lmf3626

I have a 96 GT and I put a 2.5" BBK Off-Road H-Pipe with no cats on my car. I feel that my car was faster with the stock h-pipe that had 4 cats instead off the off road h-pipe I have now. I heard that it might be because of loss of backpressure. Sure, it sounds great, but I lost some performance. Let me know what you think.

USAMuscle

I don't know from experience, but I've heard that X-pipes perform better than H-pipes. Don't really know why it would seem slower with an H-pipe though...strange.

86HOGT

You probably opened it up too much and lost some lower end.

USAMuscle

Yeah, that's possible, hopefully it opened up a little in the upper RPM range.</P>

lmf3626

Has anyone heard anything about loss of backpressure? I kinda feel that I should have gotten the high flow H-pipe with 2 cats instead of the off-road pipe with no cats. (When I go full throttle my engine is winding out too much for too long.) </P>

lmf3626

Well actually my car feels as though it has more power at first but when it gets to second gear it needs to shift sooner.</P>


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USAMuscle

Here's a little briefer on airflow and how it relates to engine performance:</P>


When you put on the H-pipe w/o cats, you reduced back-pressure which boosts the upper RPM range, but you also reduced exhaust gas velocity whichboosts thelower RPM range. The same principle applies to single-plane intakes vs dual-plane intakes. Single plane intakes have larger interior diameter intake runners, which boosts the upper RPM range, but they are designed for high-horsepower engines that operate mostly in the upper RPM range.Dual-plane intakes have smaller interior diameter intake runners, which increases air velocity, and are designed for street engines that operate between idle-5,500 RPM, approximately.</P>


Basically you may have lost a little on the bottom end, which is where your car spends most of it's time on the street, but it opens up the upper end which you will notice at WOT because you have a lot more air flowing through the engine. Essentially an engine is just an air pump, so the idea is to get as much air flowing through the engine, as fast as possible. It's a tradeoff between streetability and *****-to-the-wall performance. Hope this helps...</P>

USAMuscle

The reason you feel more power in 1st gear is because 1st is geared pretty low, so the RPM's are high and all that airflow is taking advantage of the free-flowing H-pipe.

USAMuscle

To really notice the difference with the H-pipe, keep the engine between 3,000 and about 5,500 RPM's as you shift gears.

lmf3626

Well I have an automatic, but thanks for the info.