kezwaldo

just wondering when u increase a imprezas bhp will it increase top speed i have owned 2 now and my first a 2000 turbo would push over 140 nicely on the right road (auto bahn or track of course ) i now own a 300bhp bug can i expect to be going towards off the clock ????????? id like to hear your thoughts and what top speeds u all have achieved and with what cars and bhp they had??

banny sti

iTrader: (68)

Seriously dude doing top speed runs is just asking for engine trouble in an Impreza, and my response will probably be the only serious one you will get ....

kezwaldo

i know stats say on paper they limit out at 155mph is this true to all wrx and sti models??? in my exp of owning over 50 cars they normally do a bit more than what the book says

kezwaldo

ok mate yeah i heard the intercooler doesnt take air after 100 is this also true ....... sorry but dont most people always wonder what there car can actually do.

banny sti

iTrader: (68)

My car is geared to do 200mph and given a long enough road probably has the power to do it but do I have ever want to find out... hell no

JGlanzaV

iTrader: (3)

Power has no bearing on the top speed, just gear ratios the only thing that the power will do is increase the speed that you get there.

Paulo P

iTrader: (42)

What a stupid statement! You can't throw a long ratio box at a car with say 200bhp and expect it to have the power to pull the same speed as a car with the same ratios and 400bhp You need the power to overcome the drag

kezwaldo

geeeeeezz im just asking some top end stats from people on here i had no idea it was dangerous to take a impreza over 100mph think ill get a limiter for mine on 110mph i wouldnt want it to go bang ...........looks like alot of civic type rs will be passing me LOL

hoff900

Put simply BHP = top speed. Torque = acceleration.

It's alot more complicated than this, however this is a good "nutshell"

scoobyricht

iTrader: (4)

6500 revs on a 5 speed wrx box will give you 174mph ish or 155ish on a sti ra box. 6speed is a similar ratio to a wrx 5th. Ud need a fair wack of power to get to 6500revs on a 5 speed and if you had the power to redline 5th gear then the lower gears would probably get shredded if used in anger. Aerodynamics play a major factor as speed goes up and the airbrake on the bonnet doesnt help at all.

Oil starvation at high sustained revs and Det due to the inefficency of the TMIC at high speeds are mostly the reasons people say dont do it.

I still have the Jap limiter on mine and TBH im glad its there most of the time.

Infected by sti

iTrader: (6)

I've seen 170 out of my jdm blob well 174 according to the ecutek monitor at just over 7k
Not entirely accurate maybe but it i wouldn't say it's too far away as I can pull around new M5's and the old boys xfr, and can keep them at bay until way way up the rev band.

It's amazing when you think some cars do that on a quarter mile especially when you have been giving the car a bit of grief on a much longer stretch of (private) road to get anywhere near those kind of speeds, and it doesn't feel slow in doing it, so wtf do them cars feel like

banny sti

iTrader: (68)

blackhawksti

Can someone confirm and supply the theory behind the dangers to the engine when travelling at track speeds? Call me naive but I find it hard to believe that the TMIC will not see air flow given basic principles of aerodynamics. Anyone ever done any CFD on any of the scooby bonnets scoops?

ditchmyster

iTrader: (7)

I took my old 04 WRX off the clock a few times traveling through germany @ 160mph, what speed was I doing I have no idea but i'd say judging by my bike experience it was around the 150 odd mark, that was remapped by richard bulmer running somewhere around 280bhp,which is a guess because if I said more on a td04 i'd get flamed, but he was very impressed with the way it went at the time as was I.

I have sat at speeds of around 120mph again through germany traveling out to my place in Croatia, but they don't half drink the fizzy stuff when held above a ton for half an hour or so, best car I had for the high speed cruising was my Lexus IS200 which seemed to like 140mph, my STI Type r said 150mph odd on the clock at donnington but the power fc said 126mph I think.

And before I get flamed it was actually in germany.

I will also add that I was doing those speeds at between 2am and 6am mostly in some pretty cold air and as above I wouldn't advise any one to do it knowing what I know now, ignorance is bliss.

The Trooper 1815

iTrader: (31)

The classic and Newage WRX scoops are not very efficient. The air flow over the bonnet lip and into the TMIC is poor and will cause adverse issues when sustained at high speeds.

