Brettus

iTrader: (2)

you already have all the answers in this thread - fit the 4.77 if you want more fasterrer .
Or get serious and go FI .


oops - i didn't read page 2 before i posted . me FTL

04RX8man

of course being turely faster FI will do that not a 4.777 rear end

rotarygod

To those who I was arguing with, sorry if I came off as insulting. It's actually just frustration and not any anomisity.

The key word that was mentioned was "leverage". If we look at a lever, it's really nothing more than a simple transmission. You can't just arbitrarily increase torque. There's a tradeoff somewhere. If power stays the same and torque increases, speed goes down. If speed goes up and power stays the same, torque goes down. If power goes up and torque stays the same, speed goes up. It goes on and on... When we "increase torque" through a transmission, we are slowing everything down to gain the leverage. That's the tradeoff. That's why distance and time are so important and relevant. If we had 1 hp, we could move almost anything of any size through gearing or enough leverage. How quickly we can do it however is another thing altogether. The farther back from the fulcrum you move on a simple lever, the farther you have to move to move the object a certain distance. Notice in a low gear that you aren't going very fast for the same reason but you've got great leverage. It's horsepower that is doing the work as without horsepower all the leverage in the world is useless.

“Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.” - Archimedes

solito

subatomicparticle

Just because he says it doesn't make it true that is one of the stupidist things I have ever heard that torque has nothing to do with moving the car are you kidding me, obviously the guy has no idea how a trans works or a car for that matter just because he calls himself rotarygod doesn't mean anything I read his threads and as I said there is some useful info in there but still than why does a car have torque and why is an srt-4 with less hp and more torque a lot faster than an 8 with more hp and less torque?

subatomicparticle

in that statement you just contradicted your self that fulcrum you are talking about is torque and you also earlier said that a trans does not increase torque which that is exactly what it does the entire purpose of a trans is to multiply torque which even your math is proving.I have read auto math to it's a good reference book for any tuner. and I am not saying I want 300ft lbs and 230 hp but it could definately use a boost and I plan on increasing hp to.

rotarygod

A transmission is a torque multiplier. I never said it wasn't. It multiplies torque by changing speed. Actually the math verifies torque increases through a transmission. Horsepower doesn't and this is what it verifies. Please read it better and actually plug in some numbers. Skimming through it wasn't very effective.

rotarygod

I don't really care what you think about me personally so say whatever you want but please do some research before you spout off nonsense to a person you are trying (and failing) to call out. Here I'll school you right now.

Why is an SRT-4 faster even though it has less horsepower? Are you referring to peak horsepower? Go look up AVERAGE power levels. It's got 223 hp which is realistically what the RX-8 has so peak isn't really higher anyways. I assume you are talking about the Neon SRT-4 and not the 300 hp Caliber SRT-4. The Neon SRT-4 weighs over 200 lbs less than the RX-8. Since it's got boost, it's got far more average horsepower in the usable rpm range which means that although peak numbers may suggest otherwise, that car should be faster due to a better average power to weight ratio. Incidentally the Neon SRT-4 is a bit quicker than the higher horsepower Caliber SRT-4. It's not due to torque. The Caliber weighs more and has a worse power to weight ratio.

Any other questions Einstein?

zoom44

cheater- whats wrong with us? we're not enough for you, you got another one on the side?

paulmasoner

iTrader: (1)

"Chocolate milk? This is the best day of my life!"





no direct offense to anyone in this discussion of course

Kane

iTrader: (1)

We're just friends!!!! Gah I can't take the pressure - RX8Club is smoothering me!!! Sometimes I just have to go out and be on my own!

subatomicparticle

Believe me I did read it and the funny thing is I told my trans teacher at uti what you said and he didn't believe me when I told him, and then he laughed hysterically.And I have done the math and I do it everyday and I don't think you quite understand what those numbers mean. I was talking about the neon and obviously 100 ft. lbs have nothing to do with it. And you said that the trans is a torque multiplier now and that no horsepower is multiplied in the trans then how come when your in 5th gear in an 8 which is a 1:1 gear ratio (also known as direct drive because the trans is not multiplying torque) the horsepower stays the same through all gears as you said before you don't go anywhere. it has nothing to do with horsepower it is because there is not enough torque to move the wheels.I believe we covered this before and in regards to your race car theory the reason those cars are high hp and not much torque is because they don't weigh much it doesn't take much force to get th is moving and then the rest is top end or hp. And the last time I checked the 8 is not quite that light. And the real answer is you need both you need enough torque to get you going and you need hp to keep you going.

olddragger

iTrader: (3)

