Quote from bavor :

Where do people get these strange ideas? Have they not driven FWD cars before or do they read somethign that someone wrote 30 years ago based on false assumptions and assume it to be true today?

There are plenty of production FWD cars that have been available over the past 15 years with 250-300 HP. There are a lot of daily driven, modified FWD cars that have more than that. Even back in the 1960's Oldsmobile had a 425 cubic inch displacement(7.0 liter) FWD V8 car with 385 bhp (287 kW) and 475 ft·lbf (644 N·m) of torque.

God forbid you ever tried to turn that thing at speed....wow what a nightmare. But then again it is / was a 60's-90's American car. Not meant for the twisty bits back then.

And those numbers are kind of skewed, the Nm was to the crank, I believe it actually lost a considerable amount by the time it got to the wheels.

Quote from bavor :

One of the high horsepower FWD cars I helped build won 1st place in Car & Driver's superfour challenge and about the same lap times as a forced induction lotus elise.
http://www.caranddriver.com/ar ... d=10165&page_number=8

It took first in the FW class, they never did an overall winner between FW & AWD/RW IIRC.

The ridiculously overpriced HKS EVO took first in the AWD /RW segment.

http://www.caranddriver.com/ar ... =10165&page_number=16

Preface:

Sure some of the times on the road course can come down to the driver (IIRC they weren't driven by the same person around the track, each one was driven by somebody from that company / team), but surely that car should have been able to make up some of the difference by sheer brute force. It wasn't even .50 a second within reach of the best time of the Audi, and > 1 second off the times of the Hondata Lotus.

The SRT-4 had blistering straight line speeds, but pretty slow on the road course considering the weight, power and torque numbers IMO.

Power (mfr's claim): 452 bhp @ 5500 rpm
Torque (mfr's claim): 476 lb-ft @ 4000 rpm
Curb weight: 2934 lb

Road-course time, sec
60.25
54.60
DNF
51.95
52.45

Best in class FW road course was the Mini;

Power (mfr's claim): 265 bhp @ 7200 rpm
Torque (mfr's claim): 225 lb-ft @ 6600 rpm
Curb weight: 2634 lb

Road-course time, sec
52.60
51.80
51.15
51.70
51.55

Nearly 1/2 the HP and well under 1/2 the torque and at its best still ~.80" faster than the SRT-4. Sure it's 300lbs lighter, but again, 1/2 the total grunt numbers of the Dodge.

For comparison from the other classes:

The Hondata Lotus (RW);

Power (mfr's claim): 320 bhp @ 8500 rpm
Torque (mfr's claim): 220 lb-ft @ 7200 rpm
Curb weight: 1935 lb

Road-course time, sec
49.95
50.65
48.65
50.20
50.75

And the thoroughly disappointing, heavier and last place in class, A4 (AWD);

Power (mfr's claim): 340 bhp @ 6100 rpm
Torque (mfr's claim): 332 lb-ft @ 4100 rpm
Curb weight: 3581 lb

Road-course time, sec
52.60
52.25
51.80
51.50
51.25

I would have liked to see them get an independent driver for all the road course times because after all is said and done, those values really only serve to show AWD / RWD cars are easier at being driven around a track.

But still at the end of the day, you can put as much power in a FW car as you can any AWD or RW car, problem is using that power on, in or around corners is lost. FW tuners are getting better at curing that, but there's only so far it can go before ol' Mr. Physics rears his head again and shows that fundamental flaw w/ FW cars.

Quote from skiingman :

Also, I do believe they were using either a locked center or locked front diff.

It would not have been a locked front diff, you cannot run a locked diff on on any car that has to go around corners on a fixed surface, this is a common misconception in the LFS community, most likely caused because LFS allows you to set the car up with locked diffs, which is totally inaccurate.

Quote from Gentlefoot :

In most caes, only cars with power to the rear wheels can produce 'power oversteer'. However, even front wheel drive cars can experience power oversteer with certain setups and a diff under some circumstances.

