08 MT Type S vs 11 Audi S4
#81
#82
^^ Reese trapped 104.
Are you saying my 21.5mph gain isn't believable? If you want, I'll PM you pictures of my slips with the car # and when I get home I'll take a picture of my car with that same #. I haven't washed it off.
Are you saying my 21.5mph gain isn't believable? If you want, I'll PM you pictures of my slips with the car # and when I get home I'll take a picture of my car with that same #. I haven't washed it off.
#83
Anything above 23mph in an NA car typically takes both displacement and lungs to continue accelerating a car hard through the air. 26mph with an NA motor is stellar. 26-28mph with a turbo car isn't unheard of due to the characteristics of the power delivery.
#85
No they look 100% correct....what I was saying is EVEN the SC TL were in the 22/23 range. That actually surprised me since I thought they would be 24 or so.
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justnspace (11-01-2011)
#87
I was doing some background research on my car based on previous dyno results....Take note that all my dynos have been conducted on the same one over and over again....
My car stock pulled 253whp = 286bhp according to Acura...Thats 33 hp of difference between crank and wheel...Now...My last dyno 6 months ago claimed by my mechanic was 296 although i only hold the slip for a 294whp/262wtq...Lets add 33 hp more to the 296= 329 crank hp...
Given now the new set up on the TB, IM etc...I am assuming the car is at least 300whp thats 6 more to the wheels = 335hp crank...
The S4 is at 333hp crank horses with a 300lbs more weight than my Type S...AWD cars on a roll on do not have the advantage over the fwd..That is why I always pick the battles under certain conditions...Having said this...It is feasable for those non-believers that the result of the race was a kill...Anyways...I wanted to share that thought since numbers dont lie...
Like I have mentioned before...I need to dyno soon and the times will be proven at the track with traps and ET's...Thanks
My car stock pulled 253whp = 286bhp according to Acura...Thats 33 hp of difference between crank and wheel...Now...My last dyno 6 months ago claimed by my mechanic was 296 although i only hold the slip for a 294whp/262wtq...Lets add 33 hp more to the 296= 329 crank hp...
Given now the new set up on the TB, IM etc...I am assuming the car is at least 300whp thats 6 more to the wheels = 335hp crank...
The S4 is at 333hp crank horses with a 300lbs more weight than my Type S...AWD cars on a roll on do not have the advantage over the fwd..That is why I always pick the battles under certain conditions...Having said this...It is feasable for those non-believers that the result of the race was a kill...Anyways...I wanted to share that thought since numbers dont lie...
Like I have mentioned before...I need to dyno soon and the times will be proven at the track with traps and ET's...Thanks
#88
Seems the S4 is WAY underrated, as I suspected and Dave B corroborated. 330 WHP/336 tq to the wheels, and it's actually over 400 lbs heavier than your car stock, but with all your bolt ons you've probably shaved off ~50 lbs, most of it in the exhaust. You probably have ~ 500 lb advantage.
http://www.quattroworld.com/blog/apr...stock-2010-s4/
Makes sense now, since the previous 4.2 S4 was rated at I believe 340 BHP and wasn't nearly as fast as the new one.
http://www.quattroworld.com/blog/apr...stock-2010-s4/
Makes sense now, since the previous 4.2 S4 was rated at I believe 340 BHP and wasn't nearly as fast as the new one.
Last edited by anx1300c; 11-02-2011 at 12:48 AM.
#89
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LOL u cant just add the horsepower loss
stock = 286hp
your = 253hp which is a loss of {(286-253)/286}x100=11.5%
MT's usually have a loss of 15% which tells me the dyno is a little optimistic....AT's see a loss of 20-22%
once you put on mods like lightweight pulley/innovative mounts/Exhaust side mods....what you are really doing is free-ing up the HP lost from the crank to the wheels....so now your loosing like 8-9%....
my point being if your stock car is at 286 to the crank and 253 to the wheels...by doing exhaust side mods/pulley/weight reduction you will NEVER pass 286hp to the wheels....since your motor is making only 286....you will become quicker but not faster....
stock = 286hp
your = 253hp which is a loss of {(286-253)/286}x100=11.5%
MT's usually have a loss of 15% which tells me the dyno is a little optimistic....AT's see a loss of 20-22%
once you put on mods like lightweight pulley/innovative mounts/Exhaust side mods....what you are really doing is free-ing up the HP lost from the crank to the wheels....so now your loosing like 8-9%....
my point being if your stock car is at 286 to the crank and 253 to the wheels...by doing exhaust side mods/pulley/weight reduction you will NEVER pass 286hp to the wheels....since your motor is making only 286....you will become quicker but not faster....
