^ but doing that setup would be very expensive needing a new manifold + 2 wastegates

Michael@ETS did one for a customer and turned out really nice but the price tag was 1500 I believe.

Mikey

 

Oh at least, more work/materials than your standard stock frame plus two wastegates.

 

im currently running a map compgate setup aka external wastegated o2 housing and it seems to work pretty well. I had the internal wastegated parts removed and the hole welded shut. it does seem to spool a little slower, but on a stock block w/ an fp black it seems to work out well. with more hp left in the car i stopped at 560whp 430 tq vdr. this is my first factory turbo car and felt from past experience an external would suite my needs better.. personally i would do it again

 

OK Chris, I'll have to "chaw" on that "actuator in place with a direct boost source" idea until I can visualize what you mean exactly. But, it makes sense if you can retain the TS effect. Thanks.

If I am understanding the setup...it would be inline dual gated but the valve on the remote gate wouldn't "see" any exhaust flow until the internal gate lifts. Mikey's system is a bit different as he has to some extent done away with the TS effect due to hogging out the turbine inlet area(i.e. removing the divider wall)of the turbine housing and hogging out the turbine bypass port that leads to the flapper valve location(If my memory serves me well).

The way that I see it the TS effect is mostly an issue in the turbine inlet area and downstream beyond on into the scroll area of the turbine housing. That is it is relevant when discussing the main axial flow through the housing that directly impacts the turbine blades tips.

Whether, and to what extent, it is essential to maintain TS pulsations tangentially out through the turbine bypass port being bled off the main axial flow at a 90 degree angle is another issue. The importance of the pulsating exhaust energy impacting the turbine blade tips is obvious. But to what extent it is actually needed to maintain TS pulsations at the flapper valve face which lifts according to the flapper valve's overall seat pressure and the pressure differential between that seat pressure and WG spring tension is not necessarily a given.

In fact it would be interesting to do a comparo(though probably only to me) using your remote gate setup on a stock housing vs. a housing with the bypass port divider bored out and totally removed. It's just that ultimately I see the flapper valve itself as well as the bypass port divider wall as becoming obstacles to bypass flow out through the bypass port.

Placiing a larger, valved remote gate further downstream while leaving the significant bypass port divider wall obstruction and the flapper valve itself in place when we are trying to improve flow out through the bypass port does not leave me convinced that there still wouldn't be room for improvement ?

I guess that you have tested the setup with and w/o the flapper valve in place and you got the best results with the method that you have outlined above.

I wonder whether on a 2.3 motor leaving the flapper valve off and totally boring out the bypass passage might result in better bypass flow without detracting too much from spool up. What do you think? Have you played around with this idea at all when designing or installing one of these remote gate setups? I am not trying to be argumentative. It is just that if you look at the stock bypass port as cast with the divider wall in place...the divider wall takes up about half the potential volume of the bypass passageway.

 

I can't comment on several of your more technical points above, but we did test it and removingthe internal flapper from the equation results in loss of spool. I think you're missing the point of this modification though. We're not interested in improving flow through the wastegate outlet (which would help resolve boost creep) rather we're trying to make sure the additional backpressure in these high output applications doesn't prematurely force open the wastegate limiting potential boost pressure, an area in which the external wastegate design excels.