Compound stock turbos
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From: Florida
They do. Thats BD's setup. However if you look around you'll find there are TONS of S300 configurations.
The S300 that is the secondary has a 57mm compressor and a 14cm exhaust housing. BD calls this the Super B.
The S300 that is the primary has a 66mm compressor and a 26cm exhaust housing. BD calls this the Super B Special.
I may be a little off on these specs, I can't remember exactly what I've read on here, but you get the picture.
They are both S300's but they are different and are run in a compound configuration. BD has done a lot of work with them and for what they do, they do well.
Look up onetun's profile and find some posts where he switched to BD's R700 twins with a S400 primary. He has pictures of the two different S300's.
The S300 that is the secondary has a 57mm compressor and a 14cm exhaust housing. BD calls this the Super B.
The S300 that is the primary has a 66mm compressor and a 26cm exhaust housing. BD calls this the Super B Special.
I may be a little off on these specs, I can't remember exactly what I've read on here, but you get the picture.
They are both S300's but they are different and are run in a compound configuration. BD has done a lot of work with them and for what they do, they do well.
Look up onetun's profile and find some posts where he switched to BD's R700 twins with a S400 primary. He has pictures of the two different S300's.
The differences you described are what I was getting at. Although those two S300's are very different turbos, it might be hard to tell them apart visually when they're installed.
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From: Home of the Beaver
The primary on the BD towing twins is larger than a super b special.
Secondary 60lbs per min~ s300
Super B 70-72 lbs per min ~ s300
Primary 80 lbs per min ~ s300
R700 96 lbs per min s400
Secondary 60lbs per min~ s300
Super B 70-72 lbs per min ~ s300
Primary 80 lbs per min ~ s300
R700 96 lbs per min s400
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From: Alaska
They do. Thats BD's setup. However if you look around you'll find there are TONS of S300 configurations.
The S300 that is the secondary has a 57mm compressor and a 14cm exhaust housing. BD calls this the Super B.
The S300 that is the primary has a 66mm compressor and a 26cm exhaust housing. BD calls this the Super B Special.
I may be a little off on these specs, I can't remember exactly what I've read on here, but you get the picture.
They are both S300's but they are different and are run in a compound configuration. BD has done a lot of work with them and for what they do, they do well.
Look up onetun's profile and find some posts where he switched to BD's R700 twins with a S400 primary. He has pictures of the two different S300's.
As to using a stock turbo in a compound configuration I spoke with Nathan Wright about using an external wastegate. He offers an external wastegate with his stock/S400 setup but recommends going to a larger secondary turbo instead of the wastegate. He did some testing and showed that there were some improvements but not enough to warrant the wastegate. His testing showed at WOT a boost of 67psi and 77psi drive pressure without the external wastegate. Using an external wastegate the boost remained at 67psi but drive pressure dropped to 73psi and egts only dropped 100 degrees. He said this was done with a Bullydog setting that dynoed 400 hp.
The S300 that is the secondary has a 57mm compressor and a 14cm exhaust housing. BD calls this the Super B.
The S300 that is the primary has a 66mm compressor and a 26cm exhaust housing. BD calls this the Super B Special.
I may be a little off on these specs, I can't remember exactly what I've read on here, but you get the picture.
They are both S300's but they are different and are run in a compound configuration. BD has done a lot of work with them and for what they do, they do well.
Look up onetun's profile and find some posts where he switched to BD's R700 twins with a S400 primary. He has pictures of the two different S300's.
As to using a stock turbo in a compound configuration I spoke with Nathan Wright about using an external wastegate. He offers an external wastegate with his stock/S400 setup but recommends going to a larger secondary turbo instead of the wastegate. He did some testing and showed that there were some improvements but not enough to warrant the wastegate. His testing showed at WOT a boost of 67psi and 77psi drive pressure without the external wastegate. Using an external wastegate the boost remained at 67psi but drive pressure dropped to 73psi and egts only dropped 100 degrees. He said this was done with a Bullydog setting that dynoed 400 hp.
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i think running two stock turbos in compound configuration with seperate air intakes and the turbos feeding into a 2-1 intercooler may be a cool idea. plus stock turbos are way cheaper which would cut cost big time. maybe a constant 50PSI could be had. could figure out how to control turbos the same as one stock one.
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From: Airdrie, Alberta
What you just described (two turbos, two intakes, two discharges) is a parallel configuration. You can get twice the flow rate with two identicle turbos, but you are still restricted to the max pressure they can run effeciently, which with an HX35, is in the 35-40 range. Beyond that, you are superheating the air. If one HX35 flows 40 lbs/min at 35psi (3.4:1 PR), two will not flow 80 lbs/min at 35 psi on the same engine at the same rpm.
With the compound setup (big and small chargers), the big one takes in your 80lbs/min, compresses it to say to 14.7 psi (2:1 pressure ratio). Now your secondary charger will see effectively 40 lbs/min, and can compress that to whatever pressure is needed to get it into the engine, which would likely be around 70 psi (5.6:1 PR). The seconday compressor was already seeing 14.7 PSI of postitive pressure at the suction (29.4 PSIA), and is discharging at 70 PSIG (84.7 PSIA), so its PR is only 2.88:1.
With the compound setup (big and small chargers), the big one takes in your 80lbs/min, compresses it to say to 14.7 psi (2:1 pressure ratio). Now your secondary charger will see effectively 40 lbs/min, and can compress that to whatever pressure is needed to get it into the engine, which would likely be around 70 psi (5.6:1 PR). The seconday compressor was already seeing 14.7 PSI of postitive pressure at the suction (29.4 PSIA), and is discharging at 70 PSIG (84.7 PSIA), so its PR is only 2.88:1.
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