#90
lol u cant just add the horsepower loss
Stock = 286hp
your = 253hp which is a loss of {(286-253)/286}x100=11.5%
mt's usually have a loss of 15% which tells me the dyno is a little optimistic....at's see a loss of 20-22%
once you put on mods like lightweight pulley/innovative mounts/exhaust side mods....what you are really doing is free-ing up the hp lost from the crank to the wheels....so now your loosing like 8-9%....
My point being if your stock car is at 286 to the crank and 253 to the wheels...by doing exhaust side mods/pulley/weight reduction you will never pass 286hp to the wheels....since your motor is making only 286....you will become quicker but not faster....
Stock = 286hp
your = 253hp which is a loss of {(286-253)/286}x100=11.5%
mt's usually have a loss of 15% which tells me the dyno is a little optimistic....at's see a loss of 20-22%
once you put on mods like lightweight pulley/innovative mounts/exhaust side mods....what you are really doing is free-ing up the hp lost from the crank to the wheels....so now your loosing like 8-9%....
My point being if your stock car is at 286 to the crank and 253 to the wheels...by doing exhaust side mods/pulley/weight reduction you will never pass 286hp to the wheels....since your motor is making only 286....you will become quicker but not faster....
#91
LOL u cant just add the horsepower loss
stock = 286hp
your = 253hp which is a loss of {(286-253)/286}x100=11.5%
MT's usually have a loss of 15% which tells me the dyno is a little optimistic....AT's see a loss of 20-22%
once you put on mods like lightweight pulley/innovative mounts/Exhaust side mods....what you are really doing is free-ing up the HP lost from the crank to the wheels....so now your loosing like 8-9%....
my point being if your stock car is at 286 to the crank and 253 to the wheels...by doing exhaust side mods/pulley/weight reduction you will NEVER pass 286hp to the wheels....since your motor is making only 286....you will become quicker but not faster....
stock = 286hp
your = 253hp which is a loss of {(286-253)/286}x100=11.5%
MT's usually have a loss of 15% which tells me the dyno is a little optimistic....AT's see a loss of 20-22%
once you put on mods like lightweight pulley/innovative mounts/Exhaust side mods....what you are really doing is free-ing up the HP lost from the crank to the wheels....so now your loosing like 8-9%....
my point being if your stock car is at 286 to the crank and 253 to the wheels...by doing exhaust side mods/pulley/weight reduction you will NEVER pass 286hp to the wheels....since your motor is making only 286....you will become quicker but not faster....
Secondly, hp is a function of tq over time. In simple terms, car X makes a dyno run in 4th gear from 2000 to 7000rpms and the does the run in 15.0 seconds. You add a few bolt-ons and retest and the car does the same run in 14.5 seconds, the motor is clearly making more power (tq) and it will show both a hp and tq improvement. At the strip, the car will be quicker and faster.
#92
I'd pass on more dynos and just get out to the strip and finally make some passes before it's too late in the season. You've been talking about going to the strip for months. You're one of the few on here that's stuck with the same dyno and tracked gains. It also sounds like you know how to drive. You sound like the ideal cannidate to show the us what type of numbers these cars can put down. ET might suck due to cold weather, but the truth will be in the trap speed.
#93
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Assuming you're removing some restrictive part, the motor will most certainly make more power. Powertrain losses are a constant. By what you're saying, if you were to reduce restrictions, the motor isn't making more power, but drivetrain losses like gear and accessory drag, torque converter pumping losses, or tire friction would become less significant. That's impossible.
Secondly, hp is a function of tq over time. In simple terms, car X makes a dyno run in 4th gear from 2000 to 7000rpms and the does the run in 15.0 seconds. You add a few bolt-ons and retest and the car does the same run in 14.5 seconds, the motor is clearly making more power (tq) and it will show both a hp and tq improvement. At the strip, the car will be quicker and faster.
Secondly, hp is a function of tq over time. In simple terms, car X makes a dyno run in 4th gear from 2000 to 7000rpms and the does the run in 15.0 seconds. You add a few bolt-ons and retest and the car does the same run in 14.5 seconds, the motor is clearly making more power (tq) and it will show both a hp and tq improvement. At the strip, the car will be quicker and faster.
imagine a scenario where a MT car weighs 3000lbs and is at 300hp @ crank and assuming 10% drive-train loss and hence 270hp @ wheels....now the owner does ONLY weight reduction mods and is down to 2000lbs....now the loss will be down to 5% and hence the hp to the wheels will go up to 285hp....
no matter what he does he will NOT pass 300hp to the wheels since thats how much the motor makes !!!
power (hp or tq) is basically calculated by air and fuel...the ECU keeps the AFR constant....hence the more air you add the more fuel goes in the more power you get....by removing restrictions, your motor is not making more power....
