4WD power vs 2WD power

[Charcoal RS]

Guys,
This has always bugged me. If you have two cars that are similar weight etc, they have the same power at the wheels but one is 4wd and the other 2wd. My question is, which is faster on rolling starts, which negates the 4wd traction advantage

Cheers

[adam|RSLC|]

if they have the same power at the wheels and wiegh the same on the roll they will be side by side . However a 4wd car must make more power at the engine to help off set the power loss from the 4wd drive train . This also goes for auto vs manual , auto has higher drivetrain loss and must make more power to overcome this

adam

[subarursliberty]

I have found the RS to be good in drive train loss. Take an RS vs a VL. similar power and weight but the RS seems to pull away from say a second gear star. Obvi there are more things to consider.

[whitey]

Charcoal RS

Well this is interesting actually I use to have a 4wd Tx3 laser, and two of my friends had 2wd mazda familas. These cars have the same 1.6 L Turbo engine and we all had similar mods.

As we where mates we would of course race each other all the time and there was not much difference. I remember we had a race that started as we got onto the motorway from a 50 k zone and there was stuff all difference. It seems the 2wd advantage with rolling starts only really applies at lower speeds as at faster speeds the power taken to push the car through the air (drag force) is way more than the rolling friction

any way i am just rambling :?

[2l_milk]

yes

[evade]

The front wheel drive Liberty will only be quicker until a certain point in power where traction loss occurs.
Then the AWD takes over and is quicker all round.

Mine, although probably makes more power at the wheels when in front wheel mode, wheelspins evey gear, hence being a lot slower than when in AWD.

Manual to Auto power loss cant be justified, as I found out with mine a while back:
Had 251kw ATW in manual---12.6@114mph
Had 170kw ATW in auto------11.5@117mph
No engine changes, big KW drop ATW but also big increase in performance.

[leg46y]

Are you serious???
Thats a big difference!!!
So if you had put an auto box while at 251kw what would of happened?
would you have been quicker than the 11.5 at 170kw atw?

or am i getting this all wrong :oops:

[subarursliberty]

Ummm I think that is what happened. Exact same engine just a box change and that was the result. Evade will tell us if i'm wrong or right.

[Az]

Are you serious???
Thats a big difference!!!
So if you had put an auto box while at 251kw what would of happened?
would you have been quicker than the 11.5 at 170kw atw?

or am i getting this all wrong :oops:

what the???

are you asking if a 12.6 is quicker than a 11.5? :roll:

point is, you'll never be a dyno queen when you run an auto. :wink:

[paddo]

i dunno.. evades making 271atw with an auto now ;)
im pretty sure thats more than anyone else here

[Marty]

as has been said, mostly a weight thing... had a run or two with a FWD version similar to my car and it won, not by much but, without the extra awd gear adds to the weight

[leg46y]

O.K so there isa loss of power through the boxes, but the et is quicker because of gearchanges etc.

Or am i still way off :oops:

[TOMO]

You had over 250KW ATW with the manual and ran a 12.6@114mph is that correct Evade :?:
Not to be a smartass but were you granny shifting :D :D
Any way to keep on topic I would love to have 4WD and than a click of a button half track
engage RWD mode and fly of into the sunset :twisted: :P

[Al]

The tiny amount of geartrain drag of a 4wd car has bugger all to do with it, it's just the weight of the rear end and shafts that changes the performance. Please note that I am not talking about the difference between a manual trans and an auto trans modified for drag racing.

The real point is that dynos are for tuning a car's engine so that it performs on a racetrack, not for comparing rooster sizes.