ideal x-pipe positioning for performance gain?

[Icer006]

Originally Posted by JCL

A larger diameter, to reduce restriction and flow more. That assumes you need to flow more; the standard exhaust isn't particularly restrictive IMO. If you combine a larger diameter exhaust with free-flowing catalytic converter and a free-flowing muffler, you can gain a few hp. Wouldn't be worth it (hp/$) but it is technically possible.

I agree with everything JCL has said, but just be careful when putting a too large of an exhaust. The car (if an automatic) still needs back-pressure for the torque converter. This *could* be the reason why TowX had to tow in lower gears because there wasn't enough back-pressure for the torque converter.

[JCL]

Originally Posted by Icer006

I agree with everything JCL has said, but just be careful when putting a too large of an exhaust. The car (if an automatic) still needs back-pressure for the torque converter. This *could* be the reason why TowX had to tow in lower gears because there wasn't enough back-pressure for the torque converter.

I wouldn't consider putting a larger diameter exhaust on, unless I was doing something like a forced induction system and had more exhaust gas flow to deal with.

I do agree that reducing the back pressure can reduce low-end torque. I don't see the connection to the transmission torque converter, but it can reduce engine torque. The torque converter is downstream. And once you are moving you should be getting it into lockup mode and removing the torque converter from the equation in any case.

[Icer006]

Originally Posted by JCL

I wouldn't consider putting a larger diameter exhaust on, unless I was doing something like a forced induction system and had more exhaust gas flow to deal with.

I do agree that reducing the back pressure can reduce low-end torque. I don't see the connection to the transmission torque converter, but it can reduce engine torque. The torque converter is downstream. And once you are moving you should be getting it into lockup mode and removing the torque converter from the equation in any case.

I see your point, but ultimately, the connection is that there may not be enough low-end torque to lock-up the torque converter. I'm talking in the worst case scenario where the engine would simply stall. The torque converter is downstream from the engine, but still coupled to the motor via the flywheel.

It's almost like taking off in 6th gear on an MT car. But I think I digress and you and I agree that backpressure is somewhat needed for low-end torque.

[IMOLA 4.6is]

Great this thread has just thrown another bone in the mix... I have a 4.6is replaced resonator with straight pipe, not happy at all with the sound or feel. The sound is not smooth and I feel a loss of torque with a lot of back pressure on deacel.

So I ordered the X pipe and it will be here today, but based on what Tow is saying should I have gone with a simple H?

Originally Posted by Icer006

I see your point, but ultimately, the connection is that there may not be enough low-end torque to lock-up the torque converter. I'm talking in the worst case scenario where the engine would simply stall. The torque converter is downstream from the engine, but still coupled to the motor via the flywheel.

It's almost like taking off in 6th gear on an MT car. But I think I digress and you and I agree that backpressure is somewhat needed for low-end torque.

[TowX]

Don't use me as an example. I seem to be the only one who lost torque when I did the x-pipe. Perhaps if I'd moved it 2" forward or 3" back it might have worked, but based on where I had it mounted I was extremely disappointed. As I've said in other posts, I lost so much power/ torque at 2500-3500 rpm that I had to tow in one gear lower than stock. If I had to guess, I lost 20-30 lb-ft in that rev range. Sounded great at 5500, but I don't drive that way.