paul_huryk

Anyone who tells you that with so many variables, only one is the biggest factor, they are mistaken.

Danielsc400

well, the most important.... it seems like its power to weight ratio

erick3

know the limits of your car - braking for example, unless you're in it for the "killing"

vhtran

You control the car, don't let the car control you. OR don't crash.

iforyou

iTrader: (1)

Hmm..there's no definite answer. Your car might have a high redline, but it's meaningless if the engine doesn't make much power at high rpm - some examples would be the K-cars in Japan and STi (I think the Mazdaspeed 3 too). You will find that, using the STi as an example, even though you can rev it to 8000rpm, its torque curve drops quite fast after 5000-6000rpm. The engine doesn't produce more horsepower at high rpm. I heard that for these cars, it's better to shift up before the redline.

Another thing to worry about is engine reliability. The valves are opened and closed much faster - in other words, they undergo many cycles, much more than typical engines. And as you know, there's something called fatigue, and undergoing that many cycles will reduce the life a part faster. In short, choosing the right material and right processes in making a part is important to improve fatigue life. If the stress is low enough, for some materials you will have infiniti life (theoretically), but if the stress is high, then that's a design problem that has to be solved.

I hate cars

When talking high rpm high hp vs low rpm high torque, and different wear rates it comes down to two things.

Low rpm high torque engines produce tons of cylinder pressure.

High rpm high hp engines have more centrifugal stresses in the rotating assembly, valvetrain stress, and typically more problems with harmonics.

Danielsc400

Hey I see your GN is 4.2L, I thought they were 3.8? Also is it good to bore out engines in say a T.L?

Soseductivesf

Hmm I would think the fastest cars would be the V8/V10's putting down 1000+ hp....of course the GN's.. I watched those video's of them literally doing the 1/4mile bouncing through most of it.. How the hell are they running 10's if for half the race there on 2 wheels?

vhtran

You don't need V8/V10, try this one and find the 1/4 mile videos on them. There are plenty out there. http://www.wotmstore.com/rywo98qu.html

I hate cars

I like doing things the cheap way. I found a Buick 4.1L V6 in the junkyard in a Cadillac, it's identical to the 3.8L except it has a larger bore. I bored it .035" over to bring it to a 4" bore so I could use off the shelf JE Chevy pistons which saved me $300. Everything else just carried over to the new block. It's 256 cubes which is just about dead on 4.2L. I could make all the power I wanted with the 3.8 but the 4.2 has so much better spool up and drivablity.

I prefer to get displacement from the bore if possible but it's hard to get much from it. The larger bore will usually help it breath better, unshrouding the valves. For example, the stock 4.1L was 252 cubes. I bored it .035 which is the max and gained only 4 cubes. You have to be careful with the bore because if you go too thin, you lose ring seal and power or worse, you break things.

On the other hand, going from a 3.4" stock stroke crank to a 3.65" will bring a 3.8L to the neighborhood of a 4.1L (can't remember the exact displacement anymore).

I guess the simple answer is don't bother boring the TL. Get a different block with a larger bore, or stroke it for more displacement.

RUF87

Right . . . if all things are equal, and one of those things falls short, then that becomes the most improtant thing. But since all things are not equal there is no such thing as the most important thing.

Just maybe, if you forget to step on the gas, then that is the most important thing.

Ruf

MobTownTL

iTrader: (1)

Important factors in racing?

"JDMMMM, VVVVTECCCCC, NOSSSSS, POWERRRR SHIFFTINGGGGGG"
-lol


go watch modded civic hatches (4 bangers) walk all over modded v8's and tell me that the number besides the "v" matters xP.

I hate cars

That's extremely rare and it's usually a shitbox gutted POS against a full interior daily driver V8.

vhtran

MobTownTL

iTrader: (1)

lol maybe, but a shitbox putting down 9 sec 1/4 times is a pretty damn fast shitbox nevertheless.

and it may be rare, but the point was, it happens, so does the number really matter? maybe, maybe not.

vhtran

They will have to trade off with no A/C, no comfy seats + no back seat, road noise, probably no radio either, sound like a fart can, most of people look at you just like looking at another dumba$$.

I hate cars

My point is you can take most V8s, namely an LSx based engine and run 11s with practically nothing done (in some cases stock) with all the creature comforts the car came with from the factory. In fact, you can have a 10 second and even the rare 9 second full interior car that you could drive to work every day.

Besides all the other negatives of a gutted race car, you will never have the drivability or reliability of a V8 at the 9 second level.

To get my V6 streetable at the level it's at has taken a lot of patients and money for different combos. As much as I like my car, I realize that the same combo on a V8 would generate 30% or more power with the same streetability. I'm just glad the V8 guys usually don't go the turbo route for some reason.

