Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Strengthing metal engine harness bracket to support intake pipe

  1. Jun 23, 2011 #1
    hello! My first post here.

    I am by no means a mechanical engineer as I studied computer science in college. My question has to do with adding what is known as a cold air intake onto my vehicle.

    The design of the intake is such that the pipe fits at the throttle body via a silicone/rubber coupler and there is a support bracket that goes from the bottom of the aluminum pipe that the intake is made from to a brass/metal engine harness bracket mounted on engine from factory.

    What happens over time with this design, is that the movement of the engine seems to cause the engine bracket to shear/break where the bracket overhangs the area of the motor it is mounted to.

    here is a pic of how it breaks.
    http://i908.photobucket.com/albums/ac282/bzavetsky/xterra%20bracket%20mod%20for%20kool%20vue/broken.jpg [Broken]

    here is a pic of the bracket as it is now on my vehicle, you will notice 2 bolts, top and bottom in the picture. one has a ground wire on it per factory and that area sits above nothing but air. The other bolt sits above engine metal and has good support.

    http://s908.photobucket.com/albums/ac282/bzavetsky/xterra%20bracket%20mod%20for%20kool%20vue/ [Broken]

    I am thinking about adding a strip of steel in between the two bolts acting as a shim of sorts which should add strength to the area that breaks.

    Do you see any problem with this logic? Will is cause issues elsewhere at that support connection? perhaps where the other bolt threads into the solid engine area? On pipe where the other end attached to, is a bolt hole in a thick column welded to the outside of the pipe.

    the pipe and air filter weighs about 14 lbs total at most..

    thanks alot and if you have any other ideas i am all ears!!!
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Jun 24, 2011 #2

    Ranger Mike

    User Avatar
    Science Advisor
    Gold Member

    yes the more support you can fabricate the better..14 pounds is a bunch..can you add more brackets? more is better in this case
  4. Jun 24, 2011 #3
    here is a pic of the installed pipe in engine:

    http://i908.photobucket.com/albums/ac282/bzavetsky/xterra/two.jpg [Broken]

    if you look at the pic, you can't see the bracket i am talking about but it's near the red filter hidden in the pic but it goes to the area near that light green cap on the engine. The only other place i think i can mount something easily, is in the middle of the pipe and going towards the engine cover- that read v6- there are two threaded holes below that cover where the factory intake mounted to, that i can use as a mount point somehow. maybe get a couple hose clamps with a rigid strap or something to span the distance between the pipe and that area.???
    Last edited by a moderator: May 5, 2017
  5. Jun 26, 2011 #4
    alright, i made a shim out of 1/16" galvanized steel and drilled 2 holes, 1 to secure to aluminum engine component and the other to attach the intake pipe bracket to. It seems alot more stout.

    Only question remains is if the torque being applied by this "lever" of sorts will cause any issues with the threads in the aluminum engine component casing. Depth of threads in casing is 9/16" or so. Original bolt was 1/2".

    By design from factory, there is no load/force on that bolt pulling up or pushing up. It's meant as an engine harness bracket and ground point.

    The design of the intake bracket attachment to that bracket on the engine acts as a lever, slowly applying force up against the bolt head. I can't see that being a problem but not 100% sure as I am no mechanical engineer.

    i added the shim, used a longer grade 10.9 bolt- 7T was oem bolt which is japanese spec equiv to a grade 5 i believe. 10.9 is equiv to grade 8. So it's a stronger bolt i put in there. I went longer to a 16mm bolt, from 12 (1/2" == 12 and 16== 9/16") to compensate for the added shim of 1/16" PLUS the washer i needed as the new bolt didn't have a flange like oem.

    Anyways, the thread depth on both the stock and the new bolt/shim/washer combo is identical once installed.

    Finally the question:

    Will the additional weight of shim (an ounce maybe?) PLUS the originally designed (by intake manufacturer) force being applied to the threads by the intake bracket cause problems with the threads in the aluminum engine component?

    From my physics days in college I know torque= force x distance.

    in my case, the torque applied to the original intake bracket design would be about 5 lbs or 11 kgs (a guess as i felt how much force needed to keep the pipe up) since the throttle body secures one end of the intake mainly and this bracket acts as just a balancer to that, x the distance from the mount point on the intake pipe to the bracket i modified- about 3 inches or .0762 meters so that would be T=FxD

    F=11kgs x 9.8ms/s

    would g be 9.8 as the force is being applied at an angle not 90 degrees but around 30 degress max?

    = 108 newtons

    T= 108n x .0762m

    Torque =8.2 nm. or 6 ft/lbs

    that was original torque to the bolt head where the bracket from intake attached to. That's what would break the original bracket in half due to cyclic loading/unloading due to vibrations.

    Now I don't know how to figure out how much force is being applied to the bolt that goes into the engine because from the bolt mentioned in the above calculation to that bolt hole, there is solid engine metal under that bracket for support.

    Anyhow sorry for the long rant. Any ideas if i should be good or not?

    here are some pics of the engine bracket. the gray colored thing is the new shim. the hole closest to the radiator/front of engine bay is the whole i attach to the intake pipe bracket and the other hole- seen in the original bracket pics, is what mounts the whole bracket to al engine case.

    http://s908.photobucket.com/albums/ac282/bzavetsky/xterra%20bracket%20mod%20for%20kool%20vue/ [Broken]

    Last edited by a moderator: May 5, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook