Announcement

Collapse
1 of 2 < >

ANY BUYING/SELLING IN THIS FORUM WILL RESULT IN AN INSTANT BAN!

Read the rules: http://www.cb7tuner.com/vbb/showthread.php?t=43956

Myself, and the other mods have been very nice and lenient with the rules. We have been deleting threads, and giving out warnings. Some members didn't get the clue and re-posted over and over... Now ANY member buying or selling in this section will be banned... No IF's AND's or BUT's.
2 of 2 < >

Beginner Forum Rules - EVERYBODY read! (old and new members alike!)

Beginners start here. Once you have 30 worthwhile posts (off topic doesn't count) you may post outside of the Beginner forums. Any "whoring" (posting simply to raise your post count) will return your count to 0, or result in a ban.

These are the rules. Read them. Live by them.

1) Absolutely NO flaming! "Flaming" is an outright attack on a member. ALL questions are encouraged to be asked here, no matter how basic. Members with over 30 posts will be subject to a ONE WEEK ban if caught flaming in this forum (and yes, moderators can read deleted posts). Members with under 30 posts will be subject to a ONE DAY ban.

2) Use appropriate language. Racial or sexual slurs will not be tolerated. A ban will be issued at the discretion of the cb7tuner.com staff.

3) No items may be sold in the Beginner forums. Any "for sale" threads will be deleted.

4) Temporarily banned members will be PERMANTLY banned if they are found posting on another account.

The rules can and will be added to. Any updates will be marked in the title.

The rules for the overall forum can be found here:
http://www.cb7tuner.com/vbb/forumdisplay.php?f=144
Read them. You will be expected to follow them.
See more
See less

Cruising RPM's

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Cruising RPM's

    ok so basically i would like a slight drop in rpm @ 70 since thats usually my flow in highway

    could i slightly oversize the diameter of wheels n tires to help compensate that ?

    less revolutions the better right ?

    or will engine be strained the same ?

    #2
    Which engine and transmission do you have?

    Larger diameter tires will reduce the driveline (including engine) rotational speed at a given vehicle speed, but 70 mph on the speedometer will no longer be 70 mph on the road.
    90 LX 4dr 5 spd 389,000 - MRT: http://www.cb7tuner.com/vbb/showthread.php?t=201450
    07 Element EX AWD 193,000 - MRT: http://www.cb7tuner.com/vbb/showthread.php?t=210623
    07 Element EX AWD AT (2) 89,000 - MRT: www.cb7tuner.com/vbb/showthread.php?t=211920

    LOTS of CB7 parts - ENTIRE COLLECTION - FREE
    Come and get it. http://www.cb7tuner.com/vbb/showthread.php?t=192583 or watch for banner ad at upper right

    Comment


      #3
      The technical and short answer is, no. There’s some wiggle room, but not enough for a firm yes.

      It depends on how much of a drop in RPM you want. This is, most of the time, controlled by the gearing of the transmission/final drive/differential. There's variable timing which also is used in vehicles with a drivetrain, but the older generation Hondas really didn't have it (they had VTEC, but it wasn't as advanced as let’s say a VANOS when it first hit the scene). Change your final drive/last gear out. It's an idea I came up with a few years back, and @Losiracer experimented with it in his M2B4 yielding great results.
      Last edited by Straight Success; 09-05-2020, 02:16 PM.
      The Lord watches over me!

      "...they did the bowties, I did the ascots, as much as I have, I'm still reppin' the have nots..."

      - So Raspy

      Comment


        #4
        There are a number of engine rpm calculators online, most of which include tire size. You’d need to know the exact specs of everything else in the driveline. I don’t know that we have that information on here, but it should be available somewhere.






        Comment


          #5
          In addition, what do you consider a slight drop in RPMs (25, 50, 100, 500, 1000, etc...)?
          The Lord watches over me!

          "...they did the bowties, I did the ascots, as much as I have, I'm still reppin' the have nots..."

          - So Raspy

          Comment


            #6
            car is a 92 ex accord ..

            mostly highway approx 70 mph

            i know about the speedometer mismatch when changing sizes as well ..

            i was just sitting back after dabbing some Larry Bird and that crossed my thoughts

            i was looking at a tire comparison site and trying to match some 17's to stock 15's when i thought what if i went up either sidewall or to 18's ( granted weight be close ) would that in any way shape or form drop my rpm's significantly ???

