NissanForLife

Throw an EFR 8374 on there Sean and watch your rev limit go way higher

The bigger the overlap in the cams, the longer (time) there is a straight passage through to the exhaust housing from the intake manifold. As the pressure builds in the small exhaust housings, you need more and more boost pressure to push against the exhaust pressure to scavenge the cylinder. This is why you don't need as much PSI on larger single turbos, the exhaust flows much better and the lower pressures of boost inlet is enough to achieve the same LPM of air into the cylinder. This why I laugh when people gauge an engines "stress or strain" based on PSI figures, it really tells very little, other than how much load the turbo is under, not the engine. Heat is the killer for twin setups, one because of increased PSI inlet temps and 2 because you can't evacuate the cylinder as well as you can a large single setup, the flow is not there and keeps heat from exiting effricently. Yes the increased pipework surface area etc is a factor, but is one of the smallest contributors IMO. Inlet temps are very important, especially when you do the maths for the compounding effect of inlet temps and then compress it in the cylinder, the cylinder temps skyrocket. Just my 2 cents worth and hope my experience helps others

It will be the turbos losing their efficiency and engine pumping losses through small housings. If you could get external gates onto these twins, I think it would be a different story. My engine would not rev much past 7000rpm for this same reason, but man, the response was phenomenal. I had to run 33psi to get 648hpatw out of my GTX2863 hybrids, when trying to get LPM out of small turbos, sadly the pressure has to go up which hurts intake temps and efficiency.

Yeah choking it is definitely a term I would describe it as, I know Paul says this. I have always been against singles............until I hit 600hp I would have loved to have kept it and done the development on it, it get's very interesting and challenging.

High PSI and big tight bends in pipe work create heat, the tight pipe work will create a lot of heat. EGT temps are crucial when you get up to this level, along with intake air temps, this all worked out alongside PSI all helps with heat and efficiency big-time

There is a good reason Racepace don't push their cars past 500-550hp on twins, it's heat. If you just must run twins on a track past this, it's huge amounts of development and loads of coin. The exponential factor really kicks in at 650hp I found, how the guys in the 80's ran 70-80psi F1 cars is beyond me, I guess the fuel plays the biggest part. Methanol would help keep things cooler, but who is going to run that on a street car. Water/methanol injection would also help bigtime for a circuit setup, maybe this would have been something for me to try?

Look guys, I'm the guy who had the white 34 with 2863's in -5 housings, it made 489kwatw but at 33psi. It was a mental track car, I actually never got a proper time with that power figure on new tyres, but at 440kw it was enough to hold the fastest lap record at QR for more than 2 years, it also held a few records in VIC with Aaron behind the wheel. It wasn't all engine obviously, but since we are talking about turbo's and engines, I'll keep it on point. My car ran hard for the first 2-3 laps, it really got hot after that and I mean 127deg coolant temps, the Rad was a custom PWR unit made for Targa tassie, the next step was to put another half RAD in front of it, but the real issue wasn't coolant temps, but EGT's and combustion temps, the dynamic compression ration must have been quite high and the intake heat at 33psi would have been very significant, you cant cool it quick enough, even with an after-market IC which I had without sprayers and dry ice, you start to push **** uphill. The pipework is also very restrictive with twins, the bends are many, which also adds to the heat factor making a lot of turbulent air hotter and thus the amount of actual O2 will be down even at 33psi. 33psi at 40deg is a lot different than 33psi at 80deg. Even though the GTX upgrade was fantastic, it did not suit well to endurance runs, it was for short sprints only with awesome results, but if it was my time again I would have gone the single route in a heartbeat now. A few nice little 32's are over here in WA ahve shown me that and trust me they are setup nicely on singles, they do very well for sprints and they seem to be quite reliable and are not suffering from excessive heat issues. Guy's if you are doing this upgrade for a ballistic street car and time attack sprints for 2-3 laps, go right ahead, you will love it, my car was a crazy machine on the street and short circuit runs, but for a proper circuit car, I can't say it enough, go the single route, just get a tuner who spends more time on low end and mid range to keep the tune linear for great drive-ability. The singles around these days are fantastic, it's all down to the tune. It also won't be long til the E turbo comes out, so the days of lag and need for a wastegate will be soon over I don't own the car any-more, it's now in NSW. I ended up buying a Juno 2008 Lemans car now, at 530kgs I'm loving it, it's reliable and very fast at only 250hp and it will leave my GTR for dead by around 6 seconds per lap on a 1min long circuit, I just need to get more seat time

Gee I think for circuit work you would want restrict the power delivery to be more linear and I didn't think I would ever say that. The power increase is far to rapid for my liking, although easily fixed and controlled, so job well done.

