Correct! There is more attention needed than with a single turbo. I have gone back in twice and tightened boot clamps, and made minor adjustments.... but no R&D required to get them running perfectly. All that was done at the factory!

RJ

 

I think that is the biggest reason to buy an engineered set like the BD's. You don't have to guess about the drive pressures and if your head is going to hold. They are engineered to have low drive pressures and be head friendly.

 

I read on here in another thread that they run out og steam on the top end in a 12v?

 

The only tinkering that is needed would be if you wanted to adjust the wastegate. The housings are already clocked, all the plumbing and fittings are supplied as well.

 

They shouldnt run out of steam if you adjust the wastegate up on them. I have seen these do 80psi. That is enough air to keep quite a bit of power cool. With our setup we keep the wastegate set at 50psi from here to make them "head gasket" friendly. If you stud and ring the head you can definately crank up the boost. It would be very difficult to overspin these. We have also seen in a few cases people not having enough fuel to still efficiently drive the twins which can cause the to "run out of steam" This is a fueling issue, not a twin issue.

 

Your saying that even at 80psi your not over speeding these turbos and over heating the air? Now I'm really curious as to what your 300/400 combo is gonna do.

 

With the right engine and fueling they are going to be very impressive.

 

What's your drive pressure at 75psi of boost? I'm having a hard time believing that the BD twins (small) are able to feed a 700rwhp without drugs. I can see 550 rwhp but 700 rwhp you don't have enough air flow to feed the engine. Does anybody have a set of BD twins, running only #2 make 700rwhp? I think that highest number that I've seen is around the 600rwhp. A sweet combo is the HX-40/B2 combo. You'll have tons more air and the spool-up is almost as fast as your stocker. My set is slightly lagger than the BD set, but honestly is doesn't bother me. The bigger issue is keeping your egt's cool and reasonable.

 

Mike,


Drive pressure......, sounds like you have been talking to the boys at PDR. They try to tell everybody that our drive pressures are high, which simply isnt true. Drive pressure is going to be relative to where the wastegate is set at. In our testing as long as you were below where the waste gate was set drive pressure was 5-10% below boost pressure. Once the wastegate starts to open then you get into the negative delta p pressure which causes the drive pressure to rise. If you keep that wastegate closed and still have enough fuel to drive the chargers then higher horsepower readings wont be a problem. We have done 600+ here on our dyno on #2 and egts were 1275deg. One thing to remember is every dyno is going to be run at different atmospheric conditions which is going to affect the overall numbers. Our dyno also seems to usually read a little low compared to other dynos.

 

FYI, I measure 1:1 at 65 psi boost (WOT) with my BD twins. What I don't know is what the wastegate (factory set at 40 psi) is doing at my compounded boost pressure. Based on what your saying, Pat, it's closed?

RJ

 

It looks like it is very close to being completely closed. At 70psi we saw .95-1 here. But on a good day here we are very close to sea level. Sometimes we are even below sea level here.

 

Most people keep there secondary turbo wastegate set lower than if you where to run it as a single turbo. Mine is set to 24psi on the HX-40. Pat, I just having a hard time seeing that those small turbo can push enough air to feed a 700rwhp truck on #2. PDR hasn't said anything about your turbos, period good or bad to me. PDR is one of the few shops that don't try selling you on BS. If you guys get a truck that could push the numbers, I'll come out and go for a ride. BD has to do some PR work to get me to want to put a set of BD turbos on my truck.

 

Mike,

Efficiency is the key word in how we can make it work on that kind of power. Now turbo chargers are probably the most complex portion of our trucks. I dont pretend to know all, because I dont. Our turbo engineer could feed me information for eight hours a day and probably be able to go for a week on all the different ways turbo chargers work.
If you were happy with your twins that is fine, I dont need to get you into ours. But there is a reason why our twins are gaining in popularity. People are trying them and realizing how well they work and passing the word along.

I dont want to try and start a pissing match here. Our 02 is here any time you want to go for a ride in it.

 

Well said! We all know that turbos have a narrow band of 'ideal' conditions. This fact makes putting a turbo on an 18 wheeler easy (cruising at 70 all day).... and finding the right turbo set up for our trucks, such a compromise.

I've wondered for a while if the BD twins just happen to match my power set up perfectly... and might not work so well for others? But I don't think that's true. Too many reports from others have me convinced BD has taken compound turbos, for our trucks, to a new level.

But, that's JMHO, since I have no experience with other twins.

RJ

 

Pat,

I would really like to ride in a truck with BD towing twins. Do you have any customers in Afghanistan?