Bought a B6T Turnkey!

[Rocketman]

With the exhaust that short, you're not really going to be able to tame the boost levels. Even with porting.

Nice car though!

[Advancedynamix]

Full exhaust! How about a 3" straight pipe? Exhaust is wide open right now

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By full exhaust I meant a complete exhaust system with muffler, resonator and cat. Preferably a 2" diameter.

[mikemounlio]

I have read the posts saying others get boost creep by just going to a cat back! I like the fender exit tho. Just have to pay attention when I drive.

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[Advancedynamix]

Is there a formula for this. Certain minimum size for set amount of horsepower. Or only if you're internally gated?

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2" is just what is known to work with a b6t that has an rhb5 vj14 or 11 turbine. If you go bigger, especially without a cat, it'll boost creep. The cause is the rhb5 vj14 or 11 wastegate size is too small. Porting helps and aftermarket downpipe helps, but the ultimate cure is more wastegate flow capability. An external gate or a turbo with a larger internal gate will fix the problem. When these engines boost creep past 16psi with the stock turbo you are asking for trouble. Look forward to melted pistons by the valve reliefs or a wasted turbo.

[bhearts]

2" is just what is known to work with a b6t that has an rhb5 vj14 or 11 turbine. If you go bigger, especially without a cat, it'll boost creep. The cause is the rhb5 vj14 or 11 wastegate size is too small. Porting helps and aftermarket downpipe helps, but the ultimate cure is more wastegate flow capability. An external gate or a turbo with a larger internal gate will fix the problem. When these engines boost creep past 16psi with the stock turbo you are asking for trouble. Look forward to melted pistons by the valve reliefs or a wasted turbo.

Cause lean, or cause inefficiency?

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[Advancedynamix]

The heat backs up and flames back through the exhaust valves during overlap. This melts the pistons like a cutting torch. Before that happens though, the exhaust heat and pressure will cause detonation as well. The b6t management runs rich. But rich isn't necessarily safe when you have a short runner exhaust manifold and a restrictive turbine. The extra unburned fuel will burn in the exhaust manifold and add to the heat, pressure issue. This problem is compounded by the fact that the compressor is now working out of its range and the inlet air temps are climbing as well.

You must keep in mind that a turbo engine requires a fine balance of exhaust flow and pressure. This is one of the most untold stories in turbocharged performance tuning. If the exhaust manifold pressure climbs too high the engine will fail much quicker. This exhaust pressure and heat is the single most destructive force in a turbocharged engine. I've seen this overlooked on many failed engines where people assumed the boost pressure or air fuel ratios was to blame.

[mikemounlio]

Could I cut a section of pipe out and replace with a neck down to 2 or 2.5" then back to my 3" outlet

[Advancedynamix]

Maybe. You'd want 2" or smaller with that short of an exhaust. I'd do the whole thing in 1.75" pipe till the outlet. The stock downpipe is like 1.75" i.d. and it's longer than your pipe and with a 2.5" exhaust and muffler (after the stock downpipe) it still crept up to 16psi in Tweak.

[mikemounlio]

I wounder how it would work out if i made a small slip in db killer.
something like http://www.ducati.ms/forums/77-sport...evolution.html.

It would help increase the back pressure but still give me the open exhaust and cut down some sound.

[sketchman]

^Yes do that. Years ago I built a muffler on that idea. It works better than you could imagine.



Had it on a 2.0, and it was the only muffler in the exhaust. Worked so well you would start to hear the engine up front above the exhaust above a certain RPM.

It was like the higher pitch the sound the more it worked.

[mikemounlio]

^Yes do that. Years ago I built a muffler on that idea. It works better than you could imagine.



Had it on a 2.0, and it was the only muffler in the exhaust. Worked so well you would start to hear the engine up front above the exhaust above a certain RPM.

It was like the higher pitch the sound the more it worked.

That is just what i was thinking about.

[bhearts]

I did one similar, except I didn't make the exhaust going into the outer chamber. I just drilled holes and wrapped it in steel wool.

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[sketchman]

So open holes just wrapped with the steel wool? Did that work? Sounds like a glasspack without the outer casing.

[bhearts]

So open holes just wrapped with the steel wool? Did that work? Sounds like a glasspack without the outer casing.

With the outer casing.

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[sketchman]

Oooooh. Gotcha.

Reason routing it through the outer chamber works so well is that the divider that does it reflects the sound nearly completely back on itself and into the back cap of the casing. Then it gets reflected again inside the casing before finally leaving. It's so stupid simple you wouldn't think it would work so well. But it does. I sized and numbered the holes to more than equal the cross sectional area of the pipe too, so it was not restrictive at all.

I'll actually be making another one soon for a Yaris, so this time I will get before and after vids.