comparing rwkw to kw at all 4 wheels

blueoval · 18-10-2012, 06:38 PM

I hear a lot of people talk about power at all 4 wheels with AWD cars, then on the other hand I hear the RWD lads chime in about how my rwkw they have in their cars etc and how superior that power is.

One thing I'd like to know theoretically speaking is how does a car with 200kw at AFW compares to a 200rwkw RWD vehicle, assuming both vehicles weigh the same and got the same traction off the line?

Is it considered the same kind of power? Which car is more powerful/quicker? The one with power to AFW (all four wheels) or the RWD car? Is it purely a traction thing?

Please keep this thread civil.

Sprint · 18-10-2012, 06:45 PM

4wd better for corners
2wd better for speed

irish2 · 18-10-2012, 07:27 PM

It is simply used as a tuning tool. You don't often tune an engine and pull it out and whack it on an engine dyno to get fly wheel kilowatts (fwkw). It is simply saying at the wheels a car makes X amount of power on a given day, on a given dyno.

In the above instance the AWD vehicle would be producing slightly more fwkw due to the fact there is more drive line losses in an AWD vehicle. If they both weighed the same, had the same gearing, and the same torque curve, whilst losing no traction, then in theory they would be capable of the same acceleration.

blueoval · 18-10-2012, 07:34 PM

hmm interesting. So in essence, would the AWD car need to make more power at the fly to even be competitive against the RWD car and still have the same output?

StockieXR6T · 18-10-2012, 08:35 PM

More wheels driven means more drive train frictional loss. So in theory you are correct.

irish2 · 18-10-2012, 09:12 PM

Quote:

Originally Posted by blueoval

hmm interesting. So in essence, would the AWD car need to make more power at the fly to even be competitive against the RWD car and still have the same output?

Up to a point. Then you get to levels where the RWD car can't make use of the power until it has some speed on board (wheel spin). On the other hand AWD can be very hard to launch properly, to make use of the extra grip without bogging down or snapping something.

Nic85 · 18-10-2012, 09:13 PM

My Evo made 190kW at all 4 wheels (at one point in time), and on a roll on was exactly the same speed as a BF2 Typhoon (not sure on their kW at the rear wheels, maybe like 230kW?) Does this help?

irish2 · 18-10-2012, 09:21 PM

Quote:

Originally Posted by Nic85

My Evo made 190kW at all 4 wheels (at one point in time), and on a roll on was exactly the same speed as a BF2 Typhoon (not sure on their kW at the rear wheels, maybe like 230kW?) Does this help?

Yes but the Evo is significantly lighter. I think he is simply talking theory.

The Evo was probably also losing another 20 odd kw through the extra driven wheels as well. Meaning it probably had similar peak output at the flywheel, to the Typhoon.

blueoval · 18-10-2012, 10:05 PM

Cheers guys. That explanation sounds logical.

Another hypothetical. Could a awd car that weighed 200kg less with 200kw at all 4 wheels keep up with a rwd that had 250rwkw?

Nic85 · 18-10-2012, 10:08 PM

Maybe not 200kg less, but it will get you off the line for sure.

What cars are you talking about?

zilo · 18-10-2012, 10:24 PM

Quote:

Originally Posted by blueoval

Cheers guys. That explanation sounds logical.

Another hypothetical. Could a awd car that weighed 200kg less with 200kw at all 4 wheels keep up with a rwd that had 250rwkw?

divide the mass by the kw at the wheels and all things being equal the more power per kilogram the faster the car.

Think motorbike versus kenworth truck.

blueoval · 18-10-2012, 10:29 PM

Wrx vs xr6t?

Just thinking about how weight, driveline and power have an effect on speed comparisons.

XR6Runner · 18-10-2012, 10:36 PM

Quote:

Originally Posted by blueoval

Cheers guys. That explanation sounds logical.

Another hypothetical. Could a awd car that weighed 200kg less with 200kw at all 4 wheels keep up with a rwd that had 250rwkw?

Off the line if you know how to properly launch an AWD, then it would destroy the 250kw RWD. But roll start, it would be hard to tell, unless you have a PHD in physics, otherwise only way to tell is to actually test it out on the drag strip.

BaraFGXR6 · 18-10-2012, 10:44 PM

All things equal, tires, weight, power etc..

As long as the gearbox can take the launch, i see the AWD vehicle beating the RWD everytime in terms of how quick it can get off the line in a stop/start scenario.

zilo · 18-10-2012, 10:48 PM

And when you get to a corner and both lose traction the only difference between the two is the AWD would see the tree coming and the RWd wouldn't know what hit it.

Both would still get the tree though...

Nic85 · 18-10-2012, 10:53 PM

Being a WRX he will destroy his gearbox on the launch anyway, so you will win by default.

Rodge · 19-10-2012, 09:41 AM

I've been looking into exactly the sort of issue this thread is aimed at.

My research indicates that typically a car like a WRX or Evo loses 28% of power through driveline losses and a RWD car like a XR6T typically loses about 20% through driveline losses.

In my personal experience I completly wasted a stock WRX in my stock 270 kw BF2 Typhoon, it wasn't even a contest, doubt the result would be much different in an XR6T.

lockieoc · 19-10-2012, 09:48 AM

You would hope so Rodge considering a WRX only has 170kw

302 XC · 19-10-2012, 10:54 AM

Quote:

Originally Posted by Rodge

In my personal experience I completly wasted a stock WRX in my stock 270 kw BF2 Typhoon, it wasn't even a contest, doubt the result would be much different in an XR6T.