you can reduce the drive-train losses to a limit....reduce weight of the car...adding exhaust....adding lightweight pulley....solid motor mounts....but over all you will still have 6-8% losses in MT's and ~15% in AT's
#94
Basically, the motor is putting out 286hp the way it stands in stock form. Stock intake, stock exhaust, stock head, etc. By increasing the volume of exhaust gases that are released and maintaining the velocity, this makes the engine run more efficient, thus gaining power. The motor already makes this power, you are just making it easier to push the air out, and more air at that, which causes a power increase. I get that. But to say that the car will never put down more wheel hp than the crank number states just doesn't make any sense to me since the two numbers really have nothing to do with one another. One is crank hp and the other is wheel.
EDIT: You're basically saying mods don't add horsepower, but reduce drivetrain loss. Wtf?
Last edited by Sonnick; 11-02-2011 at 10:06 AM.
#95
we not on the same page bro....
imagine a scenario where a MT car weighs 3000lbs and is at 300hp @ crank and assuming 10% drive-train loss and hence 270hp @ wheels....now the owner does ONLY weight reduction mods and is down to 2000lbs....now the loss will be down to 5% and hence the hp to the wheels will go up to 285hp....
no matter what he does he will NOT pass 300hp to the wheels since thats how much the motor makes !!!
power (hp or tq) is basically calculated by air and fuel...the ECU keeps the AFR constant....hence the more air you add the more fuel goes in the more power you get....by removing restrictions, your motor is not making more power....
you can reduce the drive-train losses to a limit....reduce weight of the car...adding exhaust....adding lightweight pulley....solid motor mounts....but over all you will still have 6-8% losses in MT's and ~15% in AT's
imagine a scenario where a MT car weighs 3000lbs and is at 300hp @ crank and assuming 10% drive-train loss and hence 270hp @ wheels....now the owner does ONLY weight reduction mods and is down to 2000lbs....now the loss will be down to 5% and hence the hp to the wheels will go up to 285hp....
no matter what he does he will NOT pass 300hp to the wheels since thats how much the motor makes !!!
power (hp or tq) is basically calculated by air and fuel...the ECU keeps the AFR constant....hence the more air you add the more fuel goes in the more power you get....by removing restrictions, your motor is not making more power....
you can reduce the drive-train losses to a limit....reduce weight of the car...adding exhaust....adding lightweight pulley....solid motor mounts....but over all you will still have 6-8% losses in MT's and ~15% in AT's
It's power to weight ratio WILL increase, obviously, as will the rate of acceleration; but horsepower will remain stagnant if no performance mods are added. I'm not sure how you're coming up with this notion that weight reduction adds power...That's like saying if someone weighing 300lbs loses 100lbs, they'll actually be stronger. Makes absolutely no sense.
Last edited by Sonnick; 11-02-2011 at 10:06 AM.
#96
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^^^ ok for starters....hp at crank means how much power the motor is making....
read this now:
by doing exhaust side mods the gases move quickly the motor run efficiently which means your are only reducing restrictions....if the motor can produce 286 @ crank everything stock and by the time it put its to the wheels it has some losses called as "drive-train loss"....this is basically the weight of the car, restrictions by the exhaust, transmission losses, wheel hop, etc etc
by eliminating these (you cant really eliminate everything) but by reducing the weight of the car, putting on solid mounts, crank pulley, lightweight rims/tires, slick tires you are helping the motor put down MORE power....but the MAX power the motor can produce is 286....
catching my drift ?
read this now:
imagine a scenario where a MT car weighs 3000lbs and is at 300hp @ crank and assuming 10% drive-train loss and hence 270hp @ wheels....now the owner does ONLY weight reduction mods and is down to 2000lbs....now the loss will be down to 5% and hence the hp to the wheels will go up to 285hp....
by eliminating these (you cant really eliminate everything) but by reducing the weight of the car, putting on solid mounts, crank pulley, lightweight rims/tires, slick tires you are helping the motor put down MORE power....but the MAX power the motor can produce is 286....
catching my drift ?
#97
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I don't agree with this either. How can you say weight reduction adds horsepower? It doesn't. Will it make the car faster? Yes. Will the car be more nimble and agile? Yes. But the car will certainly NOT gain more power.
It's power to weight ratio WILL increase, obviously, as will the rate of acceleration. But horsepower will remain stagnant if no performance mods are added. I'm not sure how you're coming up with this notion that weight reduction adds power...That's like saying if someone weighing 300lbs loses 100lbs, they'll actually be stronger. Makes absolutely no sense.
