MustangExhaust.com is happy to announce that our first tech article, Power Struggle: H-pipe vs. X-pipe. We pitted an off-road H-pipe against an X-pipe to see which would blow the other away. The results, to say the least, were quite unexpected.
Tech Article: H-pipe vs. X-pipe is online!
- Thread starter Nino
- Start date
wtf
You can actually pick up 20 horses by just replacing the stock mufflers?!?!? :rolling:
You can actually pick up 20 horses by just replacing the stock mufflers?!?!? :rolling:
Spit it out maaaaan!!! we all know its the mufflers that restrict the cobra exhaust, so just give us the results of the mid-pipe test without clicking the link! ;-)
Hard to believe the bottle-neck is in the mufflers and not the 4cat H-pipe. Does anybody have any dyno results with an after-market cat x or h pipe? Sounds like a good marketing pitch.
Also, Mangnaflow PN 14377 is this a 2.25 or 2.5 inch muffler?
Bill
Also, Mangnaflow PN 14377 is this a 2.25 or 2.5 inch muffler?
Bill
First of all, let me say thank you to everyone for reading the article and commenting on it. I welcome all comments and will try to address them all.
Let me start off by saying that this test was primarily to see which mid-pipe transition type, H or X, produced the most power. I have to admit that the peak power levels of the off-road pipes compared to the stock H-pipe kinda stole the show but I'll try to remain focused.
Some observations/comments:
1. MIL Eliminators - not necessary for testing the off-road pipes. I got this info from Dan Smith, maker of the MIL Eliminators.
2. Disconnecting the battery to clear the computer - I'm certainly no OBD expert but it seems to me that this practice is debatable when changing the exhaust. The only sensors on the exhaust are the two front and rear O2 sensors. The fronts are upstream of the catalytic converters so they wouldn't sense any difference between a catted and non-catted mid-pipe and these are the sensors that the computer uses to adjust a/f ratio. The rear sensors are there only to make sure there are cats on the mid-pipe and don't have any effect on the tune of the engine. I can't explain the strange dip in power that's mentioned in the tech article, but I do know that it was gone after driving the car for a few miles. I will try to investigate this issue to get a difinitive answer from someone with OBD authority.
3. Power gains - looking at the dynographs shows that there were some significant power gains in the upper rpms and I imagine that removing the restrictive mufflers would enhance this power even more. In a drag race situation where the engine is above 4000 rpm most of the time, these power gains would absolutely improve quarter mile times. The off-road mid-pipes also have a significant weight advantage compared to the stock H-pipe, which would improve performance as well. Remember that peak numbers don't tell the entire story.
4. Power trends - the trend I see between the H and X pipe is that the X-pipe seems to move the torque curve more to the right than the H-pipe. This goes right along with the common notion that the X-pipe is a better high-rpm performer. Again, removing the restrictive mufflers might magnify the differences even more.
5. Pipe diameter - how can the stock h-pipe with 4 cats produce more low-end torque than the off-road pipes? Simple: tube diameter. The larger 2.5" tubing used to make the off-road pipes is hurting low-rpm exahust velocity, but helping it in the upper rpms. There may also also be the issue of lack of back-pressure, but with the very restrictive stock mufflers I don't see that being the case here.
6. These results don't apply to everyone - like I mentioned elsewhere, these results may only apply to 2001 Cobras. The stock H-pipe on the 2001 Cobra looks different than the any previous year. The cats look smaller and the pipes are all mandrel bent. This H-pipe may well be more efficient than previous H-pipes and so we don't see the big peak gains that we're used to seeing. Here's a pic of the 2001 Cobra stock h-pipe.
Mufflers are also different for different model years. The '99 Cobras got new mufflers because the originals were too restrictive. The '03 Cobra has new mufflers that, from most first hand accounts, are very quiet.
I want to stress to everyone again that peak numbers don't tell the entire story. The pipes that were tested are not losers. The X-pipe we tested gained 12 rwhp and the H-pipe 10 rwhp over the stock h-pipe, just not at peak. You WILL see some performance gains at the track with either off-road mid-pipe.
Thanks again everyone.
Nino
Let me start off by saying that this test was primarily to see which mid-pipe transition type, H or X, produced the most power. I have to admit that the peak power levels of the off-road pipes compared to the stock H-pipe kinda stole the show but I'll try to remain focused.
Some observations/comments:
1. MIL Eliminators - not necessary for testing the off-road pipes. I got this info from Dan Smith, maker of the MIL Eliminators.
2. Disconnecting the battery to clear the computer - I'm certainly no OBD expert but it seems to me that this practice is debatable when changing the exhaust. The only sensors on the exhaust are the two front and rear O2 sensors. The fronts are upstream of the catalytic converters so they wouldn't sense any difference between a catted and non-catted mid-pipe and these are the sensors that the computer uses to adjust a/f ratio. The rear sensors are there only to make sure there are cats on the mid-pipe and don't have any effect on the tune of the engine. I can't explain the strange dip in power that's mentioned in the tech article, but I do know that it was gone after driving the car for a few miles. I will try to investigate this issue to get a difinitive answer from someone with OBD authority.
3. Power gains - looking at the dynographs shows that there were some significant power gains in the upper rpms and I imagine that removing the restrictive mufflers would enhance this power even more. In a drag race situation where the engine is above 4000 rpm most of the time, these power gains would absolutely improve quarter mile times. The off-road mid-pipes also have a significant weight advantage compared to the stock H-pipe, which would improve performance as well. Remember that peak numbers don't tell the entire story.
4. Power trends - the trend I see between the H and X pipe is that the X-pipe seems to move the torque curve more to the right than the H-pipe. This goes right along with the common notion that the X-pipe is a better high-rpm performer. Again, removing the restrictive mufflers might magnify the differences even more.
5. Pipe diameter - how can the stock h-pipe with 4 cats produce more low-end torque than the off-road pipes? Simple: tube diameter. The larger 2.5" tubing used to make the off-road pipes is hurting low-rpm exahust velocity, but helping it in the upper rpms. There may also also be the issue of lack of back-pressure, but with the very restrictive stock mufflers I don't see that being the case here.
6. These results don't apply to everyone - like I mentioned elsewhere, these results may only apply to 2001 Cobras. The stock H-pipe on the 2001 Cobra looks different than the any previous year. The cats look smaller and the pipes are all mandrel bent. This H-pipe may well be more efficient than previous H-pipes and so we don't see the big peak gains that we're used to seeing. Here's a pic of the 2001 Cobra stock h-pipe.
Mufflers are also different for different model years. The '99 Cobras got new mufflers because the originals were too restrictive. The '03 Cobra has new mufflers that, from most first hand accounts, are very quiet.
I want to stress to everyone again that peak numbers don't tell the entire story. The pipes that were tested are not losers. The X-pipe we tested gained 12 rwhp and the H-pipe 10 rwhp over the stock h-pipe, just not at peak. You WILL see some performance gains at the track with either off-road mid-pipe.
Thanks again everyone.
Nino
They are 2.5" inlet and outlet.
What is the price for the muffler by themselves??!! (PN14377) I called around and they are more expensive than flowmasters!
They are also made of polished stainless steel so they will last longer than Flows, not to mention they will make more power. Try http://www.fulllineexhaust.com
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