Bit hard to judge on a once of time ....
My lil bros 2 L corona used to eat 5 L V8 commos for breaky of the mark
Even has time slips to prove his backing,so it wasnt a one of

The main issue is with most rear drive cars they are single pegger diffs
Two identical powered cars,one an all wheel drive one a single pegger, the all whell drive will be long gone while the single pegger is trying to hook up
Too many differences in driver styles, tyre types,pressure to do a fair comparison on the street

blueoval · 19-10-2012, 11:22 AM

I think my main query is when people sprout off that their AWD turbo powered cars are getting say 200kw at all 4, (which to most of the xr6t boys is less than stock) and yet are pulling some impressive 1/4 miles. Is it due to the weight advantage, traction etc? Is it worth bragging about?

MAGPIE · 19-10-2012, 03:10 PM

Quote:

Originally Posted by Rodge

In my personal experience I completly wasted a stock WRX in my stock 270 kw BF2 Typhoon, it wasn't even a contest, doubt the result would be much different in an XR6T.

You wasted a $45k WRX with a $70k+ F6

Did you waste it in the corners too

Come on Rodge you sound like a school kid with a statement like that

Psi-Pop · 19-10-2012, 03:24 PM

If it has the same power and the same weight it will accelerate at the same speed, of course if all things are equal.

Remember that hp/kw is a ability of performing work. Essentially how much weight can be moved, so if the weights the same and it accelerates at the same rate you can say they make the same power. That's a pretty simple version though.

302 XC · 19-10-2012, 03:27 PM

Quote:

Originally Posted by blueoval

I think my main query is when people sprout off that their AWD turbo powered cars are getting say 200kw at all 4, (which to most of the xr6t boys is less than stock) and yet are pulling some impressive 1/4 miles. Is it due to the weight advantage, traction etc? Is it worth bragging about?

Too many factors between power at the wheels and 1/4 mile times
Weight advantage/disadvantage and traction make a huge difference
My altho small example above,proves massive power in a car with minimal traction doesnt cut the mustard in heads up action

Sioso · 19-10-2012, 03:28 PM

I have had 3 WRX's - '94, '01, '06, the '94 and '06 were both making around 180kw @ AFW with some basic mods and the '01 was making just over 200kw @ AFW with usual mods + aftermarket turbo and front mount intercooler.

While those figures don't sound real high they were all quick cars.
The '01 was a seriously quick car and I'm comparing this to a number of tuned turbo fords and modified LS1's.

Again, 200awkw doesn't sound like much but is nothing to sneeze at in a WRX or EVO.

Deaks · 19-10-2012, 04:47 PM

I have had a 94 Subaru Legacy GT Wagon with 210kws atws and an 03 XR6T sedan with 290kws atws, all things not being equal, the Subaru would flog the XR6T, until about 120-130kph, then the turbo Ford would get into its stride and disappear really quick.

Power delivery is a very important factor that always seem to get overlooked. The Subaru was explosive out of the hole, where as the XR6T was an animal up top. The XR6T was the easier to drive everyday, but the Subaru certainly shocked a few people.

blueoval · 19-10-2012, 05:16 PM

Quote:

Originally Posted by Deaks

I have had a 94 Subaru Legacy GT Wagon with 210kws atws and an 03 XR6T sedan with 290kws atws, all things not being equal, the Subaru would flog the XR6T, until about 120-130kph, then the turbo Ford would get into its stride and disappear really quick.

Power delivery is a very important factor that always seem to get overlooked. The Subaru was explosive out of the hole, where as the XR6T was an animal up top. The XR6T was the easier to drive everyday, but the Subaru certainly shocked a few people.

To me, the punchy power delivery to 120kph is what I consider usable for the street. Your Legacy GT sounded like a killer combo. If I was dragging a car at the local track, then yeah a 6T would be my choice also.

MITCHAY · 19-10-2012, 06:17 PM

All things being equal you would think performance would be close to equal. Anyways 200awkw is quick enough in a WRX and plenty have done 12s quarters with that power especially the GC8 model.

blueoval · 19-10-2012, 06:35 PM

Quote:

Originally Posted by MITCHAY

All things being equal you would think performance would be close to equal. Anyways 200awkw is quick enough in a WRX and plenty have done 12s quarters with that power especially the GC8 model.

I had a mate with a 98 WRX with 150awkw and that felt pretty dam spritely to 100. I was quite impressed. Doesnt sound like a lot does it.

Nic85 · 19-10-2012, 09:43 PM

Quote:

Originally Posted by blueoval

I think my main query is when people sprout off that their AWD turbo powered cars are getting say 200kw at all 4, (which to most of the xr6t boys is less than stock) and yet are pulling some impressive 1/4 miles. Is it due to the weight advantage, traction etc? Is it worth bragging about?

200kW at all 4 wheels on a WRX/Evo *should* run mid 12's at around 108MPH and run to 100km/h in around 4.5s.

My Evo with 190kW at all 4 wheels ran 13.1 @ 107MPH. I rebuilt it to 260kW at all 4 wheels a while later and while I didn't get a quarter mile time, it's 80-120km/h time was 2 seconds flat and I timed 0-100km/h in 3.5s on a G-Tech timer. It was brutal as hell.

blueoval · 19-10-2012, 10:42 PM

Quote:

Originally Posted by Nic85

200kW at all 4 wheels on a WRX/Evo *should* run mid 12's at around 108MPH and run to 100km/h in around 4.5s.

My Evo with 190kW at all 4 wheels ran 13.1 @ 107MPH. I rebuilt it to 260kW at all 4 wheels a while later and while I didn't get a quarter mile time, it's 80-120km/h time was 2 seconds flat and I timed 0-100km/h in 3.5s on a G-Tech timer. It was brutal as hell.

Thats impressive. Wonder kind of power you'd need from a falcon to get those kind 0-100 times???

Getting a smaller bodied car like that 0-100 in say under 5 seconds is pretty quick in my eyes.