Notices
Evo General Discuss any generalized technical Evo related topics that may not fit into the other forums. Please do not post tech and rumor threads here.
Sponsored by: RavSpec - JDM Wheels Central

sti vs evo rolling start

Thread Tools
 
Search this Thread
 
Old Mar 11, 2005 | 10:36 AM
  #61  
gsujeff55's Avatar
Evolved Member
iTrader: (4)
 
Joined: Sep 2004
Posts: 2,838
Likes: 1
From: GA
Originally Posted by silvery_eagle
i'm going to make another idiotic post here.
unless you're running on high boost at 60mph on 3rd gear (maybe 6000rpm)
and then "punch" it until 100mph the time i guess would be very similar as 0-100 minus 0-60.

Inertia force or momentum i dont know the term will drag you down when you're starting at 60mph with no boost... and let's not get into the turbo lag ok? whenever you punch it at 60mph there will be turbo lag ...
so, time( 0-100 ) - time(0-60) != time(60-100)
no, because rolling through 60 you are already running 19psi. punching it AT 60 you are running in vacuum, no matter how you do it.
Reply
Old Mar 11, 2005 | 12:51 PM
  #62  
twinevo's Avatar
Evolved Member
 
Joined: Aug 2004
Posts: 778
Likes: 0
From: Minnesoter
Originally Posted by silvery_eagle
i'm going to make another idiotic post here.
unless you're running on high boost at 60mph on 3rd gear (maybe 6000rpm)
and then "punch" it until 100mph the time i guess would be very similar as 0-100 minus 0-60.

Inertia force or momentum i dont know the term will drag you down when you're starting at 60mph with no boost... and let's not get into the turbo lag ok? whenever you punch it at 60mph there will be turbo lag ...
so, time( 0-100 ) - time(0-60) != time(60-100)
I understand inertia and momentum, but i've noted in earlier posts that i'm assuming an ideal situation, i.e. Constant Acceleration. As I mentioned earlier to SterlingEvo, I realize that if you're cruising in 5th gear at 60mph and punch it to reach 100 mph, you will reach it in a much, much slower time than if you start from a lower gear. You guys didnt read any of that and just started flaming away.

Edit: i asked this question on a physics forum, check it out:

http://www.physicsforums.com/showthr...866#post488866

Last edited by twinevo; Mar 11, 2005 at 01:07 PM.
Reply
Old Mar 11, 2005 | 01:11 PM
  #63  
grendel's Avatar
Newbie
 
Joined: Apr 2004
Posts: 47
Likes: 0
From: ft. worth, Texas
go watch that lambo vs evo vid and pay close attention to the race between the evo and the rental car.
Reply
Old Mar 11, 2005 | 01:15 PM
  #64  
twinevo's Avatar
Evolved Member
 
Joined: Aug 2004
Posts: 778
Likes: 0
From: Minnesoter
Originally Posted by grendel
go watch that lambo vs evo vid and pay close attention to the race between the evo and the rental car.
again, that is not an IDEAL situation. my calcualtions were based on constant acceleration through the rolling start speed. and who in their right mind starts from a 20mph roll in 6th gear?
Reply
Old Mar 11, 2005 | 01:19 PM
  #65  
grendel's Avatar
Newbie
 
Joined: Apr 2004
Posts: 47
Likes: 0
From: ft. worth, Texas
but that doesnt help this guys question. What about the torque each have, the gear ratios, all that plays a big part of a rolling start. just because you can beat a car 0-60, or 0-100 doesnt mean you will automatically win from a roll.
Reply
Old Mar 11, 2005 | 01:24 PM
  #66  
twinevo's Avatar
Evolved Member
 
Joined: Aug 2004
Posts: 778
Likes: 0
From: Minnesoter
Originally Posted by grendel
but that doesnt help this guys question. What about the torque each have, the gear ratios, all that plays a big part of a rolling start. just because you can beat a car 0-60, or 0-100 doesnt mean you will automatically win from a roll.
you're exactly right. when i posted those numbers, i said "infer" from it what you may. I also stated that you can make an educated guess that the evo will pull on an STi from a rolling start up to around 100-110 at which point the STi will catch up and pull away. It was just a guess, but I bet it would be a good one for real world situations.
Reply
Old Mar 11, 2005 | 01:24 PM
  #67  
SterlingEvo's Avatar
Evolved Member
iTrader: (5)
 
