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Is the IE stainless exhaust big enough for a turbo???


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I posted this same question a while back, but can't find it.

I'm getting ready to install my turbo motor and don't really want to do another full exhaust (especially since there isn't an exhaust shop in Kodiak). So my question is, is the IE stainless exhaust (2") big enough to handle a turbo??



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what are your power goals? 2" is pretty small for a turbo, not that you couldn't run it but you'd probably have a hard time making above 200hp and even that would really be pushing it. With the calc below 2" is good from ~160-165hp but that is straight piped not including the muffler and resonators in the IE system.

2.5" would probably be perfect and give you breathing room up into the high 200's.

I'm kinda stuck with 3" and it's going to be a PITA to fit.

Here's a good general idea to calculate diameter, quoted from David Vizard who has written a handful of books on building small block V8's.

1. For avoiding significant restriction from back pressure, the pipe should flow at least 2.2CFM per horsepower produced.

2. A straight pipe will flow ~115CFM per square inch of area (using inside diameter of the pipe)

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Everything I've encountered w/Turbo motors in my previous life w/red block Volvo's says the piping size is critical for the first 2-3ft after the turbo. If you can get that at 2.5-3" and then neck down once the exhaust starts to cool, you should be able to keep velocity up and not inhibit power. Most of the 240/740 turbo guys will run big downpipes but neck down due to space constraints. Of course, bigger is always better.

PS: If you decide to dump it, just throw it on the next Herc heading down to Sacto =o)


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Mighty Warship 87344 (aka HERON) out of beautiful Sabine Pass, TX. Challenging AOR/Home Port, but I had a rockstar crew which made all the difference.

Unfortunately, I don't think MAUI will be coming home, but she's doing good stuff in her final years.

Take it easy, and Happy Thanksgiving!


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i'd say it depends on your torque vs. horsepower requirements-

a smaller exhaust will restrict flow after a certain point

The down side with a turbo is that it usually won't boost low- end

torque by scavenging like a normally- aspirated car will.

The turbine really just wants to get rid of the exhaust, and

the scroll restriction reduces the pulsing that you can tune.

So if you just want a solid 150 hp car that pulls off the light, I bet the

2" ireland setup would be just fine. But you'll start to lose turbine

efficiency a lot sooner than you would with a bigger exit pipe.

I figured out that, for a 2L Volvo B20 (a bit less flow than an M10) a 2 1/4"

Would be good up into the 5500 range- and that was all I wanted from that motor.

I DID use a chunk of 2 1/2" to get out of the turbo and through the first 2 bends,

the idea being that it would give the turbulent exhaust flow a chance to

smooth out just a bit before it hit the 2 1/4".

Still haven't gotten THAT project going, so I dunno if it'll work.


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