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View Full Version : video proof 3.96/3.69 final drive works...



run_4_cover
05-06-2006, 09:44 AM
This is my proof from a debate I had with a few members a while back about the merits of a taller than 4.08 final drive in a 240. I owned two s14's while I lived in Germany, and one was an auto, the other a 5-speed. Both cars would ride-out on the autobahn with the 3.96 and 3.69 (respectively) final drives.

I had a few members trying to tell me the cars would be dogs on the highway with these final drives...however, they had never ridden in an s-chassis with either final drive. (see original thread here)

forums.freshalloy.com/ubbthreads/showflat.php?Cat=&Board=UBB9&Number=68005731 (http://forums.freshalloy.com/ubbthreads/showflat.php?Cat=&Board=UBB9&Number=68005731&Forum =UBB9&Words=3.69%20gears&Match=And&Searchpage=0&Li mit=25&Old=allposts&Main=68005731&Search=true#Post 68005731)

Anywho, I finally converted some of my footage from 8mm vhs-c to digital....so....you naysayers bow down....your physics arguments just got put in the same file with the law about a bumble bee not being able to fly (or a CH-47 helicopter) http://forums.freshalloy.com/images/graemlins/shocked.gif

Remember, my speedo is in KMH....sorry for the shaky videos, but, you get the picture. This is my auto s14:
greddy v-spec fmic
greddy intake (filter)
255 walbro
3" downpipe
blitz nur-spec exhaust
16psi
245/45/17 tires on all four
automatic, fully loaded s14
*everything else stock*

All you 4.08 and shorter (numerically higher numbers) geared people feel free to compare my acceleration with yours, I'm sure you'll find the results surprising, especially at speeds over 100mph (`160kmh).

(just a look around the car)
http://s23.photobucket.com/albums/b378/run-4-cover/?action=view&current=s14outside.flv

(me vs. a BMW318(camera car) with a 328 engine swap)
http://s23.photobucket.com/albums/b378/run-4-cover/?action=view&current=s14vsbmw328.flv

(part II of the raping above)
http://s23.photobucket.com/albums/b378/run-4-cover/?action=view&current=s14vsbmw2.flv

(me vs. a 911 N/A on the autobahn)
http://s23.photobucket.com/albums/b378/run-4-cover/?action=view&current=s14vsporsche.flv

(me doing a 70 - 230kmh pull with 2 people in the car)

http://s23.photobucket.com/albums/b378/run-4-cover/?action=view&current=70-230kmh.flv

Finally, If anyone still thinks 3.96 gears make an s-chassis a dog on the highway, feel free to look me up when your in the ATL area for a run in my s13 with a 3.96 final and 205/45/17 tires.

run_4_cover
05-06-2006, 11:26 AM
Oh yeah, for those too lazy to convert kmh to mph....that 70-230kmh pull is more or less ~43 - 140mph ....took about 18 seconds.

_Def_
05-06-2006, 01:24 PM
Like I said in the previous thread, you are discounting the effect of tire size on overall gearing. Do some math and you'll see your 205/45-17 with a 3.96 isn't much different than the common 255/40-17 that lots of people run with the stock 4.08.

Your car really didn't look that quick to me either...

fstsil80
05-06-2006, 02:02 PM
Your car really didn't look that quick to me either...



http://forums.freshalloy.com/images/graemlins/iagree.gif

240Shorty
05-06-2006, 03:07 PM
^^+2

killjoy
05-06-2006, 03:33 PM
Hahaha.

Let me do a run from 40 to 140 with my 4.36's and I bet I can do it in a lot less time. I have a digital dash though so no luck on actually seeing the 140. I have hit the rev limiter in 4th though and do it at about 125 mph.

Hugh
05-06-2006, 09:45 PM
My 180sx with a 4.9 final would hit redline in 5th gear (thats over 150mph) before it would let up. I'd rip through every gear damn quick and then I'd bury the speedometer so hard sometimes it got stuck to the plastic.

Wanna see that?

Watch this video, the second run is starting in third and wrapping out to 5th at redline, around 150+mph:

http://72.29.75.31/~videof6/features/hugh/speedostuck.mpg

The car also would run from a dead stop with silvias/180sx's that had 100+ more HP than me. They were usually pushing 4.083, and my 4.9 made me quicker all the way through the quarter mile... even the half mile.

Freeway cruising? Well it sucked. High RPM all the time.

In a race from 80mph to 150, I would crush anyone though. Most people can't even get up to 150mph... so say what you want about top speed running out.

The theory that more load = more power is crap. More power doesn't = faster.

Getting your car down the road is what matters. However you can get it from A to B quicker, you will win the race. My times proved my theories.

gatecrasher
05-07-2006, 02:09 AM
http://forums.freshalloy.com/images/graemlins/banghead.gif

i'll be sticking with my 4.36.....like i said before. whatever works for you i suppose

run_4_cover
05-07-2006, 07:02 AM
Like I said in the previous thread, you are discounting the effect of tire size on overall gearing. Do some math and you'll see your 205/45-17 with a 3.96 isn't much different than the common 255/40-17 that lots of people run with the stock 4.08.

Your car really didn't look that quick to me either...

that car in the videos isn't my s13, it's my s14....that car had 245/45/17's on it...with the 3.96 final drive....it was also an automatic.

run_4_cover
05-07-2006, 07:10 AM
you guyz are comparing apples to oranges....I posted the video to show how a car ran with the taller geared rear end....I wasn't saying the car was fast....it just wasn't a dog by anymeans.

How can you compare that s14 with lighter, more powerful s13's and 240z's? hahaha....that car was a fully loaded s14 with an automatic transmisson....what do yall think a bpu s14 puts down to the wheels with an auto tranny at 16psi?....mabey 220rwhp?

I would like to see the same pull from a swapped 240 (s13 or s14) with similar power.

