Engine/Transmission (1994 - 1998) K31 vs 3B

[JAmos]

I was looking at turbos on ebay and saw a guy selling a borg warner wastegated K31. How would it compare to a 3B in a set of twins? Could it be a workable set-up using the stock turbo on top, till a better top turbo could be afforded? On average, how much fuel would it take to light a stock/K31 set?



Jordan

 

[PRattenbury]

I'll be using a K31 as a bottom turbo with a PS62 on top. Industrial Injection Towing Twins. To answer the top turbo question, yeah you could use the stock one for a little while but it prolly won't like it for long. I'm not sure how much fuel it would take to light them. I'm pretty sure I got enough, though. What's been done to your ride for fueling?

 

[Forrest Nearing]

with a stock turbo on top, you could just run an agressive plate w/ the stock injectors and probably do pretty good. I got 55psi out of an sps62 on my last 98 with stock injectors in it

 

[JAmos]

I have read about Industrial Injections towing twins, especially seeing that the K31 is wastegated, I was thinking that it should be a quick spooling setup. Currently I have the plate out and the governor springs tightened-so far:-laf



Jordan

 

[JAmos]

Has anyone used both and can share the differences?



Jordan

 

[BPonci]

62. 80 with a k31 is nothing new but it does make a great combo.

 

[JAmos]

Sorry I don't think I specified what I was asking. My last post should read as--- has anyone used a 3b and k31 as bottom turbos? That being said, of the two, is the k31 the better choice? This is just an asumption, but since the k31(at least the one I saw) is wastegated, it should theoretically spool faster. BUT, I don't know any of the facts on compressor and exhaust housing choices. What I have learned here(tdr) is that the ex. housings for the 3b are 22, 23, 26. There may be more choices still and I dont know what compressor choices there are for the 3b either.



Jordan

 

[Jim Fulmer]

After seeing the K-31 wastegated version I personally would take it over a 3B any day, think of the power output of each, K-31 and a 62 (like a SPS 62) now put them together.



Been thinking seriously about this combo for my project truck.



Jim

 

[BPonci]

I have built kits with the k31,s400, bht3b-22, bht3b26 and a bht3b1/2. The k31 spools quicker than all the other ones but lack some up top. Its a great daily driver system thats hard to beat. You really have to ask yourself what do you really need. What rpm do i drive at? Were do i want my power to come on at? What do i want for max power? Am i really after horsepower or torque? What my fueling level at? Timing also play a role in when your power comes on. Things to think about.

 

[JAmos]

Is there just one K31 option? Any different compressor sizes?



Jordan

 

[Jim Fulmer]

There should be several versions but that I'm not sure of. I sure like that wastegated version that I. I. has, been really thinking about it and a SPS 62 for a Twin setup.



Jim

 

[RonA]

I ran a k31 for about a year and a half. I've only tried a couple of different setups, but it is still my favorite.

I only recently took it out to see if I could get something that spooled as good but put out more air. Haven't found it yet.

My K31 is waiting for a bath and some paint. Only one version that i know of, 70mm compressor(measured), 83mm turbine, 1. 24 exhaust housing.



RonA

 

[JAmos]

Hmmm, kinda figured that it would be a little bigger. What does a 3b have for a compressor?



Jordan

 

[RonA]

I've tried a 3B/23 and /26, a couple of 96mm turbine s400's, an 87mm turbine s400 with a 1. 1 ex housing and 80mm compressor, and also a 75mm compressor. The K31 gets the air to the motor before the temps even start to go up and has excellent throttle response. I don't care for it with an hx35 on top. It spools quick, but runs out of steam early. An SPS 62 on top is a great setup. If you don't mind just a tiny bit more lag, a 64mm top charger ads a bit more to the top end and still tows like a dream. As a daily driver, the k31 is really tough to beat.

 

[Jong]

Would a Silver 62 possibly be better than a 64 as the top turbo over a k31? Also, does anyone know what mods II does to their k31's versus other turbo retailers?

 

[JAmos]

Any hybrid possibilities/larger compressor housings that would bolt on? If not, this might be a good idea for VENDORS TO LOOK AT.



Jordan

 

[RonA]

If you want a larger compressor, get a GT42-02 Garrett. It has an 83mm turbine side like the K31 and a 74mm compressor.