Mind describing some of those circumstances?

Quote from ajp71 :

It would not have been a locked front diff, you cannot run a locked diff on on any car that has to go around corners on a fixed surface, this is a common misconception in the LFS community, most likely caused because LFS allows you to set the car up with locked diffs, which is totally inaccurate.

how often do we have to tell you that this is utter nonsense ?

You can run a locked front diff on FW cars, it just handles like total sh**e.

It will cause a sizeable change in steering; damn near impossible to turn in under braking and it produces higher understeer because of it, but does allow all the power to be put down on exit better.

so why can't you correct for the understeer with a bigger rear roll bar, damper tuning, or any of the other usual options...?

The outside front tire is more heavily loaded under braking in this situation, so it will always pull you out. When you are able to turn in and get to the entry of the corner you're going to have an outside front tire that is; trying to steer, and put power down equal to its inside and much lighter brother and in doing so, voila, added understeer. You compound that with the natural tendencies of FWD cars to understeer and fun times ensue! It shifts the whole balance of the car to push out even more.

It's inherent nature on a locked front diff which is why people tend to stay away from locking front diffs on anything but off road vehicles.

You can offset it to a degree with car setup, but it's still prominent.

Quote from ajp71 :

It would not have been a locked front diff, you cannot run a locked diff on on any car that has to go around corners on a fixed surface, this is a common misconception in the LFS community, most likely caused because LFS allows you to set the car up with locked diffs, which is totally inaccurate.

Wrong! Oval Racers run locked diffs but with larger rolling radius on the outside wheels.

Quote from Blowtus :

Mind describing some of those circumstances?

Sure. I have a MkII Golf. It is set up to lift off oversteer (big rear bar and appropriate spring rates). It has a Quaiffe ATB LSD. As the LSD begins to lock in a corner it allows the inside wheel to pull the front round the corner. This pulls the front towards the inside of the corner.

Now, in wet conditions the oversteering characteristics of the car are magnified. I would normally soften off the rear bar in these circumstances.

However, at Donnington in November I decided to have some fun and left the rear bar set to hard. I noticed power on oversteer coming out of Coppice. It occurred as the diff began to lock. Coppice is a fast right hander, slightly up hill with some helpful camber and opening up onto the straight. The power oversteer occurred under full throttle on the exit of this corner.

ok, but you're hardly initiating the rear wheels sliding with power. you're just getting a bit of extra bite from the front once the rear is hanging out...

This is power oversteer though mate - oversteer brought on by the application of throttle.

You don't have to be spinning the rear wheels for it to be power oversteer. You just need to be on the power and steering the rear of the car, as was the case coming out of Coppice.

seems we have a fairly different idea of power oversteer. obviously you could put some maccas trays under your fwd hatchback's rear wheels, get on the power, and call it power oversteer if you wanted, but that's hardly behaving like a rwd

I never have and never will say a FWD handles like a RWD. That is nonsense. They do handle differently but the difference is not to do with lift off or power oversteer, its to do with the forces these different configurations experience during transistional states.

Power oversteer is called such because it is oversteer caused by the application of power. Conversely, lift off oversteer is caused by lifting off.

Whether it is the rear wheels or front wheels spinning is compeletely irrelevant.

Just so we're clear:

Oversteer - the car turns more than the steering input
Understeer - the car turns less than the steering input

Power Oversteer - the car turns more than the steering input and the throttle is open.

Lift Off Oversteer - the car turns more than the steering input and the throttle is closed.

To my knowledge there is no such thing as 'rear wheel spinning oversteer', which I believe is what you are referring to.

you can play definition god all you like if you really want
to my mind, the forces involved in your fwd 'power oversteer' are very similar to the forces involved in lift off oversteer. weight shift is the sole contributor to the oversteer, whereas 'power oversteer' to me implies that power is the main contributor.

Quote from der_jackal :

You can run a locked front diff on FW cars, it just handles like total sh**e.

