burnouts4ever

My car is automatic with 2.73 rearend i believe it has a hypertech chip, what is the estimated 0-60 and 1/4 mile time and what are some good mods? would rearend gears help alot if so what ones are best?

camaroboy92RS

The best mod is the open element air filter. Its cheap and easy. And yes rear end gears will turn your world upside down if you want to change them. I would never change mine unless I want to get 7 mpg instead of 15........ The crucial mod is to get rid of the stcok exhaust. The stock exhaust on a stock 305 TBI is HORRIBLE and very restrictive. Ditch that and get flowmaster or hooker or something and that will add like 10-20 horse to you car....

James Montigny

I swear every board on the web for every type of car has "our stock exhaust is the worst" posts LOL

Exhaust definitly helps though No argument there

kevm14

That is crap. RPMs alone don't determine fuel economy. The torque curve/volumetric efficiency is fairly important to consider. Generally speaking, you're most efficient at the highest manifold vacuum, at whatever road speed you want to analyze.

Depending on the car, you may develop more manifold vacuum at a higher rpm (but maybe a more closed throttle). Not to mention that the car becomes somewhat easier for the engine to motivate in the city (provided you turn that ease into fuel economy instead of performance). The quotients you have calculated are almost entirely invalid, FYI...if you factor in aftermarket cams, your calculations would prove even farther from the truth. I bet if you installed a fairly aggressive cam, your highway mileage might improve with 3.42 gears instead of 2.73s because of the poor efficiency (valve event overlap, etc.) of the cam at lower RPMs (this results in poor vaccum at low RPMs, and poor torque).

NJ SPEEDER

changing rear gears does not have a dramatic effect on fuel economy. i went from stock 2.73's to 3.54's with no change in around town or highway mileage. blackbird305 went from 2.73's to 3.73's with no change in mileage.
gears will only effect you mileage if you decide to go really radical with your gearing, like 4.88's or bigger. that is when you start gettign the cruising rpm into the range where the ecm is reading into other boxes on teh fuel map outside of the normal cruising operating range.

later
tim

r90camarors

I agree that gears won't effect gas milage too much. I went from 2.73 to 3.73 and at most lost 2 miles to the gallon, but I think that's just me having to much fun with the gears! Anyways, my torque converter actually locks up on the highway now because I'm at a higher rpm.

brharris27370

Stock 305 TBI Camaro runs between mid to high 16's in the 1/4 mile and high 8 to low 9's in 0-60.

Gears help tremendously. I switched from 2.73 to 3.42 posi and lost 2 mpg but the car is ALOT sportier to drive. Open air filter element and COMPLETE exhaust will be your next biggest gains.

dmair5_0

for all you guys who swapped gears. what did you do to correct your speedo? is there a kit avail with the different gear ratio's? also, about how much did you pay to have em' installed?

Dan94GT

only been 16.8 best. Bone stock with not even a full tune up. Had open element though.

Just added hedman hedders, y-pipe, and 3' from there back to a hooker w/ dual 2.5 outs. + added dragsprings, removed swaybar and a little bit of weight. Traction will be a big problem on a single 2.73 rear with bald crappy street tires. Hoping for low 16s next time but the tranny is going I think so we'll see.

brodyscamaro

i just got the speedo gears from SLP, with the posi too. dont pay to have them intstalled, please. its really easy, just kind of time consuming. the tech article on this sight is very good. i used a pipe wrench to get the gear off. i damaged the gear while removing it but i did not damage the shaft. i long puller would be great for this. it is really easy. i had never opened up a tranny before and did this in about 1.5 hrs.

Pukka

I bought mine from GM. Replacing the gears on an auto is easy, there is a tech article on this website that explains it.

Changing the gears on a manual involves removing the tranny and splitting the tailshaft. It took me two days to do it with a bit of help from an auto shop worker (I have never done such a thing before) but the process is pretty straight forward. You could also replace the shifter and D/S since you are removing them anyway.

