Performance from a FWD vehicle.

Still searching and asking around aboutsemi practicle and cheap solo1/2 vehicles has giving me quite a few good words about quite a few FWD vehicles such as a CRX. But there are quite a few things I dont understand about how a performance oriented FWD vehicle so with out further adu...
In a RWD car you want a good portion of your weight twords the rear or center of the car to give the rear wheels traction but what about a FWD car? I have heard people say to do things like put the batery in the trunk to even the weight up but why? Wouldnt that hurt its acceleration and cornering since the weight isnt over the tires that controll that aspect? I can see how it would help in braking though since it will help keep the rear tires down so they can get traction when stopping or am I confused onthis as well?
Also, its known that FWD have problems with accelerating but is that only in 0-30 type scenarios or does it still retain a huge disadvantage beyond 30mph? I have also heard FWD cars have problems handling high ammounts of hp. What kind of power does it before a fwd vehicle starts to really show these problems?
How much of a problem is torque steer in a FWD vehicle that has double wishbone suspenion? I have heard it helps quite abit over mcpherson struts.

thx

I love Front Wheel Drive. The more power you got, the more you will burnout. When you floor it at a stop, alot of weight transfer is the issue, it all goes to the back, and the front wheels lose weight, making it burn out. I believe alot of people put more weight under the hood area-to give the FRONT wheels more traction.

I like FWD much better on the highway, much. Over 80mph the car will pull straight-a good thing, and a bad thing. But RWD you tap the steering wheel at high speeds, and into the wall you go. RWD will ALWAYS be better on the dragstrip cause the benefit of the weight transfer.

Power, well for a FWD, if you got some serious torque, especially if it's low in the rpm range, watch out. Torque steer will greet you. If you had 2 equal cars, same exact engine's and everything. One is FWD, the other is RWD, lets say they both have 250hp at 4000rpm, and 270ftlbs of torque @3000RPM, you'll see a MAJOR speed differance from 0-60, or in the 1/4 mile run. You would have to baby the FWD (not just floor it) much more to not burnout when floored.

Me, the main reason why i like RWD is the tight turning, and well thats probably it :-) Oh, and they do some great donuts... But honestly, i'd much rather FWD, better in the snow/rain, easier to control if you "lose control", AND they pull sraight at high speeds. I used to know a PO in the nypd, and we were talking about the fact the no longer use the 5.7L caprice's anymore, and he mentioned that the newer SS FWD impalas (sc'ed V6) where no where as powerfull, but pulled straight as i noted. If you ever drove a RWD in any weather but DRY, you know how dangerous they are at high speeds, especially with some power to em.

BTW.. My friend has a late late 90's hyundai sonata, and he had the works on that girl, body kit, this that etc.. And i believe a 120?? hp shot NOS kit. He said if you hit it at going 50-60mph, that the front tires will burnout for like a second-you gotta be carefull, but have fun :-)

Torque steer only occurs when one wheel is providing less resistance to being turned than another.
In many FWD cars one axle is longer than the other, the short axle weighs less, and so is easier to turn. Hence with lots of power you get torque steer.
Your suspension set up does not affect it.

There are two ways to solve it however:

Use a limited slip differntial.

Use equal length drive shafts by fitting a secondary shaft to the longer axle. This runs in a straight line, usualy along the back of the enigne block, and makes both axles (which have to work at an angle through CV joints) the same length.
Its a system used by Honda since the late 80s an all its DOCH VTEC powered cars, and has even been used on many of the later SOHC VTEC powered cars.
I used to own one, and with 160hp I could acclerate chirping the tyres into 3rd gear at 100kph with only my little finger on the steering wheel correcting for minior deviations in the road surface.
There was no Torque steer.


As a general rule, anything over about 150hp in a light weight FWD car (say compact or smaller) is going to need some carefull use of the acclerator in the wet, anything over 200hp is going to become a potential handful in the dry, and anything over 250hp is reaching the limits of what a FWD set up can handle, and still be nice and easy to drive while offering create handling.
There are of course plenty of exceptions to this, but all have some comprimises somewhere.

Weight transfer can be an issue.
Most dedicated FWD drag cars lean the engine forward to get as much weight over the front wheels as possible, while dedicated track cars often try and lean it back to center the weight.
And most of the best handling FWD cars use rear suspension that is a lot stiffer than the front, the idea is to create slight oversteer that improves the cars turn in, and balances the FWD tendancy to understeer.
The Honda works racing team in Japan for example developed race suspension for the Type R Integras that was at least twice as hard at the back as it was at the front.


