Re: Which is the lesser of 2 evils when running a W/G setup?
Electronic computer control will provide the best electronic control - but a good physical wastegate situation that controls the exhaust pressure before the turbo is necessary to make the most of the electronic controller. A good electronic controller might work like crap with a bad wastegate setup (and usually does).
The wastegate on the crossover is the easiest way to implement an external gate on a stock-ish syty. Best way? No, probably not. It does work a heck of a lot better than the stock setup.
Locating the wastegate so that it dumps exhaust pressure from all banks equally is the best situation, so usually at or after a collector before the turbo, and with a large enough oriface/valve to adequately control turbo speed and maintain exhaust pressure pre-turbo at low levels. Again, this isn't easily done in a stock-ish syty setup. So you are back to serious fabrication or something like the valve/flange setup you linked to. I didn't think much of that setup; saw it years past. I asked a well known turbo builder out west what they though of it. They didn't think much of it either, their experience was bad with it, and basically it sounded like one of those band-aid solutions. I can't comment on if it's better/worse/same as running a stock wg or an external on the crossover.
Here's my thoughts on ext. wg setup on a syty:
Best to worst
1) external gate on final collector pre turbo, with good flow rate (a valve mounted at 90 degrees to exhaust flow isn't a good setup). I maybe have seen one or two syty's done this way. I rigged up my ATR headers with this configuration on my old Syclone.
2) external gate off of exhaust housing, like RPM can work up with the PTE housing, or like ATR did with their original big turbo setup for syty's. Some people said this doesn't usually work as well, as the exhaust has already entered the turbine housing.
3) external gate on crossover, just make sure it can dump enough volume of gas to control boost. Controlling boost on a stock turbo is much more difficult than controlling boost on a larger turbo (given the same engine). The smaller turbo will react faster to exhaust pressure, and will run higher turbo speeds (all else equal).
No incredibly sophisticated control will make up for a bad wastegate situation. Years ago, a slew of people tried the Profec that had the fuzzy logic controls with all sorts of doo-dads. Didn't make a lick of help with boost control. Still had spikes and creep.
Another thought - years back Duttweiler had a test where they had a Buick setup with a wastegate in a sub-optimal location. I believe it was the crossover pipe from one bank to another. They found that the car made more hp with a gate mounted there versus a large single one further downstream. I'm guessing it had to do with exhaust flow/temperature in the area between the crossover and the turbo inlet. I can only assume a Syty would experience this same phenomenon with an ext gate on the crossover. It'd be an interesting experiment at least.
Speaking on this same subject, did anyone see the turbo tach at Sema that Turbonetics had out? Nifty idea. Never saw anything like this offered to the general public.