It's power to weight ratio WILL increase, obviously, as will the rate of acceleration. But horsepower will remain stagnant if no performance mods are added. I'm not sure how you're coming up with this notion that weight reduction adds power...That's like saying if someone weighing 300lbs loses 100lbs, they'll actually be stronger. Makes absolutely no sense.
as Dave said...hp is tq over time....
it takes a motor 15 seconds to take a 3000lb car from 2K rpm to 9K rpm hence it has 300hp (just figures)
so if the car now weights 2000lb....the motor will go from 2K to 9K in 14 seconds hence 310hp.....
so you gained HP to the wheels and NOT what the motor produces by reducing weight of the car....
#98
YES it will....
as Dave said...hp is tq over time....
it takes a motor 15 seconds to take a 3000lb car from 2K rpm to 9K rpm hence it has 300hp (just figures)
so if the car now weights 2000lb....the motor will go from 2K to 9K in 14 seconds hence 310hp.....
so you gained HP to the wheels and NOT what the motor produces by reducing weight of the car....
as Dave said...hp is tq over time....
it takes a motor 15 seconds to take a 3000lb car from 2K rpm to 9K rpm hence it has 300hp (just figures)
so if the car now weights 2000lb....the motor will go from 2K to 9K in 14 seconds hence 310hp.....
so you gained HP to the wheels and NOT what the motor produces by reducing weight of the car....
The same holds true for a car. Weight reduction will not show up on the dyno NOR will it lessen any drivetrain loss. Drivetrain loss is just that, losses through the drivetrain. Neither exhaust or engine mods have anything to do with it. Lightweight cranks and flywheels may decrease drivetrain loss, I'm not sure, but exhaust mods have no effect whatsoever.
Engine mounts will indeed help put the power down better, but this does not translate into less drivetrain loss. All it does it keep the engine planted so that the power can be put down more effectively, ultimately resulting in a faster car. No effect on drivetrain loss. I'm not sure where you are getting your info from. And don't take any of this wrong as I'm not attacking you, I just really disagree with it, and have no idea where you are coming from. Lol
#99
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^^^ bro seriously, are you reading ur own sentences ?
again your NOT getting the main point...your beating around the bush....
here is an example....you have been to the track....
a car weighs 3000lbs run 1/4 mile in 15 seconds and the same car comes back @ 2000lbs....will run the quarter mile faster ? which means its has more HP/TQ
a lot of people think by doing weight reduction/exhaust mods/other mods than INTAKE/FI/INJECTOR UPGRADE your motor makes more power....
if you PROPERLY read my post # 89 my point of saying was if your motor makes 300hp at the crank and out of those 300hp, puts down 260hp due to the losses, you can reduce those losses by doing some mods and hence ur motor will now put down 270....in no means you can say that hey my motor is rated at 300 and i was putting down 260 so a difference of 40 and now am putting down 270 so am making 310 at the crank....NO your motor is still making 300 but u just REDUCED the amount of losses....
making sense now ?
does that mean his legs got stronger, propelling him faster?
here is an example....you have been to the track....
a car weighs 3000lbs run 1/4 mile in 15 seconds and the same car comes back @ 2000lbs....will run the quarter mile faster ? which means its has more HP/TQ
a lot of people think by doing weight reduction/exhaust mods/other mods than INTAKE/FI/INJECTOR UPGRADE your motor makes more power....
if you PROPERLY read my post # 89 my point of saying was if your motor makes 300hp at the crank and out of those 300hp, puts down 260hp due to the losses, you can reduce those losses by doing some mods and hence ur motor will now put down 270....in no means you can say that hey my motor is rated at 300 and i was putting down 260 so a difference of 40 and now am putting down 270 so am making 310 at the crank....NO your motor is still making 300 but u just REDUCED the amount of losses....
making sense now ?
#100
I don't think it makes any sense, I think you're somehow mixed up with the power to weight ratio. Here's my refine version (Sonnick's POV);
Let's say I can squat 300bls. Now, I am piggy back a 100bls person doing a 40m dash in 5.5s. Same distance without that person, I can dash faster and I still only be able to squat 300lbs.
Let's say I can squat 300bls. Now, I am piggy back a 100bls person doing a 40m dash in 5.5s. Same distance without that person, I can dash faster and I still only be able to squat 300lbs.
#101
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^^^ whats with running and squating....
simple question....answer in yes/no
3000lb car runs 1/4 miles in 15 seconds....will 2000lb same car run quicker ?
ALso did you read post # 88 and #89 ? u know u cant add HP right ?
simple question....answer in yes/no
3000lb car runs 1/4 miles in 15 seconds....will 2000lb same car run quicker ?
ALso did you read post # 88 and #89 ? u know u cant add HP right ?
