EFR 8474's and 9274's
 

Saw them at SEMA and talked to the reps a bit about them.

The compressor map looked very different (flow more at lower pressures), even though both the comp and turbine wheels are the same physical sizes, they have a very different characteristics.

The key take-away is that they are less diesel focused (e.g. 50 PSI) and more oriented for the street/gas performance applications.

@Turblown, any info on availability and more details?

Saw something about them also available on the SXE platform, and that the compressors were a dark color?

I'll be doing a write-up for them later this week for Full-Race.com.

Essentially the compressor ratio itself from Inducer and Exducer are dramatically changed, but they are still B2 Frame Turbochargers.

9280 vs. 9180 = Same 91mm Exducer, but 9280 has 74mm Inducer and 9180 has 68mm Inducer.
9274 vs. 9174 = Same 91mm Exducer, but 9274 has 74mm Inducer and 9174 has 68mm Inducer.
8474 vs. 8374 = Same 84mm Exducer, but 8474 has 68mm Inducer and 8374 has 62mm Inducer.

I can get more into details later, but that's the gist of it. The effects, we'll wait and see.

More shaft speed required (before approaching choke flow) for the same boost but significantly more flow. Should be slightly less responsive but allow more power on the same frame size for the boost levels most people are running on street/track/standing half/mile events.

Be interesting to see 9280 vs sxe369 & sxe372 for the guys who wanted a touch more than the efrs could provide previously. Still a big price difference.

That is my best guess too based on the wheel sizing. I haven't seen any maps yet, I've been waiting on them.

BW takes a long time usually to put stuff on the shelves, so I wouldn't hold your breathe for any real world results anytime soon..

I haven't seen the compressor maps, but typically the larger inducer on the new EFR 8474 would fix the compressor surge issues the EFR 8374 has from spooling so hard in the 3,000 to 3,5000rpm range and above 15psi.

what are the symptoms of the compressor going past the surge line?

The car/drivetrain shakes as the engine shutters and makes a chh-chh-chh-chh sound and the boost needle bounces.

Which is more of an issue on a stock, or stockish port car that is running 20+ psi by 3-3400rpm range.

I just ran a street-ported 8374 on the dyno a couple days ago with zero surge( OEM medium actuator, 3" exhaust, E85, seeing 20 psi by 3400rpms).

I have all of the compressor maps... They're in my brochure right here in front of me. I guess I could snag a few pictures for y'all.

Yup, anything you can do that improves overall engine flow (porting, less restrictive intake/IC, add a rotor) will move the engine operation Right on the compressor map away from the turbo surge line.

instead of using 8474 or 9274 which i imagine would increase lag, wouldn't it accomplish the same thing by using one of the similarly sized SXE turbo? those have abit more lag but have a wider compressor map area interms of the surgeline.


My 2nd question for the experienced tuner, if let's say you went with a EFR8374, and you experienced surge at low rpm, would you be able to tune the boost control to remedy that?

^^
Yes, if you have any form of electronic boost control (a solenoid) in your turbo system you can easily tune around the surge prone area.

I predict the EFR 8474 will just simply be the new hot sh1t for the 2 rotor in the 400-550rwhp range.

D: Shows what I know.

Larger inducer with same size exducer on the compressor actually makes the turbo more prone to surge...

EFR 8474 compressor map in Red overlaid on 8374 compressor map in Black
https://bmw.spoolstreet.com/attachme...wsu-jpg.13075/

EFR 9274/9280 compressor map in Black overlaid on 9174/9180 compressor map in Red
https://bmw.spoolstreet.com/attachme...axb-jpg.13076/

If they give this treatment to the 7670 I'll be very interested

Full catalog download FYI;

file:///C:/Users/turbl/Downloads/bwts_performanceturbosgeneral_1920_2169.pdf

Very happy to see they kept the same turbine wheel sizes, as all of these will fit our new turbine housings..
https://cimg3.ibsrv.net/gimg/www.rx7...5ca7098aea.jpg

You pointed to a local file FYI.

Tease! :drool:

Whats the deal? Did you integrate exhaust manifold and turbo exhaust housing into one unit for rotary? :shocking:

Variable a/r :)

https://cimg8.ibsrv.net/gimg/www.rx7...f1e2c0ea8c.jpg

Ah, that should lead to some compressor surge on the EFRs if people don't get the switchover point low enough :rock:

Nice work! That will be nuts on the rotaries.

It definitely requires tuning, which is why we also cast EMAP bungs into the turbine housing, and recommend using the shaft speed sensors.

We've also changed the turbine discharge to be interlocking, so people can use the Tial downpipe flanges. We've made other additional changes like removing excess material, and smoothing out areas inside etc.

Seeing as these new EFRs will be laggier, this should help compensate.

I think bigger the inducer to exducer ratio then more that it flows at the lower pressures. The idea is that these will make a lot more power in the 15-25psi range where most people run these.

@Turblown, cool innovations as always.. These may not necessarily be much "laggier", since they will be delivering more air at lower pressures, but rather a more linear power delivery which is what we can hope for. Thanks for pitching in!