_Def_
05-07-2006, 09:18 AM
Like I said in the previous thread, you are discounting the effect of tire size on overall gearing. Do some math and you'll see your 205/45-17 with a 3.96 isn't much different than the common 255/40-17 that lots of people run with the stock 4.08.

Your car really didn't look that quick to me either...

that car in the videos isn't my s13, it's my s14....that car had 245/45/17's on it...with the 3.96 final drive....it was also an automatic.



My point exactly... You seem fixated on the final drive ratio, when tire size is also making a measurable impact.

Hugh
05-07-2006, 04:56 PM
I stated in the first sentence of my post that I was talking about my 180sx.

I have discussed this issue with several people, not just you. Longer gears don't make the car faster. They make it slower. Shorter gears make it faster.

Taking out a 4.083 to swap in a 3.96 is pointless. Why would you do that? The only reason I can see is if the 3.96 had an LSD in it, and the 4.083 didn't.

The slight change in gear ratios will barely be noticable, but what little change there is would just slow the car down.

You should run a gear thats as short as you can tolerate and suits your racing style. If you wanna go fast in a straight line, short gears are the way.

I guarantee you that a completely basic 220rwhp swapped 240sx with a 4.9 final VS a 3.9 final would show the 4.9 car raping the 3.9. (as long both drivers are using the gearing to its ability)

240_kid
05-08-2006, 03:08 AM
where R these 3.69 & 96 gears coming from?

Kookz
05-08-2006, 08:59 AM
3.69 is Euro (or German), 3.96 is for auto-tranny cars.

BTW, your car would be faster with shorter gears.

Amalgam
05-08-2006, 10:41 AM
I agree with the above posts about shorter being better...however at a certain point traction issues and time wasted shifting due to short gearing can have a negative impact, as with anything it's best to find a happy medium, but don't fear the gear.

Also, the Porsche was not racing, he was cruising. The driver was most likely on his way home from work and had no idea, nor did he care you were racing/flying by him.

Kingtal0n
05-09-2006, 09:48 AM
I Disagree with what you people think makes the car faster with a lower (numerically higher) gear ratio. I do agree that it makes these particular cars, "faster"

The Truth is, Torque is what wins races. Engine torque, multiplied by the drivetrain in the form of leverage to the wheels- "Area under the curve" and "powerband" come to mind- is what physically push the car down the road.

The problem, or trick, is this:
Since work over time is your physical equation for horsepower, you want your engine to spend as much of its time as possible in the best possible area under the curve (or powerband) of the motor.
If this means I have to run a 2.73 gear and shift as early as 4000 RPMS to do it, then so be it (think 5.7L V8 Van motor) It will still be faster than the same motor in a 240sx with a 4.63 rear gear and shifting at 6000RPM.

The Total TRUTH of the matter is, your rear gear and transmission gearing is just a form of gear-reduction to allow an engine to apply more leverage to the ground AND optimize its operating powerband. If our engines didnt make power high in the RPM range, going with lower (numerically higher) gearing would NOT be beneficial.

I buy a stock 1992 5.0L Camaro it comes factory with a 2.73 rear gear. I change it to a limited slip 3.73 rear gear and it will get SLOWER in the 1/4 mile... the new gearing takes the car up and out of the powerband where the car makes the most "power under the curve". I then do a head/cam/intake swap to move the powerband up where Im shifting more often.. and the car will get faster.

An other way to see it is this:
Average horsepower over time applied
Look at a dyno graph of your engine. See where it makes the most power, now optimize the rear gear to keep you in that place as much as possible for the given distance (such as a 1/4 mile) you are going, this will give you the absolute best results as far as E.T., however this is why power output will generally keep MPH unchanged regardless of gearing unless you have a huge mismatch on your hands.

Kookz
05-09-2006, 11:04 AM
The Truth is, Torque is what wins races. Engine torque, multiplied by the drivetrain in the form of leverage to the wheels-

The truth is, that's wrong.

knate
05-09-2006, 05:54 PM
The Truth is, Torque is what wins races. Engine torque, multiplied by the drivetrain in the form of leverage to the wheels-

The truth is, that's wrong.



No, Kookz, you don't understand. If you shift at 5000 rpm so you are staying at peak torque, you are faster. Also if I launch in 4th in the 1/4 mile, not only is this nearly as good as putting a 2.7:1 out back, but I don't have to shift at all. Try it sometime, then you'll be a believer. I am currently swapping a diesel into my 240sx so I can win my autocross region in SM.

gatecrasher
05-09-2006, 06:34 PM
The Truth is, Torque is what wins races. Engine torque, multiplied by the drivetrain in the form of leverage to the wheels-

The truth is, that's wrong.



No, Kookz, you don't understand. If you shift at 5000 rpm so you are staying at peak torque, you are faster. Also if I launch in 4th in the 1/4 mile, not only is this nearly as good as putting a 2.7:1 out back, but I don't have to shift at all. Try it sometime, then you'll be a believer. I am currently swapping a diesel into my 240sx so I can win my autocross region in SM.



[devils advocate] Audi already beat you to it......although on a slightly higher level. the R8 LMP car is Diesel powered. [/devils advocate]

Hugh
05-09-2006, 08:20 PM
I Disagree with what you people think makes the car faster with a lower (numerically higher) gear ratio. I do agree that it makes these particular cars, "faster"

The Truth is, Torque is what wins races. Engine torque, multiplied by the drivetrain in the form of leverage to the wheels- "Area under the curve" and "powerband" come to mind- is what physically push the car down the road.

The problem, or trick, is this:
Since work over time is your physical equation for horsepower, you want your engine to spend as much of its time as possible in the best possible area under the curve (or powerband) of the motor.
If this means I have to run a 2.73 gear and shift as early as 4000 RPMS to do it, then so be it (think 5.7L V8 Van motor) It will still be faster than the same motor in a 240sx with a 4.63 rear gear and shifting at 6000RPM.