Last edited by swoosh; 11-02-2011 at 11:02 AM.
#105
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hp to the wheels is power to weight ratio....same CRANK hp / less weight = more hp to the wheels....
AGAIN am not saying the MOTOR will make more power....it will just put more power to the ground since you have REDUCED the losses
AGAIN am not saying the MOTOR will make more power....it will just put more power to the ground since you have REDUCED the losses
#106
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LAST ATTEMPT TO EXPLAIN IT
when you do weight reduction your car becomes quicker....YES
it does not affect your hp at the crank i.e. what the motor is making stays the same....YES
it only affects on how much power you are putting down....YES
on a track or on a dyno you will be quicker....YES
which means you have put down more HP even thow your MOTOR is making the same power.....fucking yes
now what part of running and squatting dont you get LOL....
say if you weight 300lbs and run 1mile in 20 minutes....if you drop down to 200lbs you can run the same mile in 15 minutes which means you are now CAPABLE or putting down the same BODY power more efficiently and since you wiegh less it TAKES less effort to cover the same mile....got nothing with being about to squat 870 pounds....
when you do weight reduction your car becomes quicker....YES
it does not affect your hp at the crank i.e. what the motor is making stays the same....YES
it only affects on how much power you are putting down....YES
on a track or on a dyno you will be quicker....YES
which means you have put down more HP even thow your MOTOR is making the same power.....fucking yes
now what part of running and squatting dont you get LOL....
say if you weight 300lbs and run 1mile in 20 minutes....if you drop down to 200lbs you can run the same mile in 15 minutes which means you are now CAPABLE or putting down the same BODY power more efficiently and since you wiegh less it TAKES less effort to cover the same mile....got nothing with being about to squat 870 pounds....
#108
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So a man weighs 300lbs. He runs the 40m dash in 6.0 seconds. If he were to lose 100lbs and run the same 40m in 5.5 seconds, does that mean his legs got stronger, propelling him faster? No, not by any means. It means his legs had to do 'less' to move him the same distance, increasing his power to weight ratio, but not power in itself.
Last edited by Monte TLS,MAX; 11-02-2011 at 11:29 AM.
#109
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Post 97
YES it will....
as Dave said...hp is tq over time....
it takes a motor 15 seconds to take a 3000lb car from 2K rpm to 9K rpm hence it has 300hp (just figures)
so if the car now weights 2000lb....the motor will go from 2K to 9K in 14 seconds hence 310hp.....
so you gained HP to the wheels and NOT what the motor produces by reducing weight of the car....
as Dave said...hp is tq over time....
it takes a motor 15 seconds to take a 3000lb car from 2K rpm to 9K rpm hence it has 300hp (just figures)
so if the car now weights 2000lb....the motor will go from 2K to 9K in 14 seconds hence 310hp.....
so you gained HP to the wheels and NOT what the motor produces by reducing weight of the car....
^^^ bro seriously, are you reading ur own sentences ?
again your NOT getting the main point...your beating around the bush....
here is an example....you have been to the track....
a car weighs 3000lbs run 1/4 mile in 15 seconds and the same car comes back @ 2000lbs....will run the quarter mile faster ? which means its has more HP/TQ
a lot of people think by doing weight reduction/exhaust mods/other mods than INTAKE/FI/INJECTOR UPGRADE your motor makes more power....
if you PROPERLY read my post # 89 my point of saying was if your motor makes 300hp at the crank and out of those 300hp, puts down 260hp due to the losses, you can reduce those losses by doing some mods and hence ur motor will now put down 270....in no means you can say that hey my motor is rated at 300 and i was putting down 260 so a difference of 40 and now am putting down 270 so am making 310 at the crank....NO your motor is still making 300 but u just REDUCED the amount of losses....
making sense now ?
again your NOT getting the main point...your beating around the bush....
here is an example....you have been to the track....
a car weighs 3000lbs run 1/4 mile in 15 seconds and the same car comes back @ 2000lbs....will run the quarter mile faster ? which means its has more HP/TQ
a lot of people think by doing weight reduction/exhaust mods/other mods than INTAKE/FI/INJECTOR UPGRADE your motor makes more power....
if you PROPERLY read my post # 89 my point of saying was if your motor makes 300hp at the crank and out of those 300hp, puts down 260hp due to the losses, you can reduce those losses by doing some mods and hence ur motor will now put down 270....in no means you can say that hey my motor is rated at 300 and i was putting down 260 so a difference of 40 and now am putting down 270 so am making 310 at the crank....NO your motor is still making 300 but u just REDUCED the amount of losses....
making sense now ?
