produce traps in the 93-95mph range, then 3.73s may be better. The performance calculators on this site are really nice and will help in choosing your gear. Like nj said, you want to pass just after peak hp in your 1:1 ratio (3rd)gear

No matter what gear you go with, the shifts are going to yield the same rpm drop regardless. Also you always want to cross in the 1:1 tranny gear, so shifting more or less throughout a run should not be even consider. 2 shifts for an auto, and 3 for a manual.


Keep in mind this is for the best quarter mile times. For those that like to race on the street from 20mph rolling starts and up is a different story.

 

Spinning?