The Total TRUTH of the matter is, your rear gear and transmission gearing is just a form of gear-reduction to allow an engine to apply more leverage to the ground AND optimize its operating powerband. If our engines didnt make power high in the RPM range, going with lower (numerically higher) gearing would NOT be beneficial.

I buy a stock 1992 5.0L Camaro it comes factory with a 2.73 rear gear. I change it to a limited slip 3.73 rear gear and it will get SLOWER in the 1/4 mile... the new gearing takes the car up and out of the powerband where the car makes the most "power under the curve". I then do a head/cam/intake swap to move the powerband up where Im shifting more often.. and the car will get faster.

An other way to see it is this:
Average horsepower over time applied
Look at a dyno graph of your engine. See where it makes the most power, now optimize the rear gear to keep you in that place as much as possible for the given distance (such as a 1/4 mile) you are going, this will give you the absolute best results as far as E.T., however this is why power output will generally keep MPH unchanged regardless of gearing unless you have a huge mismatch on your hands.




Thats a nice disertation and all, but the last time I checked... the rear end had nothing to do with what RPM my gears worked in.

For example:

my old 180sx setup had a 2000rpm power band. When shifting from say 2nd to 3rd gears, the rpm would drop from 7300 to 5300.

That was with a 4.083 final.

Once I put a 4.9 final in it, the car still made power from 5300 to 7300, and it still dropped 2000rpm when I shifted.

The difference? I applied that power to the ground at a faster rate. The car ACCELERATED FASTER. A lot faster.

The rear end did not effect getting the car into higher RPM much, unless you consider easier revving to be the cause of that.. I see easier revving as accelerating the wheels at a faster rate.


Yes, there is a balance, but throwing your theories into my practice says you're not quite on it. I'm not arguing, I'm speaking from direct experience with various gear ratios in the S13 chassis. (3.96, 4.083, 4.36, 4.66, and 4.9)

We also put a 4.6 in the back of a 360hp 180sx. His track ET's dropped, and he was crushing people who had similar power outputs. Nobody could understand why their comparable setup couldn't come close... but we knew. http://forums.freshalloy.com/images/graemlins/cool.gif

In_DET
05-09-2006, 10:09 PM
I recently swapped a 4.36 into my S13 because I'm running a .86 turbo and wanted to get to my peak boost RPM at a quicker rate of speed. The turbo still spools at the same RPM, but the car now reaches that RPM at a faster rate of speed. Sure, I still have to wait for the car to reach 4500RPM to get max spool, but that 4500 RPM comes on alot faster than it used to. Since my car makes its power up top, I want to get to that point faster, and for me a shorter gear helped to accomplish this.

Hugh
05-10-2006, 12:14 PM
Yeah, I see what you guys mean.

Its when you're worried about lag.

I drag race using a 2-step rev limiter, so lag is a non-issue.

2-step it to the RPM required, and go. Easy as that.

In_DET
05-10-2006, 05:40 PM
The 2 step idea is great for drag launches, but no good for rolling start races or when you decide to just punch it. With the shorter gearing you cruise around at a higher RPM and lose some of your top speed. Shorter gears accelerate faster, longer gears give you a higher top speed. You cannot trust the factory speedo after a gear change however, now that I've got 4.36 gears, my speedometer reads 66mph when in reality I'm only doing 60. This difference gets larger the faster you go. Longer gearing would produce the opposite effect, you'd be going SLOWER than your speedometer shows.

Kingtal0n
05-11-2006, 08:16 AM
Like I said before, I dont disagree it would make your car faster, I just said
"I Disagree with what you people think makes the car faster with a lower (numerically higher) gear ratio..."

People on this board seem to think that the going from 4.08's to 4.69's is giving their car more horsepower, and it isnt. Its just optimizing how often the car gets into its area under the curve during a 1/4 mile, and stays there. Yes, hugh, with a lower gear your shift points dont change, but the RPM drop does change- and so does the amount of "work" or "horsepower" the car is allowed to show the ground, and the car goes "faster"

For instance if my car makes 500horsepower @ 8000RPM in an S-chassis, and I have a 2:1 rear gear, chances are Im not even going to get close to 8000RPM before the 1/4 mile is almost over or at all.
But I DO have 500 Horsepower, why is my car running 22 seconds in the 1/4?
Now I take this imaginary civic that makes 100horsepower @ 8000RPM, but it hits that RPM through every gear before trapping the 1/4 mile because of its 5:1 gearing. and its faster than the first 500 horsepower car.

This is a very wide and varied example, but it gets the small point accross.

But torque is what wins races. Without it, you wouldnt have the handy equation TorqueXrpm/(33,000/2pi) to make horsepower with, it would be the other way around. Engine MAKE torque, we just turn it into horsepower with our math.

Kookz
05-11-2006, 09:08 AM
But torque is what wins races. Without it, you wouldnt have the handy equation TorqueXrpm/(33,000/2pi) to make horsepower with, it would be the other way around. Engine MAKE torque, we just turn it into horsepower with our math.

No, that is ABSOLUTELY wrong. You can make 2000 ft-lbs of torque and get beat by a car making 20 because torque has absolutely nothing to do with time.

Brad
05-11-2006, 04:32 PM
hows the saying go?

hp is how fast you hit the wall, but torque is how far you take the wall with you? or something like that, doesnt make great sense to me though

_Def_
05-11-2006, 07:35 PM
Yes, hugh, with a lower gear your shift points dont change, but the RPM drop does change- and so does the amount of "work" or "horsepower" the car is allowed to show the ground, and the car goes "faster"




Wrong wrong wrong. RPM drop stays constant due to the same gearing ratio between each gears, but the speed reached in each gear is lower by the percentage change in final drive ratio.

_Def_
05-11-2006, 07:40 PM
But torque is what wins races. Without it, you wouldnt have the handy equation TorqueXrpm/(33,000/2pi) to make horsepower with, it would be the other way around. Engine MAKE torque, we just turn it into horsepower with our math.

