Is Power (rwkw) Figure Everything? Why Are People So Hung Up On Kw Figures

[DCIEVE]

FFS Power is a by-product of Torque x RPM, more torque + more rpm = more power

So you expect an engine with f**k all torque to be able to pull a heavy car through the gears?

might be quick if it had 20 gears so it could stay in the power band.

Go put your 50,000rpm motor in anything and i will race you in something the same weight with a 2 cylinder diesel from 0-40km/h, using the same gearing.

So You keep telling yourself that you are right mate.

Zebra, your argument fails. Do the maths, tractive effort at the wheels is directly proportional to engine power, torque is multiplied by the drive ratio together with speed. If we didn't have gearboxes your argument might have some merit.

[ARTZ]

Because the v8 is gutless (OK has more progressive torque curve ) and thefore easier to drive on the limit.

Have a look at the recent time attack. The Fernandes Falcon supercar had the V8 ripped out and the turbo 6 put in. It was slower than the v8 Commodore supercar. Fernandes said it produced too much power/torque and was a handfull - couldn't get traction in 4th gear....and that the v8 was an easier car to drive because of its more progressive nature.

So not only is torque important - but the way its delivered.

Link to results - note the Falcon was nearly 1 sec slower than the Mal Rose Commodore.

http://www.natsoft.com.au/cgi-bin/results..../2010.EAST.S2.Y

Also note the 1st 6 positions were filled by 4 cylinders or rotaries - probably becuase they are a bit "softer" when coming onto boost when on the limit.

Thanks..

Itis exactly ther point i was trying to make 6 months a go in a different thread where everybody was telling this guy to get the xr6t but i reckon the GT was a better buy, it may not be able to make as much power easily, it may not be as quick at the lights and it may not leave big black skidmarks as effortlessly ..

But as an all round drive i think it is a better balanced more spirited car..But most people dont drive their car on the limit that much and are simply content doin burnouts, draggging at the lights and measuring their e-wang by the kws they have, and i can understand this is where the xr6t has its place

Personally I'd like a nice balanced car that i can punch out of a corner without 15 tonne of torque breaking traction and my driveline..I also prefer something lighter which is why i have a skoiline...Would actually prefer a 200sx but close enough

[zebra]

Zebra, your argument fails. Do the maths, tractive effort at the wheels is directly proportional to engine power, torque is multiplied by the drive ratio together with speed. If we didn't have gearboxes your argument might have some merit.

I know what you guys are saying, My argument doesnt fail, but having an engine that needs to rev to a billion rpm just isnt sensible imo.

I know the maths, I live and breath this stuff, My view is that having an engine that makes bulk torque at a lowish rpm yet is still able to rev to a half decent amount will make a better engine for 99% of scenarios, nothing in F1 can be applied to the real world, but if you guys want to buy a gazillion dollar F1 motor than go for it.

Me well if i didnt have a budget I would be buying an IHRA Pro stock 815CI V8, they only rev to 7800rpm, but make over 1400hp and run 6's down the 1/4 and the torque curve would make most oil tankers look wimpy.

[Rolls]

I know what you guys are saying, My argument doesnt fail, but having an engine that needs to rev to a billion rpm just isnt sensible imo.

I know the maths, I live and breath this stuff

then why did you argue with us? all you did was misrepresent what I said to come to the same conclusion.

[zebra]

Because the way I read it, you were saying that you need a billion rpm to have a fast car, i was trying to point out that it isnt the case.

(plus I was at work so kept getting called away, so half my stuff I could've explained better lol)

[Roy]

[zebra]

LOL

[juggernaut1]

Thanks..

Itis exactly ther point i was trying to make 6 months a go in a different thread where everybody was telling this guy to get the xr6t but i reckon the GT was a better buy, it may not be able to make as much power easily, it may not be as quick at the lights and it may not leave big black skidmarks as effortlessly ..

But as an all round drive i think it is a better balanced more spirited car..But most people dont drive their car on the limit that much and are simply content doin burnouts, draggging at the lights and measuring their e-wang by the kws they have, and i can understand this is where the xr6t has its place

Personally I'd like a nice balanced car that i can punch out of a corner without 15 tonne of torque breaking traction and my driveline..I also prefer something lighter which is why i have a skoiline...Would actually prefer a 200sx but close enough

I have a reasonably responsive modified s15 and have also bought a 2010 G6E turbo (old mans XR6T). Both are great cars. For the street I prefer the G6E - peak torque at 2000rpm combined with a 6 speed semi auto makes for an easy reasonably quick cruiser - and I don't have to change gears (or I can use the manual mode) - just nail the throttle.

For fun the S15 is great - once you get traction.

[ARTZ]

I have a reasonably responsive modified s15 and have also bought a 2010 G6E turbo (old mans XR6T). Both are great cars. For the street I prefer the G6E - peak torque at 2000rpm combined with a 6 speed semi auto makes for an easy reasonably quick cruiser - and I don't have to change gears (or I can use the manual mode) - just nail the throttle.

For fun the S15 is great - once you get traction.

exactly what i wish was in my garage

I hate you so much right now....

only cause im jealous..

