Opinions on BorgWarner EFR 8374

[9 T GSX]

I’m looking at possibly running this turbo on my build and wanted to hear from anyone who has used it before — what were the pros/cons, and anything you’d do differently or things to look out for.

I’ve read a few posts saying the main issue is the physical size. Apparently these are a bit wider than Precision, Garrett, FP, etc., which means the header needs to be measured and built very precisely so nothing rubs or touches.

My goal is around 700 hp on a 2.3L for a road‑course/street setup.

One of the reasons I’m interested in this turbo is the integrated wastegate and blowoff valve. I’m not sure if that’s a good thing at this power level since it goes against the typical DSM setup. My thinking is: if the engineers who designed these turbos built the IWG and BOV into the unit, then it shouldn’t have issues with boost creep, flutter, etc.

And honestly, I’m imagining how much cleaner the engine bay would look without a BOV on the intake pipe and a wastegate hanging off the O2 housing.

I also took a look at the BorgWarner MatchBot and tried to wrap my head around the data, but it was a bit of information overload. From what I could interpret, it looks like either the 0.92 or 1.05 A/R turbine housing would be the best match for my goals.

Curious what people who have actually run these think — especially about fitment, reliability, and how the integrated hardware performs at this power level.

 

[babyviper]

Morrisonfab did one of these just a different size turbo

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[Canadian_CD9A]

I had Morrison build a kit around my T4 IWG EFR7670 with the capability to go up to an EFR8374. I didn’t end up using it and stayed with my HTA68 on stock manifold because I didn’t want to cut up my car. Packaging was very difficult in an Evo 1 (and 2G DSM?) for many reasons that I’ll mention later. If I were to do it again, I’d put a EFR7163 on an undivided T3 manifold on a 2.0L, which is an extremely simple, versatile, compact, and responsive setup. The EFR7163 has the unique ‘Mixed Flow’ turbine wheel that doesn’t gain anything from twin scroll housings, so it’s basically getting the efficiency of TS in the packaging of a super basic open T3 setup.

The 8374 is a bit outdated, I’d use the 8474 with the higher power ceiling if you’re going to do it. They’re still great turbos by 2026 standards. R/T Ernie has a bunch of data on both on EvoM. You won’t want to use a generic manifold and exhaust setup because there are a lot of problems that can pop up; and a lot of power that can be lost with the wrong setup.

The IWG is only found on the smaller 0.92 housing, and it presents fitment issues because it is a physically longer turbo - that makes packaging near the accessories difficult since the compressor housing will be right up against the block/transmission. To get maximum power, it will require a big, smooth downpipe exit and turn that will invade the oil filter, alternator and PS area. The wastegate canister also bulges out considerably into the radiator area, which is very tricky to overcome. The smaller turbine housing is going to drive higher exhaust pressures and make tuning a bit more tricky to manage heat as a result. Personally I’d go 1.05 TS EWG with the 8474 and let it sing.

The built-in blowoff valve isn’t adequate for 700hp worth of airflow either; Turbosmart recommends going full standalone BOV on the 7670 and up.

With all that said, the EFR8474 rocks very hard, but you can’t cut any corners to make it roll at 700+ with maximum efficiency. You need the whole setup with the right parts to get there.

 

[9 T GSX]

Thanks for that information those are the things I was interested in hearing about. 8474 might be the better way to go if I ever wanted more power as the extra head home is always nice to have, but I think 700hp will be plenty for what I want to do.
Would you have the link from Ernie on EVOM? Would be interested in reading what he has to say
“Nothing like a BorgWarner to remind you your wallet still has a little life left to squeeze out. Guess this is just the next level up.”

 

[Strm Trpr]

I was all over the twinscroll bandwagon for a long time and abandoned it when the Ultra High Flow turbine wheels came out from Xona Rotor.

Large Runner vs Small Runner 900whp Dyno Test – Morrison Fabrications

morrisonfabrications.com

Check out.
The small runner v-band manifold and .64 A/R TiAL v-band turbine housing pushed that 2.0L to over 900whp.

Keep this in mind, you’ll be running a 2.3L.
You’re going to reduce boost response time due to increased displacement, period.
Plus you’ll have to soften boost onset or have a couple spare transmissions handy.

Twinscroll adds complexity to the system and extra cost. If you decide to run the EFR8474, do yourself a favor and go with the 1.45 A/R T4 divided housing.

One can learn a lot on the EvoM forums.
Do a google search on “R/T Ernie evolutionm.net”
Once you’re into the forum, find his screen name in a thread, click on his screen name, then find profile, click that and then you’ll be able to find all posts and more importantly all threads started by him.

 

[We're on Boost]

Would you have the link from Ernie on EVOM? Would be interested in reading what he has to say

R/T Ernie's main thread in Evom is very long, 97 pages.
Here's a link directly to page 86 where in post 1277 he gives the update that he has sold the 7670 and has the 8374 on it and it's running again.
So that should be a good place to start.

Hint about navigating pages in Evom if you haven't been over there much. The page selector is at the very bottom of the window, towards the right.
One of the page tools there is a blank for "Go to page".

I was following the EFR stuff too and eventually decided to do a simpler setup, which I'm still using to this day.

 

[Canadian_CD9A]

I thought it Ernie swapped to the 8474 but I can’t seem to find it. Anyway, there are 2.3 8474 results out there and they’re pretty impressive: https://www.evolutionm.net/forums/evo-dyno-tuning-results/757931-805-whp-evo-ix-2-3l-efr8474.html

 

[We're on Boost]

I thought it Ernie swapped to the 8474 but I can’t seem to find it. Anyway, there are 2.3 8474 results out there and they’re pretty impressive: https://www.evolutionm.net/forums/evo-dyno-tuning-results/757931-805-whp-evo-ix-2-3l-efr8474.html

Do you know if the EFRs still have a very strict shaft speed limit? They did ~10 years ago. It was because of their turbine wheel material.
Last I knew, their solution was to use a shaft speed sensor on the turbo and make sure you didn't exceed the limit.
One time I managed to get a BW tech support person on the phone and had a pretty good conversation with him.
I asked him, wouldn't the shaft speed limit have some to do with exhaust temperature and exhaust forces on the blades? He said no not really, the wheel flying apart could be nailed down almost 100% to shaft speed, regardless of that other stuff.
He said they tested by running one at room temperature and it blew the wheel at the same speed. He said they even tested one running it backwards and it still blew up at the same speed.
So now I'm trying to remember if the speed limit they tell you to observe is actually the top speed line on the compressor map, or what. I don't remember what he said on that. But I think that's what it was. And I don't know if all that is still the same, 10 years later.
Anyway, pretty sure you gotta log turbine shaft speed and observe a certain shaft speed limit.

 

[9 T GSX]

Dont know about the shaft speed limit issue but I do know they are now using a "Gamma-Ti turbine wheel which has the lowest friction and fastest spool/response, most extreme durability" according to their site. Thanks for all the InSite on this, think I have some research to do.

 

[Canadian_CD9A]

The shaft speed limit is an issue on the under-turbined models (9174 failures were common) - it really needed to work that turbine wheel up to support the flow. That was addressed with the 9180, which supported more flow at lower turbine RPM. Since the 8474 compressor can support the same flow as the 9174, it’s a concern here too.

The 8474 is good to 127,000 RPM. At this level, I’d absolutely be running a speed sensor if I intended to run it at high boost on ethanol to find the limit.