Paying a mechanic to do this would set you back about $300 where I live.

vic_V8

look at my sig, I was basicall stock and ran a 15.8, and I have a heavy fully loaded car

SOLID LIFTER

1/4 mile = high 16s to low 17s

r90camarors

I've seen it posted on this board before that the 0-60mph times for an auto were 8.1s, for a 5 speed 7.6s. It was taken from a car and driver mag or road and track-some magazine.
1/4=low 16's for stock TBI if properly maintained
Mine ran 16.1 with only a shift kit in it when I bought her

burnouts4ever

how much of a difference will a shift kit make would i need a transmission cooler also if i get a shift kit?

kevm14

Theoretically, a cooler should reduce the need for an external cooler, since the shifts are quicker with less clutch/band apply time and overlap. But it CERTAINLY doesn't hurt - if the hard parts and friction surfaces are in good shape, installing a shift kit and external cooler might very appreciably prolong the life of your 700R4.

Buck268

My RS ran 16.4 with the A/C on (needed fan on, forgot to turn it off ), bone stock, with a dual snorkle air cleaner (no cold air induction though)....

brodyscamaro

you need a cooler anyways

r90camarors

Though a tranny cooler won't hurt and is recommended (by me), it is not "needed". I never ran one when I had the auto in there, and it had 140k, with the shift kit being installed at the 90k mark. She worked perfectly, but with 3.73s in the rear, the T56 was just to hard to stay away from!

Imadude_134

iTrader: (9)

How can you have a dual snorkle air cleaner with an A/C? How did you manage to set that up? Got any pics of it?

brodyscamaro

read what he put in the paraenthesis, i assuming he had the air cleaner but no ducting. i could be wrong though.

Slade1

Rear gears hurt my highway economy, city economy is still the same.

I had as high as 38 mpg with my 2.73 gears, now with 3.23 I can manage a 32 mpg at best. Not bad of a sacrifice I think considering these cars are already economy oriented.

I can do 15's on this setup, I think I've squeezed out all I can with this setup, need to get to the major stuff, headers, cam, intake, heads in that order...

I'm sure I can get it to pull 14's maybe break into 13's without forcing another gear swap, but traction mods will be high priority if I intend to break 13's... palric's 13.9 TBI is my guide...

Gunny Highway

iTrader: (1)

PALRIC's 13.9???? Got a website?

Slade1

Just met him in person.. it was funny though.. met him before I found out about the 13.9 sec TBI... some people on the TBI board made some comments about him and was odd.. one of the guys I met went by the name palric and he used to drive a tbi...

put 2 and 2 together, asked him about it next time we met up and he got all sappy and remembered his beast build up...

the thing about it was it was made 10 years ago back when parts were harder to come by. Now you have such a wide selection of cams, heads, intakes (save for the 670 TBI, which is still what he used back then) that you can easily make the same power he had provided you have the money... as for et, you'll need a lot of traction else that power goes to making a lot of noise..

My guess is if he had dynoed it, it would have made in the 250-275 HP range which is just about the range low 14 high 13 sec cars make...

I'm documenting all I did to this car and what times and dyno numbers she had after mods, for sure for next summer I'll have heads, intake and cam done, then see what times I get with a well matched set. If I do break 13's I'll make a guide myself. I'm aiming for the cheapest path to 13's on a TBI so that'll help anyone else.

My later project is the LS6 into a thirdgen car... just need the money for that...

Gunny Highway

iTrader: (1)

Well I found one of his guide on here, but sounds like there was some things that he would have rather done, and that some things were overkill. I think the post was on the Ontario page??

My goal is to get into the low 14's or high 13's, w/o really dipping into the motor too much. Impossible, maybe........but nobody ever got anywhere w/o trying. Street drivability is a real must seeing how it's my daily driver.

I have my own little side project going with this buildup that I'm experimenting with. With the exception of the open-element, I'm doing all suspension and drivetrain modsfirst, just to see what kind of numbers the LO3 is really capable of, with the right mating of other systems.