No, that is ABSOLUTELY wrong. You can make 2000 ft-lbs of torque and get beat by a car making 20 because torque has absolutely nothing to do with time.



Just to clarify since people seem to be struggling with the concept of torque versus horsepower...

Torque is how hard your engine is pushing you, horsepower is how much WORK the engine is doing to actually move your car. HORSEPOWER WINS RACES! Simple as that.

If you take a car with infinitely variable gear ratios and want to see where it would accelerate fastest at a fixed speed - say 60 mph - would it happen at the torque peak or the HP peak? It's the Horsepower peak! At any speed, if you can gear the car to be at the RPM that its HP peak occurs at, then you will have maximum drivewheel torque for that speed. HP is not just some meaningless mathmatical forumla - it is the real representation of how much ACTUAL WORK the engine is doing per unit time.

Shorter final drive gearing tends to get these cars around their peak HP for a longer duration of the drag race since you have more gear changes in a quarter mile, and thus let the engine rev back up towards its HP peak.

Hugh
05-11-2006, 08:47 PM
Yes, hugh, with a lower gear your shift points dont change, but the RPM drop does change- and so does the amount of "work" or "horsepower" the car is allowed to show the ground, and the car goes "faster"




Wrong wrong wrong. RPM drop stays constant due to the same gearing ratio between each gears, but the speed reached in each gear is lower by the percentage change in final drive ratio.



No kidding, the RPM changes HOW? http://forums.freshalloy.com/images/graemlins/confused.gif

run_4_cover
05-11-2006, 09:14 PM
I agree with the above posts about shorter being better...however at a certain point traction issues and time wasted shifting due to short gearing can have a negative impact, as with anything it's best to find a happy medium, but don't fear the gear.

Also, the Porsche was not racing, he was cruising. The driver was most likely on his way home from work and had no idea, nor did he care you were racing/flying by him.

sorry son, I don't know how you figure the porsche wasn't racing, but whatever..it was our third time racing actually....not too many people 'cruise' at 120mph...not even on the autobahn...so keep your rice boy opinon to yourself...especially when the proof is right in front of you.

_Slappy
05-11-2006, 09:25 PM
hahahaha, what it looks like to me is...

you would take off, and the guys in each camera car would'nt.

just to make it seem like you had tons of acceleration..

that soooooo lame.

run_4_cover
05-11-2006, 09:28 PM
As for the rest of you arguing moot points....remember, no one said that 3.69's would out accelerate 4.08's or whatever....the point MADE is; 3.69/3.96 final drives do not make s-chassis dogs...that was the original point.

I put the proof there....so no need to argue about it...you all can keep spouting off your formulas all day....the video doesn't lie, regardless of what your formulas say. If you want to prove a point, find a 4.08 or shorter geared car with similar bolt-ons and perform the same run....easy enough, right?

Amalgam
05-12-2006, 01:56 AM
Torque is how hard your engine is pushing you, horsepower is how much WORK the engine is doing to actually move your car. HORSEPOWER WINS RACES! Simple as that.

If you take a car with infinitely variable gear ratios and want to see where it would accelerate fastest at a fixed speed - say 60 mph - would it happen at the torque peak or the HP peak? It's the Horsepower peak! At any speed, if you can gear the car to be at the RPM that its HP peak occurs at, then you will have maximum drivewheel torque for that speed.



Actually, that is incorrect. The torque is what is actually moving the car. As you said, HP is a measure of work over time, and torque is just the twisting force, but the torque curve is representative of the acceleration of the vehicle in each respective gear. You will hit peak acceleration at peak torque not peak HP.

As you know, changing the final drive ratio doesn't increase horsepower, but it does increase the torque multiplying factor thereby putting more torque to the ground. If the HP values were moving the car, then there would be no gain at all from a shorter final drive.

I agree it's important to have HP, it does win races. FOr example, if you make peak horsepower high in the RPM band, but less torque than a motor that peaks lower, you can adjust your gear ratios accordingly, so that the torque you put down to the wheels, is as much or greater than the other car. In addition, your torque near redline will not fall off as quickly as a car that peaks lower, which will allow you to maintain a steady rate of acceleration towrds the top of every gear.

HP allows you to take advantage of gearing, but the end result of the horsepower is it being converted into a twisting force at the wheels...torque....and pushing the car down the road.

Amalgam
05-12-2006, 02:03 AM
sorry son, I don't know how you figure the porsche wasn't racing, but whatever..it was our third time racing actually....not too many people 'cruise' at 120mph...not even on the autobahn...so keep your rice boy opinon to yourself...especially when the proof is right in front of you.



Actually, quite a few people cruise at 110-120mph on the autobahn...the only reason most do not is because they can't afford the gas, people who can afford a Porsche most likely don't have that problem.

And yes, I am saying he was NOT racing. Here's what happened in the video...Hanz(or Franz) was in the passing lane passing the trucks limited to 100km/h, then he got over and you hit the gas and went buy him and put it on video to demonstrate your awesome acceleration, simple as that.

Unless, you really think your automatic bolt-on SR20 S14 has enough power to walk away from a 996 911 that quickly at 120mph roll.

And you're calling me a riceboy??

Hugh
05-12-2006, 10:21 AM
the torque curve is representative of the acceleration of the vehicle in each respective gear. You will hit peak acceleration at peak torque not peak HP.



So why would my car be faster if I drove it within the peak horsepower range and not the peak torque range?

Amalgam
05-12-2006, 12:01 PM
So why would my car be faster if I drove it within the peak horsepower range and not the peak torque range?



I felt the same thing when I first struggled with this concept. As with my prior cars...Hondas...peak HP occured very later in the RPM range, peak torque still occured relatively high in the RPM's but the car felt faster to me as it kept going into its peak HP. That's just it...it only feels that way, but if you measured the acceleration force form within the car, you would see that peak acceleration would happen at peak torque.

