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Twin Turbo Question?
https://slantsix.org/forum/viewtopic.php?t=51549		 Page 1 of 1
Author:  crazyjjk [ Fri Mar 29, 2013 8:19 am ]
Post subject:  Twin Turbo Question?
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Been lurking here for a while and decided to finally join.
Plan on replacing my 360 Magnum in this for a turbocharged slanty. All ready have a 225 and a 904. My question involves the use of twin turbos. I keep hearing don't use two smaller turbos because of more difficulty tuning. Why is it more difficult? If you have a blow thru system and you run each turbo off of 3 cylinders of exhaust and after the turbos you combine the two into one induction pipe into the top hat on the carb why would it be more difficult? Couldn't you use one blow off valve and even one combined waste gate. Wouldn't the advantage of two smaller turbos spooling up quicker be worth it?[/img]
Author:  Joshie225 [ Fri Mar 29, 2013 8:53 am ]
Post subject: 
Tuning isn't the problem, but packaging two turbos is a problem. One properly sized modern turbo has little issue with spool time. I would get one ball bearing turbo from a good supplier myself, but if you have extra money to burn go ahead with twins.
Author:  crazyjjk [ Fri Mar 29, 2013 9:36 am ]
Post subject: 
As you can see from the above picture of what the turbo slanty is going in I do not have many of the space restrictions the A bodies have. No shock towers or low hood to worry about. Like I said though are there tuning issues like I have seen stated on here?
Author:  CNC-Dude [ Fri Mar 29, 2013 11:40 am ]
Post subject: 
What kind of turbo system are you considering, blow-thru a carb, draw-thru or EFI or something else?
Author:  crazyjjk [ Sat Mar 30, 2013 5:52 am ]
Post subject: 
Actually I am considering a single Holset HX-35 blow thru system. I am just a newbie and curious why a twin turbo system would not work better, both from a spool up standpoint and from the aspect that small turbos from 4 cylinder cars are plentiful. I am almost 60 yrs old and have been wrenching cars all my life but turbos are new territory for me and just want to learn. John
Author:  1974duster kev [ Sun Mar 31, 2013 11:00 am ]
Post subject: 
From what i've seen at the track the guys with single turbos run just as well the only real call for a twin turbo setup that ive seen was on very big cubic inch motors like the outlaw and prostock guys. I have a single turbo setup but, for future plans I would love to build a twin turbo v8 but mainly because I like the way twin snails look because i'm sure a single turbo would be fine for what I want power wise :)

Kev
Author:  Ssg Pohlman [ Sun Mar 31, 2013 7:52 pm ]
Post subject: 
If the hx doesnt spool fast enough then just get a smaller exhaust housing. typically they is a "12" stamped on the inside just up from the mount flange. They make a "9" cm houseing as well.

As for twins, theres almost dual everthing, oil, water (if used), mounts, cold side wouldnt be too bad with a Y pipe given you dont try to run an intercooler. Then the downpipes for both is another deal. Not saying it cant be done but even in my D150, I wouldnt want the head ache of all the extra that would be needed. Easier to just get one and size it for exactly how you want the engine to perform. Ill even admit that I have a TDO4-12b in the garage next to my WH1C, but im going h1c so I dont run out of turbo :twisted:
Author:  crazyjjk [ Mon Apr 01, 2013 5:53 am ]
Post subject: 
Thanks guys for getting back to me in a helpful way without an attitude. Like I said I am new to the turbo thing and your answers have started to show me the downfalls of twin turbo's on a slanty. I guess part of the reason I was asking was I have some of the same thoughts as Kev. Twin snails are awful cool looking. :shock:
Author:  CNC-Dude [ Mon Apr 01, 2013 9:46 am ]
Post subject: 
Well keep in mind its your project, and you are the one that has to drive it and be satisfied with it. So just keep in mind that whether your going for the WOW factor of twins or for a truly good combo with a single, trade-offs can be a part of it also.
Author:  Ssg Pohlman [ Mon Apr 01, 2013 9:36 pm ]
Post subject: 
If twin snails look cool, go way outside the box and build a compound setup :shock: :twisted: I guess having a TDO4 and an HX-35 laying around I could, but I dont make that kind of money, cant weld (yet), and dont feel like doing it. I do have a ton of room under the hood given i have a D150 :!:
Author:  crazyjjk [ Tue Apr 02, 2013 4:40 am ]
Post subject: 
I guess one other questions to ask some of the much more knowledgeable here. I know 1 small turbo such as one off of a 4 cylinder application will sort of run out of steam around 3500 RPM on a 225 when being spun by the exhaust of all six cylinders. Will the addition of the second (twin) turbo, each run off 3 cylinders of exhaust give the slanty additional boost up to say the 5000 RPM plus range? Or would there still be some restriction where the twin boosted 225 would run out of poop at a lower RPM because of the small size of the turbos? Sorry if these questions have been asked before. I have looked all over the forums here and haven't seen this addressed before. Thanks in advance, John.
Author:  1974duster kev [ Tue Apr 02, 2013 11:21 am ]
Post subject: 
My opinion on that subject would be two small twin turbos serve the purpose of acting like a bigger single turbo. The example i'm thinking of is my neighbor denny run twin 73's on his mustang instead of say, a 100mm single turbo but he runs a very large cube motor so a huge single turbo may hurt his spool time. The slanty with two small more abundant 4 cylinder turbos would be fine in my mind because you would still spool up quick and gain some breathing room. Yet ultimately if they were both on the small side for a 1.6liter then they are gonna be on the small side for a 3.7 liter even with two of them because most factory turbochargers are pretty small so they didn't create much turbo lag if any. My pte6262 dual ball bearing cfm wise seems big considering it supposedly supports up to 700hp but that dang thingy spools up fast with the present ball bearing technology.
Most of this is opinion with some experience based stuff so fact check me! :)

Kev
Author:  crazyjjk [ Wed Apr 03, 2013 4:53 am ]
Post subject: 
Thanks Kev, being a total newbie to turbos I really appreciate your input. John
Author:  1974duster kev [ Wed Apr 03, 2013 9:13 am ]
Post subject: 
Hey no problem this was my first time messing around with a turbo setup. I just spent a ton of time researching articles and asking questions from the guys who have been going the fastest with a turbo on the forum. Lots of planning ahead of time made the whole fabrication part of the build not to bad, tuning has been tricky :)
I got 21mpg on the highway on my way home for spring break so i'm starting to enjoy where the setup is going specially after some highway WOT pulls :twisted:
Kev
Author:  slant6 wonder [ Thu Apr 04, 2013 12:29 pm ]
Post subject: 
I didn't realize I was logged in! Twin turbo set up would be too complicated in regards to plumbing, room constraint and reliability issues, potentially. I would recommend someone running a small twin turbo layout for someone who is looking for faster spool low to mid torque and responsiveness for for example someone looking for power for auto cross or auto circuit racing. For someone wanting a street terror, single is fine. If you got deep pockets, Garrett GT2860R or GT2871R would be choice.
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