I can confirm the response that Steve's 'Vette has from:
1. riding in it,
2. looking at the various dyno plots taken at each step of the way from stock to current state.
and
3. from the rep of the tuner that has done the work. You don't get in the car mags year in and year out by turning out bad installs.
The name MTI of Houston, TX should ring some bells.
I am new to the performance game. I have had some "performance" cars in the past, but was always content to stay with the factory configuration. Having said that, there are some constants in the GT that I have noticed that should go far in obtaining predictable results.
1. The stock turbo has small volume and spools fast. It begins building boost at 2300 RPM.
2. The 2.4L engine has a natural powerband that starts at 3500 and continues to 5500 (the 5500 figure is from N/A models; I cannot swear that it still applies to the turbo). The top end figures are a toss up between engine capabilities and PCM programming.
3. Torque should be high from 2300 to near redline on a stock configuration.
4. Increasing the flow of the intake air or the exhaust path MAY decrease low end torque.
5. In order to have the highest torque available at the earliest time, the design parameters of the system should be followed; until new "calibration" is offered by the PCM to offset flow modifications in a positive manner.
Number 5 will probably cause some comments of dispute, and possibly comments of support.
There are more and more indications from both the GT and SRT-4 members that the various intake options have had negative effect when used in conjunction with the Stage I programming.
Stage II is projected to include additional programming to handle a 3" exhaust system. The upstream O2 sensor housing chokes the exhaust path down to 2 1/4" leading up to a 2 1/2" exhaust system. This may lead the way for a progressive increase system to be developed that will allow smooth transition to a larger diameter exhaust system that uses stepped increases from the smallest (2 1/4" O2 sensor housing) to the larger (3" exhaust system), and will preserve the low end torque characteristics of the small turbo. It would seem that a sudden transition from small to large would give the exhaust gasses a chance to cool and become more dense. This would lead to restricted extraction. On the other hand, the larger volume of the 3" system would allow more exhaust gasses to be extracted once they became dense enough to recreate the flow that was present before the increase size; thus retaining the low end torque inherit in the smaller turbo. If this is possible, the net result would be higher volume extraction without any deterrent to low end torque. This would seem a desirable goal, and with proper flow design, I would think it would be attainable.
Mopar Performance dropped their CAI project due to not being able to predict noticable performance gains. The removal of the air box could have a negative effect on how efficiently the Charge Air Conditioning system can cool the compressed air entering the actual throttle body. Higher volume of air present at the input of the turbo's compressor may tend to reduce the efficiency of the turbo's ability to match the flow on the output side. In my estimation, the turbo has to be viewed from the tip of the input (size of the intake to the airbox) to the tip of the exhaust system (volume and density of the gas flow at the tip of the exhaust pipe. A change made in the intake volume and/or temp may result in a change in the predicted output volume and resulting power gains made by the turbo; same goes for the exhaust..
Any changes in these areas would require the proper broadening of acceptable data present to the PCU by it's sensors in order to change the "calibration" to reflect the possible gains.
A physical change without an available PCM reaction would only tend to reduce performance to the level that the PCM's incoming data would result in a programmed response. Another reason for followin
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