Joined: Feb 2004
Posts: 3,487
Likes: 0
From: StVa
I guess here's the answer to the original question... They're about equal
Reply
Old Mar 11, 2005 | 01:26 PM
  #68  
grendel's Avatar
Newbie
 
Joined: Apr 2004
Posts: 47
Likes: 0
From: ft. worth, Texas
good answer!
Reply
Old Mar 11, 2005 | 01:26 PM
  #69  
twinevo's Avatar
Evolved Member
 
Joined: Aug 2004
Posts: 778
Likes: 0
From: Minnesoter
Originally Posted by SterlingEvo
I guess here's the answer to the original question... They're about equal
did you read this physics guru's response to my question. i still don't understand a lot of what he said

http://www.physicsforums.com/showth...8866#post488866
Reply
Old Mar 11, 2005 | 02:03 PM
  #70  
silvery_eagle's Avatar
Evolving Member
 
Joined: Dec 2004
Posts: 447
Likes: 0
From: Long Beach
This is a big quote from Krab at physicsforumscom
Originally Posted by evolved8
Hi all. Newbie here who has a simple question.

In car magazines, you see these speed tests they do. For example, they'll list a 0-60 time, 0-100 time, and a 0-130 time. My question is, would the times be different if you just made one run from 0-130 and mark down the times when you hit 60, 100, and 130 as opposed to doing three separate runs of 0-60, 0-100, and 0-130.
No. The times would not be different. Why should they be? Different would mean that the 0-60mph time would depend upon what you did after you hit 60mph. That contradicts causality.

Thank you for your help. The bottom numbers I used were just random. The actual numbers WOULD be linear if you graphed them out. I'm a car enthusiast who is comparing the performance of two cars. This helps.

Here are the actual numbers

0-60 mph 4.8
0-100 mph 12.6
0-130 mph 25.0
The numbers are assuredly NOT linear. Linear would mean that if 0-60mph is 4.8 sec, 0-130mph would be 4.8*130/60=10.4 sec. It would not be linear even if your wheels exerted a constant force to the road. This is because of aerodynamic drag. That's also the reason you top out at some speed. So if 135 mph is top speed, the time needed to reach it (or just higher than it) is infinite.

In fact, your tires do not exert a constant force, because vehicles are power-limited. So the force to drive the car is power divided by speed. Power varies a bit because you cannot stay at peak power except with a continuously-variable transmission, but this is not a large effect. So a good description of an accelerating vehicle is given by

m(dv/dt) = P/v - bv^2

where b is an aero drag coefficient, m is mass, P is power (to the road). You will notice acceleration is zero when . The v that satisfies this formula is of course top speed. So you can rewrite the equation of motion as

m(dv/dt) = P(1/v - v^2/ v^3 inf)

Which is nicer because you don't need to worry about how to find b. Solve this equation and you have v as a function of time. No road test needed. I've done this and it agrees with car magazine test reports. (Well actually it's a little more complicated than this because the force does not go to infinity at zero velocity as P/v would indicate, so you also need the torque in first gear.)
Reply
Old Mar 11, 2005 | 03:08 PM
  #71  
plokivos's Avatar
Account Disabled
iTrader: (3)
 
Joined: May 2004
Posts: 4,902
Likes: 4
From: Atlanta
no magazine racers allowed on this scenerio.

Between those two, it's all about the driver.

If the driver were the same person in mirror? depends on the car, some cars are stong from the factory, some aren't.

if they had the same situation, i got my money on evo, until you hit 4th gear.

Their gear box sucks a ss.
Reply
Old Mar 11, 2005 | 04:28 PM
  #72  
Santhology's Avatar
Evolving Member
iTrader: (1)
 
Joined: Jun 2004
Posts: 411
Likes: 1
From: Perris, Ca
Originally Posted by SterlingEvo
I guess here's the answer to the original question... They're about equal
^^
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
eling99
Evo General
44
Sep 21, 2021 09:35 PM
Dragking2189
Evo General
2
Oct 14, 2016 06:02 AM
coltm16
Evo X Tires / Wheels / Brakes / Suspension
6
Apr 25, 2012 10:01 AM
kuvesh
Evo X Tires / Wheels / Brakes / Suspension
6
Dec 4, 2010 05:17 PM
striderx88
Evo General
61
May 22, 2005 08:28 PM




All times are GMT -7. The time now is 01:17 PM.