Rolling Road and power loss Questions?

Notices
 

Thread: Rolling Road and power loss Questions?

Reply to Thread
Page 1 of 2 12 LastLast
Results 1 to 10 of 19
  1. Rolling Road and power loss Questions? 
    #1
    BMW Guru
    Car Details
    Xmak 330d's Car Details
    Model of Car:
    330d e46
    Year of Manufacture:
    2000
    Transmission Type:
    Manual
    Car Body Type:
    Saloon
    Xmak 330d's Avatar
    Join Date
    Nov 2009
    Location
    Cheshire
    Posts
    1,950
    Thanks
    1,250
    Thanked 1,188 Times in 1,013 Posts
    Basically I've been getting confused

    Been looking at the results from my rolling road day at the weekend and the ones posted in the RR graphs sticky thread. The thing striking me as odd is the flywheel HP compared to the wheel HP.

    According to my graph its lost 15 HP from flywheel to wheels.

    The majority of the others posted seam to have lost 50+ HP

    Thinking further physically energy cannot be destroyed just changed into a different form. So bearing that in mind the kinetic energy from the flywheel will loose some energy from heat and noise through the gearbox, prop, diff, half shafts, wheel bearings, tyres ect.

    Surely the looses from those shouldn't add up to 50-60 HP ect Big percentage of power to loose. I work in agriculture, and tractors are often quoted with there engine power and PTO power (power take off, shaft for powering machinery) if there's much over a 5% loss at the PTO they aren't very efficient.

    So what I'm trying to say is my graph accurate, and why do some cars have such a loss of power at the wheels?
    Last edited by Xmak 330d; 05-07-2011 at 22:49.
     
     

  2. Remove Advertisements
    BimmerForums.co.uk
    Advertisements
     

  3.  
    #2
    BMW Guru
    Car Details
    TheEnd's Car Details
    Model of Car:
    540
    Year of Manufacture:
    1998
    Transmission Type:
    Auto
    Car Body Type:
    Saloon
    TheEnd's Avatar
    Join Date
    Jun 2010
    Location
    Birmingham
    Posts
    8,981
    Thanks
    478
    Thanked 2,990 Times in 2,440 Posts
    I guess that dyno does the calculations different to what I have seen before, but the power loss is from meshing teeth in gearboxes, sloshing the oil around, and also from the contact patches of the tyres.
    The dynojet is a single drum so only one contact patch, but most twin drum rollers have 2 contact patches which means you lose power going to flex and heat the rubber.

    Most moving objects have some sort of friction and create heat, even stuff like differentials which is why you'll see the Alpina Diffs and newer M power stuff with cooling fins.
     
     

  4. The Following 2 Users Say Thank You to TheEnd For This Useful Post:

    mikaveli (08-07-2011),Xmak 330d (05-07-2011)

  5.  
    #3
    BMW Guru
    Car Details
    Xmak 330d's Car Details
    Model of Car:
    330d e46
    Year of Manufacture:
    2000
    Transmission Type:
    Manual
    Car Body Type:
    Saloon
    Xmak 330d's Avatar
    Join Date
    Nov 2009
    Location
    Cheshire
    Posts
    1,950
    Thanks
    1,250
    Thanked 1,188 Times in 1,013 Posts
    You can see my point though?

    To actually loose 67 hp (using Steves M3's results) at the wheel is just impossible, can't loose that much power in heat and noise. You'd be boiling the oil and making a hell of a lot of noise etc to loose 67hp.

    Can see why autos are less efficient, as they often have oil coolers. So more heat produced in them means less power coming out.
    Last edited by Xmak 330d; 07-07-2011 at 22:40.
     
     

  6. Remove Advertisements
    BimmerForums.co.uk
    Advertisements
     

  7.  
    #4
    BMW Guru
    Car Details
    Xmak 330d's Car Details
    Model of Car:
    330d e46
    Year of Manufacture:
    2000
    Transmission Type:
    Manual
    Car Body Type:
    Saloon
    Xmak 330d's Avatar
    Join Date
    Nov 2009
    Location
    Cheshire
    Posts
    1,950
    Thanks
    1,250
    Thanked 1,188 Times in 1,013 Posts
    Found this after a quick google http://www.pumaracing.co.uk/trans.htm
     
     

  8. The Following User Says Thank You to Xmak 330d For This Useful Post:

    Bonse (08-07-2011)

  9.  
    #5
    BMW Guru
    Car Details
    TheEnd's Car Details
    Model of Car:
    540
    Year of Manufacture:
    1998
    Transmission Type:
    Auto
    Car Body Type:
    Saloon
    TheEnd's Avatar
    Join Date
    Jun 2010
    Location
    Birmingham
    Posts
    8,981
    Thanks
    478
    Thanked 2,990 Times in 2,440 Posts
    That's where I got my +10, divide by .88 figures from.
     
