I know there's million things to factor in but I want to know what does it come down to? Light weight FWD cars? Heavyweight V10/v12's RWD's? 4cyl Turbo'd AWD's? Auto's,manual's or tiptronic? Does it come down to WHP or torque? 4,6,8,10 or 12cyl? Does a 300 V8 match a 300hp V6? How about a 300hp RWD v s a 300hpFWD? 300hp vs 300hp F.I? Sorry for all the questions

 

I think it all comes down to the driver....of course you cant compare someone driving a v12 and the other driving a 4 cyclinder!

 

I kno that's a given but if they were identical drivers.. Ok for example u have a V6 mustang putting out 300hp vs a V8 mustang putting out 300hp with the same drivers.. Would the QT be the same or would the V8 puller harder?

 

Good question ^^ Wish I knew all the answers I would say the V8 will pull harder

 

the v6 would proabably pull harder because a v6 will "usually weigh less than a v8" Its really power versus weight will determine the victor but gearing plays a large factor in acceleration. There really isnt a generic formula to who would win it has to be done on a case by case example.

 

Correct, because the V8 will typically put out more torque.

 

^^ Less mass = quicker acceleration.

~Cheers~

 

So torque win races? It seems like everyone states RWD is better than FWD.. are there any advantages in racing with FWD?

 

i believe you should repost this or have it moved to Car Talk, more ppl read through there

 

It's not that simple but remember that horsepower is mathematically derived from torque. And FWD does have the inherent advantage of less parasitic power loss than RWD and an even larger advantage over AWD in that regard.

 

Torque has nothing to do with typical racing, not even tractor pulling.

The only thing that matters is HP. Look at any math formula regarding performance predictions. It is always HP, not torque.

Look at a diseal truck. It has 600 ft lbs torque. Is it fast? Hell no, not in the slightest.

Why does torque not matter ?

Because it does not consider the overall gearing. Gearing multiples the torque to the ground. How much can you lift ? I can lift a car with leverage !!! If anyone had a set of pullies, anyone can lift a car. That is the same idea as gearing. And, THAT IS THE DEFINITION OF HP. HP is torque with gearing taking into consideration.

As a final thought - the above assumes that the race car is properly geared to utilize that HP.

 

Op is confusing me

 

I don't think a 300hp V8 will perform any better than a 300hp V6. I believe the advantage of having more cylinders is to be able to rev higher, and thus make more hp (ie, keeping the torque up at high rpm). If both engines are making the same hp, then I don't see why the V8 engine will be any faster.

 

I'll tell you . . . . if it's an easy answer you are looking for . . . there is none in my opinion. Now I can say the best thing is a properly set up car, and that means everything is tuned to work together. As some of us know, put down too much power and we can't get traction, too much fuel the engine will stumble or fall flat . . . to much air and it runs too lean and looses power . . . that's why the best cars are professionally set up . . . engine block, cam, crank, heads, valves, rods, pistons, compression, fuel supply, ignition system, tranny set up, stall converter if automatic, gearing, tires, chassis, weight, suspension, etc etc . . . if it's not all in balance . . . you'll never get the most out of it.

And of course . . . the driver does play a role as well . . . so there is no one best answer . . . there's always some way to overcome someone with more HP or that weighs less . . .


Ruf

 

well, yes . . . you'd really need to know what the powerband for each is for each, and then which one gets more power to the wheels, and then has better traction, and then gearing that's set up for 0-60 or 1/4 mile runs vs top speed . . . like I noted, there's a lot to it . . . in a sense it is really almost rocket science.

Ruf

 

hum, almost but not quite as I would explain torque, that is unless you are assuming all things are equal.

So where torque comes in to play is the power to get heavier vehicles moving. If you had 2 cars each with 300hp and there is only one differences between them . . . say weight

Car 1: 300hp/280tq - 3200lbs
Car 2: 300hp/340tq - 3200lbs

then car 2 will get off the line quicker because it has more torque to get the 3200lb car moving. As the weight of a vehicle goes up . . torque becomes more important. That's why heavy haulers have big diesel engines . . . of course low gearing helps too. But all things the same, car 2 would be quicker 0-60 or in the 1/4 mile.

That's the best way I can think of to explain the merits of torque.

