O/R X-pipe to headers and cats...lost power

[txA&M08]

I searched but couldn't find a thread specific to this change in setup.

So I went from stock manifolds and Lethal 3" O/R x-pipe to ARH 1 3/4" and catted x-pipe. The rest of the exhaust is a Magnaflow Street catback. AED tune before and after.

A few things surprised me...

First, the car is MUCH quieter than it was before. I was expecting an increase in volume. This is fine though...I'm sure the neighbors appreciate it. Maybe the cats are a bit more restrictive than I had anticipated.

Second, butt-dyno told me there were either no gains or it was actually slower. I drove about 100 miles throwing codes for no O2 connection (harnesses suck) and overfueling like crazy, before I used some Raptor O2 sensors to fix the issue. I had no choice, unfortunately. It's a possibility the plugs could be fuel fouled. Once I got the O2s hooked up, I went and put it back on the Mustang dyno that I had run on before. The two runs were 6 months apart and the Weather was way different but the graph below has both runs SAE corrected, for what it's worth.

Since the colors don't contrast well, the new torque curve shows huge gains down low and slight loss after 4700. The HP curve also shows slight gains under 3500 and a slight loss of power over 4700. Basically, I wasn't expecting to lose peak power. Throttle response isn't as snappy as it was either.

I have datalogged it since, and everything checks out with Shaun. Cat deletes are on their way from ARH, so I'll put it back on the dyno to see exactly how restrictive their cats are when they come.

Anyone else out there lost power with this combo? Any chance it could be the plugs?

 

[blackbeast12]

So you went from no cats to cats, and you expected more power and more sound! It's pretty obvious the cats are restricting you!

 

[txA&M08]

Lol when you put it that way...

I figured the gains from the long tubes would offset any restriction from the cats but the cats are downstream so I guess that theory doesn't make sense.

Still wondering if 100 miles is enough to foul the plugs though...

 

[blackbeast12]

When I went with a stainless works off road x, my car said thanks, that's what I needed! And that's with kooks super street shorties with 1- 7/8 primaries. The 2 together netted me 30 hp! And the sound is awesome!

 

[Ron Mexico]

Would be interested in seeing your numbers with the cats off and headers on.

 

[Monster5.0]

Surprise surprise people. I have been saying this for a while now and I know it to be true. Headers are not what makes power on these cars when you are boltons/na. Its removing the cats and this can be done with cat deletes or an offroad midpipe. Headers are better suited for boosted coyotes because then the manifolds will become a restriction. But NA, there is nothing more there that can be had.

 

[13GT5.0]

Surprise surprise people. I have been saying this for a while now and I know it to be true. Headers are not what makes power on these cars when you are boltons/na. Its removing the cats and this can be done with cat deletes or an offroad midpipe. Headers are better suited for boosted coyotes because then the manifolds will become a restriction. But NA, there is nothing more there that can be had.

Hmm.,some have claimed a big jump in torque under 3k with long tubes, but yea hp isn't much of an increase.

 

[txA&M08]

Would be interested in seeing your numbers with the cats off and headers on.

I'll post an overlay of cats and no cats whenever the pipes arrive from ARH.

Surprise surprise people. I have been saying this for a while now and I know it to be true. Headers are not what makes power on these cars when you are boltons/na. Its removing the cats and this can be done with cat deletes or an offroad midpipe. Headers are better suited for boosted coyotes because then the manifolds will become a restriction. But NA, there is nothing more there that can be had.

I have FI plans down the road but this was pretty expensive for something that "couldn't hurt" lol. I wish I had more time to research these things but I don't.

Hmm.,some have claimed a big jump in torque under 3k with long tubes, but yea hp isn't much of an increase.

Yep..you can see I'm up about 50 ft/lbs below 3000.

 

[slagburn]

Thinking about making the switch to headers but the expected power gain may change the price point a bit. What sort of gains are people seeing on a supercharged application, already have an ORH pipe but stock OTA pipes. Car makes around 730 rwhp uncorrected as is, going off trap speed/ weight.

30hp gain.. meh, for the price. 60+ would be another story.

edit: should mention car is 2.9, unported heads, Boss exhaust cams, 11.5:1

 

[sinistr302]

so you gain more power with an off road h/x pipe then you do with longtubes! :shrug:

 

[corysmach1]

Hmnn.....

 

[nosscort]

looks like your before number is higher because of the weird Spike at the very end.. otherwise looks like you gained all the way through the power band some. not much but some. The torque is up like you said in the lower rpms.

 

[Blazer707@TBR]

OP there is nothing to be concerned about, you went from no cats to cats. That's where all the HP lose is from.

Going from an o/r X to LT's you will see an increase in HP. Might not be 15rwhp+, but there will be some.

Long tubes most definitely help low end torque out.

 

[corysmach1]

I agree Blazer.....some people claim 25-30rwhp some gain hardly anything. I am just so on the fence with Longtubes.

 

[mach330]

Thinking about making the switch to headers but the expected power gain may change the price point a bit. What sort of gains are people seeing on a supercharged application, already have an ORH pipe but stock OTA pipes. Car makes around 730 rwhp uncorrected as is, going off trap speed/ weight.

30hp gain.. meh, for the price. 60+ would be another story.

edit: should mention car is 2.9, unported heads, Boss exhaust cams, 11.5:1

At your power level, you would pick up around 30hp and it would reduce boost.

 

[txA&M08]

I've since dialed in an additional 7whp (peak) at Triangle Speed Shop for anyone who's interested. Long tubes, especially ones with less-than-ideal O2 placement, take some fine tuning apparently.

 

[cb900f]

Daniel @ TSS is the man!

 

[Mach828]

Was the car tuned afterwards?

 

[txA&M08]

Was the car tuned afterwards?

Yes. AED before and after.