fdl

So today I tried several hard 1/4 mile type runs with my car (trying to burn off some feul..for reasons specified in my other post ). I've complained before about 6th gear not being tall enough ... but now I've really got to complain about 1st not being tall enough.

I know its been casually mentioned heere before, but i really think this is whats hampering the TSX's 0-60 times, 1/4 times etc (in the 6mt anyways .. not sure about the ratios in the at).

Shifting from 1st to second causes the rpms to drop WAY too much. It puts you too low in the rev range, causing the car to almost bog. I tried may times and could not get a really nice 1-2 shift. If 1st was a bit taller ... it would be closer to second and shifting would keep you in the sweet spot. Furthermore...1st is so high thats its overkill and causing tons of wheel spin. I'm not sure what would happen with better tires, but in the stock car...a taller 1st gear should shave between 2/10's to a half second in my humble opinion!

Buff-Daddy

Maybe it's bogging down because someone filled it up to it's ears with gas?

ClutchPerformer

That's not it.

I still don't understand the choices the Honda engineers made about these gear ratios. It's like their logic was backwards or something (6th is close to 5th, but 2nd isn't close to 1st--should be the opposite, right?). The bog is something you'll have to live with unless you want to "powershift" and bounce off the rev limiter until you let the clutch pedal out again. I'll pass...

TinkySD

lol..buff daddy has finally hit the breaking point..he's having a nervous breakdown right here on the site

Two things
1) look at the dyno, the lower in the rpm band you are the more torque you actually have. Being in 2nd at 4000rpms is actually putting more power to the ground than 2nd at 5500rpms. if my interpretation of this is wrong please tell me.... but I think i'm right.
2) gears are all about multiplying power -- By having a taller gear all you are doing is creating a smaller efective area under the curve.

So in the case of the stock tires the super short top gear might be too much multiplication to keep power to the ground and a taller one *might* help a teeny bit..but it's going to be at the expense of the amount of power the car is actually putting the road. A better way to fix it would be to put some stickier tires on it. Stock for stock the tsx top 2 gears are shorter than those in the rsx...I think the real culprit here is the all seasons along with the super heavy 17s. Cut those down and 0-60 should help dramatically.

fdl

torque does not equal power. horsepower = power and you will have more horsepower at 5500 than at 4000. You want to keep your engine at the highest hp possible, and that is at the highest rpms. Otherwise redlining would be pointless.

Agreed ... but the main point is to make 1st closer to second..and I think there is room to do this without sacrificing useable power in 1st (there is more than enough power to have a taller 1st gear ratio and still spin the tires). Think about it this way...you could make 1st gear ratio as high as you want...and get as much power to the ground as you want...but with only 6 gears to work with you need to spread it out as effectively and efficiently as possible, and I think it could have been done better.

I feel like i am shifting from 1st to 3rd.

Buff-Daddy

Do you know what the hell you are talking about? I was referring to this genius...
http://www.acura-tsx.com/forums/show...&threadid=5114

slats

fdl,
What is the highest speed you reach in 1st gear? I read that it was only like 32. My friend has an integra 4dr. and when he shifts outta 1st at redline, he's going about 42. Strange huh? Then again, his car has an 8000 redline rather than 7100.

Slats

fdl

I'm not exactly sure, but I do know thats its lower than I'd like it to be.

dom

I was reading through this interesting thread but the thing thats sticks out to me the most is that fdl was on his PC at 3:19AM in the morning (Eastern Time)

Go to bed dude

fdl

LOL, I'm a night owl Plus I am on holidays ...hence the noon time first post today

You know this board really sucks that late at night....noone around...not even the west coasters ..... not even Larchmont!

illmeltxwithyou

This car just needs alot of practice to get the shifting down. I complained alot at first too about 1-2 gear. Now that have practiced alot with it it's fine. I can almost keep in the Vtech from 1st to 2nd. Learn to drive your car people it pays off. I would have to agree there is alot of tire spin in first that is un-needed

DEVO

If anything you want a shorter and closer ratio gear for 1-3. Also... you only want to shift once to get to 60. Actually if you can get a high torque engine... no shift is even better.

The problem with this approach is that now you have optimized the car to sprint to 60... but that's not what the TSX is all about, IMO.