Ruf

 

True, but note that the quickest vehicles at the track aren't Honda Civics or motorcycles . . . they cannot handle the mass/power that a larger vehicle can . . . . the quickest and fastest are the ones that can handle the nastiest engines . . . for example . . . Top Fuel dragsters . . . drag bikes are quick, but still only as quick as Pro Street cars. At some point as you increase power, you'll need a chassis that can handle all that power.

Ruf

 

Exactly. Couldn't have said it better myself!

~Cheers~

 

Wouldn't the V8 pull harder at higher speeds?

 

So what are the top dragsters? V8?RWD? Auto or manual?

 

Wrong question to ask... Top fuel dragster are freaks of nature. They are HIGHLY specialized works-of-science. Anything that you would learn by asking about TF dragster would not apply to anything else except maybe a Funny Cars.

For example, TF dragsters had NO transmission. Direct drive. They laydown a solid blackmark from start to finish. That is how much power they have.

 

If you have the same power output, then it won't pull any harder. From my understanding, theoretically, given the same displacement, if you have a V8 instead of a V6, the engine should be able to rev higher and be able to hold the torque up longer, and thus produces more hp. But then you will also have to look at other factors like if your valve springs are good enough to handle the speed etc. I believe the reason why a V8 would be able to rev higher is lighter engine parts. For example, given the same engine displacement, if you have 8 cylinders rather than 6, then each piston is smaller, and thus should be lighter. If it's lighter than the inertia should also be lower and it's easier to accelerate a lighter part with less inertia.

 

but aren't most high revving engines 4 bangers? or is that a misconception of mine

 

Yea, I'd imagine it's a misconception. Most high revving 4 bangers are from Japan, and most of them are from Honda too, with some Toyotas and Nissans. I think it's easier to design a 4-cylinder, and it's cheaper to manufacture. It should take up less space and doesn't weigh as much as a 6-cylinder. Also, most of the high revving 4-bangers don't have large displacement, from 1.6L to 2.2L, you don't really need a V6 to reduce vibration and stuff. I guess the other question why are they using small engines. I think it's due to the taxation/insurance. In most other countries, Cars are categorize based on engine size, and you need to pay more insurance/taxes if you have a large displacement cars. In order to squeeze more power from a small displacement engine, you will need revs and/or boost, and we have seen many examples from both. For high rpm engines we all know about the Type R, S2k, and Celica. For boosted engines we all know about Evo, Silvia, STi, etc. Also, they don't want too much weight hanging in the front for these little cars, so a small displacement 4-banger with lots of revs makes sense to a lot of sports compacts.

There are many high revving 6 cylinder engines too, for example, the C32B, the VQ, 911 GT3, and the old M3 engine. If these cars were to use 4-cylinders with over 3L of displacement, they will have vibration problems, and not be able to rev that high.

And that are a few high revving V8's, V10's, and V12's like the Gallardo, Murcielago, and most Ferrari's. Obviously these engines would be too $$, big, and powerful for sports compacts and that's why you don't see them in a Civic or Integra.

 

Good read.

 

hmm so how do you increase torque performance? Does high compression have anything to do with it?

 

high compression is mainly for combustion efficiency. It will increaase torque and HP by a few percentage (minor amount).

"Torque motors" (torque at lower rpm levels) happens by burning larger volumes of air/fuel mixture at lower rpm's. How ? Mainly, large displacement engines. Forced induction (supercharger and turbo) is the same thing as larger displacement. To a much smaller extent, stroker motors (longer stroke than bore) produce slightly more lower-rpm torque per given displacement.

 

the most important thing in racing?
be smooth

 

By "increase torque performance," do you mean having good low end torque, or having a high peak torque, or do you mean something else? There are quite a lot of ways to increase torque. Here are some examples.

For better low end torque, you can have less valve overlapping and less valve lift. If you want better high end torque, then you need the opposite - more valve overlapping and more valve lift. So if you want to have good low end torque and high end torque, and thus increased torque performance, you will need variable valve timing and lift, such as VTEC.

Another way is to use variable intake manifold. Basically, you want short length for high engine speeds, and long length for low engine speeds for better torque. I think it's easy to understand why you want a shorter length for high speed - less restriction is one reason. For low rpm, you want long intake manifolds because it lowers the frequency of the air going into the cylinder to match the engine rev. This also helps the mixing process somewhat and thus better torque.

