Im almost to the point where I want to be replacing the turbo. My truck is past that point as its pretty easy to hit 40PSI which isnt good for a stock turbo. My tuner tells me I 'really dont want to get twins on the truck' (and I do trust the guy's experience) and the consensus here is that twins are great. His race truck is based on a big single so he might be a bit biased or have experience with older twin setups that had issues.
Im looking for a toy hauling DD with the ability to smoke ricers every once in awhile. Probably up around 500hp. I hear the lag from many of the big singles is a problem so Id like to find the single with the least lag and best spool at that level of fueling. So far Im leaning towards a super phat shaft 62.
Anyone know where I could find before and after dyno's or twin versus single dynos that I can use to see what the powerband looks like with both?
Obviously head studs, an exhaust manifold and l lower timing are in my future too.

 

Obviously having come from a truck with a single.

and now twinned, I will tell you my honest opinion... GO WITH THE TWINS!!! I love the way my truck drives now. The power is insane, and the whistle and exhaust is downright vicious sounding...

Here is what i feel is a downside with the twins, The twins are actually a little bit slower spoolup than the stock HX 35 was, but they more than makeup for it once the large charger lights, Also an oilchange will become a bit more of a chore, u must remove the piping and everything else to get to the filter, but again, once its out, its not a problem to change the oil on the truck. Thirdly, and not so much an issue, is making a second drain hole in the oil pan to get the second turbo to drain in there, Fourthly,you have alot of testing and tuning to do once u get everything bolted up, Its a hassle to look for leaks (boost and oil) and make sure everything is well tightened up, Next u have to worry about the stock headgasket and bolts, i would advice retorquing the head

The upside to twins is simple, the truck accelerates much more smoothly, it almost drives like a gas engine now once the turbos are lit, and it just pulls and pulls till the blow off valves hit or in my case once im out of fuel which was backin off the plate halfway to hit a measly 46 lbs of boost. With a load these things are just plain nuts, They keep my EGTS cool, my first official load was a 20 foot gooseneck with five horses, and it was not even an issue. EGTS NEVER EVEN GOT above 1250 degrees with my setup, this thing just tows effortlessly... smoke was but a haze with this load However, if i do tow super heavy, a valet will be in order, the stock coolin system will handle about 450 horses max...

Big single, NO experience with one, but as far as my HX35 even with the 14 cm housing, well it just felt so limited and the smoke was just nuts, now with the twins the power ends when my fuel does, i dont even think im tickling these turbos... The stock turbo made things alot easier to work on without removing so many parts for an oil change, and i didnt have to worry too much about boost or oil leaks, (i dont anymore with twins i took care of it already)

I dont regret my twins, believe me, and if i did theyd be for sale on here, I can honestly say, i will not drive another diesel without twins ever again, its just a night and day difference..

My dynosheet was with a destroyed clutch, i was at 350 rwhp, now with a good clutch, and twins, i wouldnt doubt im in the high 400's or quite possibly the low 500's, more likely than not id be in the 500s for sure with DDP 4's and LC DV's.. But before i do that i gotta strap down the head and stud it just right....

Im talkin out of experience with both, ive only had twins a week, and i still get a HUGE grin all over my face when i hear that 400 light, its a feelin like no other, and with power on tap and no egts to worry bout, and a couple of yuppies already spanked, need i reiterate my decision more?

PM me if u have any further questions...

Thanks!

Rick

 

man, if you're going to be towing and want to be able to use your power while you're towing, go with twins... they're the only way to go.

I don't pull anything, so I went the other direction... I went from a PDR35-12/S400 setup to an sps62... with DDP4's and the twins at 50psi, I would just barely be hitting 1300* at about 2700-2800* in 6th... with zero adjustments to the pump and stock 215 injectors in place of the DDP4's, I'm seeing 1250*! ya think the DDP4's just might warm things up past 1300*?

but I like the way the single hits on my truck vs. the twins... with the 6sp and only a 3k kit (4k springs are in the truck, just not in the pump yet!) when the turbos would really start getting light up in lower gears, it was time to grab the next gear... it's still kinda like that w/ the single, but the boost hits harder once the turbo is lit, so it's nicer to drive. with an automatic or a 5sp, it might be a different story.