Keep in mind though, I am sure your last set-up had a very high peaking HP, and your torque curve did not dive off sharply at the end of your rev range...I would guess you came up onto peak torque(4500-5000rpms??) and held it pretty steadily to your redline. Correct? So gearing comes into play when you speak of HP....it's better to be able to make power high in the RPMs and take advantage of gearing to produce your torque through multiplication, which is where HP comes into play....so shifting and operating your car dependent on the torque peak alone would give less than optimal results for obvious reasons. Which is why your car, was best shifted very high in your RPM range, if you shifted sooner to concentrate on peak torque you would loose torque multiplication in the next gear, and run the risk of coming into the next gear below peak torque, and below your turbos efficiency range.

So, this is why it seems dependent on HP rather than torque...the change in the rate of acceleration from your peak torque where the acceleration is greatest to redline is very small, because your motor is continuing to make HP past your peak torque and only losing torque in a very small amount so your car pulls hard to redline. Your rate of acceleration is decreasing although very slightly as your torque falls off...you just don't notice it due to other factors, so it "feels" like it pulls harder.

I guess this is a bad analogy....but if you jump from a building, the first 10 feet would probably seem fairly calm, but as you being to travel faster things would get exciting/scary rather quickly...and it may seem that your rate of acceleration has increased due to other factors surrounding your increasing velocity, but you are still accelerating at a rate of 9.8 m/s/s.

I have already begun to second guess myself, even though I am sure of this...Def is alot smarter than me, so disagreeing with him goes against my better judgement in normal circumstances.

okashira
05-12-2006, 04:04 PM
God I love this argument. It's amazing to me how many people who know so little about physics,mechanics,reality will post refuting arguments based on what they think 'feels right.' Im not talking about anyone in particular, just making this comment based on the 100 previous threads on this topic. Kinetic Energy vs Momentum is not intuitive at all.. so its an understandable result...






I felt the same thing when I first struggled with this concept. As with my prior cars...Hondas...peak HP occured very later in the RPM range, peak torque still occured relatively high in the RPM's but the car felt faster to me as it kept going into its peak HP. That's just it...it only feels that way, but if you measured the acceleration force form within the car, you would see that peak acceleration would happen at peak torque.

Keep in mind though, I am sure your last set-up had a very high peaking HP, and your torque curve did not dive off sharply at the end of your rev range...I would guess you came up onto peak torque(4500-5000rpms??) and held it pretty steadily to your redline. Correct? So gearing comes into play when you speak of HP....it's better to be able to make power high in the RPMs and take advantage of gearing to produce your torque through multiplication, which is where HP comes into play....so shifting and operating your car dependent on the torque peak alone would give less than optimal results for obvious reasons. Which is why your car, was best shifted very high in your RPM range, if you shifted sooner to concentrate on peak torque you would loose torque multiplication in the next gear, and run the risk of coming into the next gear below peak torque, and below your turbos efficiency range.

So, this is why it seems dependent on HP rather than torque...the change in the rate of acceleration from your peak torque where the acceleration is greatest to redline is very small, because your motor is continuing to make HP past your peak torque and only losing torque in a very small amount so your car pulls hard to redline. Your rate of acceleration is decreasing although very slightly as your torque falls off...you just don't notice it due to other factors, so it "feels" like it pulls harder.

I guess this is a bad analogy....but if you jump from a building, the first 10 feet would probably seem fairly calm, but as you being to travel faster things would get exciting/scary rather quickly...and it may seem that your rate of acceleration has increased due to other factors surrounding your increasing velocity, but you are still accelerating at a rate of 9.8 m/s/s.

I have already begun to second guess myself, even though I am sure of this...Def is alot smarter than me, so disagreeing with him goes against my better judgement in normal circumstances.



Dude, hes talking about peak acceleration at a particular speed. Sure, from a dead stop... whoever has max torque at the wheels will accelerate the fastest... but this can be done with zero horsepower! but you wont accelerate any more then .0000000000000001 mph without POWER.
I'll try to explain it with some really simple mathematics, I'm going to dumb it down, but everything is still 100% correct.

Power(P) equals(=) Force(F) times Velocity(V) times k, where k is an arbitrary constant:

P = kFV

for the purposes of the discussion and to simplify I will drop the constant. This is perfectly correct if we invent our own units for power:

P = FV

solving for Force,

F = P/V

from Newton's 2nd law, F = mass(m) * acceleration(a),
F = ma since mass is a constant I will drop it and replacing F in our original equation we get:

a = P/V

I think that looking at this it should be easy to see that the maximize acceleration, you need to maximze power. torque has NOTHING to do with it. Pick a particular starting velocity, maxmimum acceleration will occur when you maxmize Power(P)







now... in a real world scenerio if you start a roll on race at say, 60mph. would you be best served to select a gear for max power or max torque to win? probably not max power. but this has absoulutly nothing to do with physics. It's just because if you start out at max power, its likely you will be forced to shift right after you floor the throttle, slowing you down. so wou want to start somewhere below max power, enough to give you a decent amt of time before you're forced to shift.

Amalgam
05-12-2006, 05:14 PM
I think that looking at this it should be easy to see that the maximize acceleration, you need to maximze power. torque has NOTHING to do with it. Pick a particular starting velocity, maxmimum acceleration will occur when you maxmize Power(P)



Well, since the HP and torque are always directly proportional, then of course, HP does play a significant role. However, torque is what's actually moving the car, not the horsepower. So, in this aspect your are incorrect. The horsepower figure is just a summation of the work being done over time. As you stated I can use a wrench and hold 200 lb-ft of torque on a nut, but if I don't move it I'm not doing any "work" and making no power. So, you are in correct in some ways, but it seems you are looking at HP and torque like they are completely unrelated entities, when in reality they are dependent on each other and are just different ways of quantifying the same thing.

