Page 2 of 3 FirstFirst 123 LastLast
Results 21 to 40 of 52

Info & question about gas saving w/4.11's

This is a discussion on Info & question about gas saving w/4.11's within the Drivetrain forums, part of the LSx Technical Help Section category; ^^^but our tires are much more near 24.5'', and that results in 1968 RPM at 70, and 1678 at 60, ...

  1. #21
    Senior Member Too Fast's Avatar
    Join Date
    Nov 2006
    Location
    Indianapolis
    Age
    54
    Posts
    5,170

    Black
    2000 WS6 6spd Hooker LT

    ^^^but our tires are much more near 24.5'', and that results in 1968 RPM at 70, and 1678 at 60, and all this means that with a .5 OD, these cars easily handle the 4.10 gear ratio with a small loss of MPG. Love that .5 OD!

    I like that calculator, works well.

  2. #22
    Moderator Firebirdjones's Avatar
    Join Date
    May 2006
    Location
    Arizona
    Posts
    12,552
    Quote Originally Posted by Eganslp View Post
    I noticed today I could drive around the city streets in 6th @ 40/41mph @ 1100 rpms, but I'm curious to know If that is too low of an rpm to be driving around in. Now if I just lay my foot on the throttle it sounds smooth like it doesn't need much throttle to keep it moving, but if I were to just give it a tad bit more throttle then it sounds...... well..... sounds a bit like engine lugging to me. Now I'm not sure if that's what its actually called or not. Idk if i'm using the correct terminology for it. So plz correct me if I'm wrong.
    So I guess my question would be; Is this a safe rpm to keep driven in at 40 mph? I just thought by keeping it in a lower rpm would help save gas.
    Hope you's can help me out with this. Also hope this could be some useful info for someone wanting to go with a higher gearing but worried about gas mileage.
    In which I forgot to add. My city I get roughly 159-170miles per tank & 225-245miles per tank on highway.
    We drive our 6 speed with the stock 3.42's around town in 6th gear all the time. I lug it down to about 40 mph tops without a problem,,,which is about 800 rpms. It picks up speed just fine as long as it's not a real steep grade.
    It consistently gets 22-23 mpg around town. Most of that driving around town though are speeds of 30 mph or so,,,and I can lug it down in 5th gear just fine. That's one of the nice things about fuel injection. We've been driving our 6 speeds this way for years without any ill affects. As a matter of fact, going up through the gears, once I hit 40-45 mph in 4th, Alot of times I'll skip 5th and just go right to 6th and save me the effort of another shift.
    These cars came with skip shift eliminators that went from 1st gear to 4th at light throttle and lugged the motor down below 1,000 rpms anyway, not a big deal.
    On the highway, at 80 mph it's 1800 rpm, and it gets right at 30 mpg. I get over 300 miles out of a tank with 1/4 tank left on the gauge. Could push it farther if I wanted to but I always tend to fill up around 1/4 tank.

  3. #23
    The Demon Demon_Z28's Avatar
    Join Date
    Feb 2008
    Location
    WA
    Posts
    648

    Bright Rally Red
    2001 Camaro SS

    @ OP:

    It could have been worse and been like a Honda CRX lol... j/k but I maybe get 200 miles out of a tank of gas because I mainly do city driving in my Camaro and it kills mileage to 13mpg. If it was all highway, maybe 20mpg. I didn't want 4.10's again cause I had them with a 10 bolt and first was useless unless it could hook and I even spun my 315 Nitto DR's with 4.10's in first on a roll lol.

  4. #24
    Member Eganslp's Avatar
    Join Date
    Oct 2009
    Location
    Philadelphia
    Age
    31
    Posts
    271

    Sunset metallic orange
    '01 Camaro SS

    Quote Originally Posted by Demon_Z28 View Post
    @ OP:

    It could have been worse and been like a Honda CRX lol... j/k but I maybe get 200 miles out of a tank of gas because I mainly do city driving in my Camaro and it kills mileage to 13mpg. If it was all highway, maybe 20mpg. I didn't want 4.10's again cause I had them with a 10 bolt and first was useless unless it could hook and I even spun my 315 Nitto DR's with 4.10's in first on a roll lol.
    @Demon, ye I still spin my 315's M/T's too till third lol I just can't get to hook up ever.



    just want to thank you guys for your responses
    The sound of your piss hitting the urinal.......yea it sounds feminine!