I remember seeing a dyno comparison on a 3rd gen between a set of mild twins (HY/HT3B?) and an sps66... the twins made 599, the single made 605... EGT's were 200-300* hotter and obviously the boost came in later

 

I've had a couple different twinsets on my old 95, and more than my fair share of singles. Here's my take!

If you tow heavy, often, or both, go twins...if you don't tow heavy, or very much, the singles what are out there will do fine! BTW, heavy to me is above 25K gross! At 33-35K gross with a B1 I had to run in 5th gear all the time under 65mph...with the twins, I could run in 6th

The singles are fun empty, and like Forrest said they feel wicked when they light....but the twins, the just pull and pull clear out to the redline if you've got them setup right

I'm going back with a more exotic set of twins this time around...should be fun!
Chris

 

I had a hx40 setup by powerbypoole.com before going to my twin setup and ill tell you the hx40 was a nice single but when you start to bolt things on more extra power the gain start dropping faster and faster the more you throw at it... unless you mod the single again... with the twins i have yet to find the full potential of them yet.. i run max fuel and at 60+psi i have zero smoke which means the twins have room to spare still on spool up they just are out of fuel....plus the pure enjoyment of twins when your cruising and you want to jump around in traffic is the biggest thing i like the most about them ill explain more simpler the single beats the twin on take off from a dead start in spool up but twins polish it off on the top end... but twins at cruising speed 40+mph have almost instantanous spool up to me to jump around in traffic or trying to merge into traffic or whatever the case is but its just pure enjoyment.... another image for ya.. you think of it this way.. your a big twin diesel cummins rolling down the road and an pretty nice sounding mustang cobra is rolling next to you not sure what it has but just doesnt sound stock trying to show off to people or better yet to an 3rd canadate which is an nissan 350z and you watch the 350z and the cobra romp on it to start pulling away and you just so happen to push on the trottle a little more then normal and start to watch the two cars that were racing each other start to drift behind you into the trail of nice thick black smoke you left.......then you start to smile at the next light because they are both starring at you. Which is an image i never had with my single....it just didn't cut it.

 

Check out BlackDiesel's videos of the sps 62 in action

My ps64 is supposed to be a laggy turbo but I can make 10 lbs at 1700 rpms during normal driving with my 24v and I see max power by 2600 rpms so I'm pretty happy as far as drivability goes. Dyno chart is in the gallery.

 

Both have pros and cons..... A 500 HP truck that tows is easy with a single, as long as you are willing to turn the box down and tow around 400-450 RWHP. If you want to tow heavy @ 500 HP twins is the only real choice. Personally I would run a single if I could, having run both the single is a lot less trouble and expense. The performance from a good single will be 95% of what twins will do, the difference is twins will do it cooler. We have single turbo trucks driving everyday on the street that are making the power of twinned trucks, so max HP isn't the question.

Doug Smith

 

I would like to try twins.... I had the 64 on my 215 auto and the pyro pegged in 2nd gear, so its stays there many seconds till you are through a 1/4 mile run!

elevation.... 5000+ feet

 

I have the dyno sheets you are looking for... but there is no surprises on them. Power curve on the twins comes in sooner (steeper) and goes higher.... just what you would expect.

I have had one medium single (KSB-1), basically an S-300 that worked beautifully up to 450 hp, and one big single (hybrid HX-40/55). I went from the latter to BD twins and gained (released) 56 more HP, with no other mods. 572 to 628! Also eliminated all smoke problems and all egt concerns.

Dyno sheets are a little hard to read but are in my gallery.

RJ

 

Twins are for drivability. Power will be there too. It is my next mod.
Less smoke, quicker spool, and cooler on the top end.