Views on Borg Warner EFR turbos?
 

What are your thoughts on Borg Warner EFR turbos on RX8 13B REW swaps, for example will they actually fit?

I ask ask as there is a lot of discussion on RX7 forums about the 'best' turbo for a 13B REW single turbo set-up but nothing here. I'd summarize all that as:
*The generally preferred higher power turbo for street-ported cars is the Borg Warner (BW) 8374 IWG.
*Some owners prefer the quicker spool of the BW EFR 7670, say to 350 rwhp and 400 rwhp with high boost.
*The 'value for money' prize goes to the BW S366 SXE (billet compressor update of S366)
*A small number prefer the Turbonetics equivalent of the S366 SXE.

Rambling a bit:

However, hidden in that is a great deal of confusion, particularly as people throw out power figures or put up dyno charts without saying whether they are rwhp/fwhp, pump fuel or E85. Rotary specialists' opinions seem to be based purely on what they or their mate sells.

More importantly, we don't have the room that RX7 owners do and I've struggled to fit my mock-up of a 8374 EWG let alone the bigger 8374 IWG. Whilst its not relevant to most here, RHD cars like mine have the steering column to watch out for too, making manifolds more complicated so that none of the rotary specialists will now make manifolds for my car.

An IWG turbo would save me the hassles of building wastegate piping on my manifold, integration with the downpipe (trackday noise restrictions are becoming an increasing pain over here) and the risk of burning out wastegates. However, I've got 2 new Turbosmart wastegates sitting ready to be used.

My situation is further complicated as I have an old turbo, a Greddy TD7S 25g, that I could still use (plenty of power but what's the lag like?). I'd use it if I hadn't spent so much money on this conversion so that spending on a newer turbo makes sense.

On a Renesis? In a RHD RX-8?

Or a swapped REW?

I have a S366 with a billet compressor wheel on my REW swap. I think bang for the buck it is a good turbo.

What are you going to do with the car...and what kind of power do you want to make and it will be easier to give you some feedback

Thanks. I've amended the first line to make clear that I'm primarily looking at 13B REW swaps (apologies - I'd accidentally deleted it there and the bit in the second paragraph doesn't stand out).

For myself personally:
*My benchmark is for 400 rwhp on a street-ported 13B REW with 97RON pump gas for primarily street use and the odd track day.
*Reliability (such as it is for these engine swaps) and driveability are probably just as important as power and I'm happy to come down to 400 bhp (355 rwhp?).
*I've a Turbosmart e-boost street controller that can run 2 main boost levels and am happy to have a lower boost for street and a second, higher, boost for track days.
*I aim to use her whenever practical; I have an R3 for my main driver and a Honda Accord whenever I need 5 seats, drive my father or drive in snow.
*I've an Apexi PFC but am considering changing to Adaptronic if I need to do that to get my DSC working.
*Value for money (judged against its effect on a $15,000+ project) is more important than outright cost.

The EFR's are nice turbos....but definitely pricey. A 8374/9180 is 3-4X the price of the S366

There are some nice things about the new IWG versions ....they make the plumbing a lot cleaner...and no external wastegates. With the power level you are looking at you will have no issues with either.

At 400RWHP you are skirting the power level where the transmission will become an issue...look for a 5 speed at a wreckers...they should be easy to find in the UK. Much harder here in NA

I would stay with the S366 and spend that money on an ECU :)

How stuck are you on the DSC working? It will mean you have to stay with the RX-8 DBW throttle...and will need to keep the OMP wired in to keep the ECU happy running the throttle

Here's my view on the EFR :yesnod:

Attachment 218984


Having rode in my friends 8374 FD.
The efr is most definitely worth the price, if you can afford it. If not sell a kidney to buy one, they really are the best.

He went from a gt35r, divided T4 to the 8374 iwg and it's a night and day comparison.
The only thing he changed in his setup was the turbo then retuned.
He liked his gt35r it was great but the 8374 is in another league.
Cant wait to get mine finished up.


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Those EFRs are expensiveeee. But really nice, and if you think about it the expense kinda pays off as you'll save roughly $500-1k since you wont need external wastegate(s). Also it has an air re circulation valve which is just a built in BOV. So that saves you another $200-300 on a BOV.

Guys, thanks. Your thinking chimes with mine.

The EFR turbos are great turbos and the IWG version certainly save a lot of work and the risk of damaged wastegates (Turblown say they have to take great care with their manifolds to get the wastegates aligned correctly to reduce this risk). However, the EFR 8374 has larger diameter snails and, as you can see from firecran's pic, takes some fitting in. Clearly the EFR 8374 and EFR 7670 EWGs will fit, if only just, aligned along the downpipe centre line.

However, is there space to get in the IWG mechanism?
My quick answer is yes for LHD cars, as firecran's thread says that his is the 8374 0.92 IWG, but there may be a complication with RHD cars, so I'd like to do some more work.

I'm now centring on the EFR 7670 IWG and found an interesting summary of the 3 turbos from Turblown (Shawn, thanks) here

I will be running the 7670 and ID1300's when I switch from the Greddy to the top mount kit I have.

