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Discussion Starter #1
After reading the board for the last few hours, I was perusing the posts regarding the possible issue of the dsi not being able to provide enough feul up top. Seems to me a methanol injection system could possibly help this issue. Running methanol injection makes the A/F pretty rich, so being able to tune fuel would normally be neccessary, but maybe very small nozles could be used, and using either a boost or maf frequency activation system set to only activate up high.

This could be used to keep the ecu from pulling time and boost up top to keep the lack of fuel in check.

Disclaimer: This assumes that the theory about the dsi is correct, and also that the turbo is not maxed and also the moon is in the proper phase....well you get the idea.
 

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The DSI theory is not correct. After looking at the maps for the turbo that is used on the speed6, you can see that the turbo is unable to provide adequate boost at higher rpms. It is just too small. There is no lack of fuel issue
 

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Which is blatantly obvious when you clean your car...
[/b]
:laugh:

I think I'm going to change my sig to say

"Yes, I own a speed6 and yes I am better then you.
No, you have no clue about this car as you don't have one."

Would fit well for many members.
 

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:laugh:

I think I'm going to change my sig to say

"Yes, I own a speed6 and yes I am better then you.
No, you have no clue about this car as you don't have one."

Would fit well for many members.
[/b]
Well speedpirate does own 2 speed6's so i'm sure he'll come to know the intricacies of this car better than anyone else with enough time..ie the car seems to be running rich which is noticible from the consistant black exhaust tips
 

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Discussion Starter #7
Cool - thanks for the chart.

Does Mazda have the ecu pull boost because they know the compressor cannot handle the needs at high RPM?

I would be curious what the A/F would look like if someone did a pull with the boost held steady. Am I correct in assuming the A/F would not change, because no matter what the boost was it would still be flowing the same actual volume of air?

In my experience with turbo cars, I have not had an issue of running out of turbo. My cars have always had room to grow after I did a swap.
 

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Cool - thanks for the chart.

Does Mazda have the ecu pull boost because they know the compressor cannot handle the needs at high RPM?

I would be curious what the A/F would look like if someone did a pull with the boost held steady. Am I correct in assuming the A/F would not change, because no matter what the boost was it would still be flowing the same actual volume of air?

In my experience with turbo cars, I have not had an issue of running out of turbo. My cars have always had room to grow after I did a swap.
[/b]

It is not mazda pulling boost, it is the compressor not being able to push enough air. Do a search on ehre for the limitations of the turbo to get more info
 

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n my experience with turbo cars, I have not had an issue of running out of turbo.[/b]
All turbo's have efficency ranges. As the turbo moves away from its peak efficency, torque begins to drop, which of course effects maximum power output.

The only time you can get your cake, then get more cake, and maybe some pie and icecream, is if you have a VATN Turbo (Variable Area Turbine Nozzle). VATN turbo's have the capability to change their AR values to become both a tiny turbo, and a giant turbo, in terms of flow.




(AR ratio is the sizing of the "snail section" of the turbo feeding the exhaust turbine. It basically determines the amount of velocity reaching the turbine. A small AR ratio results in fantastic low end response and rapid spoolup, while a high AR ratio results in incredible high end power. You can't have both at the same time without a VATN)

You can see why many people call it the "snail" based on the image.

With out the ability to modulate the area of turbine fins, the turbo will always have a specific range where its most efficent.

I think the best example of this is the 3si link I posted earlier. This clearly shows the differences between a wide variety of turbo's on the same engine in terms of the power curve.

http://www.3si.org/forum/showthread.php?t=...01&page=1&pp=10

Here's the link again if you missed it. Gives you a fantastic idea of how turbo sizing effects the power curve. Pay special attention to the end of the curves.
 

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Discussion Starter #10
It is not mazda pulling boost, it is the compressor not being able to push enough air. Do a search on ehre for the limitations of the turbo to get more info
[/b]

I have read the posts. I am not arguing the fact that the compressor is maxed out. The issue I have is that if you pull the actuator vacuum hose the boost (read PSI) will not drop off. As a matter of fact it rises. This results in no additional power gains, but something is pulling boost off on top, and was curious if Mazda has the ecu pull boost because they know the compressor cannot handle the needs at high RPM?