I'm currently in search of an aluminum driveshaft if anybody knows where I can find one. I'll then drag it over to the track and post some "real" numbers for yall to divulge.

brodyscamaro

i think that LS1 camaros have aluminum driveshafts that will fit our cars. i have seen them go at cz28.com for about 125-150 bones. thought about getting one myself a few times. might want to search the tranny board or make a post there, do me a favor and post the answer in this thread would ya

1989camarorsrs

iTrader: (-1)

Hey slade not trying to flame yah or anything but are u sure u got 38 mpg that seams a little too good to be true. The most ive realy heard of by the lo3 is like 32-34 tops. Maybe u calculated wrong or something.

brodyscamaro

i have already given him **** about that

92fire-audio

When i had mine, after all my mods I was lucky to get about 15mpg... I never drive on the highway though... Before modding, i got about 22mpg at best...

34 sounds very hard to believe..

r90camarors

Aluminum driveshafts go on ebay all the time. I bought one outta a 2000 T/A for $140. It was in perfect condition and works pretty good- less vibration at higher speeds.

brodyscamaro

notice any difference in 0-70 mph accelertion?

r90camarors

No. It pretty much felt the same as it did when I had the stock rusted driveshaft, only a little smoother. The aluminum driveshaft was larger in diameter, but noticably lighter. Have no before and after dyno or timeslip, but my guess would probably 3-5rwhp due to less rotational mass. Definetely not SOTP though.

brodyscamaro

thanks

Fish89

Didn't the 1LE's come with an aluminum driveshaft? Maybe want to look into that as well.

Buck268

I dont have any ducting for my dual snorkle. Pointless, yes. Ammusing, YES!

Slade1

I'm at 32 best at the moment, only in cold air though... car's very succeptible to changes in weather thx to ram air...

On avg I can pull 28 highway mpg. Those best numbers are under best conditions remember that.

I'm working the keeping stock engine, mating better parts to the engine deal for my car right now and she runs 15's on the track in humid/hot air.

I'm going to add headers and cutout valve and see how much the cat back hurts performance. If you've read recently, there are some cut gutters who have pulled 14's with the cat gut... makes me curious, but I can't dump the smog parts...

brodyscamaro

you dont have to have a cat in canada do you?

Gunny Highway

iTrader: (1)

The 1LE's did come w/ a 2.75" aluminum ds, but I've already searched all the junk yards around to no avail. The LS1's are 3" aluminums, but once again, to no avail. There are some on ebay, but I'm not really into the whole ebay thing just yet.

Slade1

nope need a cat here.. we have emissions laws borrowed from california...

Gunny Highway

iTrader: (1)

I'm sorry. Nothing should be borrowed from California except for the weather.

91-Z-Speed

What size alum. driveshaft would best fit my '91?

2010camaross

[QUOTE=NJ SPEEDER;825552]changing rear gears does not have a dramatic effect on fuel economy. i went from stock 2.73's to 3.54's with no change in around town or highway mileage. blackbird305 went from 2.73's to 3.73's with no change in mileage.
gears will only effect you mileage if you decide to go really radical with your gearing, like 4.88's or bigger. that is when you start gettign the cruising rpm into the range where the ecm is reading into other boxes on teh fuel map outside of the normal cruising operating range.

Either you are Hunter Biden's protégé or you've never investigated why automakers instituted low rear axle ratios before overdrive was prevalent. Hell, I guess you've never ridden a 10 speed bicycle. Gearing is everything

Schurkey

Why would you drag up a twenty-year-old thread to post THAT?

Don't get me wrong, I agree that gears are important and lower numerical gears on stock tuning/stock engines generally improve fuel economy at a sacrifice in performance. Conversely, raising the numerical gear ratio makes the vehicle more perky, at a sacrifice in fuel economy and--probably--emissions performance.

In general, I wouldn't walk across the street to get a free "hot air induction" system like an open-element air cleaner. NASCAR found out they were detonation-promoting crap in the early 1960s; they haven't gotten any better since then; and engine-compartment temperatures haven't decreased since then, either.