SUb--- in all that you are saying you are forgetting "speed"
an old racing saying: hp=to how fast you hit the wall, torque is how far you take the wall with you.
Think speed ok---like this
example --- for this accept that the weight and all the gearing is the same, same rpm shift points--
one car has 400hp and 250lbs tq, and a 8Krpm rev cut the other has 300 hp and 300lbs torque and also a 8k rev cut . Which one will get to its maxium speed first? The 400 hp car will.
Now gear the car with the higher torque to maximize its performance and gear the highest hp car to fit its max performance which way do you think you have to go and why?
maybe this will help you understand what RG is trying to say.
olddragger

subatomicparticle

right i understand that, but the point is to find a good balance of both he is saying that you don't need torque at all it is all hp. As far as your hitting the wall analogy that is absolutely true which like I said before torque is what gets the weight of the car moving once you get up to a good engine speed the hp takes over but you need torque to get you going. When you are taking the wall with you that is pulling power how easily you can move the weight.

rotarygod

Either you have a moron for a teacher or you told him what you think I've been saying rather than what I have been saying. I supect it's the latter as I hope your teacher isn't in fact a moron. However if your teacher doesn't agree with me (it's not really agreeing with me as I didn't make this stuff up) then I have no choice than to not recommend UTI as a viable school. Sorry. Get your teacher on here and I'll clarify it with him so he can go back and teach it to you. If he still doesn't understand, see my previous sentence.

Clearly the reverse is true here as I understand just fine. Again, sorry. Just remember which of us is a student currently trying to learn this stuff and which one of us actually works in an engineering department in the real world and has a career making money from designing up to 2200hp equipment because of this knowledge. If you make a mistake, it's a mark on a piece of paper. If I make one, it's potentially millions of dollars.

Not sure what you're getting at here as your entire argument has been solely focused on torque and now you're saying it has nothing to do with it.

The transmission doesn't multiply horsepower. It can't. You always have the amount of horsepower coming out of a transmission as you do going in. Obviously I'm ignoring drivetrain loss but you get the drift. In a 1:1 gear where it is just a direct drive scenario, you are saying that the trans is not multiplying torque. That's correct. It has everything to do with ratio. You have the same ratio out as in. I don't see what the problem is. That gear, that one ratio wouldn't be a torque multiplier. The rear end still does though.


This isn't even a rational thought as torque can't move anything. Only horsepower can. In your thinking, don't confuse the words "force" and "work". They are different.


Again, not really much in the way of rational thought here. The reason many race cars make good top end horsepower and little low end torque has to do with the engine setup. Intake and exhaust port/valve timing along with runner sizes, lengths, and a host of other things determine where an engine makes it's best power. As you are focused on torque, bigger engines make more torque than smaller ones. But why? It all goes back to leverage. You have more displacement to absorb the shock of combustion and transfer it to the drivetrain. A smaller engine at the same rpm doesn't have this leverage. How do we get around that. We need to get the same amount of leverage per the same amount of time. You keep ignoring time. How do we get this? We have to spin the smaller engine faster. If we have a 350 cu in piston engine and are spinning it at 2000 rpm, it's displacing 350,000 cu in of area in 1 minute. Remember that a piston engine sees full displacement in 2 revolutions. Now lets say we have a 190 cu in Honda piston engine at 2000 rpm. It's only displacing 190,000 cu in in that same minute. How do we make each see the same amount of displacement in the same 1 minute time period? We speed the smaller engine up. It need to be travelling 1.82 times faster which means instead of 2000 rpms, it needs to be moving at 3640 rpms to see the same amount of air. Of course this is simplifying things greatly and I'm not taking into account VE of each engine.

Now we can see that no matter what rpm we are at, our engine of whatever size will always have the same amount of leverage on the air since this is a function of displacement. Remember torque should really be thought of as leverage. Obviously if a "torque curve" isn't flat, it's due to changes in VE. If VE were a constant, torque would be completely flat regardless of rpm. Since this leverage (torque) isn't doing any work, as it has this displacement even if the engine isn't moving, the only way to make it do any work is to add motion. However adding motion means adding time which you constantly want to ignore. The faster we spin an engine, the more we are using this leverage on the crank. Fortunately once we apply this new variable of time and distance into our stationary engine, the output now becomes known as horsepower. As long as VE doesn't fall off, the faster we spin the engine, the more horsepower we can make. Once we get to a point where VE falls off, there's no point in going any higher.

Race car engines rev high because they are getting the most horsepower out of their engines. Pure and simple. They tune everything here because their VE is highest up here which means a sacrifice of low end horsepower or as you keep wanting to refer to it as, torque.


I see no reason why you are bringing weight into it as that involves a HORSEPOWER to weight ratio and not a torque to weight ratio. Incidentally, have you ever wondered why you never see a tq/wt ratio listed? Its because it doesn't tell you anything! Your last sentence again is an irrational thought. Sorry.