#110
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Correct correct. Its like when I look at my load for a paticuliar flt that I fly several times a month...........DFW to LAX for example. I take on the the same thousands of pounds of fuel, use the same 90% thrust rating for takeoff for the 738 (737-800). Day 1 150 passengers day 2 I have 60, using the same thrust setting and same fuel load similiar weather situations I reach V1 and V2 faster with the 60 passengers vs the 150 and can climb faster due to wallah a better power to weight ratio on day 2. Nothing has changed in the dynamics of the plane except except it performing better due to hauling less weight!
thus proving my point....u become quicker (hence more hp/tq put to the ground because you are lighter)....
btw u fly AA ?
#111
^^^ bro seriously, are you reading ur own sentences ?
again your NOT getting the main point...your beating around the bush....
here is an example....you have been to the track....
a car weighs 3000lbs run 1/4 mile in 15 seconds and the same car comes back @ 2000lbs....will run the quarter mile faster ? which means its has more HP/TQ
a lot of people think by doing weight reduction/exhaust mods/other mods than INTAKE/FI/INJECTOR UPGRADE your motor makes more power....
if you PROPERLY read my post # 89 my point of saying was if your motor makes 300hp at the crank and out of those 300hp, puts down 260hp due to the losses, you can reduce those losses by doing some mods and hence ur motor will now put down 270....in no means you can say that hey my motor is rated at 300 and i was putting down 260 so a difference of 40 and now am putting down 270 so am making 310 at the crank....NO your motor is still making 300 but u just REDUCED the amount of losses....
making sense now ?
again your NOT getting the main point...your beating around the bush....
here is an example....you have been to the track....
a car weighs 3000lbs run 1/4 mile in 15 seconds and the same car comes back @ 2000lbs....will run the quarter mile faster ? which means its has more HP/TQ
a lot of people think by doing weight reduction/exhaust mods/other mods than INTAKE/FI/INJECTOR UPGRADE your motor makes more power....
if you PROPERLY read my post # 89 my point of saying was if your motor makes 300hp at the crank and out of those 300hp, puts down 260hp due to the losses, you can reduce those losses by doing some mods and hence ur motor will now put down 270....in no means you can say that hey my motor is rated at 300 and i was putting down 260 so a difference of 40 and now am putting down 270 so am making 310 at the crank....NO your motor is still making 300 but u just REDUCED the amount of losses....
making sense now ?
What I am 100% correct on, is your theory is skewed, no disrespect intended.
You're not understanding the idea of the power to weight formula. Power to weight ratio is calculated by dividing a cars power by its weight. Say car A makes 250hp and weighs 3000lbs. By doing 250/3000, you get .0833333. In essence, there is .083hp/lb. Now say you dropped weight and made it 2500lbs. So as the formula goes, 250/2500 is .1hp/lb. So, this means your car would accelerate AS IF your power increased by .17hp per pound on the car. You didn't actually increase the car's power, but by decreasing its weight, the ratio changes. By decreasing the denominator in this case and keeping power constant, you will effectively raise it's power to weight ratio. Although the car has the SAME power, it is lighter, which increase it's rate of acceleration, NOT power.
You can also do it by dividing weight by power. 3000/250 = 12. What this means is for every 12lbs, there is 1hp. So 12lbs/hp. If you were to decrease the weight to 2500 in this case, your new power to weight ratio (or weight to power if you will) would be 10lbs/hp. What this means is, the car now accelerates as if there were 2 less pounds per horsepower. Or (2 x 250hp) = 500, which is the same 500lbs you took off the car (3000 - 2500).
Make sense now?
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vhtran (11-02-2011)
#112
takin care of Business in
iTrader: (5)
Joined: Jan 2008
Posts: 30,994
Likes: 4,732
From: Kansas City, MO
^^^ lets bet on it...
since am in the Philippines and and car in under a cover....wanna be the volunteer ?
1> take ur car to a weigh place and weigh it....then take it to the dyno and get the hp/tq numbers (of course to the wheels)...
2> do some weight reduction mods ONLY....take ur rear seats out + passenger seat out + spare tires etc...upwards of 150-200 pounds....
3> repeat step 1
if the numbers are the same I WILL PAY FOR THE DYNO EXPENSES AND YOUR TIME YOU HAVE SPEND ON REMOVING AND PUTTING EVERYTHING BACK TOGETHER
if the numbers have changed....you have learned something
since am in the Philippines and and car in under a cover....wanna be the volunteer ?
1> take ur car to a weigh place and weigh it....then take it to the dyno and get the hp/tq numbers (of course to the wheels)...
2> do some weight reduction mods ONLY....take ur rear seats out + passenger seat out + spare tires etc...upwards of 150-200 pounds....