Scooberpete

I've had 140 easy out of my blob I think I could get to 155 or 160mph if I really wanted. I think I'm running about 320bhp but have no proof of this. Getting there quickly is the fun bit IMO.

ScottyPPP

Impreza's are more about acceleration rather than top speed.

I barely go over a ton in mine, just like taking it up through the gears. I had an E39 540i (4.4L) a couple of years ago that would sit headbutting the 155 limiter all day long.

legacy_gtb

iTrader: (3)

Banny ...... probably?????? ....... i think your wrong! best squeeze some more GG's in there!

Kezwaldo, if you just want to know what the top speed is, go to half your redline (3750) and see what a gps device says your doing ..... take that number and double it and youll have the theoretical speed of your car at redline in top gear.... much easyer way to tell than risking your licence with a covert 3am mission.

As to wether it has the power to see its Vmax will probably depend on its gearing! Depending on what box it is, that could be anywhere between 125ish (classic RA 5spd) to just over 200 (hawkeye 6spd).

Dont use the speedo, they read high! Satnavs are bang on when theres good signal.

As said, torque gives acceleration and power gives speed as its sustained power that is needed to push the car through the air, and air is bloody thick when your trying to push a few square metres of car through it.

As for the bonnet scoops not working at high speeds .... theres something in this! bonnets by theyre shape create a low pressure above them due to the air being thrown upward by the grill surface and the air recirculating over the bennot ..... as such, higher powered cars struggle with cooling on a topmount. Having said that, subaru tested these cars in all sorts of conditions before releasing them so its fair to assume a standard setup should be of no concern..... least thats the theory! ..... might explain why the later higher powered cars have much larger scoops.

tubbytommy

iTrader: (20)

are you retarded???

because that statement makes me think you are....

huzzy1

iTrader: (1)

Tommy you do make my day!

JGlanzaV

iTrader: (3)

How? The car will only do what the gear ratios allow, so at rev limit wether I have a million horsepower or 500 the top speed is the same. You can't go any faster than the gear ratio and revs will allow.

So torque and power are only how fast you get to said speed. If you don't have enough power or torque you either get there very slowly or not at all lol.

More power and torque the easier it is. But the top speed always remains the same

Bristol98

That comment about the beemer made me ROFL!

JGlanzaV

iTrader: (3)

So actually I would beg to differ tubby tommy, and for christs sakes learn some respect. There is no need to be so ****ing rude.

tubbytommy

iTrader: (20)

man up its only the internet.


you wrote in your original post power has no bearing on top speed.

of course it does you retard you need enough bhp to overcome the aerodynamic drag to reach said top speed.
a 45 bhp mini will never get to 200mph no matter how long the road is

Scooberpete

It's not difficult guys you need all three and the faster you wanna go the more of each you need. Your gear ratios will eventually limit you so you'll need to upgrade or change them.
And obviously your power output and drive train also have limits it's just finding the optimum. It all effects top speed and acceleration.

JGlanzaV

iTrader: (3)

Read what I am saying, the rev limit will be at what point the power cannot overcome the drag. Add more power or less wind resistance etc and you will chnage that but never to more than the macimum revs and gear ratio.

tubbytommy

iTrader: (20)

read it yourself, post 6

JGlanzaV

iTrader: (3)

lol you are a ****... The top speed a car car can ever do is at rev limit combined with gear ratio. So where ever you car revs out combined with that factor gives you your top speed. Wether it revs out due to lack of power or wind resistance or lack of fairy dust is irrelvant.

I'm not sure you've ever revved your car out in 6th gear tommy? Probably not...

mazmike

iTrader: (5)

i have had 165 mph out of my classic heading towards avon rise at castle combe track would go more but ran out of room

chopperman

The Hawkeye bonnet has better air flow over the bonnet into the scoop at high speed which is why it gets away with a lower scoop than the blob.

To answer the op question. Standard Rb320 @316 bhp has a top speed of 158 mph according to the stats from prodrive. Im not sure if that was limited with the ppp map or not. The gearing would at 7000 rpm in 6th gear be 183.4 mph. My power should be around 370-380 bhp and i have seen 155 mph on the speedo. It was still climbing and i had plenty of revs left. I actually lost my bottle when i saw the ally bonnet moving around in the wind lol