What is the max hp that the BD Twins can handle
01-20-2005, 08:21 PM
#2
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I would look elsewhere if MAX power is the game. Olee Poole made a sweet set for a fella. He recently dynoed 574 HP with a TST, EZ and stock injectors on a Dynojet. The truck is an 04.
Olee can build anything and has all the CNC mills and lathes, TIG, and the powder coating equipment to make it happen. Many turbos and a few buddies that help him with ideas and tips on what will work best.
Don~
Olee can build anything and has all the CNC mills and lathes, TIG, and the powder coating equipment to make it happen. Many turbos and a few buddies that help him with ideas and tips on what will work best.
Don~
01-20-2005, 09:41 PM
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Their web site says up to 550hp.
I guess good work costs, but man......Olee wants $5K for his complete set. That's spendy.
There is a guy running the BD twins on a 3rd Gen with DD2s and TST on 5/5 that did 508hp on the dyno with max EGTs at 1280*F. You could darn near tow your camper at 500HP with EGTs like that. "Forthcomingtwin" is running DD3s, TST on 5/5, and EZ on 4, and can not get EGTs to hit 1400*F with his BD twins at 60+lbs of boost. We need to get this guy on the dyno. We know honed injectors are not the most efficient at making power with the TST, but you have to admit that combination is dumping an awful lot of fuel in the cylinder. Those EGT numbers are impressive. I wouldn't count the BD twins out just yet. We just need some more out there to get a good idea of their performance.
The general consensus is that they spool incredibly fast for twins and flow a lot of air for their size thanks to their extended tip wheels. They provide awesome low end and mid range power, but lack on the top end as far as twins go due to backpressures. At 50lbs of boost, they are producing just over 50lbs of backpressure. At 55lbs of boost, they are producing about 60lbs of backpressure. At 60lbs of boost, they are producing over 70lbs of backpressure. BD gates these twins to provide 50lbs of boost to protect the head gasket due to backpressures, but you will see more than that if you have the fuel to push them. High backpressure is your trade-off for good spool-up with twins utilizing stock, unmodified turbos. Piers can spend the time to modify an HX35 to provide good twins spoolup without any backpressure issues at 65lbs of boost and no external wastegate. It does cost more though. The BD twins are being run at over 65lbs of boost without problems, but can you imagine the backpressure at that level? That is what takes away from the top end flow that has been reported on these twins. The backpressure on the exhaust side at 60lbs of boost is so much higher than the intake side, it is not letting all the available cool boost into the combustion chamber.
The fix is simple. You install an external wastegate to bleed off the backpressure from the exhaust manifold and dump it into the hot pipe just before the large turbo so you don't waste that energy. Almost every set of twins that you see, except Piers twins, uses this method. Twins approaching 80psi have picked up a documented 65hp and a 200*F reduction in EGTs just by installing an external wastegate to take backpressure out of the picture. I wouldn't expect no where near that much with the BD twins, but a significant improvement should be noted. Nothing like feeding a full 60/65psi of cool boost into the cylinder. What is sad is external wastegates are cheap and BD could have added one to their system for less than $300 total and had a kick….butt set of twins right out of the box.
Unconfirmed, but the flow numbers on Borg Warner's web site indicate the large turbo will flow 1102 CFM, same as the HT3B, so the potential is there if that is correct. I stress that that is unconfirmed due to shady CFM conversions from the numbers they give you. If you can get a good price on them and splurge $300 to put on an external wastegate, they still won't be the best, but I suspect they will hold their own very well against the $5,000 twin kits that are available. They don't cost $5K either....that is the good part. BD's new pricing is $4,500 retail, but they can be had for around $3,800 every day from the right people.
I guess good work costs, but man......Olee wants $5K for his complete set. That's spendy.
There is a guy running the BD twins on a 3rd Gen with DD2s and TST on 5/5 that did 508hp on the dyno with max EGTs at 1280*F. You could darn near tow your camper at 500HP with EGTs like that. "Forthcomingtwin" is running DD3s, TST on 5/5, and EZ on 4, and can not get EGTs to hit 1400*F with his BD twins at 60+lbs of boost. We need to get this guy on the dyno. We know honed injectors are not the most efficient at making power with the TST, but you have to admit that combination is dumping an awful lot of fuel in the cylinder. Those EGT numbers are impressive. I wouldn't count the BD twins out just yet. We just need some more out there to get a good idea of their performance.
The general consensus is that they spool incredibly fast for twins and flow a lot of air for their size thanks to their extended tip wheels. They provide awesome low end and mid range power, but lack on the top end as far as twins go due to backpressures. At 50lbs of boost, they are producing just over 50lbs of backpressure. At 55lbs of boost, they are producing about 60lbs of backpressure. At 60lbs of boost, they are producing over 70lbs of backpressure. BD gates these twins to provide 50lbs of boost to protect the head gasket due to backpressures, but you will see more than that if you have the fuel to push them. High backpressure is your trade-off for good spool-up with twins utilizing stock, unmodified turbos. Piers can spend the time to modify an HX35 to provide good twins spoolup without any backpressure issues at 65lbs of boost and no external wastegate. It does cost more though. The BD twins are being run at over 65lbs of boost without problems, but can you imagine the backpressure at that level? That is what takes away from the top end flow that has been reported on these twins. The backpressure on the exhaust side at 60lbs of boost is so much higher than the intake side, it is not letting all the available cool boost into the combustion chamber.
The fix is simple. You install an external wastegate to bleed off the backpressure from the exhaust manifold and dump it into the hot pipe just before the large turbo so you don't waste that energy. Almost every set of twins that you see, except Piers twins, uses this method. Twins approaching 80psi have picked up a documented 65hp and a 200*F reduction in EGTs just by installing an external wastegate to take backpressure out of the picture. I wouldn't expect no where near that much with the BD twins, but a significant improvement should be noted. Nothing like feeding a full 60/65psi of cool boost into the cylinder. What is sad is external wastegates are cheap and BD could have added one to their system for less than $300 total and had a kick….butt set of twins right out of the box.
Unconfirmed, but the flow numbers on Borg Warner's web site indicate the large turbo will flow 1102 CFM, same as the HT3B, so the potential is there if that is correct. I stress that that is unconfirmed due to shady CFM conversions from the numbers they give you. If you can get a good price on them and splurge $300 to put on an external wastegate, they still won't be the best, but I suspect they will hold their own very well against the $5,000 twin kits that are available. They don't cost $5K either....that is the good part. BD's new pricing is $4,500 retail, but they can be had for around $3,800 every day from the right people.
01-21-2005, 12:01 AM
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Well put AK. Everyone has their opinions obviously, I sell the bd twins because I like all my performance in the low and midrange rpms. If you called me and said I'm looking for 800hp out of my truck I would steer you elsewhere probably to piers but for a good streetable setup with some serious power BD's setup is right on the money.
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