3> repeat step 1
if the numbers are the same I WILL PAY FOR THE DYNO EXPENSES AND YOUR TIME YOU HAVE SPEND ON REMOVING AND PUTTING EVERYTHING BACK TOGETHER
if the numbers have changed....you have learned something
#113
Swoosh, you ever see "Clueless?" The movie. "AS IFFFFF." That's what we're talking about here. By reducing weight, your car would accelerate AS IF you had more power because there is less weight to push.
I'll use a new example. 2 cars. Car A and Car B.
Car A = 250hp/3000lbs
Car B = 250hp/2500lbs
Car A would need more power to push the car at the same rate of acceleration as Car B. Car B has less weight, which makes the 250hp work easier, hence an increase in the rate of acceleration of car B when compared to the heavier car A.
You are confusing it. You are saying that the car WILL in fact increase horsepower, when in reality, it acts AS IF it has more horsepower.
I'll use a new example. 2 cars. Car A and Car B.
Car A = 250hp/3000lbs
Car B = 250hp/2500lbs
Car A would need more power to push the car at the same rate of acceleration as Car B. Car B has less weight, which makes the 250hp work easier, hence an increase in the rate of acceleration of car B when compared to the heavier car A.
You are confusing it. You are saying that the car WILL in fact increase horsepower, when in reality, it acts AS IF it has more horsepower.
#114
I agree with Sonnick. Power to weight is simply that, HP vs curb weight. The lighter you are, the faster you'll go. Period. The weight has no effect on power to the wheels or crank power.
Crank power in SAE terms is the power of the motor without any coupling to a transmission. It's measured dyno power measured directly at the flywheel. This is power sent through the manifolds/headers, not a motor without manifolds because that would run like crap.
The easiest way to reduce drivetrain losses is to reduce rotational inertia. This would include:
1) Lighter/narrower wheels and tires
2) Lighter driveshafts, halfshafts, flywheels, brake rotors, smaller accessory/crank pullies
3) Lighter, more efficent torque converter
4) Smaller pullies on belt drive water pumps or alternators
You can also remove accessories and belts or go with lower output alternators.
Crank power in SAE terms is the power of the motor without any coupling to a transmission. It's measured dyno power measured directly at the flywheel. This is power sent through the manifolds/headers, not a motor without manifolds because that would run like crap.
The easiest way to reduce drivetrain losses is to reduce rotational inertia. This would include:
1) Lighter/narrower wheels and tires
2) Lighter driveshafts, halfshafts, flywheels, brake rotors, smaller accessory/crank pullies
3) Lighter, more efficent torque converter
4) Smaller pullies on belt drive water pumps or alternators
You can also remove accessories and belts or go with lower output alternators.
#115
takin care of Business in
iTrader: (5)
Joined: Jan 2008
Posts: 30,994
Likes: 4,732
From: Kansas City, MO
Posting from my cell...it's 1 AM here and I really need to sleep lol....
Honestly am done with examples... My questions is even thow both Cars A and B are rated at 250hp and the only mods they have is weight reduction, if u put them on a dyno will car B (lighter one) come out with higher HP/TQ ?
What about the bet ? U in or will u make me wait 6 months to prove it lol
Honestly am done with examples... My questions is even thow both Cars A and B are rated at 250hp and the only mods they have is weight reduction, if u put them on a dyno will car B (lighter one) come out with higher HP/TQ ?
What about the bet ? U in or will u make me wait 6 months to prove it lol
#116
Swoosh,
You're confused, man. Let's go to school and I'll save you some money in a very risky bet. A chassis dyno is a very simple device. It's basically comprised of a weighted or brake manipulated roller, an rpm pickup, and a timer. You strap you place drive wheels on the roller, hook up the rpm pickup, and zero the timer. You bring the rpms up to the desired start rpm in a gear closest to a 1:1 ratio. Once you're ready, you mash the gas and timer switch at the same time and time the run until you let off. A simple calculation is done using the rpm data and rate at which the weighted/braked rollers were spun over the time of the run. From there you get hp/tq across the rpm range.
So that's a dyno in nutshell. So now, how does the weight of the car come into play here? The motor isn't tugging the weight of the car at all. It's simply spinning a 1,000-2,000lb roller or a roller being drug by a brake.
By your rational, a 306hp Camaro V6 6AT shouldn't make the same power as a 306hp Caddy CTS 3.6 6AT. Same drivetrain, same engine, same power. The only difference is the Caddy weighs about 300lbs more. On the dyno, they make the same exact power.