It will cause a sizeable change in steering; damn near impossible to turn in under braking and it produces higher understeer because of it, but does allow all the power to be put down on exit better.

Even if you were able to turn the car you'd find that with the torsional forces on the differential it would simply rip it apart. Running a car with a locked rear differential on an aesymetric oval car has about as much relevance as the fact they are used in drag racing, ice racing or off roading.

You can run a FWD car with a locked diff but (on fixed surfaces) you will not be able to go round corners under power, so whilst it may be possible to build a car that could cope with road loads and maybe racing loads it still defeats the point as it would be slower than a car with an LSD because it could not be driven hard enough.

Even running an LSD a racing Mini (UFR) made them extremely heavy to drive and fragile due to the huge forces. I remember hearing somewhere that in a Car & Car Conversions report of testing a selection of BTCC cars in the '70s the Mini with an LSD was heavier to drive than an unpower assisted big block Camaro (when they really did handle like a dog despite what some here may argue).

Quote :

I like to think of the locked diff as having 'zero slip'. By definition, a locked diff is rather poorly suited to normal roadgoing situations on 2WD cars because of the increased tyre wear created by both wheels being forced to rotate at the same speed. However, a locked differential can be put to very good use as the centre differential in a 4WD vehicle... as proven by umpteen rally wins around the globe by the legendary UR quattro and its three world championship titles to prove it. The rally quattros always ran with a locked centre differential because of the predictable handling on the limit - especially on mud, gravel and snow.

The biggest disadvantage of a locked differential is that the car always 'wants' to go in a straight line. This gives rise to severe tyre wear and bizarre handling on sealed surfaces - especially at low speeds when turning tight corners.

http://s2central.net/tranny_intro_p2.html

Locked diffs can be run at the centre of a 4WD system on fixed surfaces but are not ideal, this maybe where the confusion arose from, I have know idea whether the the 63 ran a locked centre diff.


Whilst I've heard enough shit about locked diffs being used IRL I've never actually heard of one example of a car running a permenantly locked diff (except in the centre of a 4WD system) on a fixed surface in any form of motorsport which involves turning both left and right, can anyone actually find an example?

I find you can adjust the driving style for a FWD car with a locked diff and make it frighteningly fast. True a proper set up differential would work best but it is the braking (coast) setting of a diff in a front driver which make it a bear if wrong- the car lifts the rear and woooop
spin.
the lockeddiff simplifies much of the racing, as the driven wheel now are very predictable the behavior is no longer variable. in LFS it certainly works for me.
Turn in later than usual and hammer down through the apex out and you will be cookin around the circuit.

in real life it seems that a locked front diff is madness- but i know of a few front drivers (outside of drag racing who do this)
the car in the attached pic runs a locked front diff- it does the FIA border series (a weak touring car series on the mexico/california border cities- mostly street races and some mexican cicuits)

Different drivers can get away with much, and rules can allow for FWD AWD and 4WD compete equally (WTCC alfas vs. BMW- the Alfas certainly do the right job quickly) Ford Mondeo any one BTCC? fast as any comer for sure.

^^ Do you know how he sets that car up? I guess a very heavy rear brake bias and turning it under braking, or even disengaging the power through the corners?

Quote from Blowtus :

if you think oversteer is what defines 'behaving like a rwd' then you lack an understanding of vehicle dynamics in general

I never said that. Thanks for putting words in my mouth.

Quote from der_jackal :

God forbid you ever tried to turn that thing at speed....wow what a nightmare. But then again it is / was a 60's-90's American car. Not meant for the twisty bits back then.
And those numbers are kind of skewed, the Nm was to the crank, I believe it actually lost a considerable amount by the time it got to the wheels.

However, there are still many peole that seem to think that high power FWD cars are undriveable.

