k31 or s400 for a bottom turbo

tony597fitter

tony597fitter

Tax Payer
I will be ordering my bottom turbo soon and I was wondering what would be better. I will be using my HTB2 62\14 for the top. I use my truck as a daily driver and I also tow a 7000 pound camper a few times a year. I like the k31 because of the wastegate, but plumbing in an external is no big deal. I will be doing all my own piping considering I run pipe everyday for a living. I will be running everything in my sig. I am looking to also make in the 600 and up in horsepower, but I also want something that will get me more if I decide that.
 
What if you were a plumber for a living? Would you plumb your own turbos? Is there a difference?
 
I have been thinking about the same thing and from what I gather the k31 will spool quicker than the s400 but it will also limit your top end potential. If you tow and your not worried about all out Hp go with a k31.....
 
Double check and make sure the internal gate on the K31 won't interfere with the frame rail. I know an internally 'gated GT42 won't fit because you can't rotate it so it won't hit the frame.
 
IMO if you plan on turning over 3500rpm I would buy the S475, if you are going to stay at 3200-3500 I would do the K-31. I would rather have the setup geared more for it's most often use (towing, daily driving, hotrodding) so if it is primarily your daily driver I would want the quicker spooling turbo.
 
The K-31 will fit with no problem many are running it now. But if you are wanting 600 and maybe more the K-31 is not for you, at least not on a 12 Valve! If your going to be towing much you'd probably be best to stick with the K-31 but you have to decide if you can live without the extra 100 rwhp or so?
 
I've been warned about the weak K31 but whenever it's brought up on here.. No one else mentions it?? I'd have a hard time believing that the person who told me was wrong.. Of course the cases he mentioned seemed to be kinda rare. But with the way I treat things it was definitely a worry of mine..
 
62/14 and the K31 are Industrials towing turbos. What is the HP limit out of this setup, anyone know?
Also who daily drives/tows with the 62/14 and S400? How do they do? Are they laggy at all?
 
My choice for the twins would be a 62/13SS or maybe a 57mm s300 with the 13SS housing. THe wastegates on the SS housings flow huge amounts. Then I wouldn't necessarily gate the big charger. adjust your fueling for the peak boost.
 
zstroken said:
My choice for the twins would be a 62/13SS or maybe a 57mm s300 with the 13SS housing. THe wastegates on the SS housings flow huge amounts. Then I wouldn't necessarily gate the big charger. adjust your fueling for the peak boost.
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thanks, but Im going to use my 62/14. If I need to pipe in a external wastegate, thats not that big of a deal.
 
tony597fitter said:
thanks, but Im going to use my 62/14. If I need to pipe in a external wastegate, thats not that big of a deal.
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That is fine, the other reason for the 13 is a little better spoolup. What is the most HP you think you want? Part of the reason for twins the cool factor? LOL Nothing wrong with that, twins are cool, and fun to mess with. Just lots of viable options for 600HP in the single world.
 
zstroken said:
That is fine, the other reason for the 13 is a little better spoolup. What is the most HP you think you want? Part of the reason for twins the cool factor? LOL Nothing wrong with that, twins are cool, and fun to mess with. Just lots of viable options for 600HP in the single world.
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Like I said originally. Its my daily driver and I use it for towing. The camper I have now is only #7000. We were just looking at 32' 5th wheels weighing close to #15000.
Think a single will handle that bad sucker?
I also go to Disney World every other year so towing a big fiver through the mountains with a single would be problems.



And,







Yeah they are frickin cool.
 
I am not bashin what your doing. Throw 600HP grossing 20K+(truck is 8+ 15K) and you will be looking at driveline problems. Your 62 is able to support 450HP useable, and that is all I would feel comfortable using while actually towing that kind of load. I drug my my 12K trailer through kentucky with a 62/12 with 140HP injectors and a low setting on my comp, with no EGT issues. More than likely your twins with the 62/14 are gonna spool later than just the 62/14 used as a single. A 600HP daily driver set of twins I would use an HX35, with some wastegate mods, or a 57mm s300. This is my preference though, as I want the soonest spooling setup as possible.