Granted... i do believe they screwed up in picking the gear ratios for this car... 6th should be so tall that you can't accelerate in (or barely accelerate)

majormojo

This is an interesting thread. I've had the same complaint about the gear ratio difference between 1 & 2. I agree that 1 should be a bit taller. I'm sure that the engineers were worried that the I4 wouldn't feel torquey enough and kept 1st low to compensate. Works great for test drives, but isn't so great to live with.

illmeltxwithyou, how can you keep the rpm so close to vtec on the 1-2 shift? Even at 7400 rpm in 1st, the corresponding speed in 2nd is < 4300 rpm. You must have some serious voodoo, dude!

I haven't made any objective timing measurements, but the butt-dyno says that the 1-2 shift feels a lot better if done at no more than about 5500 or so in 1st. That corresponds to about 3200 in 2 and there's plenty of torque available there.

The problem I have with a near-redline 1-2 shift is that one of two things happens - either I make the shift fast and the engine bogs while dropping down to ~4000 rpm in 2, or I have to wait for the rpms to drop before letting out the clutch. Both of those seem counter-intuitive. Shifting fast and early means there's less time spent without power being applied. Since there's lots of push available at 3000+, I don't see that there is any disadvantage to shifting early vs running it up to 7000+ in 1st. I could be fooling myself, but it sure feels better.

I don't remember the full scientific explanation at the moment, but I seem to recall that in the early phase of acceleration (before wind drag becomes a big factor) torque is more important than hp for quick acceleration. An early 1-2 shift does give up some top-end hp but keeps the engine in the meaty part of the torque band which is what you want.

Comments anyone? Am I out to lunch?

TinkySD

I was under the impression that drive power to the ground at any point in teh rpm band = (gear ration x final drive x toque) / wheel diamater. With this in mind the reason to wind up to redline is to keep in that lower gear and thus have all the extra torque amplification. In a car like the tsx that is great since there isn't a large enough loss of toque as you rev to offset the drive power advantage. I still think that at 4500rpm in 2nd gear you are putting down more power than at 5500 in 2nd gear. I think the difference you feel is the big difference in torque multiplication between the two gears. It's hundreds of pound feet less to the ground. I still could be wrong... but I think i'm right.

TinkySD

That's how fifth is in the auto... our 4th is about equivalen to your 6th, lol.

fdl

Tinky..you are right with your formula for torque to the ground ... but its hp you want...not torque.

This leads into the whole torque vs hp thing, which I think most people have misconceptions of. In terms of pure engine numbers HP is basically the only indicator for acceleration. Torque is one of several elements that combine to give you hp. Torque is twisting force...so you could have TONS of torque but not be able to turn something very fast. Thats why torque is combined with engine revolutions to make up the rest of the puzzle ...that puzzle being hp..the overall accelation power of a car. hp = torque* rpm/5252. So you want lots of twisting force and lots of rpms..either one or both will increase your accel. But have tons of torquer with low rpms..is not going to be good.

At 4000 rpms...yes there will be more torque .... but there will be less overall hp...which is what you want and need for acceleration. If two cars races, one with more torque and one with more hp..the one with more hp would win every time.

Torque band is important in that having lots of torque means that you dont need to rev very high to achieve power. A high torque car can have plenty of power down low for every day driving because even at low rpms is making good hp. But the bottom line is hp is still the key ingredient.

DEVO

in order to achieve optimal 0-60... you want gear ratios that keep your revs in the sweet spot for max hp (in that range), but again doing this achieve one goal and not what a daily driver needs.

the S2000 is a good example of gearing the car (gears 1-5) so that revs stay in the "sweet" spot. The only problem i have with this is that 6th in the S2000 is still not an overdrive gear as they claim it to be...

fdl

Ya , I understand the reason they wanted a high ratio first gear... I just think that its a little TOO high and they could have made it a bit taller...keeping plenty of power down low and at the same time making the 1-2 shoft a little better. But I guess this car was really never meant for 0-60 sprinting, and thats definaltey reflected in the gearing. The car is more capable than the numbers are showing. Once you get into the high revs of 2nd its all good from then on...hence the great passing times the TSX has shown.

TinkySD

HP > torque is only true if it has gearing to take advantage of it...which is I guess what is the heart of the matter here Anyway thanks for the info.

rb1

Speaking of misconceptions...