I have no idea why I keep apologizing to you when I'm not the one who's wrong. Hmmm....

rotarygod

Now you're getting confused with momentum. Torque actually wouldn't pull you through a wall anyways as torque can't do anything on it's own.

rotary.enthusiast

What RG has been saying and what I've been too stupid to understand is that the optimal torque to the ground can always be had via mechanical advantage at the engine's HP peak. Running through the math of the CVT example I gave made that blindingly obvious, and I don't know how I could have been quite so stupid. What he says is 100% correct: you want to reach your peak horsepower as quickly as possible, and remain there if you can, regardless of the amount of torque the engine is producing. Why? Because it will maximize via the transmission the amount of torque made at the wheels.

What I took issue with initially is that I thought RG was saying that if there was no transmission at all, just a 1:1 direct shaft to the engine that acceleration would be greatest at the horsepower peak, not the torque peak. That's not (I don't think) what he has been saying.

I remain both humbled and embarrassed

swoope

iTrader: (5)

i stayed out of this.

but, guessing. you are less stupid right now?

knowledge is power..

read learn, have fun....

beers

rotarygod

Gear ratio is irrelevant in this regards, 1:1 or otherwise. Your car would accelerate fastest around the horsepower peak. The torque peak is also irrelevant. Cars are geared specifically to place the engine rpms centered around peak horsepower and not peak torque. Your car doesn't accelerate fastest around the torque peak. You engine is running at it's highest VE at the torque peak though. If your torque peak were very close to your horsepower peak, then it might seem that your car accelerates fastest here as a result but it's still only based on horsepower.

I'll use my 2nd gen RX-7 as a prime example. It's torque peak is centered at 3500 rpm. It's horsepower peak is 6500 rpm. No one in their right mind would race that car with a shift point based on an average powerband centered at the torque peak. That car is fastest over 5000 rpm with a shift point of a bit over 7000 rpm. This is because that's where the car makes it's most average horsepower and horsepower is what moves cars. All cars work the same way.

At the end of the day, the only thing that moves your car down the road, acclerates it to speed, or keeps it moving, is horsepower.

Brettus

iTrader: (2)

bravo to RG

rotary.enthusiast

I'm still a little gun-shy after the last beat-down I received in this thread, but here goes:

At any given speed, if you could be at the engine's HP peak, then you would be accelerating at the maximum rate, and therefor you would always design a transmission to attempt to stay in this high HP range as much as possible. That I agree with.

However, in any single gear I would contend that you are accelerating faster at the engine's torque peak. Get in your 2nd gen sometime and accelerate in 1st gear. Does your rate of acceleration really seem to increase after the torque peak as you approach redline? All physics aside, I can say that isn't my own experience.

ASH8

Check the YT link (in your country) about horsepower and why you need more to go faster..why the BV needs another 730HP to go another 100MPH.

And yes I know many of you have seen it.

http://au.youtube.com/watch?v=LO0PgyPWE3o

Great Vid and a truly superb piece of Automotive engineering.

kersh4w

iTrader: (3)

you guys should check your maths:
http://www.youtube.com/watch?v=drE5c...eature=related

paulmasoner

iTrader: (1)

damn you!! u had to stop the video and do the spider/shoe bus stop thing...

/angry

RX8-Frontier

RG: No worries. You didn't offend. Just thought it was odd on page 2 when all the sudden you got flustered & resorted to typical internet "last resort" speak. That doesn't seem like you, and that's what promted my last post in this thread.

Honestly, we are very close to "the same page" on this, in that we both understand that horsepower, and the area under the curve, is the most important thing to talk about when talking about the rate of acceleration in a car. That's pretty obvious when 'ya understand that that's exactly what the function of the "acceleration" calculation is for...to give a numerical value to torque applied over time to find out how much work an engine can do in a period of time.

The only thing I'm stating is, torque IS important, because to increase the HORSEPOWER of an engine, you've only got 2 options: Increase the TORQUE, or increase the RPM. You can't increase horsepower, directly, because the physical things you can change are torque & rpm. And the reason to change them is to INCREASE the rate at which work can be done, aka, HORSEPOWER (to those that still don't quite get it....)

Anybody that tried to compare torque values straight up between two engines doesn't understand what torque is. I'll definately agree w/ 'ya on that one, too. When comparing, or even generally talking about an engine, horsepower is the only value that matters, because it is the TERM used to talk about how FAST work can be done by an engine. Plain and simple.

Basically, for the "every day" person, horsepower is the only thing that really matters; both peak and area under the curve. For the engineer working on increasing the horsepower, they have to focus on 2 things: increase torque, or increase RPM. They can't increase horsepower directly, because it's not a physical characteristic.

And that's where I think we disagree, if I'm reading your posts right. But, seeing as how you "work "in an engineering department in the real world and has a career making money from designing up to 2200hp equipment," then you already know all this and are just talking to "every day" people on here in terms that actually matter to them.

(Just for the e-***** comparison, I'm a Civil Engineer, but was forced to take a lot of Mechanical classes (dynamics, thermo, hydraulics, etc.) for ABET. I don't know a lot of the factory production side, but I know the math involved.)