FWD vs. RWD

[TrvlynAlec]

I am just wondering why people are so against FWD cars. I mean you can get alot of horsepower outta them and they are fast. Also in many car specs they say whether an engine block is cast-iron or alluminum. Which is better and why? Thanks.

[SaabJohan]

The problem with FWD is basicly two things, traction for the tires and understeering.

During acceleration the cars center of gravity is moved back in the car, this means less weight on the frontwheels and vice versa for the rear wheels. This makes it more difficult to get traction for the front wheels.

When a front wheel driven car is accelerating it generally understeer, but if the throttle is released the car can have tendences to oversteer, or at least it will oversteer more than it did when the car was accelerating. A rear wheel driven car is just the opposite, and that can make the car easier in turns but more difficult to handle on straight parts of the road, but there the FWD will have more problem with traction for the driving wheels when it accelerate. But in higher speeds the aerodynamics can affect the traction, which can give it good traction.

[SaabJohan]

And about the engine block material, there is no one that is better, it just depends of what you're using it for and who you ask the question to.

[swedish]

Well, aluminum is lighter.

[TrvlynAlec]

Originally posted by SaabJohan
And about the engine block material, there is no one that is better, it just depends of what you're using it for and who you ask the question to.

Why would you want aluminum though? for racing? Yes, it is lighter but i think iron is stronger.

[Seabass]

Not ot mention that FWD cars can't do cool donuts. And yes...donuts in reverse are lame.

Iron blocks are stronger.

Aluminum is lighter

This doesn't mean that aluminum isn't good. Unless your looking at running HIGH horsepower...go with aluminum if you can (especially if you have aluminum heads since you have thermal expansion).

Sebastian "Seabass"

[454Casull]

During acceleration the cars center of gravity is moved back in the car

It might make more sense if you say that the car's center of gravity is shifted backwards.

[Psman32@af]

I think there is another thing too. Torque steer. I've noticed it in quite a few in FWD cars because the car will pull to one side or the other when u slam on the gas. Ive never known a RWD car to do that. Plus I also like how the steering wheel feels while driving a RWD car compared to a FWD, as the FWD tries to pull it self staight if you are on the gas and cornering.

[SaabJohan]

The side to side thing that happends with FWD is because of two basic things, wrong torque distribution and loss in traction on the front wheels.

Wrong torque distribution can be a result of a chassi that is too weak or a ineffective diffirential.

A 4WD car also have tendenses to go from side to side, while a RWD instead throw it's rear end out like when doing a donut.


Usually aluminium blocks have more problems with thermal expansion, cause since most liners are made of iron.

[texan]

The question you pose is pretty non-specific, how about we analyze it in specific venues?

For example, if you are looking for small, lightweight and affordable performance cars in the US right now, there really aren't any rwd alternatives. So fwd is currently the king of this market niche, and the Hondas are quite a fad with most of the younger generation too. There's nothing wrong with the cars and many are quite capable performance wise in their classes, but if you are talking about no holds barred racing with no specific rules, it's doubtful any fwd car will compete favorably with a well chosen and built rwd car. The driving dynamics of rwd are superior in two equally well designed and built cars, it's just that simple. But the gap is not as large as it used to be, thanks to better fwd drivetrain and suspension setups.

The problem that's impossible to get around is that the front wheels have to do nearly all the work in terms of braking, accelerating and turning. With only so many rubber molecules available to do this work, and with most performance driving demanding two of these three modes of traction at once, it's just a better system when you split acceleration duties to the rear wheels and leave the fronts to specialize in turning and braking.

Finally, the line "you can get alot of horsepower outta them and they are fast" is all relative. If you were to say that to a Pro 5.0 car builder and competitor, they'd laugh til they cried. These cars make in excess of 1200hp and run very low 7's to very high 6's in the quarter mile, and they do it with quite a few challenging class rules. Tube chassis fwd cars with no limitations on engine power or configuration aren't even close to that mark of speed or power output, and they have a good bit more money thrown at the engines. But of course if you got your average 17 year old kid to jump in a turbocharged Integra GSR they'd think it was wickedly fast, even though it's still making less horsepower than a bone stock Camaro Z28 (which would cost you about 1-2g more out the door on new models). Just remember all these arguments are relative to the money one has to spend, the car's intended use, and the owner's specific tastes. Some love the feel of fwd, some hate it. I'm somewhere in between, but chances are the next car I buy will be rwd.

[TrvlynAlec]

Originally posted by SaabJohan
The side to side thing that happends with FWD is because of two basic things, wrong torque distribution and loss in traction on the front wheels.

Wrong torque distribution can be a result of a chassi that is too weak or a ineffective diffirential.

A 4WD car also have tendenses to go from side to side, while a RWD instead throw it's rear end out like when doing a donut.

What about a AWD car like the evo or the skyline.. Do these cars have tendencies to go from side to side? is AWD better than RWD?


Thank you all for your posts! :ylsuper

[ales]

I'm a big FWD fan. Also, I'm the first to admit that it all goes down to your personal preference. For brute power RWD is somewhat better. But it is also much more unstable (at the same time it's easier to bring it under control, but it's easier to lose that control in the first place). As for competition (and not just drag racing), in DTM Audi are currently whooping Mercedes's ass and in BTCC I can't even recall when an RWD car has won anything. Surely there's a reason for that! In the hands of a good driver FWD can be at least as fast as RWD. I remember a few years ago in Super Touring Wagen championship in Germany there were huge BMW vs. Peugeot battles. The BMW won, but narrowly. It was a close and even fight till the last ace of the season.

And there's nothing wrong with alluminium blocks

Alex

[SaabJohan]

Since a car got 4 wheels, 4WD = AWD.

I think the fastest FWD does the 1/4 mile in around 8 second, don't know how much power but I can guess of around 800 hp. If we compared that car against a HKS tuned Supra with around 800 hp we will found that it is almost 2 secons slower... so RWD must be really bad, 2 seconds... No, we can't compare these cars that way, and the same between 1200 hp rwd dragsters and fwd:s with tube chassis.

Comparing done with the cost of the car can also be bad... if the only thing that matters were speed/dollar, why don't buy a rocket and a skateboard instead, one can die trying but at least it was inexpensive...

[cadet]

Originally posted by TrvlynAlec


What about a AWD car like the evo or the skyline.. Do these cars have tendencies to go from side to side? is AWD better than RWD?

it depends on the car as there are smany different versions of AWD. depending on the setup it will behave partly like a FWD and partly like a RWD. the skyline will behave like a RWD most of the time (oversteer) whereas the evo would tend more towards understeer (FWD), as a generalised example. with a big launch and decent power an AWD car can spin its tyres so it will move around alright.

AWD gives better grip in slippery conditions but RWD is the most entertaining setup in my opinion. it depends what you want in a car.

[Steel]

4WD isnt AWD, get that straight. Two very differnt setups. I'f i were to drive my pathfinder around with 4WD conencted all the time, not only would i waste gas, and not get 20 miles before i hear the transfer box start grinding off gear teeth, but steering at speed (as if i could get very fast in the first place) would be nearly impossible. just so you know.