MobTownTL

iTrader: (1)

o_O actually i've been in a full interior t/c hatch with aftermarket seats, quiet enough cabin to hear the upgraded subs controlled by a flip-out plasma touch screen moniter while enjoying the cold a/c and blowing by most anything that challenged us. and the look on their faces was pretty priceless when we flew by "most people" =]

MobTownTL

iTrader: (1)

that is pretty crazy, wasn't doubting the power of v8's but more sticking up for the little guys xP

btw is it more beneficial for v8's to run s/c or t/c o_O

TL|GTX

Another example is the Bmw 335D. It has twin turbo deisel. It has 260hp, and 425trq, with a 6spd auto, geared almost like a 335i but the 0-60 is 5.8sec. Thats slow for 425trq. My freinds 02 Mustang GT has 260hp and 320trq. And i can take him by half a car, and he auto.

I hate cars

Good tires help high torque cars out a lot. That's why some cars pick up nothing from sticky tires while some run a second faster.

Dave_B

It sounds we'e talking about drag racing. If that's the case, the first 100' is the most important part to racing. Period. The harder and faster your car gets off the line, the quicker it will be in the 1/4 mile. Every .1 second drop in 60' equates to around .15 to .20 seconds in the 1/4 mile.

When it comes to setups, the answer is pretty simple assuming weight and gearing are the same across the cars of comparison. Four words, POWER UNDER THE CURVE. Carroll Shelby was an idiot for stating "torque wins races". What wins races is power under the curve. Simply put, if the motor makes more average power across it's powerband, it's going to be faster. For example, you've got two Toyota Supras turbos. One's twin turbo and has 450whp/450wtq and the other is a single turbo making 650whp/400wtq. Most people would say the 650hp Supra would be quicker. BUT if you overlay the dynos and do some calculation, you'd see that the single turbo doesn't make much power until around 5000rpms where it spike dramatically. Power is only sustained from 5000 to 7000rpms. The twin turbo Supra's powerband starts at 3000rpms and is sustained to 7000rpms. While making less peak power, it sustained more average power over it's powerband. It's easier to launch, easier to drive, power is everywhere above 3000rpms, and power isn't like a light switch (ie on/off). This is why GM's LSX motors are so damn effective.

Having a car with a fat powerband is ideal for any sort of racing. You want the motor to be very flexible and not rpm dependant. Technology has improved dramatically over the years and most everything they're doing to motors improves power under the curve, MPG, and emissions. Things like variable intake manifolds, variable lift cams, variable cam timing, direct injection, and ultra high compression (11:1+) all make for a very flexible and powerful motor.

Someone posed the question, would a 300hp V6 be as fast 300hp V8? Assuming weight is the same and the gearing is correct for each motor, the V8 should be faster than the V6 because it should have a fatter powerband thanks to the increase in displacement. It should launch harder too.

As for the diesels, yes, they make a ton of torque, but they have very narrow powerbands. Most diesels only make power to 3500-4000rpms. Their powerbands are only about 1800-2000rpms wide. So, while they make killer torque, their power isn't sustained.

As for HP, remember, it's calculated from torque. HP can't be measured. It's merely a calculation. Torque can be measured.

nova_G

^ what he said.

/end thread?

I hate cars

Very well written!

Honda is probably the worst when it comes to power under the curve, it's weird having to drop two gears just to ease around slow traffic.

The only thing I would have to bring up is that the 600hp Supra with a transmission capable of keeping it in it's powerband would walk all over the more tractable 450hp Supra. Usually that's not the case and it's illustrated by their 120+mph traps running mid 12s. On the street, power under the curve is king.

It's good you bring up 60'. It's the easiest way to improve 1/4 times yet I've never seen a member of this board try drag radials.

iforyou

iTrader: (1)

^ I don't think Honda is the worst when it comes to power under the curve. I will post some dynos.

2009 TSX:


2008 Accord V6 6MT

The torque actually peaks at around 3500-4000rpm and drops off slowly from there.

2008 Accord V6 5AT

Because there's no manual mode with the Accord's 5AT, the tester couldn't floor it without downshifting until 4000rpm or so. So the torque curve is weird before that rpm.

2004 TL 6MT and 2007 TL-S 6MT:


2007 Fit 5MT 1.5L



As you can see from the above examples. Most of the torque curves are pretty flat and are far from being peaky.

TLAdvanced

iTrader: (4)

Power to weight ratio, suspension geometry and driver are the three main factors in any type of racing but there are SO MANY other variables depending on what kind of race you mean...

Danielsc400

wow, Dave_b pretty much sums it up... So what about transmissions? FWD,RWD,AWD? I would think AWD would be the choice in 1/4 mile..

Danielsc400

I don't see anything

I hate cars

RWD is superior.

Danielsc400

But wouldn't AWD lauch harder? I'd figure a 400hp AWD would demolish a 400hp RWD.. ewspecially in a 1/4 mile, i wouldn't think the RWD would be able to make it up in a short amount of time

I hate cars

Street tire to street tire AWD rules. Slicks to slicks, the RWD car will out launch it. Even on the street I've had no problem putting buslengths on all the popular AWD cars out of the hole.

