1qckdodge

Sitting here on overtime so I can pay for these things
Notice Jims precise aim while in the overtime position

Mike Holmen

I drove a BD truck with there twins and that had a set of 100rwhp injectors installed. Yes they spooled nice, but the mid to top end seemed to me to fall off. They made lots of torque down low. I ran them up to 50psi. My twins are more sluggish but after 10psi that BD truck would be smelling my smoke. Remember to get to the 600rwhp area, they are using drugs. Christian truck put down a 610 run, running drugs. That was on a mustang dyno, at their dyno days. A street set of PDR twins would operate pretty much worked as well as your stock turbo just with a bigger and wider torque curve. I'm not gonna say that PDR twins are the best in the world but lots of guys run them.

Diesel-Dan

No NOS on Rowlands truck....and im willing to bet that he is over 600+ RWHP......the 16th of July will show........First dyno after twin install.....

RowJ

That's funny!!

What, no comeback??

RJ

SuperDave4x4

Sweet!

Deffinintly fill us in when you get'em intalled!!

1qckdodge

He hasnt logged on yet

Tiger Rag

Mike, I don't think anyone is trying to say that the BD twins are the best high horsepower set out there, but just an excellent option on everyday drive and spool especially when thinking about towing. Are they 600 hp twins? I don't know, I'm not there yet. Will I need drugs to get there? Maybe, either way, I'm probably going to do nitrous just because there seems to be little negatives for the investment. I will o-ring the head first of course. I'm working on that, just getting ready to drop some coin on DD clutch and hot rod VP first. Plans on the head work will follow....then nitrous. I'll keep y'all posted. I will say the drivability of the BD twins is great for everyday driving. I can keep the Mach 6's clean driving around town - no problem. That's a lot of fuel to keep clean around town. Are there better twins out there? Maybe, depends on what you plan to do but what I outlined above I think these perform very well. That's been my experience anyway.

DWeiler

Hey Mike looking at a set too,later on,just about to drop some more coin on a Kore Chase system(installed next week hopefully) along with the fender flairs---Latter bars are finally on .For now i figure i'll do the suspension before NADP's August Blackout,then look at doing the twins over the winter/spring.I'm not looking for all out race set,looking at Piers too,but i'v heard mostly good thing about the BD set.i only looking for a daily driver,nothing race or to extreme,hopefully a mild set of twins with the Smarty/Mach 4's will work.LaterDW

Dshiftff

I gotta remember to turn out the stove next time we go out on a call. At least I saved the chair from the firehouse

Mike Holmen

Tiger Rag, probably the biggest power hinderance is your HO pump. 500 is a low number for mach 6er's. You should be in the mid 600 area. My twins wont clean up the macher's until at least 50-60psi of boost. BD might have tweaked the turbo since I drove then as I told them what I was building. They told me over and over again that my truck would never make power or run decent. That was the last time that I was at their shop, about three years ago. The next day I bought a set from PDR. Must have been their good salesmanship. For trucks towing often and are around the 500 area, they are a good set of twins. If you push the 600's, I would like to see the egt's # and drive pressure with the bigger sticks.

Tiger Rag

Mike, maybe I can get a reading on drive pressures. I've got another port that is plugged that I can reading on that. I know if I want to make big HP, I may need to make a change. I've got some dialog started with BD on their "special" twins that are due out in Sept. I believe this will basically be a change of the primary to a S-400. My question to them that I'm waiting on a response is if I'll be able to change out my primary to the S-400 with the current plumbing. BD is telling me that they are still working on the plumbing so they don't know the answer quite yet. That kind of tell's me I won't be able to upgrade it too easily.....but you never know. Basically I know the BD's are limited on the top end, but right now I really like them. I may outgrow them before too long by the way it seems to be going for me though.

BTW, I've got a HRVP ordered. I guess I'll see what the 6's will do then. I may get hotter than a french hooker on nickel night then....who knows....hope not though. I think I'll be able to dial it down though. Head work to follow as soon as I find a good head. I'm a little afraid of the one I've got a lead on. It's already been machined for orings, but it's blown head gaskets before and after the machining...... Thought maybe after the head was shaved and re-machined it might be ok. I can pick it up cheap but I've been advised against it......guess I'm still looking.

Mike Holmen

I would also consider porting and installing a cam into your truck. To bad your so far away as I have a good stock spare head sitting on my bench. Your new pump should dump some fuel into your engine. I'm guessing that's your limitation. As for new set of turbo, just sell your old set-up and buy a new set. I'm sure that lots of guys would be interested. Drive pressure would more than likely your limiting factor for your twins. If you can run 60 psi of boost with less than 60 psi of drive pressure running 600 plus HP, you got a sweet set-up. Typically your egt's start to become less managable as drive pressure starts to exceed boost pressure. My set-up I'm around the 1 to 1 ratio, for 60 psi of boost. My twins just start to clean up the smoke at 60 psi.

Tiger Rag

I know Rowland checked his drive pressures and they were basically 1:1 as well. I kind of stopped worrying about them then, that is why I haven't checked them.

Yeah, that's too bad we're so far apart. I've got a shop I trust to do the head, just need to find a head not too far away. Freight would be brutal coming from Canada.

Dshiftff

On order, paitently waiting

HOHN

I think this post was mostly ignored, and since we here in DTR don't do that, I'll try to answer.


Boost levels in twins can vary wildly, from 50psi on the low and to well over 100psi for the "big dogs".

Each turbo doesn't "make" a set boost amount, per se. It's not additive, like big turbo+little turbo=total. Instead, the small turbo multiplies the pressure it receives from the big charger, just as the big charger multiplies atmosperic pressure.

Let's say we build a theoretical twins set where each turbo runs at a 3:1 pressure ratio or PR. Ignoring losses and inefficiency, we'd get a theoretical 9:1 multiple of air pressure, or (14.7*9-14.7) 117.6psi of boost!

But very few turbos are efficient at 3:1 PR, so 2:1 is mor realistic (and more efficient), giving you an overall PR of 4:1, and changing your 14.7psia atmospheric to 44.1PSIG.


jh