Benefit of Haldex when already moving

[s3_trev]

Hey guys,

So basically was having this conversation with a group of my friends the other day. Some have the Leon Cupra (the 265bhp version) and we were discussing how the S3 has the haldex 4 wheel drive and the Leon doesn't.

Obviously the haldex will assist with launch off the line (especially in slippery conditions etc) but once the car is up and going and traction has been obtained, does the haldex system then actually go against the S3 in terms of performance? Is there increased transmission power loss and from the 'gubbins' of the haldex system and the extra weight also?

If you had an S3 and a Cupra both with the same power and you done a drag strip race for example...Drivers being equal, would an observer expect to see the S3 get the upper hand on launch, and then be slowly over taken by the lighter Cupra?

All input very welcome!

 

[Flexiblemouse]

As far as I understand it, if the front wheels are spinning then the quattro is active. If the front wheels have traction then the quattro is only weighing you down. In the race you describe you are correct, the S3 would launch better but the Cupra would reel it in because it has a better power to weight ratio. The size of the initial lead enjoyed by the S3 will depend on the ability of the Cupra driver.

 

[mjr901]

^^ + 1. Thats how it is.

And yes, the Cupra or an Ed30 will eventually walk by, but you'd need a fair stretch of road.

9/10 you wont have that much room to play neither.

 

[smurfworth]

But then again, how many drag strips do you get on a B road?

The amount of times I've 4 wheel drifted around certain bends you'd never make up for the understeer in a fwd.

However on a drag strip, transmission loss would only occur when the power loss was sent to the rear wheels, which as you say would be on launch, then when grip is obtained the haldex would disengage giving minimal transmission loss.

Personally I don't see an ed38/cupra going past due to the ground the s3 would have made during the 2/3 seconds the other cars would spend spinning the wheels, loosing vital power and distance and bearing in mind over 100mph is where power comes into play instead of weight.

 

[s3_trev]

Thanks for the replies guys. Pretty much what I was thinking myself.

And obviously we were only discussing performance here, cant think of an another area where the Cupra even comes close to the S3 to be honest, unless maybe cheaper to buy of course.

 

[screechmr2]

a group test, these cars aren't standard but you'll see while the audi does have a slight power advantage none of them can reel it in even after the haldex has done it's job of launching it http://www.evo.co.uk/ford/focus-st/...-v-vw-golf-gti-v-audi-s3-v-vauxhall-astra-vxr the cupra would need speeds to be well above 100 before it could catch the s3 due to minimal loss from the hadlex meaning the weight difference is the only real advantage the cupra would have

 

[nluk100]

I had a stg2+ ed 30 and it just couldn't put the power down. The TC would kick in in 3rd gear on a straight road in the dry!

 

[s3_trev]

Interesting thanks for input gents!

 

[Sayam]

I had a stg2+ ed 30 and it just couldn't put the power down. The TC would kick in in 3rd gear on a straight road in the dry!

I can second this based on experience of my friends ED30. It only had a stage 1 map but was truly awful.