i have a 96 12 valve cummins it has a zero plate with 4k rpm gvs 60 pound valve springs and a ported and polished head it still has the sock turbo on it and i want to add some more hp modds but im afraid to put bigger injectors on it with the stock turbo i dont want my egts getting out of control so i was wondering if i piped a smaller turbo in in front of the stock one if it would help or hurt me i have a small garett 44mm laying around the shop and i was wondering if piping that in without a blowoff valve and getting a bigger blowoff valve for my stock turbo would help or if the small turbo would choke out the big one and i would be shooting myself in the foot

 

You need a bigger turbo, not a smaller one. If you had two 44mm turbos you might be able to do a true twins setup. You can get a ht3b or s475 used for like 3-400 bucks. Then you will have plenty of air.

 

i thought the small one in front would make the turbo spool faster but i didnt know if it would give me anymore air so if i put a bigger impeller shaft in my stock turbo what will that do with the little one in front of it i have never messed with twin turbo anything so i dont know much about it i need someone to edgucate me lol

 

another question what if i got a super charger how would that work on a diesel if a got a pro charger stile super charger one that mounts like an alternater and i piped that in would that be something that would be practicle and what if i put two garett 44 mm on in front of the stock turbo would that help any. These are all things i have laying around my shop and they are not going to get used so i would like to try to figure out a way to use them on my diesel. i used to be a gas burner guy but i got my 12 valve about two years ago and im finding my self getting away from gas more and more

 

The stock turbo is as small as you want to go, anything less and you are just choking everything. If you want to run compounds you can use your stock turbo and then put something much bigger under it, just like BigErk said, that is how you increase airflow.

 

You would NOT want a centrifugal supercharger! Anything belt driven is less efficient that a turbocharger, and centrifugal superchargers push a linear amount of boost, meaning that you don't have full boost until redline, and it climbs in a linear fashion from idle to redline. It would be absolutely terrible for a diesel, IMO!

 

For the centrifugal super, you need a good sized pulley just to spin that baby up. Remember a 5.9L only revs to 3350rpm's. Honestly, a centrifugal super isn't any better than a turbo, as they are both centrifugals. A roots style is a better choice, just pick one big enough, and put it before the turbocharger, not after. Roots style supers have been on a few 5.9L, they work and have tons of torque down low and there is no spool-up lag issues. They just limit how much top end power you can build. If you go thru with the build-up take lots of pictures for us to follow at home. I just would run the super with as much over driven as you can get, just so you can get enough air into the turbo.

 

I would sell the stuff you have laying around and use the money to buy an ht3b or a s475 you will make more power more efficently even if you used the 2 44mm turbos drive pressure might still be an issue

 

Could always use the two 44mm in a triple turbo set-up. The two 44mm feeding your stock turbo. It wouldn't be that hard to fab up, but it would be messy under the hood. I think that their is a 3rd gen running around with one on. Sure would be hot under the hood You would have to ceramic coat and wrap everything up. Another issue would be making sure the exhaust flow is evenly shared between the two turbos.

 

Get ya a 3b, and stick under your stock turbo, youll love it. ( and it sound really cool to,Lol)

 

Triples wouldnt be bad but you would want the hx35 set up as the secondary and then run to both 44mm just think of it like twins with an 88mm primary depending on exhaust wheel sizes and such my next set-up is gonna be running triple 62-65/12s from d-tech as soon as the weather warms up some.....spools up like a 62 but flows more than any twin set-up and there not bad to fab up ill get some pictures of triple hx35s we built last fall

 

Please keep in mind, 2 44mm turbos will not flow the same amount as one 88mm turbo, you can't just add the diameters of the compressor wheels. If you look at the surface area of the wheels, you would need 4 44mm turbos to have the same surface area of one 88mm turbo. This isnt an exact measurement because you have to take into account shaft size, blade pitch and design but it is more accurate than adding 44 + 44.

And your friends tripple 62 setup will be nice but it wont outflow any twin setup, however I hope it works out great for him.

 

yes you are correct im aware of all the flow characteristics i was mainly just referring to how to plumb them up alot of people get all confused when talking about plumbing up triples when really its the same as twins for the most part but ideally if your running triples you woul dwant all 3 turbos to be the same size

 

Good catch, those turbo's are just to small to work. I wonder what would happen if you just ran three holsets. A 351vgt over two HX-35, that would flow over 90lbs/min. Around the size of a S366 turbo which is around 80 lbs/min area.

44mm turbo flow around 28lbs/min, a 88mm flows 140 lbs/min.

 

Not really, the turbos that are plumbed parallel should be the same size, but the one in front of them plumbed sequentially can vary in size depending on the goals of the setup. Plumbing in parallel vs. series is easily understood and if someone can't differentiate the two, they should stay away from the welder. I'm not trying to be the devil's advocate but I don't want people to be misinformed.