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And didn't you lift a head or blow your motor?

Squeezing all that pressure into a tiny T3 flange, then releasing all that pressure after the restriction is counter intuitive. That's why as soon as people go to high mounts they pick up power but it's not so much the high mount it's more so the exhaust gasses be bleed off before the collector.

Boost control is subjective, and your 6tits probably doesn't have twin gates off it or the merge between both scrolls to the gate was poor.

If you ever have an exhaust pressure sensor or gauge on the collector you'll understand.

1 minute ago, Griffin said:

Is there any difference having wastegate on manifold at / before collector over the turbine housing?

Yep, you'll reduce exhaust back pressure, make more power, less things glowing on the hot side.

I did that only mod and with the same timing map, same boost, same turbo (except it was a BB centre this time round, same comp/turbine wheel) and made extra 20kW off the bat. 

4 hours ago, Dose Pipe Sutututu said:

And didn't you lift a head or blow your motor?

Squeezing all that pressure into a tiny T3 flange, then releasing all that pressure after the restriction is counter intuitive. That's why as soon as people go to high mounts they pick up power but it's not so much the high mount it's more so the exhaust gasses be bleed off before the collector.

Boost control is subjective, and your 6tits probably doesn't have twin gates off it or the merge between both scrolls to the gate was poor.

If you ever have an exhaust pressure sensor or gauge on the collector you'll understand.

Wouldn't the actual restriction be the actual turbine housing itself?
By my understanding of pressure, the pressure inside the manifold would not be altered depending on where the gate was, as long as it's between the head and the turbine wheel.

I had 1 gate in both setups, and a 45mm gate off the housing vs a 50mm gate off the 6boost. You can tell just by looking at it which gate is in the better spot for flow.

I agree with you, going external gate does free up power, once you start to really get the most out of any specific turbo. IWG's of any kinds (Even on EFR's!) seem to just not cut it once you really, really want to get the most out of a rear housing.


In this example though, the engine is likely to let go before the turbo or gate really even gets involved as a point of discussion

Here's a thought experiment.

Let's say that the exhaust gas needs to be split 50/50 between the gate and the turbine.  If the ext gate is on the turbine housing, then you are shoving double the amount of gas into the housing than if the gate was on the manifold somewhere.  Either way, we want the same 50% to make it all the way to the nozzle, but in the region between the flange and the housing mounted gate, the gas velocity must be double.  Pressure losses go up with the square of velocity.  So whatever frictional losses occur, they are doubled.  The exhaust gas is losing energy before it has even made it to the turbine.  It must therefore not be as good as if it was vented before the housing.

The difference might not be large, but it will be there.

The one big advantage of putting the gate on the housing is that it is easier to put it in a spot where the gas is definitely flowing towards the gate (because all the gas is flowing that way anyway) which makes it a little harder to f**k it up the way that people do when they put ext gate offtakes onto manifolds at bizarre angles.

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