Since F=ma, and therefore a=F/m, please explain why horsepower fits into the equation.

At a given instant in time, a car accelerates exactly according its mass and the net force delivered to the ground.

The previous analysis is so wrong it's difficult to know where to start. However, consider the following:

The torque curve in the TSX is pretty flat, and it pulls fairly steadily over this range in any given gear, yes? Conclusion: acceleration is largely a function of torque.

The horsepower curve is quite steep. Does the car pull harder and harder as the the RPM's increase? No. Conclusion: acceleration is NOT a function of horsepower.

TinkySD

yeah that's what I believe too. The reason high hp cars can compete is they have such high gearing which effectly produces comparable torque to the ground. By the way welcome back RB1

fdl

rb1..i'm afraid you are quite wrong...acceleration is most definately a function of HP. I cant beleive how many people still dont get this.

again..the formula...HP = torque*rpm/5252

So yes HP(accel) is largely a function of torque..hence why the flat torque curve helps.

HP ..is an expression of the over all accelerating power of the car. torque is mearly one peice of this equation...but the 2 are related. You can have all the torque in the world...but if your engine only spins at 100 rpms...you are not going anywhere very fast! Its the combination of rpm and torque...that describe the accelerating power of a car. Is alot of torque going to make you faster...YES...is revving very high going to make you faster...YES ...but its the 2 combined togethr that is the true indication. Hence having more torque...is good...as it increases your HP. again HP is still the key. A low torque car that revvs real high and can make high hp will be faster than a high torque car than cant rev high enough to equal or beat the other cars horsepower.

fdl

Why cant you guys get it out of your head that hp and torque are not completely separate things? HP = torque plus MORE. its the better indicator.

DEVO

I hear what you are saying but if you have a car that has an engine that weighs like any other engine and has all the torque in the world but can only spin at a low rpm.... to me the car will be geared with really tall gears to take advantage of all this torque and would compete very easily with a car that has no torque but lots of rpm.

fdl

but even at its optimum gearing..i am saying it would still be slower.

TinkySD

what you stated is somethign i've echo'd on here several times. Torque or HP alone don't tell you much, both of them together, and better yet a picture of a dyno tells you a whole lot. Then wehen you have gearing information you can accurate predict the performance of a given vehicle.

rb1

I'm quite familiar with the formula, and I submit that it is you who are wrong, and demonstrably so.

The acceleration curve of a car in any gear very closely matches its torque curve, not the hp curve. Why is this? (Again, F=ma)

Take 2nd gear in the TSX for example. The acceleration at, say 2200 RPM and 4400 RPM is almost the same. Yet the TSX is making about DOUBLE the horsepower at 4400 RPM that it does at 2200 RPM.

Don't get me wrong, hp is very good indicator of overall performance, but this is because the car with more hp can maintain a higher average torque output. To take advantage of this, you have to use gearing.

If I take 2 engines A & B with the same maximum torque, but B has higher horsepower, this just means that B delivers said torque at a higher RPM than A. This means that B can either use lower gear ratios (e.g. more torque to the wheels) or (even if the ratios are the same) that B can stay in lower gear longer than A (e.g. more torque to the wheels).

fdl

rb1...the accleration at 4400 is not the same as at 2200..its much higher. the higher in the rev range you get the faster you accelate (assuming a flat torque curve). Thats because your torque gets multiplied by your rpms to give you more hp (and hp = acceleration)

You're still thinking of hp and torque as completely separate elements, when they are in fact not.

Put what youa re saying into practice. Lets say we had a car with 300 pound feet of torque at 1000 rpms, witha torque curve that slowly got lower all the way to 7000 rpms. According to what you are saying..you would want to keep your rpms as close to your maximum torque (1000 rpms) as possible since you accelerate the most ..which is just plain wrong.

ANyways this argument is tiring me To get back on topic...I;m arguing that the 1st gear ratio is too high and is not optimal for 0-60 sprints.

rb1

This is patently false on both counts. Torque is NOT multiplied by RPM to produce acceleration, and acceleration absolutely does NOT increase with RPM if the torque curve is flat. Peak acceleration (in a given gear) occurs at the torque peak, not the hp peak.

