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This is a discussion on STi vs new vette within the Comparison: WRX vs World forums, part of the Community - Meet other Enthusiasts category; Scooby24 is a quicker typer than me......

  1. #46
    Registered User Dan00Hawk's Avatar
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    Scooby24 is a quicker typer than me...


    2007 VW GTI 6 spd. No times yet
    2000 Firehawk convertible 6spd- 12.52 @ 114.7 mph. 2.09 60'

    Sold: 2004 Mini Cooper S. 14.95 @ 93.8 mph.
    Sold: 2004 GTO 6 spd. 13.4 @ 104.5 mph
    Sold: 2002 WRX 5spd. 13.39 @100.7 mph. 1.81 60'

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  3. #47
    Registered User scooby24's Avatar
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    Quote Originally Posted by Dan00Hawk
    Scooby24 is a quicker typer than me...

    Yes!!!!

    I feel smart!
    05 Crystal Gray STi
    304 hp 353 lbs on 92 octane ------> Mustang Dyno
    12.6 @ 109.2 > new numbers coming soon.

  4. #48
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    Quote Originally Posted by scooby24
    I don't know for sure. I would think though that the loss is due to a certain amount of friction caused by gears, weight, etc. When you increase horsepower you are trying to move all those parts faster....as you try to move those parts faster you are also increasing the amount of friction and the power it takes to get that weight and friction moving that much faster is an exponentially increasing amount of power...hense the reason for a percentage causing more loss of power as more power is increased.

    Y > X
    I think RPMs are remaining constant. So yes, you're accelerating the parts faster, but, in the end, they are moving the same speed.

    If we go back to our 700hp vs 300hp STI example, at a constant load, 6000 RPM, all else being equal, would one expect the same drivetrain to be losing around 100whp more?

    And, again, I'm no expert, so, I could be dead wrong.

    Let me consult the good book of google for answers, I shall return.
    2004 Java Black Pearl STI
    Shocks... Pegs... Lucky.

  5. #49
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    Well, we both may be right (http://www.g-force-motorsport.co.uk/...surement2.html)
    :
    All mechanical systems suffer from friction and a proportion of the power fed into a system will get dissipated by friction and turn into heat and noise. Note the key phrase there - "power fed into a system". For there to be a loss there must be an input. When your car is parked overnight with the engine switched off, the transmission losses are obviously zero. When the car is running then some proportion of the flywheel power will be lost in the gearbox, final drive, drive shaft bearings, wheel bearings and tyres.
    For a given mechanical system these losses will usually stay close to a particular fixed % , lets say 10% for arguments sake, of the input power. So if the car is cruising and developing 20 bhp then 2 bhp will get absorbed as friction - under full power, say 100 bhp, then maybe 10 bhp will get absorbed.
    Now it is true that not every component in a transmission system absorbs a fixed % of the input power. Some components like oil seals and non driven meshed gears (as in a normal car multi spped gearbox) have frictional losses which are not affected by the input torque. These losses do increase with speed of course but at a given rpm can be taken to remain constant even if the engine is tuned to give more power. We'll look at real world transmission loss percentages later.
    2004 Java Black Pearl STI
    Shocks... Pegs... Lucky.

  6. #50
    Banned TSi AWD's Avatar
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    requires MORE power to accelerate things faster,
    ONCE an object is in motion it takes less and less Power to accelerate it further. SInce you are making more WHP with mods and you need the SAME whp to accelerate that mass to teh same speed, the loss is more of a constant then one would believe.

    As you apply a direct force on the weight's center it takes x amount of force to spin it. Now you want to spin it faster. Momentum keeps the weight sitting so as you push harder on it now it's taking y amount of force to spin it faster.
    Takes less and less ot accelerate it more as it has stored energy.

    I stand By my statement that the Scooby in question has 350CRANK HP at the most. The most accurate way to show his power will be his trap speed in a 1/4 mile. If he TRUELY has 400WHP, his trap will be 114++++


    I bet a Shiney red nickle (painted it myself) he does not crack 109MPH

  7. #51
    Registered User scooby24's Avatar
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    Quote Originally Posted by TSi AWD
    I bet a Shiney red nickle (painted it myself) he does not crack 109MPH
    I'll take that bet!!!


    I'm at 1k ASL and hit 107.4 mph trap...and I have less power because i'm at a higher elevation.

    Being sea level. I'm almost certain he'll be 1.5 mph faster than me.
    05 Crystal Gray STi
    304 hp 353 lbs on 92 octane ------> Mustang Dyno
    12.6 @ 109.2 > new numbers coming soon.

  8. #52
    J-H
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    Man, it is just so hard to believe that a Vette would loose to an STI.

    Eventhough it is a factory freak it is still 60whp behind and that from a roll + less weight makes it almost unthinkable (sp?).....