Edited October 26, 2010 by Arthur T3

[Beer Baron]

You want to make as much torque as possible, and hold it for as long as possible, but being as torque is so obviously confusing for everyone it is far simpler to just say make the most power possible and for the largest spread of rpm as possible.

very neatly summed up.

[ARTZ]

So what are tricks to hold torque then?

For instance, i make about 420ish just after 4k pretty much just after full boost has kicked on then drops to 300 by redline ..Now obviously 2psi drop off in boost wouldn,t help this.. But why does torque drop when power keeps building?

[Rolls]

So what are tricks to hold torque then?

For instance, i make about 420ish just after 4k pretty much just after full boost has kicked on then drops to 300 by redline ..Now obviously 2psi drop off in boost wouldn,t help this.. But why does torque drop when power keeps building?

because if you look at the formula power is proportional to torque x rpm, so even if torque is falling rpm is climbing so power can still climb.

but due to the design of engines torque will always drop off towards redline, way you can see this is lets say there is a maximum of x air available at 4000 rpm, at 8000 rpm the intake can not swallow any more air so that x air is divided by 2 as the intake cant breath anymore, hence the torque is effectively halved, however as you are firing each piston twice as often even though the power per explosion is halved your overall power is the same because you are running double the rpm.

So basically to hold torque for longer you need to make the same air available at higher rpm as is at lower rpm, this means removing restrictions or using forced induction, now turbos obviously cant supply x psi forever so they will drop off as well, but they will allow peak torque to be held much later than with out it.

So you want more torque for longer? bigger turbo, or remove restriction by getting bigger cams, intake, exhaust etc pretty simple really.

This is why talking about torque is confusing, if people said more power you would just instantly think, cams turbo etc, but when people talk about torque they get all confused.

edit: This isn't entirely correct but it is a great analogy, think of torque as the force per explosion, think of power as the force per explosion multiplied by how many explosions you get in 1 sec, more rpm = more explosions = more power

Edited October 26, 2010 by Rolls

[bigmikespec]

Rolls; your posts in this thread are your best yet...

[ARTZ]

Rolls; your posts in this thread are your best yet...

Agreed..they're pretty good

But lets say i was happy with the power i had but wanted to flatten the curve, now i could fit cams which would allow it breathe/expel more air but this would change uniformly across the rev range .

I could change my ex housing but this would lessen response. Ditto for the comp housing.

Displacement maybe be the only answer then?

[Rolls]

A great example of flat torque is the BMW tt 3L six, it runs variable boost, variable timing and possibly even variable length intake runners, but for you the best way to achieve flatter torque (straight diagonal power) is a turbo with decent sized hot side and wastegate, cams and ported head.

But end of the day this isn't the best way to spend your money, if you put it into other things you'll get better performance but you'll have to deal with the huge power jump when boost comes on and the power dying off hard after 7k rpm. If you really want a nice power curve just buy a big v8 or forced induction large capacity motor.

Edited October 26, 2010 by Rolls

[wolverine]

forced induction large capacity motor.

It must be getting late, I thought you wrote flux capacitor.......for split second anyway.

[ARTZ]

A great example of flat torque is the BMW tt 3L six, it runs variable boost, variable timing and possibly even variable length intake runners, but for you the best way to achieve flatter torque (straight diagonal power) is a turbo with decent sized hot side and wastegate, cams and ported head.

But end of the day this isn't the best way to spend your money, if you put it into other things you'll get better performance but you'll have to deal with the huge power jump when boost comes on and the power dying off hard after 7k rpm. If you really want a nice power curve just buy a big v8 or forced induction large capacity motor.

yeah i know my problems are due to crappy turbo selection, i could buy cams and all that, or just get a better turbo would solve all these problems..Ethanol will also help a little when i get around to it.

I was only speaking hypothetically really .

In which case you agreed with me, more cubes is the answer to a longer stronger curve.

For now im quite happy with my 4k kick..Could always be better though...

PS.. variable length intake runners ??

[Rolls]

PS.. variable length intake runners ??

yeah a few high end euro cars have them, very interesting piece of hardware, got to play with a prototype one at my university once, lots and lots of maths to design them correctly!

[PM-R33]

So the BMW N54 engine has variable length intake runners!? Really?

My father is currently looking for the perfect second hand one to buy (09 M Sport DCT 335i) and I have absolutely loved the engine and car since BMW brought them out (hence me mentioning it before with the peak torque at 1200rpm). I spend quite a lot of time on the e90post forums reading

EDIT: I just re-read what you wrote and you said "possibly", so I don't think they actually do You got me really excited then because that was one thing I didn't know about.

Edited October 26, 2010 by PM-R33

[Lonewolf1983]

yeah no variable intake on them.

My old VW bora v6 had one, and it made peak torque @ 3000rpm due to of it, was fantastic.

Honda's VTEC is essentially aiming for the same thing, maximising torque over a large rev range for good low down and high end performance.

Also Porsche Variable geometry turbo's are there to act like a small fast spinning turbo down low, then a big turbo up top. One of the main reasons the 997 TT is a lot faster than the 996 TT. I think this is the way forward with turbo cars.