There seems little point in discussing this further -- I'll be glad to direct you to g-force graphs that show acceleration vs. torque and speed-vs time charts that show linear speed increases in each gear (if acceleration actually increased with hp, then the speed would increase geometrically rather than linearly)

I submit that most TSX owners butt-dyno will tell them that the car accelerates fairly smoothly in each gear (what I am describing) vs. a "sling-shot" effect that increases with RPM (what you are describing).

fdl

rb1..I am getting tired of arguing with you. You keep your TSX at peak torque and I will keep mine at peak HP and we'll see who wins the race. And I can tell you for sure that my tsx accelerates a hell of alot better at 6000 rpms than at 2200 rpms..even though there is much less torque.

And to get thigns back on topic..I wish I could keep my rpms closer to peak HP during my shift to 2nd...which I beleive will result in much better accel numbers. (you can disagree with this and thats fine by me)

EDIT: Here is a website that explains it alot better than I can and I hope it will put an end to all of you arguing with me

http://www.allpar.com/eek/hp-vs-torque.html

DEVO

1st gear ratio is too high meaning not tall enough??? If anything you want second gear to be much shorter than it already is and keep 1st gear the way it is. On the TSX, a taller 1st gear mean you are going to bog it down even further at low RPM starts. Having a closer matched 2nd gear will get you what you want, that way when you switch to second you are closer to the sweet spot as far as HP is concerned.

DEVO

I have to add... that I've never heard hp = acceleration. I have always heard torque more closely tied to acceleration... to that I have to agree with rb1 last post.


also... if all else remain constant (no gear changing) you're above statement will net a zero acceleration (not zero velocity). keeping rpm constant at either the max torque or max hp will mean you have quit accelerating... lower the rpm and you are decelerating... increase the rpm and you are again accelerating.

rzee

The gear ratios are fine, just need to lower the vtec point by a few hundreds rpms. They have to keep the 2nd gear higher so that you can hit 60mph without a second gear shift.

fdl

DEVO ... you can bring second closer to first, or 1st clkoser to 2nd...either way will make the shift better., BUt I am saying that there is enoughpower in the TSX that you can make 1st taller. Its too short and the power is wasted right now. Making 1st taller would also keep 2 shifts to 60 mph. I am saying slightly taller. obviously 1st has to be a short gear.

Also...I STILL dont understand how you guys can say that torque is tied to accelration, but not HP. Its boggling my mind. In my last post I posted a url. I will post it again just in case you missed it. Please go read it and then hopefully you will understand.

http://www.allpar.com/eek/hp-vs-torque.html


I'll also say again. Lets race. YOu guys shift at peak torque, I'll shift at peak HP and we'll see who wins.

rzee

Torque is definitely tied to acceleration, that is not even a question. It's F=ma. It's physics. Given the same gear, the more torque you have the greater your acceleration is. Basically, you will have something like this, 0-10 low acceleration, 10-25 high acceleration, 25-30 low acceleration again.

With all the said, I have no idea what would happen if the 1st gear was made taller, it could very well be faster to 60mph, because that would involve different multipliers to that torque number at different rpms, and that is a lot more calculations than I can take.

Logically, I would assume that the engineers at Honda had done their research and beat the shit out of the numbers before they set those gear ratios.

Oh, and you should shift at highest possible rpm, because even though the torque is lower at high rpm range, with the higher multipler on lower gear, the torque at the wheel is still higher.

SteVTEC

Well first things first. You will maintain the highest rate of overall acceleration by keeping the engine geared so that the revs stay as close to peak horsepower (not peak torque!) as possible. You'll still get the highest rate of acceleration in any given gear at the point of peak torque in that gear. But if you were geared shorter and at higher revs (making more horsepower) then you would still be accelerating faster at that point even if you were no longer at peak torque. Max acceleration = keep the revs as close to peak horsepower as possible and you need appropriate gearing to accomplish that.

If you lengthen the 1st gear ratio you're going to have less torque multiplication and a lower peak rate of acceleration. This will slow you down, not speed you up. Why do the domestic guys all swap out the 3.27 gears in their stock Mustangs for 4.10's? Because it shortens up the gears and increases acceleration. The 3.27 gears that come stock are very long and designed for good economy but they are far from exciting, particularly on the automatics. 2nd gear tops out at 90?? sheesh. Swap in some 4.10s and now you have shorter gears with more torque multiplication and a much higher rate of acceleration. And now your 2nd gear tops out at 70, not 90.

