Jump to content
SAU Community

Recommended Posts

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.

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....

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

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.

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!

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.

img2149y.jpg

img2163g.jpg

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.

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... :)

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 :)

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.

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.

Guest
This topic is now closed to further replies.



  • Similar Content

  • Latest Posts

    • Hi, i’m making a rb25det coil loom for Vag short coil. Can anybody tell me which Ecu signal wire belong to coil number 1 and 2,3,4,5,6? The connecting switch in above pic is 8 wire i think white is for +12v and black for earth.
    • Was there ever a model of the Stagea m35 that didnt have a badge on the grill? I thought I saw that somewhere, some aero edition or something? I cant find it again? davemoto
    • Its a 2002 vr-x four VQ25DET, silver. Coil overs, lowered, polished alloys and sport exhaust. Bit of a project, was sitting in a shed for a while but runs and drives great.
    • I wasn’t able to replicate the sound anymore. It was a one time sound so maybe it was just coincidence but it was like small pebbles being dropped in a coke can.   should I try cleaning the MAF? It could be it’s functioning but dirty? I don’t know.
    • Update 4: Hi all. The car drives again! Haven't driven for long, only to store it in the garage again, but the test drive was successful. The coolant and oil leaks seem to be fixed for now. Temps on the engine were also very good, while moving I never even saw 80C water during the approx. 30 minute drive. Ate up all the coolant in the reservoir though so will have to fill that even more when I go to the car next time. One thing that pisses me off is that the RPM gauge is still f**ked, I even resoldered the board twice and used copper paste on the silly screws that are used as connections. Next time I take it out I'll take apart the board and fit new components, I'll see if I can get a replacement IC for it.  I have an appointment set for 22nd of September for the engine tune to 370hp. Alignment also still needs to be done. My hope is that I can get all the legal stuff over with by the end of this season. Anyone of you have advice regarding intercoolers? Currently there is an APEXI core fitted, one of those weird hybrid ones, 600x270x76. I don't think it's bad but it's not new and now I still have the chance to change it now to legally include it in the paperwork. Only issue is that the only options that would arrive in time are a HKS Type R intercooler or generic Ebay spec intercoolers comparable to a JustJap one. Ideally I'd order a Plazmaman but it takes over a month to receive which would mean making the car legal has to wait until next season. Would love to hear some input on this. Same story for my injectors, the previous owner was a nunce and put ID 1050x on the engine. They work but are obviously not ideal at "normal" power levels. But I don't see a reason to change them unless the tuner says it's necessary. I read online before buying a different exhaust that the top secret style rear diffusers won't fit due to the size of the rear resonators. My buddy and I made it work by slightly "adjusting the shape" of the mounting bracket and making some spacers out of 3d print for the mounting bolts. Fits like a charm. Just putting this here in case someone has this problem. Even the hefty HKS Silent Hi Power rear can fits without hitting anything.
×
×
  • Create New...