            Comment


              #7
              The engine speed will vary directly with the rolling radius of the (front) tires (not the wheels). A 195/60-R15 tire has a rolling radius of about 12 inches. A tire with a rolling radius of 13 inches would reduce the rpm at a given speed by a factor or 12/13 (about .923). For example, at whatever speed your car runs with an engine speed of 3000 rpm, a 13 inch tire would reduce the rpm at that same (actual) speed, the rpm would be 2769.
              90 LX 4dr 5 spd 389,000 - MRT: http://www.cb7tuner.com/vbb/showthread.php?t=201450
              07 Element EX AWD 193,000 - MRT: http://www.cb7tuner.com/vbb/showthread.php?t=210623
              07 Element EX AWD AT (2) 89,000 - MRT: www.cb7tuner.com/vbb/showthread.php?t=211920

              LOTS of CB7 parts - ENTIRE COLLECTION - FREE
              Come and get it. http://www.cb7tuner.com/vbb/showthread.php?t=192583 or watch for banner ad at upper right

              Comment


                #8
                Originally posted by fleetw00d View Post
                The engine speed will vary directly with the rolling radius of the (front) tires (not the wheels). A 195/60-R15 tire has a rolling radius of about 12 inches. A tire with a rolling radius of 13 inches would reduce the rpm at a given speed by a factor or 12/13 (about .923). For example, at whatever speed your car runs with an engine speed of 3000 rpm, a 13 inch tire would reduce the rpm at that same (actual) speed, the rpm would be 2769.
                thanks for the info

                Comment


                  #9
                  We do understand engine speed is the result of the amount of air and fuel being detonated at any specified time across each combustion cycle moving the crankshaft measured over a period of time (every minute), right? External forces are resultant at either the flywheel or flexplate (depending on your transmission type) act as additional loading which reduces engine speed.

                  Something along the lines of what an old chief engineer would say in this situation.

                  Have you considered all possible external forces? Weight perhaps?

                  What about the sensors and what each one measures?

                  Hmmm.

                  Wheel speed is dependent on engine RPM and the drivetrain gearing.





                  As fleetw00d said, overall tire diameter (an external factor) plays a role in acceleration. If you go up in diameter, you reduce acceleration. If you go down, you increase it.

                  Consider this. For roughly every 1.0" in diametrical change in tire size, there'll be ~+/- 150 rpm change to engine speed. Something you will probably never notice on your tach. So, go back and look at my original response and questions.
                  The Lord watches over me!

                  "...they did the bowties, I did the ascots, as much as I have, I'm still reppin' the have nots..."

                  - So Raspy

                  Comment


                    #10
                    Originally posted by 5acramento View Post
                    car is a 92 ex accord ..

                    mostly highway approx 70 mph

                    i know about the speedometer mismatch when changing sizes as well ..

                    i was just sitting back after dabbing some Larry Bird and that crossed my thoughts

                    i was looking at a tire comparison site and trying to match some 17's to stock 15's when i thought what if i went up either sidewall or to 18's ( granted weight be close ) would that in any way shape or form drop my rpm's significantly ???
                    Honda tends to gear their cars fairly low, since they tend to have relatively low torque and tend to make it at relatively high RPM's. Even their "low revving" NA engines, tended to keep the RPM's very close to 3K or slightly higher at 70MPH. It does make a tiny bit more noise, but doesn't really hurt the engine in anyway, so it probably is not really "strained." Some of Honda's higher revving engines could be close to 4K at those speeds, still with no ill effects.

                    Unfortunately, outside of swapping gear sets or going ridiculously bigger on the tire size, you aren't likely to move the RPM's more than a few hundred at that speed. Of course, if you start increasing your tire diameter, there are also penalties associated with that, as well as the penalties associated with lowering your RPM, putting you in a less responsive part of the rev band.


                    The OFFICIAL how to add me to your ignore list thread!

                    Comment


                      #11
                      Originally posted by Straight Success View Post
                      We do understand engine speed is the result of the amount of air and fuel being detonated at any specified time across each combustion cycle moving the crankshaft measured over a period of time (every minute), right? External forces are resultant at either the flywheel or flexplate (depending on your transmission type) act as additional loading which reduces engine speed.

                      Something along the lines of what an old chief engineer would say in this situation.

                      Have you considered all possible external forces? Weight perhaps?

                      What about the sensors and what each one measures?

                      Hmmm.

                      Wheel speed is dependent on engine RPM and the drivetrain gearing.





                      As fleetw00d said, overall tire diameter (an external factor) plays a role in acceleration. If you go up in diameter, you reduce acceleration. If you go down, you increase it.

                      Consider this. For roughly every 1.0" in diametrical change in tire size, there'll be ~+/- 150 rpm change to engine speed. Something you will probably never notice on your tach. So, go back and look at my original response and questions.

                      Yeah that 150 isn't to far from fleetwood's 230 calculator

                      So I'mma chalk it up to no ..


                      Thanks for the info Ill look into other factors

                      Comment

                      Working...
                      X