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For those thinking about a "performance" exhaust system

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#41
What are
I explained in the post why I think it's unnecessary. On that MRT exhaust, it looks like they have tapped the crossover (H pipe) and installed a Helmholtz resonator to give it a particular sound. I am not an acoustics engineer, @UNBROKEN could most likely answer your question.
What are your thoughts on the fact that the MRT exhaust design does not have flex pipes built in? Is that something people should be worried about? Seems like a fairly glaring oversight since they seem to be essential in preventing cracks and premature failures?

I just don’t know enough about it myself just thinking out loud.
 

F=MA

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#42
We spoke about the supercharger option on this forum about a year ago. I was actually searching for the discussion but couldn't bring it up with the forum search engine.

Given this stock 3.0 engine could I remove the turbos and go with just a supercharger setup instead. I assume I would need an upgraded hpfp and injectors. Is the engine stout enough to handle this? What kind of rear wheel horsepower could one generate? Pro and cons?
 

Cruising68

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#43
In the supercharged CTSV crowd the twin turbo guys made way more power than the supercharged guys. Now not an apples to apples comparison of course. They just had the ability to run way more boost. Hard to beat the instant off idle power of the roots style on that 6.2L i had though.

I too am curious what the bottom end and trans will handle. Those running over 500HP are getting pretty good power from a 3.0L IMO.
 

GORDO

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#44
We spoke about the supercharger option on this forum about a year ago. I was actually searching for the discussion but couldn't bring it up with the forum search engine.

Given this stock 3.0 engine could I remove the turbos and go with just a supercharger setup instead. I assume I would need an upgraded hpfp and injectors. Is the engine stout enough to handle this? What kind of rear wheel horsepower could one generate? Pro and cons?
It wouldn’t make sense in this platform, some applications the SC vs turbo is preferred. It’s a lot easier to pedal a SC car, turbos not so much. SC work better on unpreped surfaces/street at certain HP/TQ levels. I had a centrifugal SC on my last vette, on the street tune I was around 700ish rwhp in a 3,200 lbs car. The 345 drag radials keep it hook pretty good above 60ish, down low it was a constant on/off throttle to keep it pointed in the right direction. Now, if I did that with turbos it wouldn’t be as easy, a centrifugal SC has a liner power curve and is more manageable. The SC also makes boost by RPM, if the RPM’s are up, you’re not going to experience any lag, it’s pretty much instant when you roll back on the throttle. I could pulley in down and it would hit like a freight train. Something like an over driven F1-X is a beast. Now as far as PD superchargers, they are great for instant TQ off idle, they don’t perform as well as a centrifugal or turbo on the big end. They work great in heavier vehicles, the second best choice for an ST would be a PD supercharger. It’s all application driven what you choose. Even if you made 800 whp with turbos in the ST, the all wheel drive with a tire will hook, no real point in pedaling it so no practical reason to go to a SC.
 

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TMac

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Thread Starter #45
Turbos make more power and are easily tunable. Not to mention the incredible amount of work to try to mount a blower. And as far as a centrifugal blower- it's basically a turbo compressor driven by a belt and is NOT linear like a PD supercharger. There is absolutely no reason to move to a blower. As far as arguments about instant boost at low RPM on PD blowers, that's correct, and is part of the design. Many people say measure the area under the dyno curve which purports to show that a supercharger is better. But actually you need to think about "where" you start measuring the curve. Are you racing at idle? Measure the area from the rpm where your broadest gear spacing will put you after an upshift at redline. On the ST that's about 4000rpm That's the only area under the curve that should be measured or matters. Of course, a car might "feel" a bit faster when you're tooling along at 2k rpm and hit the gas with a supercharged engine, but once above 4k, (or wherever full turbo boost is available) apples to apples, a supercharger is less efficient and produces less power. The ST with its head mounted small turbos hit full boost at around 2.6k.
 