BlackBomber
05-12-2006, 08:13 PM
its all about torque curve guys.......

A good article on the much debated topic... applies to our cars as well. (http://vettenet.org/torquehp.html)

okashira
05-12-2006, 08:15 PM
I know very well how torque/hp are related. I was just trying to make my point clear. im not sure what you are trying to argue....
I did learn't a lesson, though... ill just stay out of these discussions from here on... you guys have at it http://forums.freshalloy.com/images/graemlins/laugh.gif

one last thing I have to point out though... work is the summation of power over time, not the other way around like you said. power is the time derivative of work.

Hugh
05-13-2006, 02:26 PM
Yup, just ignore all my previous posts on this subject.

I'm gonna go on doing what I do best.

forcefedS13
05-13-2006, 09:54 PM
Holy $hit this is unreal.

Lets look at physics. If you take a McDonalds straw and LARGE soda top, then take the same sized straw but SMALL soda top, when you spin them both at the same exact speed, the smaller one will spin faster physically, but slow down faster as well. The larger one will spin slower, but will continue to spin longer.

Therefore, a smaller gear sizing, (numerically larger) would spin faster and enhance acceleration, but would hurt top end speed. In fact gearing would be affected and you may run out of gear before the line depending on how smaller( numerically larger) gear you get.

Whereas the larger gear (numerically lower) would hurt acceleration, but would allow one to enhance top end speed.

Tire sizing, rim sizing, etc. would hamper this equation based on what you went with.

As an example, My old S13 had the stock 15's on it, and all was normal. When i went to a 14 inch wheel and its respective tire size, i noticed the acceleration was better, but it took some getting used to driving on the highway.

This isnt hard. The domestic guys have been doing this since the 50's. They use these huge gears to enhance acceleration at the drag strip because they dont need a top speed gearing.

knate
05-14-2006, 10:46 AM
its all about torque curve guys.......

A good article on the much debated topic... applies to our cars as well. (http://vettenet.org/torquehp.html)



Very good read!

240Shorty
05-14-2006, 01:15 PM
Holy $hit this is unreal.

Lets look at physics. If you take a McDonalds straw and LARGE soda top, then take the same sized straw but SMALL soda top, when you spin them both at the same exact speed,



Were you hungry when you wrote this?

run_4_cover
05-14-2006, 03:16 PM
sorry son, I don't know how you figure the porsche wasn't racing, but whatever..it was our third time racing actually....not too many people 'cruise' at 120mph...not even on the autobahn...so keep your rice boy opinon to yourself...especially when the proof is right in front of you.



Actually, quite a few people cruise at 110-120mph on the autobahn...the only reason most do not is because they can't afford the gas, people who can afford a Porsche most likely don't have that problem.

And yes, I am saying he was NOT racing. Here's what happened in the video...Hanz(or Franz) was in the passing lane passing the trucks limited to 100km/h, then he got over and you hit the gas and went buy him and put it on video to demonstrate your awesome acceleration, simple as that.

Unless, you really think your automatic bolt-on SR20 S14 has enough power to walk away from a 996 911 that quickly at 120mph roll.

And you're calling me a riceboy??

yeah,yeah...hate on...I don't need to post bull**** videos to try to make a car that I don't even own any longer seem fast. I know what's up, and that's all that matters, I don't need to prove anything to you....it's not hard to figure out how fast an s14 with bolt-ons would be.....you probably drive a 14 second car anyways...so whatever.

run_4_cover
05-14-2006, 03:19 PM
hahahaha, what it looks like to me is...

you would take off, and the guys in each camera car would'nt.

just to make it seem like you had tons of acceleration..

that soooooo lame.

yeah,yeah...your in the same boat as the other retard/hater. I actually let the other car have the hit...if you adjust your volume, you may be able to hear it over my car...alas...think what you will....what makes you think I would care?

Hugh
05-14-2006, 05:51 PM
When you walk in with video proof, expect people to pick it apart.

You posted the video, don't be shocked at the responses.

run_4_cover
05-15-2006, 05:29 AM
When you walk in with video proof, expect people to pick it apart.

You posted the video, don't be shocked at the responses.

It's cool...I get a little defensive when people try to call bs....oh well....I would like to know where the 2 guys that are calling bs were when we had all the OSL drag races in germany?

forcefedS13
05-15-2006, 08:27 AM
Holy $hit this is unreal.

Lets look at physics. If you take a McDonalds straw and LARGE soda top, then take the same sized straw but SMALL soda top, when you spin them both at the same exact speed,



Were you hungry when you wrote this?



LOL, not quite!! http://forums.freshalloy.com/images/graemlins/grin.gif

Kingtal0n
05-15-2006, 04:41 PM
First of all, This is getting over complicated as hell. As usual.

Second of all, you missed my point(s).

Point1: When I said torque wins races, I wasnt talking about about torqueVShorsepower, I was talking about torque, winning races. Without torque, there is no race, and there is no horsepower. Simple as that. End of that discussion.

Point2: Touching on gearing: Cars in different situations want different gearing. If you drive on the highway all the time you generally want a higher gear. But people pulling boats in their S-chassis cars want a lower gear. Situational gearing...
So lets say the situation is 1/4 Mile.
This is really easy, not complicated:
Find out what your MPH is in the 1/4 Mile at the end. This will be based on your overall AVERAGE HORSEPOWER and HOW MANY GEARS YOU HAVE TO PULL. Still with me?
Find the rear gear that puts you right at the end of your "REDLINE" (the point past peak horsepower by which shifting will not drop you out of your powerband) By the end of the 1/4 WITHOUT hitting overdrive, and WITHOUT running out of gear/MPH. The idea is to OPTIMIZE your final drive ratio to WHAT YOU ARE DOING with your vehicle(s). There isnt just one-fits-all-gear for every situation, you can average it, but you cant optimize them all.

