Sure, Mikey, theoretically it is supposed to function exactly in the manner which you have outlined above. However, this is just theory and the actual extent to which TS helps spoolup varies from case to case.

As long as the flapper valve remains closed on its seat there exists a separation of pulses. This is dependent on WG spring pressure/WG preload etc.

Every user runs a different amount of WG spring pressure. As soon as the flapper valve starts to lift or crack then the TS effect is compromised or lost, right?

 

i made this post, in various threads. Here is more info here

https://www.evolutionm.net/forums/en...-w-fp-red.html


Yes. This is more pronounced on the stock frame exhaust housing because the distance from the scroll and the flapper is so short.
Something like Ted B's setup wouldn't be so bad, because there is some length in each scrolls wastegate pipe before it merges into 1 pipe for the external wastegate.
Old School F1 did it like that too, but they probably did it more so for weight reasons.

 

Mike is right. As soon as you open the internal gate flapper you now dilute the pulses....wasting the TS. Therefore it WILL spool slower.

 

From my perspective, it is tough to isolate whether the loss in spool would be due specifically to 1) the reduced pulsations from the TS design, 2) the overall loss of exhaust pressure within the turbine housing when the flapper valve opens, or 3) a combination of the two phenomena.

For example, on a non-divided internally gated housing there is obviously also a reduction in shaft speed when the flapper valve lifts off of its seat. This is similar to the reduction in shaft speed which occurs in a TS internally gated housing isn't it?

So, how much of the reduction in shaft speed is due exclusively to the loss of the effectiveness of the TS pulsations and how much is due to the general loss of internal pressure which always occurs whenever a WG puck opens on either a divided(TS) or a non-divided housing?

 

1 and 2 are same thing. TS raises turbine pressure during spool. thats what spools turbo faster. when flapper is opened some of pressure of cylinders 1/4 can bleed into 2/3 . and some of the pressure of 2/3 bleeds into 1/4. the net effect is less turbine pressure and slower spool.

 

With this theory, do you think you could make more power/torque if you ran 2x wastegates so that the scrolls are completely isolated from each other once maximum boost has been reached?

 

All that i am getting at is this: When you weld the flapper valve open on a twin scroll turbine housing you will surely get a loss in spool. However, likewise, when you weld the flapper valve open on a single scroll housing you will also get a loss in spool. Duh!

So, you can't just go and say that the loss in spoolup on a TS housing is due exclusively to the loss in TS pulsations. The overwhelming majority of the loss in spoolup can be blamed on the welded open flapper valve. It just seems difficult to quantify the difference. I don't buy the mantra....that's all.: Cheers!

 

you have to keep the chambers divided up to the valve seat. Or divide the two passages with a divided tube and run two gates. It would require welding to cast iron and the increase it weight over the front tires...not to mention the expense would make it not advisable. You'd be better off running the factory internal gate at that point.

 

i was meaning in general, not the stock framed exhaust housing.


why will you get a loss in spool if you weld the flapper open on a single scroll housing? (obviously you'll be running an external wastegate)

With a single scroll housing, there are only 2 possible paths, through the turbine and out the wastegate. (not taking reversion into account)
For a twin scroll housing there are 3 possible paths, Through the turbine, out the wastegate and into the other scroll...

 

Someone on here released this product last week

 

My bad! In my mind, I was comparing an integrally gated TS housing to an integrally gated undivided housing....all else being equal, Mike. Nice discussion though. Ernie has a point with the separate gate for each half of the twinscroll housing. Things would become just to complex, huh?

I am just not that convinced that the TS concept applies beyond the turbine housing inlet area and the twin scrolls. The wastegate bypass ports are at right angles to the main exhaust gas flow path. I just don't swallow the pablum that easily. Sure there would be a certain degree of reversion. But, just how significant would that be. I feel that it is just conjecture.

 

Cool and juicy pics, I.R.A.!

 

What exactly do you mean here?

With twin scroll, there is little to no reversion. This is because the pulses are so far apart that they are isolated from each other (no overlapping exhaust valve timing on the same scroll). I remember Geoff from ETS posting something in the twin scroll threads. Thats one of the main advantages of it.

what does the wastegate bypass port angle have to do with anything? I dont understand what you mean


yeah i would love to see back to back testing on that versus a stock manifold!!

 

What exactly do you mean? I am having trouble with your reasoning as well.

 

I was refering to reversion at the wastegate puck's seat when the puck is lifted. We are talking about reversion at the flapper valve's seat, not in the scroll area of the housing.