eliot

I have just been told that if a Power Engineering sports cat exhaust system and the speed limiter are removed then a standard MY01 WRX can hit 170mph (possibly a chip upgrade was mentioned).

Firstly, i did not know that the cars had an engine limiter and a speed limiter - can anyone clarify this for me

Secondly, is a rolling road projection realistic as it does not take into account the drag at that speed in a big chunky saloon like the WRX?

Finally, is someone pulling my plonker and if not, can anyone prove that on the road their Scoob can hit 170mph and stay on the road!!

thanks for any info

eliot

Beemer_Deano

I would, but my speedo only goes up to 160.

Sorry,

Deano

LG John

Unlikely!! Would need big power and maybe different gearing (someone will know the gearing for sure)

polarbearit

Standard gearing is good enough isn't it? I suspect that given enough power (circa 300-340??) and distance a MY01 should hit 170mph.

Richard Askew

...and cue ChristianR's piccie of his STi going ridiculosy fast

I had my wagon off the clock (160) in Belgium

LG John

Well my car an MY99 classic could probably get to about 7k rpm before the limiter would end the fun so 7x24mph (24mph per 1000rpm) = 168mph.

So, technically if I get a long enough road, enough power and some big old ***** I could hit 168-70mph

polarbearit

And doesn't the MY01 have slightly longer gearing (about 26mph/1000revs?)

Type_RA

Too much drag, scoob is shaped like a brick and 4wd losses. 160 maybe with 300+bhp and the right gearing (and a following wind). Mike Rainbirds 2wd cossie had 540bhp and "just" touched 180mph. So IMHO reckon a 250bhp WRX is unlikely to hit 170mph dont you ?

polarbearit

Yep, but it really does depend on the road etc, a friend of mine had a standard MY99 with PPP ecu (and standard exhaust) over 160mph on a GPS (too fast for me ) he was on a slight downhill at the time but I won't say on which road, lets just say it was very scary!

daz b

As above, aerodymanics play a big part as the speeds get crazy.good cars 911 etc

Barnaby

Right, you are going to hate me for this, but I shall give it a shot anyway

As I remember from way back, power goes up with the cube of velocity.

So for a standard UK Scooby:

210bhp = a x 140mph^3

Where 'a' is some constant and the '^' means raise to the power.

This solves for a = 0.0000765

Now if you feed in 170mph:

? = 0.0000765 x 170mph^3

Which solves to give 376bhp, which sounds about right. I might have got the first speed a bit low, hence the power calculated is a bit high. And this ignores all sorts of other things like mechanical losses. If somebody can give me the exact power output and top speed of the car I shall have a go at working out power needed for 170mph.

Barnaby

Of course I could be talking complete bollocks, which wouldn't be the first time

daz b

Does that take into account aerody?

Barnaby

I think it does. The aerodynamics stays the same but the drag goes up. Hence the CD value you see quoted all the time.

Just checked it on the web and it looks like it might even be right

Type_RA

The question was asked about a slightly modded WRX MY01 not something with in excess of 375bhp I dont call an extra 160bhp slight .

MY01 WRX is 215bhp and does 143mph according to EVO magazine

daz b

so i think the answer to question is no,pity i would love 170mph for my00 ppp !!!!!

Barnaby

Your figures for the WRX would give:

301bhp gets 160mph

361bhp gets 170mph

daz b

I suppose the real thing is acceleration not top speed

Paul N P

STI7 UK with PE T75 full system hits 155mph speed limiter @ 6200rpm with 160mph showing on speedo. I guess with the speed limiter removed and on the rev limiter should be good for 170mph (indicated) easy!

Pretty p!ssed off the find there was a speed limiter in the first place, I was trying to keep up with a Viper on the way to Le Mans this year.

TonyBurns

iTrader: (3)

Ive had 167mph out of my MY00 PPP (with scoobymania downpipe )
Didnt stay there long though and the redline was close

Tony

PS it was a private test track that i submit to every year

LG John

My scooby will hit 180mph no bothers.....when I'm getting towed by a derestricted RS4

john banks

The standard car and the PPP have a boost limiter to slow you between 137 and 147 mph. So you won't get over 5900 RPM in top gear in a UK car unless going down a very steep hill. If removed and you modify the car you can go to at least 6500 RPM in top gear (162 mph) - this is with a big turbo running 1.2 bar at that point - with a TD04L you will only have about 0.9 bar tops at that point, and lots more heat and backpressure and I don't believe it is possible to do it on a standard turbo.

LG John

John has your trickery removed this limiter in my car??? Not that I particularly want to go at 150mph+

[hijack]Incidently, the decat centre section is in and the dawes unadjusted but boost is now normally 1.25 bar (up from 1.21). However, after a roasting today (in hot weather mind) she crept up to 1.3 (no det sounds though) I figured the turbo was trying to tell me something and backed off to let it all cool down, do you think I should crank back the dawes another half turn?[/hijack]

Pavlo

speed is a function of power, as mentioned.

Frontal area of a scoob = 2.04 square metres (I believe)

CD of classic scoob, without fancy splitters, lips and spoilers is 0.33 (0.35 for p1 with spoiler and splitter)

Force = 0.5 * density * cd * area * velocity^2

170mph = 76.02metres per second

standard density of air is 1.024kg per cubic metre

force = 1991.91 Newtons

Power is work done per unit of time

Work is force * distance

Distance is 76.02metres

power = 151425 watts at the wheels
power = 151.425kw @ wheels
power = 202.98 hp at the wheels

Drive losses at 170mph are going to be higher than the 115mph (or so) you see on a rolling road power run, typically 90hp @ 115mph

So 330hp would seem like a sensible estimate of the power required to reach 170mph, that also means you need to have that power at the revs you would be doing at 170mph, hich is about 7000rpm.

Most cars tend to drop power after 6500.

Paul

P20SPD

iTrader: (1)

Tims i think is 346bhp and that was not measured by his speedo, but onthe drag strip at elvington.

babber

On a private road I had 150 MPH @ 6000 and was surprised how quickly I got there, but have a few mods

Ditto Saxoboy

Cheers Phill C

Diablo

to answer the original question, yes it is bollox :P

Without serious mods and big power no way 170 mph in a 01 WRX

R19KET

Tim.W certainly got a MEASURED 166mph at Elvington, and another guy got 163 (iirc).

These cars either have, or would get circa 345bhp at PE.

Both these cars are running stock internals, but are quite heavily modified.

Mark.

RichardPON

And what's the difference in a scoob between indicated speed, and true speed.

I should think an indicated 160mph, is not far over 150......