[CRex]

I know it would produce less overall power compared to like the current apr 93 chipped car but i like that linear feel.. Like maybe keep the same curve just bump it up by the same amount over the entire band...even if its not huge 300 ft lbs of torque..... less can be a more natural feel.
All the ones i see so far have a huge peak and then die off...


Modified by CRex at 10:37 AM 11-29-2006

 

[bripab007]

I would prefer this as well. It would be simple to do:
starting at, say, 2500 RPM, just raise the stock boost target by ~1.5 PSI every 1000 RPM. 12psi at 2000 RPM, 13 by 2500, 14 by 3500, 15 by 4500, etc.

 

[jackmott]

Re: (bripab007)

you guys honestly want to make your cars slower?
I mean, if you made the torque curve flat it would be a *LOT* slower.

 

[CRex]

it would not be slower than stock obviously. I am talking about keeping the stock torque curve's linear shape with an even increase throughout the rpm range...

 

[BumbleBeeJBG]

Re: (CRex)

I'm curious, why?

 

[NS01GTI]

Re: (BumbleBeeJBG)

With the size of our turbos (resistriction at high rpms) you won't get a linear curve unless you nearly go back to stock boost levels.

 

[bripab007]

Because the car would rush toward redline differently, more fervently, than the stock car or the typical APR/GIAC/etc. programs.
My turbo'd Miata feels like it wants to bust right through the redline because of the way it builds a little extra boost in the last 1000 or so RPM.
It's a fun feeling.

 

[kharma]

Re: (bripab007)

BT files usually have a relatively flat torque curve

 

[PD Performance]

Re: (bripab007)

Quote, originally posted by bripab007 »

Because the car would rush toward redline differently, more fervently, than the stock car or the typical APR/GIAC/etc. programs. My turbo'd Miata feels like it wants to bust right through the redline because of the way it builds a little extra boost in the last 1000 or so RPM. It's a fun feeling.

Fun feeling but not atually fun. The illusion of useful power is much different then having the actual power.
The power curve is the way it is because thats all the bost the turbo can make. These turbos on a chipped car are back down to 11psi or so by redline.
In order to get what you want you would be making less power then stock as people mentioned since stock cars spike to higher then 11psi down low.

 

[BumbleBeeJBG]

Re: (PD Performance)

See, the answer is new turbo, not de-tuning

 

[bripab007]

Re: (PD Performance)

Quote, originally posted by PD Performance »

Fun feeling but not atually fun. The illusion of useful power is much different then having the actual power.

I disagree. It's not an "illusion of useful power" compared to the stock car. It will make more power everywhere than the stock car, just not as much as the typical request-20million-pounds-of-boost-everywhere-in-the-rev-range aftermarket programs currently available.

Quote »

The power curve is the way it is because thats all the bost the turbo can make. These turbos on a chipped car are back down to 11psi or so by redline.

I realize the turbo is tiny, but I guess I wasn't aware that it's only able to make ~11psi at redline. If that's the case, then there's no way to form the torque curve any differently than it already is; we can only accentuate the low- and mid-range torque as the aftermarket companies have already done (without a different turbo, obviously).

 

[jackmott]

Re: (bripab007)

But that feeling is caused by a frustrating lack of power at low rpms, lol

Quote, originally posted by bripab007 »

Because the car would rush toward redline differently, more fervently, than the stock car or the typical APR/GIAC/etc. programs. My turbo'd Miata feels like it wants to bust right through the redline because of the way it builds a little extra boost in the last 1000 or so RPM. It's a fun feeling.

 

[bripab007]

Well, if the turbo was able to maintain a pressure differential of more like 14-15psi at redline, then no, it wouldn't.
What I was proposing was having stock boost up until, say, 2500 RPM, then ramping up slowly from there until fuel-cut. But the car can't even hold greater than 11psi at redline, so there's no way to do that sort of torque/boost curve with the stock snail.

 

[BumbleBeeJBG]

Re: (bripab007)

So you're saying you want to hit the rev limiter all the time when you want power?

That's as frustrating as pulling out man. http://****************.com/smile/emthdown.gif
You're conceeding that you're making less power, correct?
For the sake of a sensation?
Well, to each his own, but I'm not a fan of this type of thing

 

[bripab007]

Dear god, would you listen to what I'm saying for a second:
I'm not attempting to compare this to the typical APR/GIAC/Neuspeed/etc. program. I know those are about as good a torque curve as you're going to get from the stock turbo.
No, I don't want to hit the rev-limiter all the time when I want power. I would, however, appreciate a torque curve that remained flat until redline, for the sake of the sensation. If you've ever driven a car whose torque curve remains flat at redline (which means horsepower rises until redline), it's quite fun. I'm not trying to argue what's better or worse, I'm trying to argue which is more fun to drive.
Say the stock turbo was large enough to maintain, say, 15psi of boost at redline. The stock ECU calls for ~11psi of boost from 2000 RPM to ~5000 RPM, then tapers to ~6-8psi. At 5000 RPM, instead of the boost dropping or staying flat, if you could ramp it up slightly, your torque curve wouldn't fall, and your horspower would peak at redline.
You would have lost no torque, and you'd have gained some high-RPM torque, enhancing the car's power and acceleration above 5000 RPM.

 

[magilson]

Re: (bripab007)

Quote, originally posted by bripab007 »

Dear god, would you listen to what I'm saying for a second: I'm not attempting to compare this to the typical APR/GIAC/Neuspeed/etc. program. I know those are about as good a torque curve as you're going to get from the stock turbo. No, I don't want to hit the rev-limiter all the time when I want power. I would, however, appreciate a torque curve that remained flat until redline, for the sake of the sensation. If you've ever driven a car whose torque curve remains flat at redline (which means horsepower rises until redline), it's quite fun. I'm not trying to argue what's better or worse, I'm trying to argue which is more fun to drive. Say the stock turbo was large enough to maintain, say, 15psi of boost at redline. The stock ECU calls for ~11psi of boost from 2000 RPM to ~5000 RPM, then tapers to ~6-8psi. At 5000 RPM, instead of the boost dropping or staying flat, if you could ramp it up slightly, your torque curve wouldn't fall, and your horspower would peak at redline. You would have lost no torque, and you'd have gained some high-RPM torque, enhancing the car's power and acceleration above 5000 RPM.

Now this I'm just not following. We have two identicle 2.0T motors. One tuned to the maximum fuel delivery of the pump and maximum air delivery of the turbo (within their safe limits). The other tuned as you describe; limiting boost down low and slowly tapering it off as the turbo's flow limit dictates.
Now what you are trying to say is that you've lost no torque tuning it your way then the first motor tuned to the limit of it's components? This does not make sense. Could you try and explain it another way?
Any way I can get the most torque from my motor is something worthwhile to prusue (cost factor aside). The work my motor is able to do (and therefore the acceleration and top speed I am able to acheive) is determined by the torque. These same two motors put in identicle cars will result in the first motor winning every race because it is at it's limits while the second is tuning limited, not component limited.
If all your after is the sensation, I'm with you. In the scenario I've listed, you are wrong. The area under the torque curve is the most important. More area is better, generally. Now, more torque up top at higher RPMs is obviously going to make you faster, but we are talking about two identicle motors with identicle components which have identicle limitations. So why not get the most from it?

 

[Kev06A3]

I think what's being missed in this discussion is the characteristic boost curve of any turbocharger. ALL turbochargers have a delay before boost builds up due to insufficient exhaust flow to adequately turn the compresser wheel. Turbo efficiency increases rapidly as rpms increase, reaching maximum efficiency at some specific rpm (depends on the turbocharger type and the exhaust flow, which corresponds to a specific rpm for a given engine). Thereafter (rpm-wise), there is a progressive reduction in turbine efficiency which results in tapering off of power.
Every turbocharger does this.
The stock 2.0T FSI engine tune simply lops off the torque peak such that you get a nice, wide torque curve. This is accomplished by reducing the boost requested in spite of much higher capability. The primary engine tune modification of all aftermarket programs is to simply "uncork" the motor by requesting the maximum available boost at all rpms, which ends up giving a huge peak torque increase with only modest increase at high rpms.
So, there really is no way that an aftermarket program could tune in a flat torque curve while substantially increasing torque only. You could *maybe* get 20 ftlbs more torque across the board (and 20 HP) through slight increase in boost and fuel/timing changes, but that's about it. It would be silly to develop a program that still does not take advantage of the full potential of the motor, though, which is precisely why you don't see such programs available in the aftermarket.


Modified by Kev06A3 at 1:46 PM 11-29-2006

 

[bripab007]

Re: (magilson)

Quote, originally posted by magilson »

Now this I'm just not following. We have two identicle 2.0T motors. One tuned to the maximum fuel delivery of the pump and maximum air delivery of the turbo (within their safe limits). The other tuned as you describe; limiting boost down low and slowly tapering it off as the turbo's flow limit dictates.

No. Re-read the second sentene in my response that you quoted.

Quote »

Now what you are trying to say is that you've lost no torque tuning it your way then the first motor tuned to the limit of it's components? This does not make sense. Could you try and explain it another way?

I'm trying to compare my theoretical boost curve to the stock car's.

Quote »

Any way I can get the most torque from my motor is something worthwhile to prusue (cost factor aside). The work my motor is able to do (and therefore the acceleration and top speed I am able to acheive) is determined by the torque. These same two motors put in identicle cars will result in the first motor winning every race because it is at it's limits while the second is tuning limited, not component limited.

I fully agree that you typically want as much torque across as much rev range as you can possibly achieve, as that will produce the faster car. However, if one was already perfectly happy with the stock car's low- and mid-range torque, but wanted to increase torque in the upper RPM range, one would follow my idea. The problem is, with the stock turbo, one would not be able to achieve such a torque "curve."

Quote »

If all your after is the sensation, I'm with you. In the scenario I've listed, you are wrong. The area under the torque curve is the most important. More area is better, generally. Now, more torque up top at higher RPMs is obviously going to make you faster, but we are talking about two identicle motors with identicle components which have identicle limitations. So why not get the most from it?

Again, I agree that area under the torque curve is king, that is not what I'm arguing/describing.

 

[bripab007]

Re: (Kev06A3)

Quote, originally posted by Kev06A3 »

I think what's being missed in this discussion is the characteristic boost curve of any turbocharger. ALL turbochargers have a delay before boost builds up due to insufficient exhaust flow to adequately turn the compresser wheel. Turbo efficiency increases rapidly as rpms increase, reaching maximum efficiency at some specific rpm (depends on the turbocharger type and the exhaust flow, which corresponds to a specific rpm for a given engine). Thereafter (rpm-wise), there is a progressive reduction in turbine efficiency which results in tapering off of power.

Only if you've reached the flow limits/edge of the turbo's efficiency early in the motor's rev range, in which case, you've chosen too small a turbocharger for your application (well, not necessarily too small, but, depending on ultimate power and power delivery goals).

Quote »

The stock 2.0T FSI engine tune simply lops off the torque peak such that you get a nice, wide torque curve. This is accomplished by reducing the boost requested in spite of much higher capability. The primary engine tune modification of all aftermarket programs is to simply "uncork" the motor by requesting the maximum available boost at all rpms, which ends up giving a huge peak torque increase with only modest increase at high rpms.

I understand this, but that doesn't mean that, with the appropriate hardware and max torque/power goal, you could utterly and completely change the torque curve so as to remain flat or even rising toward redline. You would be forced to sacrifice mid-range torque. BTW, does someone have a quick link to a requested vs. actual boost chart for the stock and chipped cars?

Quote »

So, there really is no way that an aftermarket program could tune in a flat torque curve while substantially increasing torque only. You could *maybe* get 20 ftlbs more torque across the board (and 20 HP) through slight increase in boost and fuel/timing changes, but that's about it. It would be silly to develop a program that still does not take advantage of the full potential of the motor, though, which is precisely why you don't see such programs available in the aftermarket.

Again, on the existing hardware, apparently not, but that doesn't mean it's not possible or even desirable. Obviously there's more than a couple people who've shown interest.


Modified by bripab007 at 8:24 PM 11-29-2006

 

[bhvrdr]

Re: (bripab007)

Quote, originally posted by bripab007 »

Dear god, would you listen to what I'm saying for a second: I'm not attempting to compare this to the typical APR/GIAC/Neuspeed/etc. program. I know those are about as good a torque curve as you're going to get from the stock turbo. No, I don't want to hit the rev-limiter all the time when I want power. I would, however, appreciate a torque curve that remained flat until redline, for the sake of the sensation. If you've ever driven a car whose torque curve remains flat at redline (which means horsepower rises until redline), it's quite fun. I'm not trying to argue what's better or worse, I'm trying to argue which is more fun to drive. Say the stock turbo was large enough to maintain, say, 15psi of boost at redline. The stock ECU calls for ~11psi of boost from 2000 RPM to ~5000 RPM, then tapers to ~6-8psi. At 5000 RPM, instead of the boost dropping or staying flat, if you could ramp it up slightly, your torque curve wouldn't fall, and your horspower would peak at redline. You would have lost no torque, and you'd have gained some high-RPM torque, enhancing the car's power and acceleration above 5000 RPM.

I can see what you are saying. Most people will go for either the most power they can get out of the stock turbo which will negate this ability as you understand or else if they are going to shell out several grand for a BT than they want the biggest bang for the buck which is still not a flat curve but rather the opposite of the stocker, a curve that ramps low in the beginning and up to peak before redline. There is a mid line kit out there by MTM that uses a K16 turbo which is a bit larger than the K04 and smaller than the gt28rs or larger turbos. It does make full boost pretty damn quick down low and will hold 17psi at redline so its pretty flat but it will cost you a fortune and for that amount people could buy not just a stage 3 kit but a new clutch, FMIC, and more. But yeah, it can be somewhat accomplished.
cheers! mike