Quote from der_jackal :

It took first in the FW class, they never did an overall winner between FW & AWD/RW IIRC.
The ridiculously overpriced HKS EVO took first in the AWD /RW segment.
http://www.caranddriver.com/ar ... =10165&page_number=16
Preface:
Sure some of the times on the road course can come down to the driver (IIRC they weren't driven by the same person around the track, each one was driven by somebody from that company / team),

Actually, msot of the cars, including the SRT-4 were driver by Larry Webster form Car & Driver.

Quote from der_jackal :

but surely that car should have been able to make up some of the difference by sheer brute force. It wasn't even .50 a second within reach of the best time of the Audi, and > 1 second off the times of the Hondata Lotus.
The SRT-4 had blistering straight line speeds, but pretty slow on the road course considering the weight, power and torque numbers IMO.

Actually, the car had no brakes. Well almost no brakes. Wilwood sent us the wrong brake pads and we didn't find out about it until the first run through the course. The pads were completely glazed over during the stop from the first part of the course, the acceleration run. Larry Webster from Car & Driver said the road course lap times in the car could easily be 5 seconds faster with properly functioning brakes. If you could see the magazine article with the comparison chart, you can see the car obviously had some brake problems.

Quote from der_jackal :

Best in class FW road course was the Mini;
Nearly 1/2 the HP and well under 1/2 the torque and at its best still ~.80" faster than the SRT-4. Sure it's 300lbs lighter, but again, 1/2 the total grunt numbers of the Dodge.
And it also had functional brakes.
For comparison from the other classes:
....
Also look at the results for the Forcefed Lotus Elise. It ran about the same lap times as the SRT-4.
I would have liked to see them get an independent driver for all the road course times because after all is said and done, those values really only serve to show AWD / RWD cars are easier at being driven around a track.

Most of the cars were driven with the same driver. Larry Webster form Car & Driver.

Quote from der_jackal :

But still at the end of the day, you can put as much power in a FW car as you can any AWD or RW car, problem is using that power on, in or around corners is lost. FW tuners are getting better at curing that, but there's only so far it can go before ol' Mr. Physics rears his head again and shows that fundamental flaw w/ FW cars.

True, but FWD cars aren't the poor handling pigs that a lot of people think they are. They can handle quite well. In some racing classes, they run the same lap times as the RWD cars with similar power levels and weights.

Quote from bavor :

True, but FWD cars aren't the poor handling pigs that a lot of people think they are. They can handle quite well. In some racing classes, they run the same lap times as the RWD cars with similar power levels and weights.

Any properly production based car will have serious flaws in them and the chances are with relatively low amounts of power and limited fundamental re-designs of cars in club racing a FWD car can keep up with a RWD one, however, that doesn't mean to say that you'd ever think of making a FWD racing car when designing a car from scratch, and in an ideal world you wouldn't select a RWD car either. However much people bullshit about what config is best nothing will ever actually be able to beat an AWD with modern active diff technology in an unregulated formula.

Quote from bavor :

I never said that. Thanks for putting words in my mouth.

that's why I said 'if' - it sounded like you were probably lining up to tell me that fwd and rwd can be similar because they oversteer. Still interested in what you were actually meaning...

apples, oranges...

Quote from bavor :

True, but FWD cars aren't the poor handling pigs that a lot of people think they are. They can handle quite well. In some racing classes, they run the same lap times as the RWD cars with similar power levels and weights.

No they are not. Dodge ran the SRT-4 in the runoffs last year in SCCA and did a final place of 9th overall. There was over 100 entries I believe, all of them either being RWD or 4WD dodge being the only FWD allowed from what I understood. These included everything from porshe, viper, vette, caddy ect ect.

I have driven a camaro and trans-am, both late 90's models. They dont even compaire to what the SRT-4 has in handling. Power is quicker in them(due to the turbo14PSI in the srt-4) but the power levels are the same. 230HP factory, at the wheels. or brake horse =P ( it does have a 400 pound difference in weight, but it also has 70 less HP)


But I feel that racing, especally long races if for RWD, AWD eats tires, and FWD is trying to do too many things with the front wheels.