Point 3: Hugh and _DEF_ are some of the smartest guys on the forums. Sometimes, too smart for their own good.
For most of you reading this, you just want a fast street car, Like I did when I started, and still do. DONT do what he guys running big power do with small inch motors (2.0-3.0Liters) on the track, you will hate life on the street. and DONT make assumptions: Find living proof and then GO FOR A RIDE IN IT and see if you like it. Then cookie cutter it. NO EXPERIMENTATIONS. Forget weird gears, transmissions, and situational turbos. Stick with what works.

forcefedS13
05-15-2006, 06:44 PM
Didn't i already say all of this?

Slow240
05-15-2006, 11:54 PM
Holy $hit this is unreal.

Lets look at physics. If you take a McDonalds straw and LARGE soda top, then take the same sized straw but SMALL soda top, when you spin them both at the same exact speed, the smaller one will spin faster physically, but slow down faster as well. The larger one will spin slower, but will continue to spin longer.

Therefore, a smaller gear sizing, (numerically larger) would spin faster and enhance acceleration, but would hurt top end speed. In fact gearing would be affected and you may run out of gear before the line depending on how smaller( numerically larger) gear you get.

Whereas the larger gear (numerically lower) would hurt acceleration, but would allow one to enhance top end speed.

Tire sizing, rim sizing, etc. would hamper this equation based on what you went with.




While we're dumbing it down, I would like to take this analogy to a better place for most people who were children at some point: The Big Wheel.

Why was the Big Wheel ultimately much faster than your little red tricycle?

Two reasons. The longer travel distance for each rotation, and it had a greater distance between it's pedals.

This covers gearing, and tire size adequately I believe. If you don't agree, then stop reading now because you're not going to follow this.

So let's say you've got the crack baby on the tricycle, he's going to need to pedal that thing like a mofo to beat you because each of his rotations is probably 1/3 of yours.

Now, as we know getting a bigwheel going can be the trick, you're going to need strong legs. So Johnny Stronglegs has to push pretty hard to get going, but once he's going, he's going fast and cruising nicely.

Let's call Johnny Stronglegs, torque. Let's call the Crackbaby, horsepower. Crackbaby has to "work" very hard to maintain and/or increase his speed. Crackbaby's horsepower, relative to Johnny Stronglegs torque is going to have to be relatively equal to achieve the same time results across a given distance. In order for it to be "equal" Crackbaby is going to have to have some sort of mathematical formula blah blah blah that basically means his horsepower is higher by an amount that will compensate for his lack of applicable torque in comparison to Johnny Strongleg's Big Wheel.

We've all rode the tricycle and the Big Wheel. We know which one is ultimately capable of higher rate of speed when equal "pedal power" is applied. The big wheel always wins. Sure, you CAN pedal your ass off and maybe you'll be able to maintain the big wheels cruising speed, but the question is, why would you?

Simplified of course, but then we were on McDonalds cups. I just thought this would be easier to relate to for most people.


So let's say you want to argue that short gears and high horsepower are better than tall gears and high torque.

First define your arguement with given parameters so people aren't just babeling about nothing. Because the potential variables in any physics experiment are legion when dealing with complex mechanics. Start by defining "fast" and then you can say what is "faster". Say what you're talking about, because there's a difference between having fast acceleration and being fast. And to sum it up, taller gears make the car go faster. Shorter gears make the car accelerate faster. However, this is only true if the torque and horsepower are matched relative to the machines they are running.

Now since we know that these forces are not mutually exclusive, let's just say that there are two ways of achieving the same resulting time in a given distance; tall gears, big wheels and relative high torque, and short gears, short wheels and relative high horsepower. If you can't agree with that, then you're still not following and I'm sorry.

The fact is you can balance these "forces" and have them come out equal, and if you do, you're going to find that the two cars are crossing the same amount of distance in the same time. Since time and distance are equal, the shorter gear/smaller wheels is going to have higher horsepower, and the taller gears/bigger wheels is going to have higher torque. Now before you argue this, note that it's absolutely necessary that this is true for the times and distance to be equal. It's relativity! So what's the best balance of the two? Having both the high horsepower, and the high torque, and the taller gears, and the larger wheels IMO. I want all of it. Because the answer to the question, "How fast is your car?" for me has always been time to reach top speed AND the top speed. So yeah, taller gears = ultimately a faster car. And any way you look at it, if you can have all four, you're going to be faster in the quarter mile too. Anyone who doesn't get that, well, again I'm sorry. http://forums.freshalloy.com/images/graemlins/rolleyes1.gif

Argue missed points, details, sematics, physics, or whatever til you're blue in the face, but let's get out there with a big wheel and a little trike and we'll see who wins. You'll win in the 3ft. But overall I'm going to beat you to the playground all day long. And either way, what I said is right. All four wins, the forces can be balanced so that they are relatively equal, and taller gears are "faster" using my definition of fast if the forces are balanced. The "my car did this" argument is far far far to specific, and so poorly understood by you when it comes to the actual physics involved that a comparison to any other persons car is completely worthless. It's really simple, switch to taller gear ratios in your own car, you'll have a higher top speed, and thus you should shoot for higher torque to compensate for any so-called acceleration loss which ultimately will not matter because you ARE still going to be faster than you were with a shorter gear ratio. Start comparing other cars to yours, and we have problems. That and in the 1/4 mile as I understand what was stated a few replies back, it's all about avoiding bad shifting, and topping out the ideal gear right at the end, because shifts do slow you down, and bad shifts really slow you down.

Seriously, gearing for the 1/4 mile has got to be so much more complex than changing a final drive ratio, but yeah, if I can run it without losing a second for shifting, cool.