GORDO

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#46
Turbos make more power and are easily tunable. Not to mention the incredible amount of work to try to mount a blower. And as far as a centrifugal blower- it's basically a turbo compressor driven by a belt and is NOT linear like a PD supercharger. There is absolutely no reason to move to a blower. As far as arguments about instant boost at low RPM on PD blowers, that's correct, and is part of the design. Many people say measure the area under the dyno curve which purports to show that a supercharger is better. But actually you need to think about "where" you start measuring the curve. Are you racing at idle? Measure the area from the rpm where your broadest gear spacing will put you after an upshift at redline. On the ST that's about 4000rpm That's the only area under the curve that should be measured or matters. Of course, a car might "feel" a bit faster when you're tooling along at 2k rpm and hit the gas with a supercharged engine, but once above 4k, (or wherever full turbo boost is available) apples to apples, a supercharger is less efficient and produces less power. The ST with its head mounted small turbos hit full boost at around 2.6k.
Depends on the SC, how it’s geared and if a restricter plate is being used. Saying turbos make more power isn’t correct l, they are more efficient at making the same amount of power. Tuning should be no factor with either method. But, in our application a turbo is absolutely the correct answer to the choice for FI.
 

UNBROKEN

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#47
I can say with no hesitation a Whipple at 17psi making 800+ to the tire in my last F150 was a real good time. Has no traction but still had fun. My 1000+ HP Cummins swapped F250 was a handful but only because of the huge primary charger…it would peak at just over 100psi and would go from 40ish to peak in a split second so throttle modulation especially on wet roads was paramount to staying alive. lol
 

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#48
How may factory turbo cars has anyone seen the owners swapping in a blower? Zero? Would zero be the correct answer? Is that a popular mod in the GTR, 911 Turbo, and F80/G80 M3 communities?

Yet I've seen plenty of of factory blown Mustangs getting those swapped out for turbos.
 

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#49
How may factory turbo cars has anyone seen the owners swapping in a blower? Zero? Would zero be the correct answer? Is that a popular mod in the GTR, 911 Turbo, and F80/G80 M3 communities?

Yet I've seen plenty of of factory blown Mustangs getting those swapped out for turbos.
the vehicles you mentioned are super cars… ST is a family sport suv no where near a bmw suv competition or Porsche Cayenne/macan. We would never be close to a stock GTR 1/4 mile time unless it be a stock RWD GTR.
 

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TMac

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Thread Starter #50
The fact is that the best superchargers: Eaton TVS or Whipple/Lysholm will not make more power than a properly sized turbo since the effective pressure ratios (PR) are generally less than 2.5 (about 22 psi). A centrifugal compressor can make way more boost than that. As far as compressor efficiency, take a look at various S/C compressor maps. While a couple might have efficiency islands approaching 74%, those are at low 1.6 PR or about 9 psig. As soon as the PR gets higher you're rapidly into 60-65% compressor efficiency As far as drive power efficiency, the amount of power required to drive the supercharger is higher than the exhaust energy required for the appropriately sized turbocharger. @MikeyP response can also be pointed to racing in general.

There is absolutely nothing wrong with a supercharger on a high performance street car, especially a heavy one due to it's linear nature and near immediate response, but if you're talking about overall efficiency and maximum available power, it's not comparable to the appropriately sized turbocharger.

Oh, did anyone else know there was a "stock RWD GTR"? Presumably detuned to be slower.
 

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#51
the vehicles you mentioned are super cars… ST is a family sport suv no where near a bmw suv competition or Porsche Cayenne/macan. We would never be close to a stock GTR 1/4 mile time unless it be a stock RWD GTR.
Talking about the motor only. All twin turbo 6 cylinders. Not one of those cars ever made has had its turbos swapped for a blower of any kind.

Also, there's never been a RWD GT-R. That was the lower performance model called the GT-S or GT-T, didn't have the badass RB26 but a version of the RB25, and was last seen in the R34 generation some time ago.
 