    I don't doubt that it happened, I just think that the Vette guy was not at his best....I mean, it is just a question of redlining 2nd gear.....

    I've ridden in a COBB 2 STI and that thing pulled VERY hard, but I have also driven a Z06 and the instant power of the Vette is just too much.....




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    My car sounds like a LIGER.......ERZ + SPT = LOUD......pretty much one of my favorite sounds.....



    JH

  9. #53
    Banned Mid117's Avatar
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    Ladies, please!!

  10. #54
    Moderator YBNormal07's Avatar
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    Wow...I feel like I kicked over an anthill!!

    Sorry for all the controversy folks. Just reporting what happened and tried to fill in the blanks as to the circumstances.

    I chimed in with estimated crank hp/tq figures in response to questions as to if this race was even feasible, on a theorteical level. As for real life, it is what it is, for this particular race, with these particular cars, at this particular time, with these particular drivers. Arguing anything else is pure theory, as we can see by all the energy loss theories being posited here.

    As for what my trap speed will end up, like I said, if I hit 105, I'll be happy. I honestly could care less about trap speeds over times, as it is the time that wins the race, not the speed. If you doubt this, I can list only very few production vehicles that can top the STi in the 1/8th mile, yet that number grows by quite a bit when the 1/4 mile is the basis of measurement. Yet those same cars would eat an STi alive at high speeds.

    TBH, my one true concern will by my lap times at Summit Point. My hope is to get on the leader board sometime, but I'm still a ways away from that. Next up will likely be suspension mods, once I've reached the limits of my current setup.

    I'll fill y'all in once I have 1/4 mile times/traps. Wish me luck!!
    tEh PriUs=teH faSTah!@@!
    08 Audi S5 Black Diamond edition
    SOLD: 05 SWP Legacy GT Limited 5MT, 13.3ish@105 (stage 2) crappy stock clutch
    SOLD: 04 MPS/SW WRX Sti. 12.971 @ 103.97 (stock)
    278 AWHP/283 AWT, Catback exhaust
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  11. #55
    Registered User Dan00Hawk's Avatar
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    Quote Originally Posted by TSi AWD
    ONCE an object is in motion it takes less and less Power to accelerate it further. SInce you are making more WHP with mods and you need the SAME whp to accelerate that mass to teh same speed, the loss is more of a constant then one would believe.

    Takes less and less ot accelerate it more as it has stored energy.
    I still respectfully disagree.

    We're talking about accelerating at a faster rate by using more HP, not just continuing the same previous HP acceleration curve...

    Example:
    Get on a bicycle, and accelerate from 0-20 mph in 20 seconds. Now do the same thing in 10 seconds. It requires more of your power to do it because you have to overcome the rotational inertia (objects in motion tend to stay in motion). It doesn't suddenly become easier to accomplish. You're also working harder, sweating, putting more strain on your bike components. This example seems to contradict your opinion that it "take less energy to accelerate faster".

    Think of it in reverse then as well: Brake from 60-0 in 180 feet. Then repeat and do it in 120 feet. It takes more force to get those inertia laden masses to decelerate. Same as when accelerating.

    Your trans and diff also generate more heat when more HP is put through them. Heat, as we know, is a byproduct of energy. If heat is given off, that means a certain amount of energy is being wasted. This increased inefficiency is also why drivetrain losses increase as the HP pushed through them increase.

    By the way, I'm by no means a physics expert. But I did stay at a Holiday Inn Express last night!


    2007 VW GTI 6 spd. No times yet
    2000 Firehawk convertible 6spd- 12.52 @ 114.7 mph. 2.09 60'

    Sold: 2004 Mini Cooper S. 14.95 @ 93.8 mph.
    Sold: 2004 GTO 6 spd. 13.4 @ 104.5 mph
    Sold: 2002 WRX 5spd. 13.39 @100.7 mph. 1.81 60'

  12. #56
    Moderator YBNormal07's Avatar
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    Quote Originally Posted by Dan00Hawk

    By the way, I'm by no means a physics expert. But I did stay at a Holiday Inn Express last night!

    tEh PriUs=teH faSTah!@@!
    08 Audi S5 Black Diamond edition
    SOLD: 05 SWP Legacy GT Limited 5MT, 13.3ish@105 (stage 2) crappy stock clutch
    SOLD: 04 MPS/SW WRX Sti. 12.971 @ 103.97 (stock)
    278 AWHP/283 AWT, Catback exhaust
    306 AWHP/341 AWT, Stage 2
    (Scott) Moderator-STi, Drag Racing, Car Purchasing, and Tutorial Forums