You're confused, man. Let's go to school and I'll save you some money in a very risky bet. A chassis dyno is a very simple device. It's basically comprised of a weighted or brake manipulated roller, an rpm pickup, and a timer. You strap you place drive wheels on the roller, hook up the rpm pickup, and zero the timer. You bring the rpms up to the desired start rpm in a gear closest to a 1:1 ratio. Once you're ready, you mash the gas and timer switch at the same time and time the run until you let off. A simple calculation is done using the rpm data and rate at which the weighted/braked rollers were spun over the time of the run. From there you get hp/tq across the rpm range.
So that's a dyno in nutshell. So now, how does the weight of the car come into play here? The motor isn't tugging the weight of the car at all. It's simply spinning a 1,000-2,000lb roller or a roller being drug by a brake.
By your rational, a 306hp Camaro V6 6AT shouldn't make the same power as a 306hp Caddy CTS 3.6 6AT. Same drivetrain, same engine, same power. The only difference is the Caddy weighs about 300lbs more. On the dyno, they make the same exact power.
Last edited by Dave_B; 11-02-2011 at 12:14 PM.
#117
Even though there seems to be some confusion with this, the underlying concept itself might not be that far fetched, I just don't think it will ever represent itself on a dyno, not with the rollers anyway. I am tryng to keep an open mind and give the idea the benefit of the doubt, which we do not see lot of around here.
Trying to come up with a few ways how this could be possible, I am thinking of it in this way, if weight adds additional strain on the drivetrain and you reduce a significant amount of it, you could in essence be freeing up a small bit of power at the same time but the car really becomes faster because of the underlying principle of hp to weight.
I don't know of anyway that could prove this or if it would ever be anything substantial enough to want to persue but traditional methods would not pick this up, not unless there was some form of dyno for road surfaces and while actually moving but then that also brings in a lot of additional variables and factors.
It could be another one of those grey areas, not to the extent that it may be getting made out to be but, it's possible. These areas do exist, much like how we see roughly a 10% drivetrain loss for some cars as opposed to a generalized figure of 15% and whether that means the engine is truly underrated and/or if there is actually less power loss.
Also, how despite the lower numbers form one set of parameters like a drag race, some cars can still prove to actually be faster in another set of parameters, like a roll race. Take for example the TLS and TL SH 6MT's, in stock form the TLS will never be able to run the kind of max numbers the SH does but the TLS is no slower from a roll, might actually be faster and it will always win up 130 mph, even from a dig. Just because something is not a rule or someone claims to have put it into stone, it doesn't mean it isn't possible.
Trying to come up with a few ways how this could be possible, I am thinking of it in this way, if weight adds additional strain on the drivetrain and you reduce a significant amount of it, you could in essence be freeing up a small bit of power at the same time but the car really becomes faster because of the underlying principle of hp to weight.
I don't know of anyway that could prove this or if it would ever be anything substantial enough to want to persue but traditional methods would not pick this up, not unless there was some form of dyno for road surfaces and while actually moving but then that also brings in a lot of additional variables and factors.
It could be another one of those grey areas, not to the extent that it may be getting made out to be but, it's possible. These areas do exist, much like how we see roughly a 10% drivetrain loss for some cars as opposed to a generalized figure of 15% and whether that means the engine is truly underrated and/or if there is actually less power loss.
Also, how despite the lower numbers form one set of parameters like a drag race, some cars can still prove to actually be faster in another set of parameters, like a roll race. Take for example the TLS and TL SH 6MT's, in stock form the TLS will never be able to run the kind of max numbers the SH does but the TLS is no slower from a roll, might actually be faster and it will always win up 130 mph, even from a dig. Just because something is not a rule or someone claims to have put it into stone, it doesn't mean it isn't possible.
#119
Swoosh, wouldn't it be easier to dyno with five people in the car, rather than removing items?
If your theory were correct, dynoing with an extra 1,000 lbs of dead weight in the car would decrease power, but it won't. Nor will it read any higher if you dyno the same car with the body completely removed from the chassis. The only things affecting the ability of the engine to spin the dyno rollers are the weight/efficiency of the transmission, axles, wheels, hubs, tires, rotors, (drive shaft on a RWD car) etc. Now if you removed weight from the car by replacing these items with lighter pieces, then you'd see an increase in WHP, but the weight of the rest of the car is inconsequential.
If your theory were correct, dynoing with an extra 1,000 lbs of dead weight in the car would decrease power, but it won't. Nor will it read any higher if you dyno the same car with the body completely removed from the chassis. The only things affecting the ability of the engine to spin the dyno rollers are the weight/efficiency of the transmission, axles, wheels, hubs, tires, rotors, (drive shaft on a RWD car) etc. Now if you removed weight from the car by replacing these items with lighter pieces, then you'd see an increase in WHP, but the weight of the rest of the car is inconsequential.