EM TuningJMB Retrofits
Results 1 to 10 of 10
  1. #1
    3rd Gear

    Status
    Offline
    Join Date
    Dec 2011
    Posts
    627

    Power to weight vs over all horse power

    At what point does outright power over come power to weight ratio ??

  2. # ADS
    ADS
    Join Date
    Always
    Posts
    Many
     
  3. #2
    _G_
    _G_'s Avatar
    4th Gear

    Status
    Offline
    Join Date
    Jul 2011
    Posts
    869
    Ok I'm going to take a stab in the dark here and say when the power exceeds the weight per tonne. The problem is though, that the power is often measured from the flywheel and sometimes the drivers weight is excluded from the equation.

    So for example:
    Audi A3 2.0 T with gross vehicle weight of 1930kg
    Say you had a Driver weight of 90kg
    BHP at flywheel ?? but we know on a rolling road it is around 200 bhp stock from the wheels

    Say the power at the flywheel was 200 though and gave us a Power to weight ration of 99.01

    Basically the calculation shows that the power exceeds the weight of vehicle and driver per tonne.

    So any power (BHP) higher than the weight (be it car and driver or car alone) is good. The further away you are from the figure per tonne then the better. For example, say we take a Mercedes SLR (2008) which has a gross weight of 1780kg... same driver who weights 90kg and our power to weight ration is 334.76 with the driver... you can see that figure is way out from 100 - the higher the number the better.

    It would depend on the vehicle weight though. Now if I was a rap star and people wanted me dead but I loved my Mercedes SLR so much that it had become a 4000 kg car (bullet proof glass and armour plating adding all the weight).. the power to weight ratio would be 153... which is still good but not as good if the car weighed less. This would also mean that if I was go head to head with a Stage 1 Audi S3 then I would probably be neck and neck.

    I hope that answers your question... someone correct me if I am wrong.

  4. #3
    6th Gear

    Status
    Offline
    Join Date
    Jul 2007
    Location
    London
    Posts
    3,211
    After you pass 500 Bhp it does not matter if the car is 1000 or 2000 Kg, it will just be fast ! The above example is a little bit better but if you have 300Bhp per ton or more then you're in a seriously quick car !
    FOR SALE:
    -Golf mk 5/audi a3 1.6 FSI fuel pump, brand new genuine part boxed + seals
    -audi a3 (1998 to 2003) genuine clutch slave cylinder to fit 1.6 engines BRAND NEW
    -Rear bush press tool to fit new rear axle bushes on Golf Mk3/4, Audi a3/S3, Seat Leon/Toledo, Skoda Octavia mk 1/2 used once

  5. #4
    3rd Gear

    Status
    Offline
    Join Date
    Dec 2011
    Posts
    627
    I know a guy with a Clio 172 and it has been turbo'd and is around 290/300bhp and it only weighs just a over a ton so has a very good power to weight ratio,but say I was in a fast car like a rs4 b7 414 bhp and around 250 bhp per ton.he has the better power to weight ratio,but at what speed would power to weight ratio no matter and the fact I have about 100 horsepower more come into play ??

  6. #5
    Ben S3 8P3's Avatar
    2nd Gear

    Status
    Offline
    Join Date
    Jul 2012
    Location
    Bury//Manchester//Leeds
    Posts
    313
    Quote Originally Posted by Goubo1 View Post
    At what point does outright power over come power to weight ratio ??
    For acceleration, never.
    Ice Silver Audi S3 (8P3) https://www.facebook.com/benjamin.n.long

  7. #6
    jojo's Avatar
    S3 Drift King!

