SS RRR

iTrader: (2)

whatever you say. do what you will.

joelster

You posted a few posts back that you are thinking of going 2.73's with a t56. That would be a huge mistake. Say goodbye to your clutch. I ran that in my convertible I had. You can do 50mph in reverse. You can NEVER fully release the clutch in reverse, you'll be going way too fast. 1st gear you can ride out to 50-60mph easy. Thruway driving, you'll rarely go into 5th, and 6th gear, forget about it. Unless you want to lug the motor at 1000rpm and 80mph.

KW Baraka

iTrader: (7)

If you go with more gear, and then "keep the RPM down", you will just go slower.

More gear can (but not always) improve gas mileage in city driving, but will always lower your highway mileage if you drive at the same speed in the same gear.

Example: 3.42 gears will always give you more hwy mpg at 70 mph in 6th gear than you would get with 4.10 gears driving 70 mph in 6th gear.


BTW.....your 'stop & go' traffic drivability will be extremely shitty with 2.73 gears. To improve driving under these conditions, you'll want more gear......like 4.10's. But hey.....you ain't gotta take our word for it....LOL!

KW

bowtienut

iTrader: (1)

Just get a Prius.

Phoenix'97

Fortunately for me, I ride my clutch backing up as is! The way people are driving, you can't back up immediately out of your driveway anyways! So this won't be a problem! As far as doing 50 mph in reverse, really?!

I think a lot of you don't understand that this is what I want for my spirited driving, to gun it in 1st gear up to 50-60mph without shifting in between! All I end up doing is shifting to higher gears to cruise at 60-70mph in low RPM. So again, I am not fearful of the 2.73 from the information I have come across.

Again, I have matched up the projected engine speed to road speed for both a 2.73 and 3.42 gear ratio with 25.7 inch tall tires, and for the 3.42 gear, those projections are dead on for what I am driving. The 2.73 is not much different only that I will be using third gear now for 30mph range and fourth gear for 40mph range. I can use fifth gear for 50mph range and sixth gear will be for 65-75+mph cruising. So, it will work!

Phoenix'97

I wouldn't be driving a V8 manual vehicle if I wanted a Prius, buddy. I understand the knocking of my modification ideas so keep on hating! It will be a significant feat to get the kind of mileage projected for the 6.2L LT1 out of my old 5.7L LT1. To be able to pull this off while bumping up my horsepower to a happy order above what I have now will be the icing on the cake.

There is a reason why I haven't wrapped my Trans Am around a telephone pole yet or spun out into oncoming traffic, yet. I drive my car for enjoyment and pleasure, not to show off or to claim bragging rights. Can you respect that, or no? We all have our cars modified the way we see fit, so try to appreciate mine, being on the other side of the spectrum.

Phoenix'97

OH, that makes sense! Use a 4.10 gear to get up to 30mph in first gear at a ridiculously high RPM which is only wasting fuel! I will have to use fourth, or more likely, fifth gear to drive around at my happy 1500 RPM range! My highway mileage will suck and my car will make a lot of noise above 3,000 RPM in sixth gear!

Traffic around town is very slow to begin with, this is why the 2.73 works, and once I can fully release the clutch, I am already idling at a faster speed than I would be with the 3.42, and I don't need to accelerate quickly to get up to 30 or 40 mph around town! For launches, I will stay in 1st gear longer but that is the point and that is what I want!

SS RRR

iTrader: (2)

KW Baraka

iTrader: (7)

With 4.10 gears, you wouldn't even need to use 1st gear in stop-and-go traffic. For that matter, you wouldn't have to use 2nd gear, either.

But that's fine.....don't listen to people who have already been there and done that.

Believe in your little calculations. But I have a feeling that after you go to 2.72 or whatever granny gears you use, we'll never hear from you again. You'll just quietly go with our original suggestions.....and slip away.

KW

96lt1m6

iTrader: (31)

M6 and 4.10s are a great match. the extra 600 rpm i experienced was worth it. From a light I was already across the intersection before my foot left the clutch peddle. I am tempted to swap my Bird to a T56 w/4.10s but i want to see what i can do with an A4

NewOrleansLT1

Ok this thread has turned to **** WATER!! The smallest gear I would even THINK about putting in ANY Fbody is 3.23.. 2.73 is a BIG no no with the M6.. **** it's horrible behind an Auto too.. And WHY ON EARTH are you so worried about gas mileage on an old V8 muscle car? What you should do is use your car as a weekend toy and buy a 99' Civic to drive during the week for 3k and get 35 miles per gallon and leave the F body alone before you pull all the muscle out it.. It really bugs me when people experiment with V8 muscle trying to get Prius gas mileage out it.. Not gonna happen no matter what you do bud.. Sorry..

