[Closed] Borg Warner Efr Series Turbos

[TheKeeper]

Before I quote myself again in a single turbo application is there a need for the surge ported compressor housing or was it a precaution?

All of the larger framed turbos come with the ported compressor housings. 70mm-91mm

On curtain really high flowing heads, some Hondas for instance, there is always a chance of a larger turbo surging so they are all ported.

So to answer your question (I think), it's not an option.

[bigmikespec]

So to answer your question (I think), it's not an option.

So Baron why twins?

[Beer Baron]

well in my experience two well sized twins will out-perform a well sized single. so at a given power level the twins will give better response. a few reasons. for starters if you think twin scroll is good then twin turbos take that one step further with completely separate housings, wastegates, manifolds and exhaust exit path. on a RB26 firing order means you end up with 1 pulse in the front 1 pulse in the rear, and so on back and forward. two small twin turbines also should have less inertia than one large wheel of approx 1.5 times to double the size. in this case the twin 6258s were available at the time as were the full race manifolds to mount them but none of the larger singles was available. also, some people prefer the look and packaging of twins. granted with the EFR twins they are not exactly 'compact' as the housings are longer than garrett twins most often used but they do look pretty neat.

I'll put up some pics of the install soon. It was a massive amount of work with this car being the first R32 done but I think Full Race is going to work with us to improve that for the future.

Given the performance of these twins I'd seriously question whether for a GTR you are better off with these or with a single 8374 or even 9180? these are performing pretty damn well and combined two 6258s will outflow a single 8374 (on paper at least) and come pretty close to a single 9180. and lag is certainly not an issue even on a 2.6L....

[R31Nismoid]

Ye i was gonna ask what was the fitment ended up looking like, how it was for room etc.

Are the high mounted?

[Marlin]

I'm super keen to see the result for a 9180 on a 26..... I think it will be pretty cool judging by what we saw on the 26/30, and the plumbing alleviates much of the drama that is RB26.

[bigmikespec]

Interesting indeed and 100% agreed on wheel inertia playing a role. Photos of the install please... see how messy it is

[skc]

I’ve had a couple of EFR 8374’s on order since late last year, and understand the general frustration expressed by a few in this thread. I finally managed to get my hands on one a week before WTAC to run on my otherwise tarmac-rally spec IX. After reading through all the dire innuendo expressed in this thread, I have to say, we approached tuning the car with some serious reservations. In fact, if time had permitted, I am pretty sure we would have probably reverted to running either my HKS T04z or TS GTX3582 instead.

Tuning the car for a few hours the night before the event, it made an easy 424kw atw at 2.0 bar, despite the fact it was tied down with 6 straps and running soft R’s on the rollers. For reference, the same car, on the same rollers, with the same target boost made 417kw atw running the T04z. Although peak power was comparable, what really surprised me was the relative power down low. At 4500rpm the 8374 was making ~70kw atw more power than the T04z, despite the car now running a 0.2ltr less displacement with the new bottom end.

We took the car to WTAC and flogged it for three days, and the turbo didn’t miss a beat. Ignoring the numbers, trackside the real benefit from the EFR is throttle response. With the T04z, in some short corners I used to left foot brake and get on the gas early to try and get the turbo spooling and get drive off the apex. Now, with the EFR’s responsiveness, not only is the “left foot spool” redundant, there are a couple of corners where I am short shifting and driving out on the much more lineal torque.

We will get back on the rollers later next week and refine the cam timing and balance of tune and then see how it performs at 2.5 bar. My view for what it is worth; product introduction and packaging issues aside, I can’t see why you would run anything else based on what I have seen to date.

SK

[Lithium]

Awesome! Now we're talking, that sounds like quite a serious beast - nice work :-)

[bigmikespec]

How did it compare with lap times?

[Beer Baron]

thanks Steve, I was hoping you'd post up. interesting to see two EFR powered cars (yours and EVO and John's GTR) ended up together in the results!

judging by your results with the 8374 it makes me wonder how nice something like the 7670 or 7064 would be on a street/part-time track EVO? maybe 300-350kw and very responsive.

You're running twin ext gate on your 8374 yeah? same as you did with the GTX and the T04Z?

