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Ran my twin turbo boat today and the engine behaved different in the jetboat vs the dyno. We ran the boat with a50% mix of 110 renegade and 93 oct pump gas. Made 13 lbs of boost at 6800rpm. Correlates closely with dyno sheet/ MPD AA impeller hp estimate of 1300 hp. On the dyno we applied pressure to the top side of the gate to get this number.In the boat we rigged up an AMS-500 boost contoller. Bottom gate port is vented to atmosphere. Top gate is connected to the boost control sysytem, using co2. With the Boost controller off and no pressure applied to the top of the gates,"verified with a Gauge", we had 13lbs of boost..? Lightest spring in Kit. Same thing on the dyno would only make 2 lbs of boost. The difference, other than atmospheric conditions, is we have no dyno exhaust system after the turbo. The dyno exhaust was 5" flex pipe to 8" to 12" pipe with smooth transitions. On the boat the pipes are 2 ft staight with a 30 deg bend at the end. I am a little confused on this. The boat had a 1471 with 2 doms before, much different animal. Testing continues, Plug readins say were very safe so far. Adding 2 deg of timing for next test. was at 28 now 30 total.
 

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Ran my twin turbo boat today and the engine behaved different in the jetboat vs the dyno. We ran the boat with a50% mix of 110 renegade and 93 oct pump gas. Made 13 lbs of boost at 6800rpm. Correlates closely with dyno sheet/ MPD AA impeller hp estimate of 1300 hp. On the dyno we applied pressure to the top side of the gate to get this number.In the boat we rigged up an AMS-500 boost contoller. Bottom gate port is vented to atmosphere. Top gate is connected to the boost control sysytem, using co2. With the Boost controller off and no pressure applied to the top of the gates,"verified with a Gauge", we had 13lbs of boost..? Lightest spring in Kit. Same thing on the dyno would only make 2 lbs of boost. The difference, other than atmospheric conditions, is we have no dyno exhaust system after the turbo. The dyno exhaust was 5" flex pipe to 8" to 12" pipe with smooth transitions. On the boat the pipes are 2 ft staight with a 30 deg bend at the end. I am a little confused on this. The boat had a 1471 with 2 doms before, much different animal. Testing continues, Plug readins say were very safe so far. Adding 2 deg of timing for next test. was at 28 now 30 total.
Dont know the actual setup when using CO2 and the ams but with any other boost control device you would need a boost signal line plumbed to the bottom port to help open the valve and keep boost low. The top port only raises the boost. The dyno exhaust system had way more backpressure after the turbo than the system in your boat does. The backpressure lowers the boost by diverting more exhaust flow to the wastegates.
Maybe these will help,
wstgate.gif

truboost.jpg
 

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Dont know the actual setup when using CO2 and the ams but with any other boost control device you would need a boost signal line plumbed to the bottom port to help open the valve and keep boost low. The top port only raises the boost. The dyno exhaust system had way more backpressure after the turbo than the system in your boat does. The backpressure lowers the boost by diverting more exhaust flow to the wastegates.
Maybe these will help,
View attachment 163008

View attachment 163009
Basically AMS or other CO2 setup is exactly the same theory, but has more available pressure (than boost pressure). And obviously the timers.
 
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