Sports cars: RWD or 4WD?
Discussion
If one was to design the ultimate racing sports car, would it be lightweight and RWD or a bit heavier/more powerfull and 4WD? I suppose it depends on the application, ie. track with lots of slow corners/fast open circuit. Also the 4WD car, although getting more traction out of corners would use more fuel and have to either carry more or refuel more often offsetting any advantage.
Though it would be the faster car on the track, specially if it was raining...
Though it would be the faster car on the track, specially if it was raining...
But don't most forms of motorsport actively discourage 4WD.
I seem to recall Audi turning up with 2 A4 quattros in the BTTC and whipping everyones arse.
Given no restrictions, surely it's faster to have all the wheels driven. Less fun, possibly, but faster.
If you have rules that limit power, then it becomes more interesting. 4WD means more drivetrain losses, more weight and ultimately a slower car for the power.
I seem to recall Audi turning up with 2 A4 quattros in the BTTC and whipping everyones arse.
Given no restrictions, surely it's faster to have all the wheels driven. Less fun, possibly, but faster.
If you have rules that limit power, then it becomes more interesting. 4WD means more drivetrain losses, more weight and ultimately a slower car for the power.
How about having a clutch between the front and rear diffs so you could get all the power through the rear wheels on the straight and so reduce the transmission losses? 
Ahem. The pioneers of 4wd cars for racing and rallying(AUDI) concluded that far from costing fuel, the 4wd system shows no greater loss than fwd or rwd.
Now i know im gonna get lambasted(i know what that means
) for this , but the proof is really quite simple to grasp.
Fuel consumption comparisons were done on Audis cars using the fwd, rwd,and 4wd system, the reason for no difference in fuel consumption was thus: Due to a fwd/rwd car only driving one set of its wheels, the drag from the other set (rolling resistance) helped contribute to the fuel consumption figure by raising it.
The 4wd system has ALL its wheels driving so it dosent have any "drag" from an unpowered set of wheels.
Everything else being equal, the fuel consumption figures were the same.
As for 4wd racing cars, Audis 90 Quattro IMSA racer blew the opposition into the weeds.
Pikes peak cars were also the fastest with 4wd.
As already mentioned the A4s of BTCC trounced ALL the others , even with a major ballast problem imposed on them.
Also the DTM Audis? 80 and V8s were all 4wd, again walked all over the rwd mercs/opels/beemers.
After having driven mostly fwd and rwd, i now find myself with 4wd, i wont be going back to 2 wheel drive...ever!
I reckon i could leave for dead even the fastet cerbs, chimaeras in the wet on the twisties round here, i can put all my power down mid corner, try that with a rwd and youll be takin a trip into the scenery.
Just my personal take on the comments already posted.
Now i know im gonna get lambasted(i know what that means
) for this , but the proof is really quite simple to grasp. Fuel consumption comparisons were done on Audis cars using the fwd, rwd,and 4wd system, the reason for no difference in fuel consumption was thus: Due to a fwd/rwd car only driving one set of its wheels, the drag from the other set (rolling resistance) helped contribute to the fuel consumption figure by raising it.
The 4wd system has ALL its wheels driving so it dosent have any "drag" from an unpowered set of wheels.
Everything else being equal, the fuel consumption figures were the same.
As for 4wd racing cars, Audis 90 Quattro IMSA racer blew the opposition into the weeds.
Pikes peak cars were also the fastest with 4wd.
As already mentioned the A4s of BTCC trounced ALL the others , even with a major ballast problem imposed on them.
Also the DTM Audis? 80 and V8s were all 4wd, again walked all over the rwd mercs/opels/beemers.
After having driven mostly fwd and rwd, i now find myself with 4wd, i wont be going back to 2 wheel drive...ever!
I reckon i could leave for dead even the fastet cerbs, chimaeras in the wet on the twisties round here, i can put all my power down mid corner, try that with a rwd and youll be takin a trip into the scenery.
Just my personal take on the comments already posted.
Racing cars are built to match the formula. Most formulae disallow 4wd. Track formulae that allow it (e.g. saloon cars) often impose weight penalties eg fwd lighter than rwd lighter than 4wd.
In the real (road)world 4wd will almost always be quicker than 2wd (and probably fwd is quicker than rwd down a tisty wet B road, but is often less entertaining or involving. IMHO our cars are so fast now that being able to go even faster in this nanny state is likely to make nanny very angry... and we wouldn't want that would we?
In the real (road)world 4wd will almost always be quicker than 2wd (and probably fwd is quicker than rwd down a tisty wet B road, but is often less entertaining or involving. IMHO our cars are so fast now that being able to go even faster in this nanny state is likely to make nanny very angry... and we wouldn't want that would we?
trackdemon said: I think you can count the number of successful 4wd track racing cars on the fingers of one foot. There may be a clue in that...
>> Edited by trackdemon on Monday 10th February 09:52
Audi A4 in the DTC a couple of years ago i belive they creamed the opposition mainly due to a lot of wet races ? , but 4wd is kind of a limited advantage due to the added weight
nefarious said: No successful 4wd track racers?
[cough] Skyline [cough]
Actually, I think most of the Skylines in the Jap series were RWD. Damn rules, you see.....
It's the same reason that the racing Supras have the 6 cylinder 3 litre twin turbo lump pulled out, and the 3S-GTE from the GT4/MR2-GTS dropped in. They're limited to about 450bhp, and the 2 litre engine is smaller, lighter and lower.....
Most racing series have minimun weights, most race cars run ballast to get upto those weights, if the minimums were removed the 2wd cars would be lighter, so a higher minimum weight for 4wd is representative... rwd also used to be penalised in BTCC, and still is, if not to the same extent as 4wd...
For out and out Sportscars like 917's 4wd does also present a packaging issue... you have to fit in a lot of extra hardware...
For out and out Sportscars like 917's 4wd does also present a packaging issue... you have to fit in a lot of extra hardware...
v8guinness said: For out and out Sportscars like 917's 4wd does also present a packaging issue... you have to fit in a lot of extra hardware...
Yes thats true - I seem to remember the driver's feet would be in the way of any front driveshafts. I'm sure there'd be a way round it though - electric motors in the front wheel hubs?
Maybe you could scrap the original transmission and attach the engine to a BIG generator to drive all 4 wheels? Not so good for unsprung weight though... The RS200 is what I was thinking of - maybe with an even more powerful engine and a low drag sportscar profile.
AJLintern said: How about having a clutch between the front and rear diffs so you could get all the power through the rear wheels on the straight and so reduce the transmission losses?
The Haldex unit as fitted to Audi A3/S3 and TT is exactly that. Oh, except that the front wheels are normally driven and the rear wheels only get power if wheel slip is sensed. Could try driving in reverse
. Mike
Actually, I think most of the Skylines in the Jap series were RWD. Damn rules, you see.....
It was the 4wd version in aussie racing though, wasn't it? Those cars cleaned up until they changed the rules.
I saw the Quaife GT car (GT4S?) in CCC a few months ago, if it wasn't limited but regs in so many of the GT series I reckon that would be getting quite close to a really all-time great sportscar.
regards the JGTC cars skyline/supra/nsx etc) I read somewhere that turbo cars are limited to 2 litres, and that's why the supras use the small lump, and why they don't leave the 3.2l normally aspirated NSX for dead down the straights..
as it happens, the NSX seems to be the best of the bunch in that series, from what I've seen. (although that isn't as much as I'd like.. it's an excellent series but no decent TV coverage)
as it happens, the NSX seems to be the best of the bunch in that series, from what I've seen. (although that isn't as much as I'd like.. it's an excellent series but no decent TV coverage)
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