I just read your signature and saw a 12V in there. After seeing what your thinking of towing, I would say the 62/14 isn't the choice I would use on the 12V. The 12V won't spool it like a 24V. Maybe a 62/12. Do you have the 71mm turbine wheel or the 65mm turbine wheel?
 
This 62 is a lot better then my 64 and will be just fine for a while.. If I had a head that flowed worth a crap it'd be a different story. But my 12 valve leaves something to be desired in that area.. My next move will be a set of BD twins.. I am fine with 450-500 rwhp.. But I want a whole lot quicker spoolup then any of the 6 singles I have run so far. Towing with my truck is rarely a "joy"..
 
zstroken said:
I am not bashin what your doing. Throw 600HP grossing 20K+(truck is 8+ 15K) and you will be looking at driveline problems. Your 62 is able to support 450HP useable, and that is all I would feel comfortable using while actually towing that kind of load. I drug my my 12K trailer through kentucky with a 62/12 with 140HP injectors and a low setting on my comp, with no EGT issues. More than likely your twins with the 62/14 are gonna spool later than just the 62/14 used as a single. A 600HP daily driver set of twins I would use an HX35, with some wastegate mods, or a 57mm s300. This is my preference though, as I want the soonest spooling setup as possible.


I just read your signature and saw a 12V in there. After seeing what your thinking of towing, I would say the 62/14 isn't the choice I would use on the 12V. The 12V won't spool it like a 24V. Maybe a 62/12. Do you have the 71mm turbine wheel or the 65mm turbine wheel?
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You said you read my sig. Did you see I have a stage 2 ported and polished head with a 5 angle valve job, backcut valves, 60 pound springs, orings, and a .020 marine gasket? The head was flow tested and flows as well as a 24 valve head if not better. Before the head I would start to build boost at around 1600 rpm, now with the head I am starting to build boost at 1300 rpm. Big difference!
I understand your driveline issues theory, but that's what the valet switch is for. 600HP for everyday, and a flip of the switch, towing drivability.
 
zstroken said:
My choice for the twins would be a 62/13SS or maybe a 57mm s300 with the 13SS housing. THe wastegates on the SS housings flow huge amounts. Then I wouldn't necessarily gate the big charger. adjust your fueling for the peak boost.
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That might help me out then if the 13ss wastegate can flow a huge amount, I might get away with a S400 without an extra wastegate.
 
tony597fitter said:
You said you read my sig. Did you see I have a stage 2 ported and polished head with a 5 angle valve job, backcut valves, 60 pound springs, orings, and a .020 marine gasket? The head was flow tested and flows as well as a 24 valve head if not better. Before the head I would start to build boost at around 1600 rpm, now with the head I am starting to build boost at 1300 rpm. Big difference!
I understand your driveline issues theory, but that's what the valet switch is for. 600HP for everyday, and a flip of the switch, towing drivability.
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I wasn't referring to the head as the issue. The variable timing will always let a truck run over a broader power band than a fixed mechanical setup. I am not saying your setup won't work. I am just offering some opinions. Put together a twins set using the stock 35 and the truck pulls hard, and I have no doubt it will have enough air for over 600. The 62 setup with the right bottom charger will push enough air for over 700. JUst remember whatever your truck spooled with before, it will spool later later using the same charger in a set of twins.
 
Lucky Jeff said:
I've been warned about the weak K31 but whenever it's brought up on here.. No one else mentions it?? I'd have a hard time believing that the person who told me was wrong.. Of course the cases he mentioned seemed to be kinda rare. But with the way I treat things it was definitely a worry of mine..
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All of the problems I've heard were with people using nos, or the bigger wheel avail. for them!
 
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