Look at some of the fastest Syclones and Typhoons that come from the factory with AWD. At some point, usually when they're in the mid to lower 10s they axe the AWD and go RWD. The dynamics are way different and once you're past a certain power level, you just can't put the power down with AWD.

iforyou

iTrader: (1)

shxt, I think temple of vtec just wouldn't let me link the pics directly. I was just showing some dyno plots of various Honda's/Acura's to prove that they have flat torque curves. The ones that are peaky are the S2000 and the various Type R cars. Even so, they make adequate amount of torque at low rpm given the displacement. For instance, the S2000 makes 133lbft of torque at about 3000rpm, which is not bad for a 10 yr old engine with 2.0L of displacement tuned for high end power since that's already 87% of the peak torque.

I hate cars

They may have a somewhat flat torque curve but there's just not much there. The TL is the weakest car off the line that I've ever driven and it's one of the most torquey made by Honda. It's so gutless below 5,000rpm it's annoying sometimes.

06is350

I gotta say it's all about the driver. There's an driving instructor i've heard about than can take out any is350 with his is250AWD..

iforyou

iTrader: (1)

I think it has more to do with the transmission rather than the engine. From what I've heard on this forum, the 3G TL's AT is tuned "softer" compared to the 2G TL-S. I don't know about your car, but I can spin my front tires fairly easily off the line if I stomp on the gas.

Also I think the 3.2L displacement doesn't help in torque. I mean I have a feeling you are comparing the TL to some 3.5L cars, that's why you find the TL to be rather gutless. Here is a dyno of a 5MT Maxima with a stock VQ30DE that's rated at 222hp:



It also has a flat torque curve, but its peak torque is only about 186lbft. A TL 6MT also has a flat curve and peaks at over 200lbft. A TL 5AT peaks at 183lbft (I'm sure you know this already since you posted that number in your signature..lol). So the 5AT is definitely robbing some torque.

Here are some linkes to those TL dynos:
http://www.vtec.net/articles/article...tldyno_tov.gif
http://www.vtec.net/articles/article...tl_5ATdyno.gif

And here's a plot of the TL-S 6MT:
http://www.vtec.net/articles/view-ar...icle_id=686783

As you can see it's very flat again, and peaks at 230lbft, thanks to the extra 300cc. Also, without boost, it's hard to get more torque (especially low-end torque) given the same engine size.

So in short, you feel your TL is gutless because of its 5AT, lack of displacement, no turbo/SC, and....you drive a 602rwhp GN....lol..

I hate cars

Does the auto TL really average to 183lbs? Just wondering if mine really is that average or if you just quoted my sig.

Maybe it's what you're used to. I come from a V8 background with the exception of the GN so I'm used to tons of torque right off idle.

SatinSilverAV6

iTrader: (2)

sad that the TL only averages 183wtq. My 03 Accord V6 auto managed 181WTQ with a 3.0 with just intake.

jeowen

LOL love the little dude running in circles

iforyou

iTrader: (1)

Opps, my bad, it's actually about 190lbft at the wheels. And yes, lol, that's nothing compared to big V8 and/or boosted engines.

Costco

LS1

LT1

Just for comparison, observe the two dyno sheets for the LS1 and LT1.... I know, they are from different dynos, but the numbers are still there.

I always thought this was odd... for me, the LT1 felt like it had more torque than the LS1, and others echoed the same sentiment. However, when you look at the dyno chart the LS1 clearly has it outmatched. This "feeling" of torque is usually deceptive because its dependent on a LOT of things. The main difference is that the LT1 reaches peak torque at around 3500 rpm and the LS1 comes in more around 4000 rpm. The reason I bring this up is I notice people always say "Maximas have more torque than TLs" and how Maximas beat TLs off the line, but the TLs catch up later. This is almost like deja vu with the LT1/LS1 comparison. Maxima vs. TL, peak torque is also around 3500 rpm vs. 4000 rpm, respectively. It makes a big difference believe it or not.

Our 2G TL-S spun the tires also.... but I think that has more to do with the weight transfer than anything. Less weight on front tires from launching = less traction = wheelspin. In my Z28 if I floored it from a stop it would light up the tires all the way through 1st gear.



Just assume all things equal, a car with 300 horsepower and 300 lb/ft @ 3400 rpm and another car, 300 hp and 300 lb/ft @ 4200 rpm.

Having peak torque occur at a HIGHER point in your rev band is better. When you shift, lets say from 1st to 2nd at 7000 rpm, your RPMs shouldn't dip below 5000, or at least not by much. Meanwhile, your peak torque is way down there at 3000 rpms. Oops! You make gobs of torque at the line, but some of it is lost as you approach higher RPMs... engines naturally drop in torque at the peak of their rev band. Also, as I hate cars can attest, high torque cars (or shall we say, cars that have peak torque at lower RPMs) are usually harder to launch. This is why a lot of Hondas, especially 4-cyls, despite being torqueless at lower RPMs, "feel" pretty fast at higher RPMs because their peak torque occurs later on in the rev band, which again, means they're making more torque at higher RPMs than another car with "more low-end torque" would be. Prime example being the S2000.... yes, it has no balls under 3-4000 rpm (AP1 especially) but it hauls ass around a track and at higher RPMs. That's because they reach peak torque ultimately at around 7000 rpm or so, off of the top of my head.



Well.... that's just my Sometimes I wanna go into physics to further my knowledge of calculating ultimately how much thrust actually gets to the pavement, but then again..... nah.