And I wonder why they don't put small wheeled, high revving F1 cars on the drag strip. I guess you could say, it's all about the application; Design accordingly.

http://forums.freshalloy.com/images/graemlins/beatdeadhorse5.gif

quest
05-16-2006, 10:03 PM
Take two 7000 pound dualie trucks. One powered by a 600 hp turbo honda D16, geared as best you possibly can. The other has a 500hp cummings deisel. Run 'em down the 1/4.
If you think the 600hp motor will win, check your crazy arse into an asylum.

Folks will always be split on gearing. Most don't understand a tq curve
Best results come from matching your tq curve vs weight to gear ratio.

Kookz
05-17-2006, 04:00 PM
Quest, are you serious? The Honda engine will win if you say geared as best you can.

Kingtal0n
05-17-2006, 04:48 PM
Quest, are you serious? The Honda engine will win if you say geared as best you can.



all things being equal, but he didnt give us a displacement or redline...

gatecrasher
05-17-2006, 05:43 PM
Quest, are you serious? The Honda engine will win if you say geared as best you can.



all things being equal, but he didnt give us a displacement or redline...



he said a D16 and a Cummins inline 6. you can figure a pretty close ballpark redline of both of those

okashira
05-17-2006, 07:03 PM
the honda will win. redline doesnt matter, knowing the power is enough.

forcefedS13
05-17-2006, 08:36 PM
The honda will win because its jdm tyte yo.

We will continue to explain this theory until someone locks the thread. We are all basically saying the same thing. My point was "gearing for dummies". It seems the last few posts have all added the same thing, we've all proven each other correct.

http://forums.freshalloy.com/images/graemlins/beatdeadhorse5.gif

quest
05-18-2006, 07:53 AM
the cummings has 800 ft-lbs tq. The honda, 400. 7000 pound truck
hp wins races, right ?

Kookz
05-18-2006, 10:42 AM
Right.

quest
05-19-2006, 08:12 AM
with both 7000 pound trucks geared properly, from the green light;
honda tq never falls below 270 ft-lbs, peak 400
cummings never sees under 500ft-lbs, peak 800
the 600hp truck will out accelerate the 500 ?
So tq is meaningless and peak hp is ALL that matters.
thats pretty funny

_Def_
05-19-2006, 11:50 AM
with both 7000 pound trucks geared properly, from the green light;
honda tq never falls below 270 ft-lbs, peak 400
cummings never sees under 500ft-lbs, peak 800
the 600hp truck will out accelerate the 500 ?
So tq is meaningless and peak hp is ALL that matters.
thats pretty funny



Why are you bashing others for only concentrating on peak numbers, but are doing the exact same thing.

Since the weight is the same on both, the integral of the drivewheel torque over time is the determination of which truck accelerates faster.

gatecrasher
05-19-2006, 12:08 PM
if you http://forums.freshalloy.com/images/graemlins/banghead.gif long enough, you'll eventually make a hole............in something

Kingtal0n
05-19-2006, 12:13 PM
with both 7000 pound trucks geared properly, from the green light;
honda tq never falls below 270 ft-lbs, peak 400
cummings never sees under 500ft-lbs, peak 800
the 600hp truck will out accelerate the 500 ?
So tq is meaningless and peak hp is ALL that matters.
thats pretty funny



Why are you bashing others for only concentrating on peak numbers, but are doing the exact same thing.





Damn someone finally said it. I TOLD you these guys were smart, I was NOT joking.
and this is NOT pointed at you, quest

quest
05-19-2006, 06:17 PM
aww, nevermind http://forums.freshalloy.com/images/graemlins/smile.gif

Kookz
05-20-2006, 10:43 PM
with both 7000 pound trucks geared properly, from the green light;
honda tq never falls below 270 ft-lbs, peak 400
cummings never sees under 500ft-lbs, peak 800
the 600hp truck will out accelerate the 500 ?
So tq is meaningless and peak hp is ALL that matters.
thats pretty funny

You said gearing would be optimized. To me, that means running a CVT. Put a CVT on both and the Honda will win. Guaranteed.

BlaBla
06-04-2006, 08:38 PM
Fun lol

Dont say torque or hp win a race -- they are related - hp depends on torque and speed -- that why sometimes you get a dyno where you see torque and speed.... -- from there you deduce hp.


Power = Force(lb) * Speed(ft/sec) =ft-lb/sec
1hp = 550ft.lb/sec

The torque of your engine is the force it produces at a certain rpm - multiply it by the current engine speed of your car (rpm) and you get ft-lb/sec -- hp is just another unit ... for Power.

BlaBla
06-04-2006, 08:48 PM
see Kookz got it right :D
saying that you stay at your peak hp at all time for the 1/4 mile between a 250hp 180ft-lb and a 230hp - 300ft-lb ( values for peak ) then the 250hp will win -- it has more power - P=F*S

imported__Id_
06-12-2006, 05:23 AM
Saying torque and horsepower are related is dumbing it down a little too much; its like saying mass and gravity or voltage and current are related.

As the dead horse has been beaten. Torque is a simple value; its a force dealing with circular motion vs a typical force from physics that deals with linear motion (like gravity or friction). Like displacement vs velocity vs accleration vs jerk.

Torque is nothing but a value when it pertains to MOTION. Motion implies velocity in its simplest form. Torque over time is power. Just like power is voltage times its current. The time unit we use is simply RPMS or revolutions per minute. If you're able to put down more torque TOTAL in the same amount of time (high rpms + torque = horsepower) vs someone putting down less torque over time (less rpms + torque = less horsepower) then the bigger horsepower wins; PERIOD. Gearing makes a big difference with powerband. You can be peaky as **** horsepower-wise; but if the gearing is good; then it doesnt ****ing matter.

The domestic guys were wrong; and its why there are 2jz-gte cars trapping 220mph+ in the 1/4 mile when they don't make much torque compared to a typical 500ci engine. Not to mention some of the other crazy ass 1/4 miles and top speeds we see from "torque-less" wonder motors. I am impressed when I see all-motor Hondas running 9sec times... I don't care how light they are.