  5. #25
    Senior Member TLS_Addict's Avatar
    Join Date
    Mar 2008
    Location
    PA
    Posts
    1,706

    Ray Charles blue
    1492

    Quote Originally Posted by Too Fast View Post
    ^^^but our tires are much more near 24.5'', and that results in 1968 RPM at 70, and 1678 at 60, and all this means that with a .5 OD, these cars easily handle the 4.10 gear ratio with a small loss of MPG. Love that .5 OD!

    I like that calculator, works well.
    I like it too.

    I tried it with my 275s and my RPM was about spot on with that calculator. Just think though, when your tires are bald you will run a little higher rpms as the tires have less tread and they are shorter.

  6. #26
    Senior Member Too Fast's Avatar
    Join Date
    Nov 2006
    Location
    Indianapolis
    Age
    54
    Posts
    5,170

    Black
    2000 WS6 6spd Hooker LT

    ^^^and my tires are bald, just like me! I've noticed that the speedo agrees exactly with the GPS navigator now that the tires are worn out. Before, it was off by 1 MPH.

    Got new ones ready to install, having fun with them these last few months.

  7. #27
    Senior Member TLS_Addict's Avatar
    Join Date
    Mar 2008
    Location
    PA
    Posts
    1,706

    Ray Charles blue
    1492

    Quote Originally Posted by Too Fast View Post
    ^^^and my tires are bald, just like me! I've noticed that the speedo agrees exactly with the GPS navigator now that the tires are worn out. Before, it was off by 1 MPH.

    Got new ones ready to install, having fun with them these last few months.
    Last evening I brought my car home and I was just under 1900 rpms at 55 in OD which is almost perfect to that calculator I use (Richmond). I will measure my tires though and see if they are shorter/taller. Some tire manufacturers have tires listed at the same size but in actually they are MUCH different.

    Take KDWS tires in size 245/45/17 and they are not even close to as wide as the Bridgestone RE-01R tires I ran in the same size. Bridgestone were considerably wider.

  8. #28
    Moderator Firebirdjones's Avatar
    Join Date
    May 2006
    Location
    Arizona
    Posts
    12,552
    You are right. All these tires differ in both section width and overall height even though they are advertised as (for example) 275/40-17's.

    What I do to find exact height is mount them on the car, set desired air pressure. Then mark on the floor, push car for one full tire revolution and mark the floor again. Measure that distance.

    That is your actual roll out or tire diameter with the weight of the car on the tire. You'll find some interesting results that way. Play with tire pressure and watch what happens

  9. #29
    Senior Member TLS_Addict's Avatar
    Join Date
    Mar 2008
    Location
    PA
    Posts
    1,706

    Ray Charles blue
    1492

    Quote Originally Posted by Firebirdjones View Post
    You are right. All these tires differ in both section width and overall height even though they are advertised as (for example) 275/40-17's.

    What I do to find exact height is mount them on the car, set desired air pressure. Then mark on the floor, push car for one full tire revolution and mark the floor again. Measure that distance.

    That is your actual roll out or tire diameter with the weight of the car on the tire. You'll find some interesting results that way. Play with tire pressure and watch what happens
    Good idea, think there is much swelling at higher speeds? IE the higher speed = higher tire = speedo reading wrong mph. Cant get my thoughts correct right now. If a tire gets taller the speed would be faster than indicated? Im all messed up in my head now! I wouldnt think a ton with our short side walls. The old 70 series perhaps....lol

  10. #30
    Moderator Firebirdjones's Avatar
    Join Date
    May 2006
    Location
    Arizona
    Posts
    12,552
    You really won't see any growth with DOT approved street tires. They have a certain amount of stiffness that is required to pass inspection for street use.
    With these very short sidewalls you find on 16 and 17 inch wheels ( or more) there just isn't any room for growth anyway.

    There are however several compounds of slicks made that allow for a certain amount of growth.

  11. #31
    The Bandit Wesman's Avatar
    Join Date
    Apr 2006
    Location
    NJ
    Posts
    4,033

    SGM
    1998 Trans Am WS6

    Quote Originally Posted by 98maro View Post
    lol im sure the guy was wondering why u smoke him if it was the same car lol..
    im still confused on goin higher on gears, my gas mileage is not to bad..
    at 70mpm on 6th gear rpms are around 1600 how its gonna be with 4'10s?

    will you go back to stock gears?
    At 70MPH with 4.10's you'll be at around 2200RPM.

    Which means you'll lose at least a few MPG. Stock is 28MPG highway, with 4.10's I was getting 21MPG at 75MPH. Which is complete crap.