I would be curious what the A/F would look like if someone did a pull with the boost held steady. Am I correct in assuming the A/F would not change, because no matter what the boost was it would still be flowing the same actual volume of air? Any opinions?
 

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I have read the posts. I am not arguing the fact that the compressor is maxed out. The issue I have is that if you pull the actuator vacuum hose the boost (read PSI) will not drop off. As a matter of fact it rises. This results in no additional power gains, but something is pulling boost off on top, and was curious if Mazda has the ecu pull boost because they know the compressor cannot handle the needs at high RPM?

I would be curious what the A/F would look like if someone did a pull with the boost held steady. Am I correct in assuming the A/F would not change, because no matter what the boost was it would still be flowing the same actual volume of air? Any opinions?
[/b]

This is not true once the compressor hits its choke line the compressor wheel will not take in any more air. You can literally weld the wastegate shut in this turbo and the psi will still fall significantly. The damn thing is tiny.

I did a VE analysis on the turbo mated to a 2.3 liter engine a while back. There is no way in hell this turbo will support maximum boost pressure up to redline even if you tripple welded the wastegate shut and filled the wastegate port with molten iron.

This isnt a 16g like on your evo its a turbo that flows almost HALF as much and has almost NO headroom mounted on a bigger engine.

On an Evo the turbo is large enough to support boost pressure to redline and beyond without choking the compressor. This is where efficency gains are realized by going with meth injection.
 

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Discussion Starter #12
This is not true once the compressor hits its choke line the compressor wheel will not take in any more air. You can literally weld the wastegate shut in this turbo and the psi will still fall significantly. The damn thing is tiny.

[/b]
My bad. I was under the impression (from reading another post) that another member had bypassed the actuator and saw the PSI rise as high as 19 thru redline.
 

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My bad. I was under the impression (from reading another post) that another member had bypassed the actuator and saw the PSI rise as high as 19 thru redline.
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You're not mistaken, that has happened, but I don't know who's done it on a dyno yet.
 

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Found another excellent example of turbo sizing issues on the rx8.

Check this graph out.


This is an excellent example of a few things.

1) A tiny turbo put into an engine that is designed to rev high.
2) The attempts of a tuner to extract more power out of a tiny turbo, and the limitations of doing so.

Look what happens to the torque curve when he ramps up the boost. More power is made, but look what happens to the torque dropoff. It gets even more severe...he's basically eliminated the entire upper rpm range of the renesis. Pay special attention to the steepness of the torque dropoff after he tried to spike the boost up.

I'm trying to find a dyno of a situation where only the boost is effected, and not the entire tuning of the engine (like this situation), but its hard to do. Most individuals have smartened up that its bad to just jerk the boost up without completely retuning the engine.
 

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Within the context of this discussion, it is apparent that trying to keep boost up till redline should not be our priority. however based on the RX-8 graphs, the area under the curve is still greater after raising the boost. The driver just needs to change his shift points to capitalize on the new power being made from 3K-7.5K which is not too shabby i might add. I wouldn't complain about that curve myself. I think the goal right now is to see how much you can raise and flatten the torque curve within the effeciency range of the stock turbo. So the question is, how do we do that?

Because ultimately the goal is to make the car faster, and if that means in the low to mid range so be it. Cause when it comes down to it, when the tree hits green, whether you're lined up against a big block V8 that never revs past 6K or a turbo'd civic that doesn't even make power until 7K it's whoever crosses the line first that matters.
 

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I concur dj petey. For all needs and purposes, the MPS 6 crowd should ignore anything past 5800 rpm or so, and concentrate on increasing the car's already low-mid range power. You'd have much better results concentrating on the vehicles strengths, then trying to revert its weaknesses.

Even if you managed to get tuning, swap turbo's, and retune the car...then there would be a whole slew of people complaining about where all their low end torque went...
 

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Discussion Starter #19
I concur dj petey. For all needs and purposes, the MPS 6 crowd should ignore anything past 5800 rpm
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I have thought a couple of times that Mazda should have just set the redline at 6000. My goals for this car are not very lofty as far as straight line performance. If I wanted that I would have kept my goat. I just want 35-50 more horsies, and be able to run the meth injection to cool everything down, especially on road courses. My biggest hope is someone working on tuning solutions.
 
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