Then there's also the variable back-pressure exhaust which is kind of similar to the variable intake manifold theory.

High compression ratio is helpful. In fact, compression ratio is directly related to the engine efficiency - the higher the more efficient. But it can only go so high otherwise there will be knocking. Direct injection helps increase compression ratio too. One reason is the fuel can cool down the combustion chamber during the compression stroke.

 

There's always a trade off between low-end torque and high-end horsepower. Naturally aspirated small displacement engines, especially 4 cylinders, are particularly weak in low-end torque even though they can generate lots of high-end horsepowers.

Currently, no amount of advanced engine gadgets, such as iVtec, Vanos, DI, dual intake runners, active muffler flap, 9K redline, etc. can produce lots of torque from a small displacement naturally aspirated engine. The only methods to generate lots of torque, especially low-end torque, are from bigger engine displacement and from force induction.

 

ya, after all, if you go NA, there's only so much air you can put into the engine, you can optimize all you want with all those systems, but in the end if you don't have big displacement then you don't get a lot of torque.

 

In drag racing, RWD >all. You don't want to see what it looks like when I launch on a ricer Honda in the GN.

AWD is great on the street but there comes a point (power level) where AWD becomes a negative and RWD is superior. On drag radials, I can usually launch at least even with a good driver in an AWD car and on the Hoosiers it's not a contest.

Small 4 cylinders usually rev higher to make up for the lack of displacement. Higher rpms usually equal higher hp. The flip side is you usually give up low end torque for hp. A 4 cylinder can be tuned for low end torque just like a V8, but it would be too slow for most drivers.

There are plenty V8s that rev high, it's just that most of them don't have to rev to make hp so they're built to make better low-mid range torque and average top end hp.

My friend's 4.6L Mustang is just a little slower than my TL but it's so much more fun to drive with the torque available anywhere on the tach. Where I have to downshift a couple gears in the TL just to scoot around in traffic, he can leave it in 4th gear.

My turbo V6 makes it's max 700+lbs of torque just above 3,000rpm and peak power at 5,600rpm. Once I stab the throttle, it's in the powerband the entire run. I don't have to worry about revving it to the moon to make power and then worry about falling out of the powerband on the shifts.

This is where turbo (properly sized) engines and large displacement engines tuned for torque shine. I could've gone with a larger cam, different heads, and a larger turbo for more hp but then it wouldn't be as enjoyable on the street and I would have to worry about getting caught off guard and getting it into the powerband.

Last, a large V8 with lots of torque making the same hp as a small V6 will hide a bad driver. It's more forgiving if you're not in the right gear.

 

So you say your friens mustang is slower than your TL? How.. It would seem the torque would help it if raced from a dig... maybe from a roll but it seems the V8 would prevail... When I used to raced my 01 TL "P"(RIP) against my buddies 95 mustang from a roll I would pull slightly but after 100mph he would pull and stay ahead..

 

i've seen a modded CRX put bus lengths on a corvette

 

Mine is the opposite. He pulls me off the start. By 60mph we're nearly even. By 100mph I've usually got my rear bumper at his front and still pulling away. His is a manual and mine is an auto.

I would imagine if we set up a test with both cars rolling at 3,000rpm and punched it without downshifting he would walk me.

 

Wait a minute I'm confused, I thought the more HP, the more torque?

 

You've got it all, RWD Turbo! But how would getting larger cams/turbo make it harder to drive?

 

If I were to raise the rpm range, the engine would become more "peaky". Right now, I can punch it from any gear or speed and have power instantly available. If I shifted the power band up toward 7,000rpm, it would make more hp all things being equal but would not have the same broad powerband that makes it so enjoyable.

For example, I ran a Viper years ago when I had just a couple upgrades, stock motor. At the top of each of his gears he would pull up half a car on me but through each gear I would put a full car on him with my consistant pull. He likely had more peak hp and I had more hp and torque "under the curve". I won the race with less peak power and he wanted to beat me up lol.

If we're talking an all out drag car that will never see the street and has the trans/gearing/chassis/ to take full advantage, go for peak hp. On the street I like a more streetable combo.

 

Not necessarily man. You can have a diesel that makes 300lbft of torque but 180hp with a redline of 5000rpm or so, or a F1 engine that revs to 20000rpm and makes 800hp, but only 300lbft of torque.

 

about the rpms, is it better for a car to redline higher?