As for the 1-2 gap on the TSX, that's the classic "2nd gear conspiracy". People judge a car by how well it can get to 60 mph, so compromises are made in gearing to "stretch" the 2nd gear beyond where it really "ought" to be just to get it over the 60 hump so that it will look better in the auto mags. But the problem with this is that on peaky engines that need lots of revs, the big gap on the 1-2 shift can drop the engine out of the powerband. But doing that is still much better than forcing another shift which can easily cost a few tenths depending on how quickly you're shifting. Even though a longer 2nd gear is an overall disadvantage for strong acceleration, it's a "marketing" advantage for the manufacturer because it makes the car look better in mags.

A little CarTest data...

Using the stock dyno and wheel weight compensated model I see that...

TSX 6mt with stock 4.70 gears

- 2nd gear tops out right at 60 (6.92)
- 1/4 mile is 15.48 @ 89.32 w/2.36 60'

So now lets swap in some shorter overall gears for better acceleration. The 6MT is shifting to 4th just before the line which costs you time. Lets shorten the gears so that you have just enough revs in the 1/4 mile to still finish in 4th. For the simulated TSX, 5.60 gears seem to be good with 4th now finishing at about 92 mph.

TSX 6mt with 5.60 gears

- 2nd gear now tops out at only 50 mph and you need a shift to 3rd well before 60
- 1/4 mile improves to 15.30 @ 90.50
- Launch improves (assuming traction) to a 2.23 60'
- 0-60 time drops to 7.00s

With shorter gears, peak rate of acceleration goes up, and you can also get off the line a lot harder (note the drop in 60' times). And because there is less of a drop in revs on each shift, you keep the engine closer to peak horsepower and overall accelerating stronger when going through the gears. The compromise? The gearing is now very "shifty" requiring lots of action, and your 0-60 time drops which makes the car look worse in mags.

So it's all about the 0-60 time with stock gearing. You're only going to go slower overall with taller gears.

DEVO

I've heard quite the opposite in that there is not enough torque, but if you say there is plenty then making a taller first gear will work as you say.

Also, I've read your article and I must be reading incorrectly but I still don't see anywhere where it says HP = acceleration. Anyway, I'm in agreement that you want to shift at max HP as opposed to max TORQUE. Having a high torque engine is going to allow you to rev up to the max HP quicker... but having the right gear ratio will keep you in the sweet spot so no need for torque once you are there.

fdl

rzee .. of course torque is tied to acceleration..i never once said it wasnt.

(trying desperately to get this back on topic ...)

steve..ya i know that a higher ratio will give you more power, but I think there is enough..if not too much with the 1st gear ratio right now. In your scenario..you say (assuming traction). Well I think thats a big assumption to make. My point is that in stock trim we have some room in 1st to make it taller. In any case..making 2nd shorter to get it closer to first is fine as well. Either way the point is that the 2 gears are too far apart. Either make 1st talle, or 2nd shorter (but then you would have to make 3rd, 4th, etc shorter).


actually i certainly wouldnt mind having the first 4 or 5 gears shorter. Then make 6th taller for highway cruising and I'll be very happy

larchmont

How about a poll on how many people understand this discussion?

(Me: no. And I used to be a star physics student. But yeah that was a long time ago.)

Anyway, I wanna put in my half a cent.

From the thread we had a few months ago where someone asked "What is torque," and some people (notably LeeLee) explained it, I tried to get some simple, graspable, practical image from all that physics and engineering stuff, and this is what I came out of it with.

Acceleration depends on both hp and torque. Torque (practically speaking -- forget about physics definitions) amounts to how quickly you can get the car's hp to kick in when you demand it.

No?


P.S. It's 4 AM and here I am!


P.P.S. BTW Buff-Daddy got a bum rap at the beginning of this thread. IMO he may have had some not-so-good moments lately, but this wasn't one of them.

rzee

dude, you really did...
But whatever, maybe you didn't mean it that way.

And Honda will absolutely not make the 2nd gear lower, because they need the car to hit 60mph before 2nd ends. (for that all important 0 to 60 time.)

Larch, you? star physics student?