Handling behaviour of four wheel drive performance cars

[drivin_me_nuts]

Handling behaviour...

If you were to design a sporting car with four wheel drive and reasonable performance (for arguments sake say lets just say it was 600ps output). What would be the difference in handling behaviours between the following

Engine at the front

- drive mainly to the front, rear only when needed
- drive mainly to the back, front only when needed
- equal power distribution

Engine at the middle

- drive mainly to the front, rear only when needed
- drive mainly to the back, front only when needed
- equal power distribution

Engine at the rear

- drive mainly to the front, rear only when needed
- drive mainly to the back, front only when needed
- equal power distribution

In terms of overall driver feel and responsiveness and road holding abilities, which of those configurations is likely to give the 'best' solution for delivering the power to the road? And which would give the most drive 'involvement'? and which would have the most predictable behaviour?

I realise part of the answer might in part be subjective, but is there in essence a definitive performance configuration?

[chimera40]

Well firstly I would predict that all of these cars are about to undertake their first maneuver.

[AJI]

drivin_me_nuts said:

Handling behaviour...

If you were to design a sporting car with four wheel drive and reasonable performance (for arguments sake say lets just say it was 600ps output). What would be the difference in handling behaviours between the following

Engine at the front

- drive mainly to the front, rear only when needed - basic FWD layout, lots of power understeer with high amounts of torque. Handling very dependant on geo setup and brake bias etc.
- drive mainly to the back, front only when needed - General 'muscle' car layout, oversteer via throttle but again handling very dependant on geo setup and brake balance. (Engine weight at front again would cause an amount of understeer)
- equal power distribution - the fact that significant power goes to the front turns it more FWD handling rather than RWD handling. Usually the front understeers before the back oversteers...but again largely dependant on geo set up etc.

Engine at the middle

- drive mainly to the front, rear only when needed - less understeer on turn in but still understeer with power application. Usually more balanced in corners and braking. But again, largley depandant on geo setup and brake balance etc.
- drive mainly to the back, front only when needed - generic super car layout (R8, gallardo etc) - probably the best layout for getting A to B. Best of both worlds of balance of understeer and oversteer.
- equal power distribution - Again it comes back to the fact of power going through the steering wheels, front wheels can only be asked to do so much before they say "that's enough".

Engine at the rear

- drive mainly to the front, rear only when needed - Weight at the back with weight shift going rearwards would leave front wheels struggeling for traction. Cornering would depend largely on geo setup and brakes.
- drive mainly to the back, front only when needed - (Typical Porsche 4WD layout) Good off the line traction with weight transfer acting on driven wheels. Good rear traction when accelerating in corners, but lots of rear weight to consider when the front is gripping hard under braking. Geo set up again is very important.
- equal power distribution - Again, any large amount of power at the front wheels results in understeer if cornering and accelerating above a certain amount. Weight at back under braking is similar to previous.

In terms of overall driver feel and responsiveness and road holding abilities, which of those configurations is likely to give the 'best' solution for delivering the power to the road? And which would give the most drive 'involvement'? and which would have the most predictable behaviour?

I realise part of the answer might in part be subjective, but is there in essence a definitive performance configuration?

I have added text to your quote above.
My text is very basic overview.... and I'm sure others will have differing views.

Hard to define the terms 'driver involvement' and 'feel' as some of these terms mean very different things for different people.
I could say 'good driver involvement' meaning that the steeering gives plenty of feed back and my inputs on the wheel are very noticable to what the car does. OR I could say 'good driver involvement' meaning that the car is torque steering all over and I need to keep putting in lots of 'involvement' to get the car where I want it to go.

Best solution - again hard to define. For me anything that allows me to steer the car on the throttle as well as the steering wheel is something that gives me the best solution. But then a car with fancy computers giving maximum traction to each individual wheel might be a best solution for others.

All the above being said...a car can be made to handle in many different way depending on set ups. Hence why I mention geo set up in each one. There is also suspension, downforce/lift etc. etc. to consider....these vary a lot between each car type.

Edited by AJI on Saturday 6th February 20:42

[TooLateForAName]

Well, I've owned an SVX (3.3boxer at the front with basic power split 35/65 f/r) and a 964C4 (3.6 boxer at the back with power mainly at the rear but allowing I think 30% to go to the front).

The svx was more planted and predictable (easy to do controlled 4 wheel slides), whereas I span the porker when I hit a mudslick on a roundabout. I'm sure all the driving gods here would have been fine though.

I would say the svx was the more predictable and easier to drive fast. The porker was more involving but I put that down to stiffer suspension (I upgraded the standard boge stuff to a bilstein/H&R setup).

If the svx had been manual with a little more power...

[GravelBen]

The difference there is probably more down to the engine location than the 4wd torque split.