Tracking with Forced Induction

[sw20kosh]

Originally Posted by AllDayJonRay

I understand the math, but you are still absolutely incorrect.

Actually you and CSGmike are incorrect.

In order to have a linear (straight line) power curve, you need a FLAT torque curve.

M3





If you have a torque curve that is sloping upwards, your power curve is no longer linear.

Look at how the blue line curves upwards due to the torque curve sloping upwards:

[sw20kosh]

Originally Posted by AllDayJonRay

A TQ curve that is linear at an upward angle (like those created by rotrex systems) also creates a linear HP curve, just with a steeper slope.

No this is where you are confused. It isn't actually linear. It looks that way due to scaling on the graph but it actually curves upwards.

[ptuning]

Without getting into the thick of this discussion, I'll just quickly throw in my 2 cents. A "perfect" powerband is one that has a completely flat torque curve from idle to redline referenced on a horizontal plane. A good example of this would be the VQ37HR engine in the 370Z and G37 and the 5.0 coyote V8 engine in the newer Mustangs. They have ridiculously flat torque curves which mathematically produces a ridiculously straight power curve.

Also, while a turbocharger will have a perceived transient lag to a supercharger, its powerband doesn't make it less than ideal for track use. The SC guys will say that the lack of transient boost lag will make it easier to drive fast on the track, I say that the lack of torque/power coming out of the corner makes it easier to drive in the hands of a less experienced driver. Once you've had a lot of seat time dialing in your car, you'll appreciate the much greater torque/horsepower output that a turbo powerband makes when you shift into the next gear.

In a nutshell, if you smash the throttle on corner exit and get no wheelspin and/or the rear end doesn't step out, that doesn't automatically mean that it's because you don't have to deal with transient boost lag, it's more likely because your're not making enough torque at said rpm to begin with. Food for thought.

- Toan

[s2d4]

I guess marketing took advantage of people's weak math abilities.

Sent from my Galaxy Nexus using Tapatalk

[sw20kosh]

Originally Posted by ptuning

Without getting into the thick of this discussion, I'll just quickly throw in my 2 cents. A "perfect" powerband is one that has a completely flat torque curve from idle to redline referenced on a horizontal plane. A good example of this would be the VQ37HR engine in the 370Z and G37 and the 5.0 coyote V8 engine in the newer Mustangs. They have ridiculously flat torque curves which mathematically produces a ridiculously straight power curve.

Also, while a turbocharger will have a perceived transient lag to a supercharger, its powerband doesn't make it less than ideal for track use. The SC guys will say that the lack of transient boost lag will make it easier to drive fast on the track, I say that the lack of torque/power coming out of the corner makes it easier to drive in the hands of a less experienced driver. Once you've had a lot of seat time dialing in your car, you'll appreciate the much greater torque/horsepower output that a turbo powerband makes when you shift into the next gear.

In a nutshell, if you smash the throttle on corner exit and get no wheelspin and/or the rear end doesn't step out, that doesn't automatically mean that it's because you don't have to deal with transient boost lag, it's more likely because your're not making enough torque at said rpm to begin with. Food for thought.

- Toan

You are forgetting the 4.0L v8 M3 torque curve...

[ptuning]

Originally Posted by sw20kosh

You are forgetting the 4.0L v8 M3 torque curve...

Yes, that one too.

- Toan

[AllDayJonRay]

Ok, I see the err of my statements.

I still consider linear power as power produced on a linear TQ curve, irrespective of the HP curve, but that may just be a personal defect of mine. I guess both lines need be perfectly straight to be considered linear if we are speaking technically.

And the point still stands that the SC's available create more linear power delivery than a turbocharger.

[CSG Mike]

Originally Posted by ptuning

Without getting into the thick of this discussion, I'll just quickly throw in my 2 cents. A "perfect" powerband is one that has a completely flat torque curve from idle to redline referenced on a horizontal plane. A good example of this would be the VQ37HR engine in the 370Z and G37 and the 5.0 coyote V8 engine in the newer Mustangs. They have ridiculously flat torque curves which mathematically produces a ridiculously straight power curve.