    Status
    Offline
    Join Date
    Sep 2003
    Location
    Solihull, Midlands
    Posts
    25,427
    Quote Originally Posted by Goubo1 View Post
    I know a guy with a Clio 172 and it has been turbo'd and is around 290/300bhp and it only weighs just a over a ton so has a very good power to weight ratio,but say I was in a fast car like a rs4 b7 414 bhp and around 250 bhp per ton.he has the better power to weight ratio,but at what speed would power to weight ratio no matter and the fact I have about 100 horsepower more come into play ??
    If you are comparing like for like cars, then it is easier, but to compare a Clio with an RS4, the science behind it all is more complex. 2wd vs 4wd for example, a 4wd car will always have more transmission losses to a 2wd, but can the Clio transmit all that power to the road with no wheelspin? Then there's the gearing of the gearbox, does a Clio sport gearbox really make the most of the available power with it's ratio's? I think not personally.

    Power to weight ratio is just a gauge, reality is different. An RS4 with 414bhp will still be accellerating past 150mph, whilst a Clio with 300bhp will probably near it's rev limiter at the same speed?



    99' Audi S3(APY) - Brilliant Black Click>>>Going Sideways vid!
    You've got to have a laugh! For Sale:LCR Brakes - £400



  8. #7
    3rd Gear

    Status
    Offline
    Join Date
    Dec 2011
    Posts
    627
    So power to weight for acceleration and outright power for topend ??

  9. #8
    Ben S3 8P3's Avatar
    2nd Gear

    Status
    Offline
    Join Date
    Jul 2012
    Location
    Bury//Manchester//Leeds
    Posts
    313
    Quote Originally Posted by Goubo1 View Post
    So power to weight for acceleration and outright power for topend ??
    It is complex. But simply put, for acceleration the power to weight ratio is the determining factor. At high speeds it is more of a power/air resistance battle. A 110bhp bike has no trouble getting to 165-170mph
    Ice Silver Audi S3 (8P3) https://www.facebook.com/benjamin.n.long

  10. #9
    A4_MaJiK's Avatar
    4th Gear

    Status
    Offline
    Join Date
    Jul 2012
    Location
    Leicester, UK
    Posts
    817

    My Social Networking

    Add A4_MaJiK on Facebook Visit A4_MaJiK's Instagram Channel
    As above really. Power to weight is quite relative to acceleration and overall power can determine top speed although other factors also come in to play such as aerodynamic efficiency, gearbox ratios etc.

    Audi A4 B7 3.0TDI S-Line Sprint Blue
    ~ MTEC DRLs & Sidelights ~ 8000k D1S ~ 19" A6 Le Mans Edition Wheels ~ Eibach Wheel Spacers (5mm F/15mm R) ~ Rear Ambient Lighting ~
    ~ UK Legal Pressed Plates ~ Full Interior LED Lighting ~ Rear Numberplate LED Lights ~ LCR Front Splitter ~

  11. #10
    Reverse Gear

    Status
    Offline
    Join Date
    Oct 2011
    Posts
    20
    great info

 

 

Similar Threads

  1. Loosing All Turbo / Power!! 96 A4 1.9tDi
    By imported_Audi_DavE in forum A4/S4 forum(B5 Chassis)
    Replies: 4
    Last Post: 15th December 2005, 08:55
  2. Increase horse power and torque
    By shaheed in forum A3/S3/Sportback (8P Chassis)
    Replies: 5
    Last Post: 15th September 2005, 05:27
  3. Attacking the power to weight ratio.
    By pure in forum A3/S3 Forum (8L Chassis)
    Replies: 7
    Last Post: 19th May 2004, 18:15
  4. V Interesting Stats...Power to weight Ratios...!!!
    By DreA3Turbo in forum A3/S3 Forum (8L Chassis)
    Replies: 10
    Last Post: 27th August 2003, 12:43
  5. Base Horse Power
    By c_coffell64 in forum Classic Audi Forum
    Replies: 0
    Last Post: 18th June 2003, 01:14

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Single Sign On provided by vBSSO

Garage Plus, Vendor Tools vBulletin Plugins by Drive Thru Online, Inc.

Content Relevant URLs by vBSEO