at what point is a 38mm wastegate not big enough
09-06-2012, 06:50 AM
#32
This should improve wastegate response by a fair margin - we could call this a twin scroll wastegated set up 
On a stock cross pipe exhaust gases have to go through an almost U-turn before reaching the WG - I see this significantly reduce wastegate response when backpressure becomes so low that exhaust gases will, as Tommy says, more easily flow through the turbine before flowing to the WG.
The conclusion here could be : the lower the backpressure, the smoother the direction of exhaust flow to the WG must be to keep a satisfying WG response.
Tommy, what piping size did you choose for the main body of the cross pipe? Looks like it's slightly larger than a stock cross pipe?
On a stock cross pipe exhaust gases have to go through an almost U-turn before reaching the WG - I see this significantly reduce wastegate response when backpressure becomes so low that exhaust gases will, as Tommy says, more easily flow through the turbine before flowing to the WG.
The conclusion here could be : the lower the backpressure, the smoother the direction of exhaust flow to the WG must be to keep a satisfying WG response.
Tommy, what piping size did you choose for the main body of the cross pipe? Looks like it's slightly larger than a stock cross pipe?
Last edited by Thom; 09-06-2012 at 09:25 AM.
09-06-2012, 11:40 PM
#33
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Thread Starter
They are SFR stage 1 headers; not sure if the cross-over is larger than stock.
The main issue is that the exhaust flow is smooth and symetrical from the exhaust valve all the way to the turbo and wastegate.
Definite seat of the pants in power improvement at all rpms and throttle positions.
The main issue is that the exhaust flow is smooth and symetrical from the exhaust valve all the way to the turbo and wastegate.
Definite seat of the pants in power improvement at all rpms and throttle positions.
09-07-2012, 09:35 AM
#34
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Maybe this is your problem? I've never run the boost reference line from that banjo. (other than a stock configuration only - which got changed within one hour of owning the car) Do you still have the stock banjo with the restrictor in there? - which would be the culprit of this issue....Even if it's a different restrictor, I HIGHLY suggest using a boost line straight from the turbo and the make sure that line goes straight to the (EDIT>>> Lindsey wastegate!? Is this the one that is rebuilt from the factory piece?) Then connect the line to the top only. Leave the side port open.
09-07-2012, 02:42 PM
#36
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Some guys might have a restrictor in the banjo as a means to control boost, but the stock unaltered banjo is no boost restriction what-so-ever.
09-07-2012, 10:39 PM
#37
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Turbo Tommy is most likely correct, but every damn one of these things I've seen has had a stupid autothority chip and restrictor in that banjo bolt. JUST to be sure, take a boost reference off a port on the manifold or anywhere you know you have a clean boost reference. But checking the banjo bolt first would be a great place to start.
