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Discussion Starter #1
Hey Guys. For any of you with a 2004 PPC'd Aero I have a question. My tuned car is very fun to drive but I noticed something and wondered if any of you had noticed something similar. In gears 1-3 (especially 2&3), you can really feel the torque. However, in gears 4 & 5, it almost seems like the engine is working very hard almost like something is slipping.

It is less noticeable if I gradually press the gas rather than hit it hard and seems to be less noticeable if I switch gears above 3000 RPM. Ironically enough, I do not really notice this in 6th gear. I had tuned a Linear as well (traded up) and had not noticed this. Any thoughts on what this might be?
 

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Discussion Starter #3
I bought the car with a Abbott Racing sports exhaust. It was dealer owned car that he drove for 9K miles. This is what is installed 6" Single Oval Exit Backbox.
 

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Well, you would certainly feel more grunt in the lower gears than in the upper, but you already knew that much I'm sure.

I asked about your exhaust because if the diameter from the cat-back is smaller than 2.75, then the wastegate seems to spend more time open than it otherwise would (or the recirc BOV... not sure on that). Lot's of noise from the turbo, but the benefits tail off quite a bit as the car can't extract the exhaust fast enough. That's my unofficial hypothesis based on my observations. My car still has the cheesy Saab pseudo-sport exhaust while I am waiting for a real sport exhaust to arrive.

I have found that if you keep the boost needle a bit lower than max (max for me is halfway through the red, so about on the first line in the red zone), then the boost appears to remain more useable. If the needle pegs, then the very high whistling starts (recirculating BOV or wastegate) and the power flattens out.I believe that it is because the system is attempting to pump more volume through the engine that the restrictive exhaust can effectively pass.

I'm not sure about your Abbott backbox, or how far upstream that goes, or the pipe diameter. Certainly the tip seems large! :wink:

If anyone else has any more thoughts on this, I'd also love to hear them.
 

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Discussion Starter #6
Voodoochile. Thanks for the reply. Not sure of the diameter of the pipe coming out of the cat. converter but as you mention, the exhaust tip is large. I have just notice that I feel more torque at lower RPM's in the lower gears whereas I need to shift at higher RPM's in higher gears to aviod having the engine feels like it is struggling. For instance if on the highway going 55-60, I shift to 5th, the engine seems to work harder. Alternatively, if I shift to 5th at 70, it is substantially less noticeable.

As for your question, I installed the PPC software. The dealer knows nothing about it and will not until my warranty is over. Thanks for your input.
 

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Without actually hopping in my car to map RPMs to gear and speed, I'm wondering if you are shifting too early? You indicate that you get more power at higher speeds in the same gear - I'm wondering if you are hitting too low an RPM at 50? Remember your power band is from 2,500-4,000 rpm. Lower than that and the engine is struggling, high than that and it obviously tapers off.

I have not noticed any reduction in power in higher gears. In fact, I'm impressed how I can stomp on the gas at highway speed and still get pushed into my seat. :D
 

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Discussion Starter #8
Mattrazzo, I am noticing this around 2500 RPMs. As the RPMs increase above this point, the less I notice the struggling. This week I will pay attention to when I notice this compared to the RPMs. I'll let you know what I discover later this week. In all likelihood, I am shifting to early. Thanks!
 
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