96lt1m6

iTrader: (31)

My bone stock 95 Formula that i just got has 3.23 gears car is a virgin!
50 mph at 1500 rpm w/ a 4L60e. can't wait to get my 3.42s in this bird.

My Z28 was a 6spd, 4.10s, which finally made 6th gear usable. I got went from Vegas to Clovis Ca. With 1 tank of gas thats almost 30 miles to the gallon.
When i broke the 4.10s i put my spare 3.23 rear in there and the car was a freaking TURD!!!!!!!!!!!

The sooner you can get into the next gear tbe better the fuel mileage will get in town.


Lastly, i do not know one person that logically purchased a sports car with fuel mileage in mind.

KW Baraka

iTrader: (7)

Exactly!!!

KW

98CayenneT/A

2.73's in a 6 speed..... jeeze ! Horrible idea !

At 6100 rpms

1st. 65 mph
2nd. 97 mph
3rd. 133 mph
4th. 173 mph
5th. 234 mph
6th. 346 mph

Talk about pissing a clutch off in stop and go traffic.

That_One_Person

iTrader: (4)

Talks about camming an LT1, concerned about fuel economy. Lol.

You want tall gears and more power? Buy a Corvette.

fbody_brian

you will get better mpg in town with the 3.42, some 3.73s or 4.10s.
The thing you should consider is the car will get better mpg with less load. So accelerating with 4.10 gears will have very little load on the motor vs 2.73.
you are going backwards
you are going to get worse mpg with the 2.73s...

Phoenix'97

Yeah I certainly hijacked the threat and I am waiting for the moderator to do their thing. However, I am doing research here with the expected comments.

I am repeating myself from an old post years ago with regards to this same topic. Again, I am not seeking Prius mileage out of my 5.7L LT1! What I am researching is what I can do increase power POTENTIAL out of my LT1 without reducing my fuel mileage rating and while seeking any gains in mileage, if-at-all-possible. I am modifying this car strictly for street driving, and from my experiences with my M6 with 3.42 rear, it requires too much shifting to higher gears to get my RPM range where I want it, 1500. I am using 4th gear for 30mph range and 5th gear for 40mph range! This problem will be remedied by use of a 2.73 rear requiring use of 3rd gear for 30mph range and 4th gear for 40mph range.

I understand acceleration will be a problem, but again, I don't have the luxury often to accelerate quickly in heavy city traffic where some cars accelerate just as slow as I do from a green light. So the 2.73 gear makes more sense for my driving needs. The only problem is winter driving! I know how my car will behave with a 3.42 gear, but I have no clue if it will be harder with the 2.73 or not. Then again, one secret in driving my car in winter is to also keep the RPM down so that I am not applying too much power to the tires to spin them while driving in deep snow conditions. This is where the 2.73 gear may work well for me, again!

Before I make a decision, I will consult a local dynotuning shop who will tune my modified LT1 to my bizarre specifications. I need to get his input for the custom grind camshaft anyways, to maximize his tune for my specifications. He may recommend staying away from the 2.73 and only going as high as 3.23, as they recommend on the third gen f-bodies with manuals. We will have to see.

I tried doing that years ago by saving my white Trans Am for the spring/summer months and using my dark green 6-cylinder automatic Firebird for the fall/winter months. I was working as a lowly furniture delivery man then, then as a warehouse clerk and then working in warehouse distribution and forklift operation. I couldn't afford the two cars on my low wages. This is a "wealthy man's privilege" to have your spring/summer toy that never sees winter. Me, I drive my baby year-round in rain and the worst of snow storms! So, I need to strike a compromise between performance and daily driving year-round performance she requires!

Not everyone races their muscle/sports cars. It's one thing to brag about horsepower during the summer when you show off, it's something completely different to survive the winter months driving these cars and not get her wrecked! I guess I can brag about this and this is why I must modify her against your "better experience".

That_One_Person

iTrader: (4)

Seriously, as stated above, go shorter.

Faster you get to OD = less rpm = better mileage. Which results in a happier performing baby cam car.

4.10's are almost "mandatory" on even lightly modded M6 F-body's. These cars have been out for 24 model years now. You're not going to discover some magic recipe at this point, especially on the LT1.

96lt1m6

iTrader: (31)

The only way you can have power, adequate fuel mileage and horrid gears that cannot do crap for you is to put an STS style turbo on your car. 400+ hp and perfect driving manners without attempting to reinvent the wheel

fbody_brian

Find yourself some 2.56 gears, then you will only ever have to shift from 1st to 2nd, you'll never need 3-6!
think of the mpgs!!!!