Also, while a turbocharger will have a perceived transient lag to a supercharger, its powerband doesn't make it less than ideal for track use. The SC guys will say that the lack of transient boost lag will make it easier to drive fast on the track, I say that the lack of torque/power coming out of the corner makes it easier to drive in the hands of a less experienced driver. Once you've had a lot of seat time dialing in your car, you'll appreciate the much greater torque/horsepower output that a turbo powerband makes when you shift into the next gear.

In a nutshell, if you smash the throttle on corner exit and get no wheelspin and/or the rear end doesn't step out, that doesn't automatically mean that it's because you don't have to deal with transient boost lag, it's more likely because your're not making enough torque at said rpm to begin with. Food for thought.

- Toan

Ouch. Someone please buy me some more seat time!

[glamcem]

are you guys serious? every 10 years old and their moms know the HP formula.. ever wondered why the TQ and HP are at equilibrium at 5250 RPM

linear power delivery doesn't mean a flat torque, it could be steeper or flat but definitely nothing like a turbo torque curve, haha..except some turbo BMWs they have flatter torque curve than many other turbo cars but those are exceptions and they are detuned from factory

see the difference between linear and parabolic

[King Tut]

Originally Posted by sw20kosh

You are forgetting the 4.0L v8 M3 torque curve...

dat torque curve doe. Wish it made more torque, but I do love the linear power. Here is my 2009 AA tuned:

[King Tut]

Originally Posted by AllDayJonRay

And the point still stands that the SC's available create more linear power delivery than a turbocharger.

Originally Posted by glamcem

linear power delivery doesn't mean a flat torque, it could be steeper or flat but definitely nothing like a turbo torque curve, haha..

Seems like the should be non debate rages on. Where is our damn :facepalm: emoticon?

[glamcem]

Originally Posted by ptuning

Without getting into the thick of this discussion, I'll just quickly throw in my 2 cents. A "perfect" powerband is one that has a completely flat torque curve from idle to redline referenced on a horizontal plane. A good example of this would be the VQ37HR engine in the 370Z and G37 and the 5.0 coyote V8 engine in the newer Mustangs. They have ridiculously flat torque curves which mathematically produces a ridiculously straight power curve.

Also, while a turbocharger will have a perceived transient lag to a supercharger, its powerband doesn't make it less than ideal for track use. The SC guys will say that the lack of transient boost lag will make it easier to drive fast on the track, I say that the lack of torque/power coming out of the corner makes it easier to drive in the hands of a less experienced driver. Once you've had a lot of seat time dialing in your car, you'll appreciate the much greater torque/horsepower output that a turbo powerband makes when you shift into the next gear.

In a nutshell, if you smash the throttle on corner exit and get no wheelspin and/or the rear end doesn't step out, that doesn't automatically mean that it's because you don't have to deal with transient boost lag, it's more likely because your're not making enough torque at said rpm to begin with. Food for thought.

- Toan

even with the factory turbod cars, transient response is still a problematic .. it makes the lift off oversteer a lot more dramatic compared to NA and SC cars, even so the trail braking is almost must with many of the turbo cars IMO..and I think I had enough seat time to test NA, TC and SC cars

[glamcem]

Originally Posted by AllDayJonRay

Ok, I see the err of my statements.

I still consider linear power as power produced on a linear TQ curve, irrespective of the HP curve, but that may just be a personal defect of mine. I guess both lines need be perfectly straight to be considered linear if we are speaking technically.

And the point still stands that the SC's available create more linear power delivery than a turbocharger.

I think your previous statements were also correct linear is linear regardless of the slope of the curve

[King Tut]

Originally Posted by glamcem

I think your previous statements were also correct linear is linear regardless of the slope of the curve

Linear is linear if the slope of the curve remains constant.