  13. #57
    Moderator YBNormal07's Avatar
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    BTW..my background is Nuclear Physics, but I prefer not to entangle myself in theoretical discussions like these as they are often very opnionated. Not to minimize anyone's contributions, just realizing a never-ending theoretical platform based on fact AND emotion. Sometimes, emotion wins.
    tEh PriUs=teH faSTah!@@!
    08 Audi S5 Black Diamond edition
    SOLD: 05 SWP Legacy GT Limited 5MT, 13.3ish@105 (stage 2) crappy stock clutch
    SOLD: 04 MPS/SW WRX Sti. 12.971 @ 103.97 (stock)
    278 AWHP/283 AWT, Catback exhaust
    306 AWHP/341 AWT, Stage 2
    (Scott) Moderator-STi, Drag Racing, Car Purchasing, and Tutorial Forums

  14. #58
    J-H
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    Quote Originally Posted by YBNormal07
    Wow...I feel like I kicked over an anthill!!
    Just be glad that there are a lot of respectful people here. Although your run was an amazing one, a lot of people are wondering what the hell happened. You were there, you know what happened. If it was any other board you prolly would've been called every name under the sun.

    But that is why I like this place. We can discuss the facts and be nice about it IMO any info posted is important to a degree. I rate your post a 10



    .
    My car sounds like a LIGER.......ERZ + SPT = LOUD......pretty much one of my favorite sounds.....



    JH

  15. #59
    Registered User scooby-x's Avatar
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    Push a your car up a hill, then have a friend help, which is easier? One person or two? The more power behind something to make it move the easier and faster it can hit its maximum velocity, certain boats can only go so fast cus of hull design, no matter how much horsepower and no matter what pitch of prop it will only go so fast, same with a car to a certain point, a car with X horsepower can hit a certain speed cus of wind resistance and aerodynamics, now take that car with X plus 100 horsepower, it will be able to push the air more allowing the car to reach a higher speed, at a higher rate, also cus there is more torque, and btw torque is the real factor to engine power in my opinion!

    And I sell mattresses, hahahahahahahaha
    04 Java Black Pearl - Sleek Eye

    All you see is my license plate... SCOOBY-X

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  16. #60
    Registered User Dan00Hawk's Avatar
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    Smile

    Quote Originally Posted by YBNormal07
    BTW..my background is Nuclear Physics, but I prefer not to entangle myself in theoretical discussions like these as they are often very opnionated. Not to minimize anyone's contributions, just realizing a never-ending theoretical platform based on fact AND emotion. Sometimes, emotion wins.
    But I bet you'd chime in when someone pronounces it "Nuke-uler"... It's been 10+ years since my Physics classes at Illinois, so I'm sure I've forgotten a bunch of principles. I'm just going by what seems to make sense to me. I'm rather hoping someone with an engineering background (or better yet a drivetrain engineer) could chime in with an educated response.

    I found a good example that might prove my theory that the percentage stays the same and that driveline loss is not a constant fixed amount. It will increase as HP increases...

    A stock WRX and a Stock 2.5RS have essentially the same driveline components, right? Same wheels, trans, etc... I believe the clutch might be a bit different, but not sure if it would contribute much if anything.

    Subaru rates the 2.5RS at 165 HP and 166 TQ at the flywheel.
    A dyno of a stock 2.5RS shows that it puts out 122.5 WHP and 133.3 WTQ
    Dyno results here: http://www.cobbtuning.com/impreza/im...rformance.html
    165 hp - 122.5 whp gives a loss of 42.5 HP. 42.5 divided by 165 = 25.8% loss for HP
    166 tq - 133.3 wtq gives a loss of 32.7 TQ. 32.7 divided by 166 = 19.7% loss for TQ

    Subaru rates the WRX at 227 HP and 217 TQ at the flywheel.
    A Dyno of a stock WRX shows that it puts out 169.9 WHP and 174.3 WTQ
    Dyno results here (note, done on the same shop and dyno as the above example, so it should be relatively consistent) :http://cobbtuning.com/wrx/images%5Cae-stage2-dyno.jpg
    227 hp - 169.9 whp gives a loss of 57.1 hp. 57.1 hp divided by 227 = 25.2% loss for HP
    217 tq - 174.3 wtq gives a loss of 42.7 tq. 42.7 divided by 217 = 19.7% loss for TQ.

    Note how both the HP and TQ losses are higher on the more powerful WRX despite the nearly identical drivetrain. Yet, when the math is done to calculate the percentage lost through the drivetrain, they are nearly identical. Way to close to be a coincidence...

    Thus I'd have to conclude that drivetrain loss will stay at or around 25% for a WRX, regardless of power levels. Of course, this may change as people upgrade or change components to handle the higher power levels.

    Class dismissed!


    2007 VW GTI 6 spd. No times yet
    2000 Firehawk convertible 6spd- 12.52 @ 114.7 mph. 2.09 60'

    Sold: 2004 Mini Cooper S. 14.95 @ 93.8 mph.
    Sold: 2004 GTO 6 spd. 13.4 @ 104.5 mph
    Sold: 2002 WRX 5spd. 13.39 @100.7 mph. 1.81 60'

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