    And for everyone that says the car is faster with 4.10's, its only an illusion. The RPM's will climb faster in each gear (putting you in the powerband sooner in 1st gear from a stop) but the speedometer will not climb any faster. So 4.10's will help you get off the line quicker, but once you are moving they do not help at all. It is impossible for gears to make your car accelerate any faster - acceleration is determined by horsepower, not gearing.

  12. #32
    Moderator Firebirdjones's Avatar
    Join Date
    May 2006
    Location
    Arizona
    Posts
    12,552
    Gears multiply your torque output. The car will accelerate faster down track with more gear.

    An optimum gear for any car would be a gear that allows you to cross the finish line in your 1:1 gear roughly 2-300 rpms above your shift rpm.
    If you aren't doing that, then the car isn't geared appropriately.

    Tell ya what Wesman, give me 2 cars bone stock, one with 3.42's and one with 4.10's and I'll bank on the 4.10 car every time.

    And are you sure your speedo was correct?? 70 mph with 4.10's and a 26 inch tall tire should have been just below 2,000,,,,more like 18-1900.
    Because your gas mileage is way off for such a low cruising rpm. I wouldn't blame that on the gear at all.
    I can cruise at the same rpm you listed and get 27-28 mpg.

    I can cruise at 1800 rpm which is 80 MPH with 3.42's and get 30 mpg. As long as I keep that cruising rpm the same, it will get the same mileage no matter what gear I put in. I would just be going slightly less in the mph department.

  13. #33
    Member
    Join Date
    Jun 2008
    Location
    Euclid,ohio
    Posts
    174

    Black
    1998 Z28

    A friends 01 SS was low 13s' with the OEM 3.42s', with 4.10s it became 12.60s-12.70s with NO OTHER CHANGES.
    mine with OEM 3.23s was consistent 13.70s'(stock in the horsepower dept.),with 4.56s' it became consistent 13.20s',NO OTHER CHANGES.
    You wanna accelerate at a higher rate of acceleration,without changing horsepower,CHANGE YOUR GEARS.

  14. #34
    Senior Member Too Fast's Avatar
    Join Date
    Nov 2006
    Location
    Indianapolis
    Age
    54
    Posts
    5,170

    Black
    2000 WS6 6spd Hooker LT

    Quote Originally Posted by Wesman View Post
    At 70MPH with 4.10's you'll be at around 2200RPM.

    Which means you'll lose at least a few MPG. Stock is 28MPG highway, with 4.10's I was getting 21MPG at 75MPH. Which is complete crap.

    And for everyone that says the car is faster with 4.10's, its only an illusion. The RPM's will climb faster in each gear (putting you in the powerband sooner in 1st gear from a stop) but the speedometer will not climb any faster. So 4.10's will help you get off the line quicker, but once you are moving they do not help at all. It is impossible for gears to make your car accelerate any faster - acceleration is determined by horsepower, not gearing.
    I've read on this forum people reporting 1-2 MPG loss on highway driving with 4.10s vs their stock 3.42s.

    And show me a car with 2.73 gears, then change that to 3.73s, and tell me the acceleration is the same....

  15. #35
    Member
    Join Date
    Jun 2008
    Location
    Euclid,ohio
    Posts
    174

    Black
    1998 Z28

    2.73s' to 3.73s' is a 37% change,very similar to my 3.23s' to 4.56s change in percentage value of 41%. I gained a .5 sec in the 1/4,so it took me a 1/2 sec. less to reach the end,could only be a result of more intense acceleration. I only trapped 2mph more than with 3.23s,so for all practical purposes,speed was the same.
    MPG turned out great with the 4.56s,relative to what it should have been based on the change. 7 trips from Cleveland,Ohio to Tampa with the 3.23s always resulted in 24.5mpg at freeway legal speeds, 4 same trips with 4.56s' gave 21.5mpg,where theoretically should have been 17-18.

  16. #36
    Moderator Firebirdjones's Avatar
    Join Date
    May 2006
    Location
    Arizona
    Posts
    12,552
    Quote Originally Posted by Too Fast View Post
    I've read on this forum people reporting 1-2 MPG loss on highway driving with 4.10s vs their stock 3.42s.

    And show me a car with 2.73 gears, then change that to 3.73s, and tell me the acceleration is the same....
    Ya, what people are doing is trying to cruise at the same MPH without regard to RPM after the gear change. In that sense then yes, it would use a little more gas,,,,but the percent change from 3.42's to 4.10's isn't all that much. Certainly not enough to go from a reported 28 mpg to 21,,,,I'd say something is out of whack.