     

  10. The Following User Says Thank You to TheEnd For This Useful Post:

    Xmak 330d (08-07-2011)

  11.  
    #6
    BMW Maestro
    Car Details
    Bonse's Car Details
    Model of Car:
    730D M Sport
    Year of Manufacture:
    2006
    Transmission Type:
    Auto/Semi-Auto
    Car Body Type:
    Saloon
    Bonse's Avatar
    Join Date
    Jan 2009
    Location
    Sutton-In-Ashfield
    Posts
    702
    Thanks
    104
    Thanked 103 Times in 92 Posts
    pretty interesting read tbh

    2006 E65 730d Sport - 2011 E93 325d Sport Convertible
     
     

  12.  
    #7
    BMW Guru
    Car Details
    Xmak 330d's Car Details
    Model of Car:
    330d e46
    Year of Manufacture:
    2000
    Transmission Type:
    Manual
    Car Body Type:
    Saloon
    Xmak 330d's Avatar
    Join Date
    Nov 2009
    Location
    Cheshire
    Posts
    1,950
    Thanks
    1,250
    Thanked 1,188 Times in 1,013 Posts
    Quote Originally Posted by Bonse View Post
    pretty interesting read tbh
    Still can't get my figures to work out though using the Formula on the link or for Steve23002's M3

    The M3 should have another 20bhp at the wheels using that formula. And I should either have more bhp at the engine or less at the wheels. Unless it is a very efficient drive train and only looses about 8% from engine to wheels in 4th gear? Could be possible it is about a 1.1 ratio.
     
     

  13. The Following User Says Thank You to Xmak 330d For This Useful Post:

    steve23002 (08-07-2011)

  14.  
    #8
    BMW Maestro
    Car Details
    Bonse's Car Details
    Model of Car:
    730D M Sport
    Year of Manufacture:
    2006
    Transmission Type:
    Auto/Semi-Auto
    Car Body Type:
    Saloon
    Bonse's Avatar
    Join Date
    Jan 2009
    Location
    Sutton-In-Ashfield
    Posts
    702
    Thanks
    104
    Thanked 103 Times in 92 Posts
    rolling roads arn't always calibrated right i'd assume... i have no experience in any of this stuff.

    I'd personally never bother with a RR

    2006 E65 730d Sport - 2011 E93 325d Sport Convertible
     
     

  15.  
    #9
    BMW Fanatic
    Car Details
    gazdan's Car Details
    Model of Car:
    328i
    Year of Manufacture:
    1998
    Transmission Type:
    automatic
    Car Body Type:
    coupe

    Join Date
    Jan 2011
    Location
    fleetwood
    Posts
    53
    Thanks
    10
    Thanked 23 Times in 19 Posts
    i must admit i dont understand this much but Steve23002's M3 run was on a maha rollers i think,which the back wheel connect to two rollers putting two contact patches on the wheels which on the road dosent happen.the dynojet only has one roller so one contact patch so why the atw figure is higher?.before the m50 manifold,cai,and new maf i had it rolling roaded on a dyno dynamics at rs tuning and my atw figure was 142.9bhp.this has two contact patches as well giving the low at the wheels figure.

    now by reading on the tinternet,single roller is good for printouts but the dual roller is much better for remapping tuning as it can be artificially loaded.probably a load of hog wash!!.

    as for your result.i believe it not wildly inaccurate as my car with m50,cai and a new maf hit 209bhp with 185 at the wheels certainely a lot less then most people with 328i claim!!.the astra turbo hit 194 (197) standard,and the 330 hit 225bhp but as you can see rolling roads are not all the same.a certain e36 site run at awesome and some got 200bhp at the wheels in a 328!!.so 185bhp at the wheels in me auto im pleased with!!
     
     

  16. The Following User Says Thank You to gazdan For This Useful Post:

    Xmak 330d (08-07-2011)

  17.  
    #10
    BMW Fanatic
    Car Details
    gazdan's Car Details
    Model of Car:
    328i
    Year of Manufacture:
    1998
    Transmission Type:
    automatic
    Car Body Type:
    coupe

    Join Date
    Jan 2011
    Location
    fleetwood
    Posts
    53
    Thanks
    10
    Thanked 23 Times in 19 Posts
    Quote Originally Posted by Bonse View Post
    rolling roads arn't always calibrated right i'd assume... i have no experience in any of this stuff.

    I'd personally never bother with a RR
    yep most people say dyno dynamics are the doggs but like most rolling road air temp sensor but in the wrong places(near rad) pumps up the temp and increases the flywheel calculation.

    one thing is no car got figures that you though were pie in the sky and crucially the garage dosent tune bmw's so are less likely to fiddle around,and on all runs i was looking at the back of the cars on coastdown to make sure the brake lights didn't come on,a favorite to gain higher transmission losses
     
     

Page 1 of 2 12 LastLast
Tags for this Thread

View Tag Cloud

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