I would be very careful about swapping the rear housings from the -5's when doing the GTX core drop in upgrade. I noticed that the GTX2863 drop in core to the dash 5 was exactly what the -5 needed to make it a very responsive large turbo, changing to a larger rear housing is not necessarily the right thing to do, I achieved 478kw @ the wheels with great response and was very happy with my set-up. All done with housing and rear remained the same straight off the -5. 31 psi was perfect for this set-up and could even go to 33 psi, but was starting to show signs of dropping off with small power increase.

If you are worried about surge issues, another thing worth considering is what BOV and pipework is fitted, is it obstructive and can it release the volume of air quickly enough as not to allow a continuation of boost pressure increase? Is your inter-cooler restrictive and associated pipework? Is any in-let pipework on the pressure side restrictive? especially when someone has a great exhaust set-up that promotes very efficient spooling in the turbine side, this creates an efficiency differential that than can create surge issues, and this is why every car can be different. Anti Surge compressor housings are a bit of a band-aid solution for a system that is not balanced in it's flow on each side of the turbo and I believe trying to eliminate these issues at the core is paramount in achieving an anti surge turbo setup. I know some big turbo set-ups are much more prone to this that others, but to simply only rely on anti surge housings is not the only way to solve these issues. I know a-lot of people rave about the stock BOV's on GTR's and so do I, but have they reach a poor efficiency point with these new GTX turbo's? It seems that partial throttle surging can be where it is noticed the most? Is this a sweet spot of Turbo efficiency vs a poorly operating BOV setup? I know the mid range on these new GTX range is brilliant especially the 2863's is this where the surge is being seen, in the mid throttle range on partial throttle openings because this would make a lot of sense for some cars. One thing I think about when considering this setup is to definitely keep the rear housing from the -5 in it's unmodified form, as to not increase the efficiencies of the turbine side, this could be making the flow differential issue in surge be seen at high RPM's vs low RPMS ? if the .86 housing was used then would we see the surge more up in the high RPM's? Anyway these are some the things I have been thinking about, even though I don't even own my GTR anymore...........lol. Funny how I can't stop playing cars without one.............lol.

I wouldn't be so quick to take their word as final, I have had huge success with my -5 with GTX 2863 cores in there with machined font housings and have experienced no surge issues at all.

Hahahaha, that was me writing that on Youtube, I got so mad reading another thread about it. I really want to spend the next 12 months tearing this EL bloke to the ground, he is one hell of a slime bag. This was such a good read and the outcome was great, well done Edifier, I'm so happy it worked out for you and you stuck to your guns in the end, it is a great learning experience IMO, sadly many others will learnt he hard way. Michael, your gesture was truly remarkable, if I lived in NSW and not WA at the moment I would have really liked to do the same thing. Enjoy your R34 GTR which ever you choose Edifier, good people deserve good things.

Oh gee, I wonder who the dealer was..................lol. Can't believe this is still going on, how can they get away with this? Is there not a way to report this through he correct channels to get them shut down? The evidence is huge.

Hahahahah, thanks guys, " well all I got out of that is 'tune you're car on E85 and she won't go bang!"..........lol. The platinum pro is a good ECU and if you can source the Sensor from the States, it's just the GM version you'll save quite a few dollars I've been told, but I never tried the sensor because I was hooked on E85 all the time and I could never bring myself to even think about 98 ever again......lol. It's a bit like tryres I suppose, once you have a set of 295 03G semi slicks, you are always on the hunt for the same level of grip Anyway back to GTX 63's, the E85 will def allow the boost level increase so you can get your twins on song up around the 30psi mark. 33psi was max for me and was not yielding much more over 30-31psi. Different dump pipes, exhaust systems, cam profiles might get a little more boost top end, but probably yielding the efficiencies in the mid range would be my focus, especially not going to crazy with cams up at 272 degrees which I had. I should have gone back to a 260 really and keep a 11.0 lift. Big overlap cams are so over rated with turbo cars, I think it is a mentality that has come across from the world of Natural aspiration and drag racing cars with big automatic transmissions and stall converters, not forced induction. I suppose a huge single for drag racing may benefit? Hey Anthony, I only ran 1000cc ID injectors for the increased fuel flow with the E85 and was heaps for 478kw. I would probably try a different injector than the ID's, they haven't really had the best reputation from a lot of people and Ethanol for some reason, but the capacity at 1000cc is plenty. Have you got a good fuel system to deliver the increased fuel demand from ethanol? Also a dual entry fuel rail is essential too, in fact I reckon every GTR owner should have a dual entry rail, there is a reason the number 6 cylinder is the problem one Man all theis talk about GTR's again makes me want my car back again, gee I would have liked to have kept on playing around with this.

What part of Brissy do you live in Michael?