For a street car a properly designed FWD can be just as fast as an equivilant RWD, and like the RWD, has its own set of advantages.
There is less weight, and less power is lost trough the drive train. This means engines don't have to be as powerful, which allows for flatter more useable torque curves, or engines of equivilant power are able to use more of it to acclerate the car.
Same with brakes, less weight = more effective brakes.
Same with handling, generaly lighter weight cars will handle better, just ask a Lotus Elise owner.

front wheel drive cars understeer coming out of corners. that is bad cause you cant punch it out of a corner.

rwd cars will tend to oversteer out of a corner which is usually a good thing if you know how to drive cause it will get your car facing the direction you want it to be faster.

mid engine cars are superior to both because you have close to equal weight on all wheels so that you can take corners faster and have maximum contact with the road. this also helps with braking and the weight of teh engine and all the crap that goes with it is similar to a fwd car and so are the drivetrain losses.

Many newer FWD cars have equal-length half-shafts (you'd think that two "halves" would be equal, but apparently not). This helps reduce torque steer problems and has helped raise the threshold for maximum hp in a FWD car. Before the spread of equal-length half-shafts, the theoretical maximum was 225-250hp for a FWD car.

The amount of power a FWD is capable of handling depends largely on the weight of the vehicle, whether or not the half-shafts are equal length, and the geometry of the suspension. It is typically believed that anything above 300hp is impractical in a FWD car (note that Cadillac doesn't offer a FWD model with more than 300hp net SAE).

thanks for the replies.

With the disadvantages the FWD vehicle has with traction how would it perform in braking/cornering/acceleration compared to a mid-engine car that weights more(ie 2000lb crx to 2350lb mr2) and considering all other things such as tires, brakes, and engine power are all equal.
I'm just trying to get an idea on just how much these disadvantages affect a fwd.

well my 2001 Cavalier Z24 is FWD with an I4 making 150HP stock. I think the car is a blast to drive, accleration is very quick, and i only get slipping if i just all out punch it from the line, but give like 3/4 throttle then punch it and its fine. Cornering i find it to do very well on, its holds tightly to the corners even at high speeds. I reall like the fwd car cause i live in michigan, so in the winter time, driving on slick, snowy, icy roads is an everyday thing. And with fwd it makes it just so simple to control the car, you dont have to worry about you back end coming lose. But sometimes it can be annoying, like today it was raining and made it really easy to break the tires lose. But most fwd cars have traction systems that make it so if the tires start spinning really badly, like they were today, it cuts fuel to the engine like a rev limiter for a split second so that traction can be regained. And usually this only turns on while your in a turn. The comp assumes your spinning cause the wheels are spinning and turned so in order to help control the car it reduces the HP of the car, like you would do if you were spinning.

i dunno... i think each to their own...

it's hard to make generalisations about how cars handle cause it is largely down to how they are driven...
i love getting the tail out in a RWD, balandce is all good etc. but similarly i love ripping on the handbrake of a SHORT wheelbase FWD and sliding round corners.. htere's no way i want to try that in my turbo MR2...

I never really understood the torque steer thing... thanx Moppie, aparently not all new FWD cars have it sorted though cause i have a mate with an Integra type R (current) and it swaps lanes all by itself!

Theres more than just the drive to a car as well, for example the CRX MR2 comparison... i honestly don't know how i'd go against a CRX (specially the old one) but i'd leave my g/f's FTO for dead... I don't think FWD suits heavy or long wheelbase cars... RWD is well suited to these (passenger sedan type) vehicles because the longer wheelbase makes for a more predictable drift... while it accentuates understeer in a FWD.

Weight is a good one... in the early 90's the rally scene was recovering from the loss of the Group B. the Japanese companies came out with cars like the Lancer GSR, Subaru WRX, Pulsar GTiR, Celica GT4 and the 323 GT-R. everyone should know some of them if not all. The GT4 is the most obvious... Toyota got a ban for cheating air restrictors... more weight meant they needed more power. more interestingly... only the WRX and the GSR went on to have substancial success... both the 323 and the sr20 powered GTiR had problems with understeer, they were deemed to be "front heavy". if you want to get the nose in then get the weight out of it...

i have concerns for anyone who needs the car to drive itself at high speeds...

mid engine cars are superior to both ...

Words of wisdom! Think centralization of mass.

For the sake of arguement, what is the preferred drive (ie. which wheels) layout of F1, NASCAR, Drifters, or even anyone who tows a boat. Why are they all the same?

FWD has come a long way, I would question anyone who thinks a mini is not a great handling, efficient car. It still cannot equal the inherant benefits of a mid engine car (my opinion).

centralisation of mass is pretty obsolete when all BMW's have 50/50 weight balance with a FR setup... part of their design philosophy

as i said... depends how you drive and what you want... i drive an MR2 (mid engined) but it wouldn't suit rally or drift... (could be done but FF and AWD are better for rally and FR is way better for drift...) you really need to work out what sort of driver you are and what sort of driving you like doing before you can work out which is best...

you're right rear drive is better for those forms of racing cause of better ability to get power to the ground... besides... can you see an f1 car with the big wheels on the front???