I can't want to see John's GTR with 2bar in it. Given on paper the twin 6258s sit somewhere between a single 8374 and a 9180 I'm hoping it'll get well into 450kw+ at the wheels at 2bar.

[Beer Baron]

How did it compare with lap times?

not sure how it compares to Steves other times but compared to the GTR with twins (not much value comparing 2 different cars I know) they were a bees dick apart!

[Beer Baron]

Ye i was gonna ask what was the fitment ended up looking like, how it was for room etc.

Are the high mounted?

front turbo is low and quite forward, rear turbo sits higher to allow it's intake to clear the front turbos dump.

pics just for you sweet heart.

[Beer Baron]

I should also mention that the small twins make their airflow at a much lower pressure ratio than the singles. witness steve's car with the 8374, 2bar for 424kw, John's car with the small twins need only 1.5bar for similar power. Yes the twins also run out of puff a bit earlier too (single can supposedly run into the 40psi range where as the twins I wouldn't run much past 30psi or so) but for longevity of turbo-charger and engine lower boost is certainly better. have a look at the compressor maps and you'll see how different they are at similar pressure ratios. The twins make their peak lb/min of flow at much lower pressure.

also, as a wise man pointed out to me. GTR's WERE MEANT TO HAVE TWINS!

And they sound cool too. The sound of John's car at full noise powering out of Turn 1 warmed the cockles of my heart.

[skc]

How did it compare with lap times?

Too many things changed with the chassis to compare lap times sensibly. As well as a complete change in braking package, we added a cage, removed ~75kg nett, changed the track and moved to a custom center diff control unit. To make matters worse, setup time after the build was limited to a half a dozen laps the afternoon before the event and the diff maps were.... uhmmmm... not ideal...

[Marlin]

I’ve had a couple of EFR 8374’s on order since late last year, and understand the general frustration expressed by a few in this thread. I finally managed to get my hands on one a week before WTAC to run on my otherwise tarmac-rally spec IX. After reading through all the dire innuendo expressed in this thread, I have to say, we approached tuning the car with some serious reservations. In fact, if time had permitted, I am pretty sure we would have probably reverted to running either my HKS T04z or TS GTX3582 instead.

Tuning the car for a few hours the night before the event, it made an easy 424kw atw at 2.0 bar, despite the fact it was tied down with 6 straps and running soft R’s on the rollers. For reference, the same car, on the same rollers, with the same target boost made 417kw atw running the T04z. Although peak power was comparable, what really surprised me was the relative power down low. At 4500rpm the 8374 was making ~70kw atw more power than the T04z, despite the car now running a 0.2ltr less displacement with the new bottom end.

We took the car to WTAC and flogged it for three days, and the turbo didn’t miss a beat. Ignoring the numbers, trackside the real benefit from the EFR is throttle response. With the T04z, in some short corners I used to left foot brake and get on the gas early to try and get the turbo spooling and get drive off the apex. Now, with the EFR’s responsiveness, not only is the “left foot spool” redundant, there are a couple of corners where I am short shifting and driving out on the much more lineal torque.

We will get back on the rollers later next week and refine the cam timing and balance of tune and then see how it performs at 2.5 bar. My view for what it is worth; product introduction and packaging issues aside, I can’t see why you would run anything else based on what I have seen to date.

SK

I'm drooling with anticipation re what one of these has in store for us on your "other" car Steve

[skc]

I'm drooling with anticipation re what one of these has in store for us on your "other" car Steve

Me too. With ~350kg less, it should all come together quiet nicely.

[Marlin]

Me too. With ~350kg less, it should all come together quiet nicely.

I know how busy you are mate, so, if you need a hand.... I'm only across the road from Dave's (Comp Fab)

[R31Nismoid]

I see what you mean about a tight fit. JEBUS!

Thanks for pics!!!

[FineLine]

Good to see some results starting to trickle through.

And Baron, fertile women were meant to have twins, Not skylines. If the bw singles perform as promised with earler spool times etc it will only be the diehards that run twins in the long term.

[Beer Baron]

That looks like 22kph lower onset of boost - is this about 800rpm? (4000rpm vs 4800rpm?)

Either way it's a shedload - is the response even better than -5 ?

I get about 25km/h better response for boost and I'd say it's around 1,000rpm or so. but yeah pretty close. Not sure if response is better than -5s but it certainly seems to be at least as good.