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#53
Talking about the motor only. All twin turbo 6 cylinders. Not one of those cars ever made has had its turbos swapped for a blower of any kind.

Also, there's never been a RWD GT-R. That was the lower performance model called the GT-S or GT-T, didn't have the badass RB26 but a version of the RB25, and was last seen in the R34 generation some time ago.
BMW M/competition models get a remap from dealership of a performance tune after like 1k miles. Talk about company dedicated for performance. Wish ford would eventually do it for the ST give us the ford branco raptor tune.

RWD GTR
 

UNBROKEN

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#54
Nobody even knows what the Bronco Raptor HP/TQ will be yet. They say “over 400”….that could be 405. Big deal. The ST is 400/415…it’s not like they’re gonna add another 100HP in the Bronco.
And I surely hope you’re being facetious with that pic. A full tube chassis car isn’t a GTR…it’s a GTR looking body on a chassis. We had Camaro and Corvette looking bodies for the turbo Pro Mod I used to crew on. Might as well say this is a real Corvette. 9374DE85-B22B-45EF-B583-0E93CA631529.jpeg
 

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TMac

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Thread Starter #55
Great conversation! It will interesting to see how the larger relocated turbos on Kruppa's ST turn out performance-wise.

https://www.facebook.com/kevins.cars.fb
No doubt that since he's moved to larger turbos (both turbine and compressor) he'll make more horsepower. And it's some great fabrication but two turbos are NOT better than one (except in certain cases). I'm sure this comment will draw a major amount of criticism. So, I'll open a new thread shortly on why. Stay tuned.
 

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#56
No doubt that since he's moved to larger turbos (both turbine and compressor) he'll make more horsepower. And it's some great fabrication but two turbos are NOT better than one (except in certain cases). I'm sure this comment will draw a major amount of criticism. So, I'll open a new thread shortly on why. Stay tuned.
heat has to be the enemy in this problem cause two turbo fighting to compete equally by trying to pulse the combustion fumes out through the exhaust manifold. I bet one turbo runs slower just to balance out the turbo. That is my hypothetical guess.
 

UNBROKEN

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#57
heat has to be the enemy in this problem cause two turbo fighting to compete equally by trying to pulse the combustion fumes out through the exhaust manifold. I bet one turbo runs slower just to balance out the turbo. That is my hypothetical guess.
Please point out the exhaust manifolds on a 3.0 EcoBoost.
These cars are parallel twins anyway.
 

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TMac

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Thread Starter #58
heat has to be the enemy in this problem cause two turbo fighting to compete equally by trying to pulse the combustion fumes out through the exhaust manifold. I bet one turbo runs slower just to balance out the turbo. That is my hypothetical guess.
Umm, no. But the ST with an even-firing bank V6 and turbos connected directly to the head is a case of two turbos being better than one BASED ON the manufacturer's goals. If you're at all interested, you should be thinking about the characteristic of a V6, why the exhaust manifolds don't look like headers, and why the turbos are mounted so close to the exhaust valves. Then for those with a more technical background, consider turbine/compressor weight, inertial energy, and pressure wave tuning.

This thread is moving from exhaust to turbos, so I'll start a turbo thread where I explain this weekend.
 

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GearHead_1

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#59
Please point out the exhaust manifolds on a 3.0 EcoBoost.
These cars are parallel twins anyway.
What? Did you get one of those crumby integrated set-ups? Must be an early model. ;)
 

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#60
BMW M/competition models get a remap from dealership of a performance tune after like 1k miles. Talk about company dedicated for performance. Wish ford would eventually do it for the ST give us the ford branco raptor tune.

RWD GTR
No they don't. Maybe in the Imaginationland dealership, but not in the real world.

Oh ya, that's totally a stock GT-R. Show me on the Nissan website where I can buy that car. :rolleyes:
 



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