    What I do is keep the cruising rpm the same,,,I don't really care if I'm cruising 5 or even 10 mph less than before. Then mileage isn't affected. Since I can cruise at 80 mph at 1800 (which in my opinion is ridiculous, and too fast for most areas anyway), I would be perfectly happy with that same rpm while only going say,,,,,65 or 70 mph. That's completely acceptable,,,and even that I would say is extremely tame. Know what I mean?? Just don't drive so damn fast,,,lol.

    And I agree with your statement,,,,if gears didn't affect your acceleration then why aren't we all running 2.56's in everything
    Last edited by Firebirdjones; 03-31-2011 at 05:13 PM.

  17. #37
    Senior Member Too Fast's Avatar
    Join Date
    Nov 2006
    Location
    Indianapolis
    Age
    54
    Posts
    5,170

    Black
    2000 WS6 6spd Hooker LT

    ^^^I can tell you about 2.56s, a 2 speed "super turbine 300" in my '68 Le Mans droptop, lol. 5100 RPM is about 93 MPH in low! And I don't get good MPG either! Got any 3.55s and a Turbo 350 laying around you want to donate to that old Pontiac?

  18. #38
    Member TRANS-DAD's Avatar
    Join Date
    Mar 2008
    Location
    PASADENA,TEXAS
    Posts
    391

    BLACK
    2001 T/A VERT.

    @ 70MPH my car runs 1900rpm..... & i think is perfect!.. but it's not my daily so....

  19. #39
    Moderator Firebirdjones's Avatar
    Join Date
    May 2006
    Location
    Arizona
    Posts
    12,552
    Quote Originally Posted by TRANS-DAD View Post
    @ 70MPH my car runs 1900rpm..... & i think is perfect!.. but it's not my daily so....
    That's more than acceptable to me. I'm still driving cars with 4.88's and no overdrive though,,,so....

  20. #40
    The Bandit Wesman's Avatar
    Join Date
    Apr 2006
    Location
    NJ
    Posts
    4,033

    SGM
    1998 Trans Am WS6

    Quote Originally Posted by Firebirdjones View Post
    Gears multiply your torque output. The car will accelerate faster down track with more gear.
    Gears multiply torque. Torque does not affect the rate of acceleration. Acceleration is based solely on HP at any given RPM.

    An optimum gear for any car would be a gear that allows you to cross the finish line in your 1:1 gear roughly 2-300 rpms above your shift rpm.
    If you aren't doing that, then the car isn't geared appropriately.
    Agreed. With 3.42's, I can cross the finish line in 4th without having to almost shift to 5th like I did with 4.10's.

    Tell ya what Wesman, give me 2 cars bone stock, one with 3.42's and one with 4.10's and I'll bank on the 4.10 car every time.
    From a dig, 4.10's have the advantage of helping the car get off the line faster. This is because the shorter gears get the engine into the powerband faster.

    On the highway, exactly the opposite is true, the 3.42 car will pull the 4.10 car due to better top end and less power loss through the gears themselves.

    And are you sure your speedo was correct?? 70 mph with 4.10's and a 26 inch tall tire should have been just below 2,000,,,,more like 18-1900.
    Because your gas mileage is way off for such a low cruising rpm. I wouldn't blame that on the gear at all.
    I can cruise at the same rpm you listed and get 27-28 mpg.
    Speedometer was calibrated via a dynojet, so it should have been correct. My RPM always did seem higher than it should have been though, probably because my tires were shorter than 26" overall height.

Page 2 of 3 FirstFirst 123 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Question: Saving A CETA
    By fbodyNATION in forum Firebird / WS6
    Replies: 14
    Last Post: 06-04-2012, 09:16 PM
  2. Gas Saving Mods
    By BashamWS6 in forum Firebird / WS6
    Replies: 86
    Last Post: 09-20-2010, 07:05 PM
  3. nitrous purge question? Info
    By william SS in forum Nitrous
    Replies: 3
    Last Post: 09-19-2007, 09:07 AM
  4. Saving Gas???
    By JwMonE99 in forum V6
    Replies: 4
    Last Post: 08-24-2006, 01:02 PM
  5. need some advice on saving $$
    By Orange99z28 in forum Internal Engine
    Replies: 3
    Last Post: 04-26-2006, 09:42 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •