Cobb AP Dyno Graph/Discussion

[mdogg]

Originally Posted by aaronc7 is our turbo really THAT small? Even WRXs seem to make power all the way to redline. Or are there factors like engine displacement, etc?

I hope you are kidding.... one of the most documented factors is our closing throttle.... If power really starts dropping off around 5000-5500 on Cobb's dyno graphs, then Cobb doesn't have throttle control and Cobb isn't seeing all of the power that they should.

[aaronc7]

yeah ok

A Brief Study Analyzing the Effects that Throttle Mapping have on The MS3...

[aaronc7]

this 'custom' tuned stage 2 map is better, but still power up top is just not there. Maybe FMIC (with less pressure drop or something) can help with this

[mdogg]

Actually, Christian's post refers to Peak numbers on the graph, but thanks....

If you see how sharply ALL dyno sheets on the DISI engines fall off after 5500, it's all wasted RPMs at that point. However, that should NOT be the case. If you can keep the throttle open until redline, you should be able to make more power than with it closing during those RPMs. I'm not saying that the Peak numbers will get better at all - they should decrease from the peak points, but not anywhere near as sharply as they do. It should gradually decline, not drop off like a cliff....

[AutoXRacer]

My understanding from reading various posts regarding specifically our turbo is that it can't handle high RPMs for reliable life...

Its in some thread in here were is states specifically that the type of turbo we have should not be pushed hard in the upper RPM range...

Thats what I'm attributing the power loss at high RPMs...Mazda's way to make the setup reliable with this turbo. Now, if you replace the turbo all bets are off and you probably should be able/want to have the throttle more open...

With the stock turbo...I wouldn't push it...in regards of the info I've come across on this and other boards.

Am I wrong to assume this...?

[Crossbow]

I think you have to take into account the stock intercooler when trying to get additional power in the upper rpm band. With a 4 psi drop, the turbo is actually working more like 19 psi to try and push air through at the upper rpm range...which according to the compressor maps is out of the turbo's efficiency.

Of course if you were to swap out to a different TMIC or FMIC, with less of a pressure drop, you'd now move the turbo back over into efficiency. (I'd need to relearn how to read those damn maps to be more specific, but I'm sure someone will help here).

So my understanding would be this.

1. Cobb argues that throttle plate opening all the way does nothing, because the turbo is blowing hot air. Thus Cobb does not include it, but promises to release a map later which may include some level of additional control. Cobb also reduces the psi by redline, to avoid having the turbo become a flamethrower.

2. Cobb releases a FMIC, then releases a new FMIC map, which has delayed throttle opening, and delayed psi drop off, so their product shows phenomenal gains and less drop off then the competition.

Sounds like business sense to meeeee!

[mdogg]

Originally Posted by AutoXRacer My understanding from reading various posts regarding specifically our turbo is that it can't handle high RPMs for reliable life... Its in some thread in here were is states specifically that the type of turbo we have should not be pushed hard in the upper RPM range... Thats what I'm attributing the power loss at high RPMs...Mazda's way to make the setup reliable with this turbo. Now, if you replace the turbo all bets are off and you probably should be able/want to have the throttle more open... With the stock turbo...I wouldn't push it...in regards of the info I've come across on this and other boards. Am I wrong to assume this...?

I'm not sure what the turbo's efficiency has to do with the throttle plate. Cobb should not have continued to use the throttle control as a safety feature to protect the turbo from higher RPM usage. They should have done things the proper way and created a specific map for it. If Cobb didn't want to have the turbo running high boost at the higher end of the RPM range, they should have created a boost control map for that.

[SLS MS3]

Originally Posted by mdogg Cobb should not have continued to use the throttle control as a safety feature to protect the turbo from higher RPM usage. They should have done things the proper way and created a specific map for it. If Cobb didn't want to have the turbo running high boost at the higher end of the RPM range, they should have created a boost control map for that.

They did create a boost map to keep the turbo from running high boost in the higher RPM range. They aren't using the throttle control as a safety feature, they said they aren't keeping it open to reduce wear and tear on parts. And because so many people bitched about it, they are also supposedly releasing maps that keep the throttle open.

[AutoXRacer]

Originally Posted by SLS MS3 And because so many people bitched about it, they are also supposedly releasing maps that keep the throttle open.

Supposedly with no real benefit on the stock setup...?

[Crossbow]

Ya. According to cobb, there was only a 3-4 hp difference between 100% open and 50% open, on a 91 octane map.