I think you would be better with the 8374 myself ..... unless you don't plan to push much boost .

8374 for a REW :yesnod:

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scott, I think you should go 8374 as well...

:lol: I ain't trying to make mad HP, I think the 7670 will be fine based on my goals (350-375WHP).

After much thought, research and indecision I finally went for a 7670. I decided that I wanted the 8374 primarily for the kudos of high power and track speed, admirable things in themselves but probably less useful to me than the faster spool of the 7670, particularly given the state of roads around me. Someone with the 7670 on an FD was full of praised for it. All of this added up to my going for the turbo that my head said was best rather than the one my heart wanted.

The 7670 fits quite easily. Pics to follow.

I've been around a couple of 8374 IWG cars and they already spool STUPID fast and the transient response/boost recovery is insane. I imagine that a 7670 will almost be like driving a naturally aspirated car lmao.

I would rather sacrifice a tiny bit of response and have a turbo with a compressor that will run efficiently (aka 8374).

Hell...the 9180 spools more than fast enough for any sane person ;)

I actually like it to spool a bit less violently so that you have a chance of getting some of the power to the ground

I wouldn't go smaller than the 8374 either

I was even thinking of going with the 1.45 A/R housing for my 9180 lol. But the investment cast housings by themselves are $$$$$. Going to try out the 1.05 A/R first.

I like this BW vs. Precision comparison as it's on the same car with only the turbo changed between dyno runs:
Precision-6266-vs-Borg-Warner-8374-EFR-DYNO-TESTING-RESULTS

It's no apples to apples comparison against running the same turbos on a rotary, but it's still interesting. I imagine this test on a rotary engine would show even better spool from the EFR due to the wider range of exhaust gas flowing between low and high rpms.

The only line that matters in this "comparison" is this one:

Precision units were Undivided .81 A/R turbine housings & BW EFR Divided 1.05 A/R


You can go ahead and disregard that entire test as it's pretty much fucking useless.

They also ran the precision with 3lbs more boost than the borg warner, so no shit it made a little more power. Not to mention they were probably over speeding the shit out of the EFR unit up at the 800WHP range.

Pffffffft, whatever angry guy. That article is not about comparing turbo specs (housing, trims, etc.) but rather about testing the turbo unit as a whole with the boost that's put in vs. the power that comes out.

The results in the article I was referring to were the first set, not the second set you mentioned above. They go like this:
Results
Precision 6266 CEA Journal Bearing .81 A/R (undivided), 80 degrees on dyno day
843whp & 844wtq @ 29psi

BW 8374 62mm EFR DBB 1.05 A/R (divided), 65 degrees on dyno day
786whp & 815wtq @ 30psi

https://cimg8.ibsrv.net/gimg/www.rx8...4254dd3c72.jpg
Dark red = PT, light red = EFR


So while the EFR spooled 100rpm faster with a divided housing the PT made more power with less boost on a hotter day with an undivided housing.

Regarding your overspeeding comment, they were both running 30psi, and the datasheets for these turbos state the EFR is good for 800hp vs. the PT for 735, so I'd assume it's more likely the PT was overspeeding :dunno:


But since you brought up the difference in the housings, let's discuss. If the following were true....
...then that same PT with a divided housing would spool approximately 900rpm sooner and make 100whp more than the EFR on a hotter day with less boost. This makes me thing the PT kool aid tastes better than the EFR kool aid.

I'm discussing this as I'm looking at different turbo options currently (actually for a Renesis), and it's very difficult getting a real world comparison between turbo brands. I'm not here to troll, I'm here to learn.

Jimmy what do you find interesting about these findings?

Jimmy, are you forgetting the fact that they seem to be using a non-divided manifold for all of these?

All this says to me is that firstly, they don't know how to pick out parts that work together. Second, they don't know how to pick a properly sized turbo.

Had they picked the EFR 0.83 singlescroll the results would have been more interesting but I suspect they did the test around the way the car was already set up and therefore went with an EWG .

There would seem to be some bias towards the Precision for whatever reason as the spoolup comparison definitely isn't valid . The overall power result is interesting though as you would think the EFR would do better with a larger AR exhaust housing.

Perhaps the twinscroll housing on a single scroll manifold was a handicap ?????

9krpm, I find the article interesting as (assuming a divided manifold), after all the good things people have reported about the EFR, I was expecting it to outperform the other turbo in at least one area of the graph, either down low or up high, but it appears that the PT walks all over it. Changing the turbine housing could allow the EFR to perform better in one area of the graph, but I don't think it would outperform the PT in all areas of the graph simply by changing the housing. This may all be a moot point though, as Arca is correct in that they didn't specify whether the manifold was divided or not. If it's not divided, I think we can agree that the results are close to worthless.

Arca, you worded your opinion that the manifold housing is non-divided like it's a fact, which can be misleading to some. I missed this when reading the article, can you explain why you came to this conclusion? Maybe we can put this to bed and find a better real world turbo comparison.