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Bw s257sx-e

10K views 8 replies 4 participants last post by  AlmightyFork 
#1 ·
So im very close to pulling the trigger on this turbo. Currently im on the stock block, stock head.

Im looking at this turbo because it will give me room to grow when I build the motor. Ive only seen one other post of someone running the BW SXE turbos, but its the S252.

Just wondering what everyones opinions are on the S257sxe. While the motor is stock I'd like to keep the power in the sub 400's.
 
#2 · (Edited)
horrible turbo for those goals....that's a 600+ whp turbo. Getting that much more turbo than you need is just reducing your powerband. A similarly powered 50T would drag that car down the street....and back

People chase peak numbers and don't pay attention to usable powerband....lots of guys heart broken when their XXX whp car doesn't perform like they thought it would; 9/10 times it's improperly sized parts
 
#3 ·
That's the one reason ive been hesitant about getting it. It just seems like too much turbo. Thank you for the input.

I think I may go with the s252sxe instead. Its capable of 525whp, 55lbs / min. so it seems a bit more reasonable, especially considering im on the stock block/head.
 
#4 · (Edited)
Yeah you never want to get that much turbo and not take advantage of it...because you pay for it in where the power is made in the RPM band. I've seen guys with 600+ turbos and they make my power (low 500s) but when you look at when their power comes in VS a turbo sized for low to mid 500s....it's night and day.

Carrying power from 4k to 7k is a lot more interesting than 5k-7k
 
#5 ·
s257sxe
compressor
57.15mm inducer 76.2mm exducer FMW Forged Milled Wheel (Billet)
turbine
-61mm exducer, 70mm inducer turbine wheel

s252sxe
comp
52.17mm inducer 69.5mm exducer FMW Forged Milled Wheel (Billet)
turbine
-61mm exducer, 70mm inducer turbine wheel

------------

Comparing the 252 vs. 257 measurements listed above. They both have the same size turbine wheels. It's only the comp wheels that are slightly different.
The inducer of the 257 is 4.98mm larger than the 252, and the exducer is 6.7mm larger than the 252.
Since the turbines are the same on both turbos, does the slightly larger compressor wheel on the 257 really shift the powerband that much?

Is this what you meant when you said 4k to 7k powerband is more interesting than a 5k to 7k powerband? The slightly smaller comp wheel of the 252 allows for the power to be utilized at a slightly lower rpm? Since the redline of these motors is not very high, the sooner the power the better (so to speak)?
 
#6 ·
The bigger wheel will spool later and it'll shift power up further than the S252 since power doesn't come in till a later RPM. What you can see happen though is smaller turbos will run out of breath sooner the more RPMs you turn; this isn't a big deal to you on a stock motor but for guys building a motor and revving to 7-8k it becomes a consideration.

It's a give and take...for example I have a 58mm but my exhaust housing is small (.63) so it spools fast but dies off after 7k and the turbo is probably out of steam around 550whp. If I were to get a bigger exhaust housing (similar effect to a bigger wheel) then I'd carry power beyond 7k but I'd probably spool closer to 5k. My powerband is now shifted from 4-7k into 5-7.5/8k but I gained more power potential (600+ whp capable). For someone with a stock motor...you want to stay away from shifting the power further up because stock motor is out of breath by 6k...(TQ starts falling like a rock at 5500)

 
#7 ·
Nicely said! Thank you for clearing that up for me.

I placed my order for the S252! :D
I also ordered a 38mm EWG.

Ill create a new thread after I get it all installed with some pictures.

Seriously cant wait
 
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