Gibson black-ceramic (PN 69548-B)

[smurfslayer]

yeah, the thing is, zero back pressure makes for some unfortunate dips in the power curve. Look at any Harley shop dyno database of before / after “drag pipe” install. There’s a reason that open pipe HD are annoying as $hit, they’re not just loud, they’re loud and lose SIGNIFICANT horsepower and torque where they used to spend most of the time in the Rpm range. So post drag pipe install, instead of having 60 pound feet of torque they have 40, and so they need to nail the throttle even more to get the same acceleration they had before installing open pipes ! Sure, they get about 8 horsepower at 5500 rpms, but lose more than that through a majority of the power curve.

I know blown / turbo engines have a different power curve and behavior, but one of the key elements of the Raptor’s engine performance is the early onset of torque, and the linear delivery of the available power.

Silverbolt is right, dyno, cut new muffler in, dyno again no other changes.

Nobody has any tangible and credible back to back results now and we’re all just speculating right now.

 

[nikhsub1]

There is plenty of evidence that zero back pressure on turbo applications is the way to go. Citing a v twin Harley is not relevant at all. Less exhaust restriction will result in more torque earlier in the RPM range.


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---------- Post added at 04:33 PM ---------- Previous post was at 04:25 PM ----------

An example of the car I've got, 2.0 turbo 4 (Golf R)




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[shelteredraptor]

This exhaust is actually really well thought out and made from the factory. I believe the adapters from the hot side of the turbos will free it up as they are about 5/16' bigger than stock. The pipes are well bent and have little restrictions in them, from a casual glance. My take on it is that there is nothing but noise to be gained on this exhaust (besides the adapter rings). Until there is accurate dyno proof showing otherwise, Ima sticking with stock exhaust and adapter rings.
As a good comparison, my CTSV stock exhaust had a MAJOR crimp right at the X pipe (well documented) that was a huge restriction. What is kinda funnny is that I have a gazillion bucks into ARH longtubes into custom 3" stainless through custom resonators back to STOCK mufflers modified to accept 3" pipe. This is necessary to accommodate 17 psi of boost and to try and keep the thing quiet.

 

[Guy]

So back Tony original point of topic...
not that this hasn't been a great discussion because it has...

Spoke with Gibson and they promised me no drone at highway speeds or otherwise but expect it to be raspy during acceleration and when lugging it.

They also apologized and said the ecoboost sounds like the ecoboost and they have not had any luck making it sound better than where they are now with it... which is kinda brapppy and not rumbly.

15-20 and 25-30 ft*lb is their claim based on a 30+ percent reduction in muffler restriction.

There you have it.

Guy

 

[robbys3m3]

While not their catback, welding their wma muffler inline I highly doubt there will be any highway drone issues. I'm experiencing a little about 2500 rpm in sport mode around the city, but still not horrible...most folks that heard my truck before and after are fairly impressed with the overall tone change from stock

 

[smurfslayer]

There is plenty of evidence that zero back pressure on turbo applications is the way to go. Citing a v twin Harley is not relevant at all. Less exhaust restriction will result in more torque earlier in the RPM range.


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---------- Post added at 04:33 PM ---------- Previous post was at 04:25 PM ----------

An example of the car I've got, 2.0 turbo 4 (Golf R)



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so what changes are in the 2 ’stages’ listed on the graph?

changing a muffler and nothing else is not going to net 25 hp, turbo or not unless it is the only choke point in the system. The cats almost always will easily yield more power than a muffler - at least, that’s the dyno experience I’ve seen - I’m thinking...12, maybe 15 runs, many of these with groups, who were doing exactly this, baseline, make a change, test, repeat.
Bikes I’ve got probably 250 dyno runs done over 3 motors. I’ve seen probably half a dozen (car) people come to dyno muffler or cat backs maybe one of them picked up horsepower, 2 of them lost power. I’ve seen high flow cats pick up 10 hp at the wheels easily half a dozen more times.

Maybe others’ experience is different? Anyone ever seen, first hand, not reported to you, but you actually witnessed a cat back only produce more power ? If so, how much?

 

[nikhsub1]

so what changes are in the 2 ’stages’ listed on the graph?

The difference between stage 1 and stage 2 in the graph is simply an aftermarket down pipe. The stage 2 tune is optimized for the increased flow and also to code out any CEL. The thing is, the driveablitily is MILES better between stage 1 and 2 even though the dyno says gains are rather moderate.

 

[smurfslayer]

So, good gains for a down pipe, but that’s not a muffler, or cat back. Also a good looking curve, but, are you at practically zero back pressure?

do you run open headers, no cats, no mufflers?

If so, impressive torque curve. If not, I’d still want to see some relevant dyno graphs. Yeah, an open pipe HD is an extreme example because they have relatively low hp numbers to begin with, and while straight pipes will gain them maybe 5 hp up top, they losing ~10 throughout the range where you spend most street time, and the torque takes a huge hit. I used this as an extreme example but the point about zero or practically zero back pressure is probably taking us way off topic because how many of us are going to run around with dumps, cut outs or straight pipes?

I’m skeptical that any muffler is going to yield anything HP wise, maybe low single digits at best. That said, stranger things have happened.
- years ago, my local speed shop offered a ported stock MAS for a Mustang. cheap, and they swore by it. Internet wisdom SCOFFED at this for all manner of scientific reasons. +9 hp at the wheels, back to back dyno test. I even tested against an aftermarket MAS, it gained 4 hp over stock. Then back to the one that shouldn’t have worked, but gained 9 hp - picked up 5 (from the aftermarket unit, so right back to where I was).

so... Guy, take one for the team already and get the exhaust...

 

[Guy]

Smurf,

I am. Lol. Guy spent a little too much this month on rims, Baja lights, and stereo upgrades. So Guy has gotta wait a few weeks. Lol

 

[Guy]

Budget constraints!

I really like these black KMC XD129 hole shots though.

Guy