BNR S4, One heck of a turbo!

I'm sure some of you have seen this, but here is a blog I wrote concerning the BNR S4. I can't say enough about how impressed we are by this turbo and what it is capable of.

The Biggest Little Turbo

 

Glad this is the turbo I went with. The interesting part is straight out of the box my first impression was, well this is much smaller looking than I had expected but the evidence shows that despite appearing small it can lay down some power

 

Very true! And the small package makes for a relatively easy install.

 

So let's get down to brass tacks: with proper supporting mods and fueling, what can this snail reliably push? 450whp? 475whp? I'm already getting 385/380 @ the wheels in good weather on my BNR S3, so I'm interested to see the actual increase in flow headroom and the consequent power numbers differential.

 

This is probably the turbo I'm going with when it's time to upgrade!


@EdgeAutosport.com Sir you are a magician.. 14 mins to swap out turbo!

 

Correct. My car jizzed coolant all over my face multiple times when I swapped in an S3.

 

Really if you are shooting for 450-500 I think another turbo (PTE 5858 or GTX3076) might be more what you are looking for. Even if the S4 can run up that high, it has to be pushing the extreme limit of the turbo at that point.

 

Did you at least lick the coolant like any normal cats would do??

 

My car treated me like a prison bitch. It went into my mouth whether I liked it or not.

 

Does the s4 have a ball bearing cartridge?

 

I think that's just maybe a Mazda thing. Just removing my ko4 my car decided to act like I was in a porno and gave me a real big coolant shot and facial

 

So far the highest the S4 has been pushed is 450. I would imagine it could go a little further but that is about the top of what it can efficiently do. If you want more than 450 you should go with a bigger turbo. However, the S4 will make the most out of your power band, especially within the constraints of the stock fuel system.

BNR uses journal bearing cartridges in all their turbos.

 

Good points. But my dream turbo is an EFR7163: top-end of a GTX3076 with better spool/transient response than a K04. Pricey, though.

Anywho, so what would the "happy" range be on an S4 with sufficient fueling? Are we talking 450? 425? If we're getting down to 425, I think I'd just stick with my S3 and go EFR if I really wanted some power and awesome turbo responsiveness, boost threshold, etc.

 

Well, 400whp is no problem for it. I feel like 400 is to the S4 what 350 is to the S3. And there you are maxing out stock fuel. If you are already pushing the s3 to 400whp then the s4 is not going to be the upgrade for you. Granted you are working the S3 much harder to do so than you'd need to work the S4, but I still don't think it would be worth it for you.

The EFR on the other hand... We ran a GTX2867 on our focus ST then switched to the 7163. It actually spooled about 100rpm faster than the 2867. Granted, it had a smaller a/r, but still. Also, it flowed enough air to get us to the stock block 1/4mile record and we did it at 5800asl. In other words, I can't say enough good things about the EFR 7163...

 

Making me want an S4.

 

Don't let your dreams be dreams!



Sent from my Nexus 6P

 

Since you're running 425 wtq I'm gonna assume you're on a built block. Is it stock compression? Did you use a stock exhaust manifold or an upgraded one?

Also can you post those dyno graphs in a higher resolution so I can see the axes? I'm interested in how this big/little guy is spooling.

 

I'll have to see if the dyno owner can email them to me. And these are corrected dyno's at 5800asl on stock block. Torque is more like 360 uncorrected. Car still has stock exhaust manifold.

The S4 hits peak torque by 3800rpm. This would be faster at sea level... By comparison, the GTX3076 hits peak torque by about 4400rpm. It isn't exactly a fair comparison though as the GTX3076 graph is 91oct only and the S4 is running E30.

 

Yeah, I'll take that 7163 over a GTX2867r any day. The GTX can hit 450 in good altitude. The EFR should easily hit 500, and with superior spool and transient response, it's a win all the way around. It's a next-level turbo, technology wise.

An easy 400 for the S4 sounds reasonable. But if you're gonna built, why stick with just 400? I'm thinking most people who build want at least 450-500. Sweet deal for a capable turbo, though. I wish Bryan offered advanced tech compressor wheels to make even more power.

 

There are some people who prefer the power band of the S4 and are okay not going past 450whp. But most people who are going to get an S4 are probably not planning on building any time soon. It is the new perfect stock block turbo.