AndyStuttgart

Actually I don´t think it´s such a good idea of potentially having two different charge temps and boost levels for the front and rear cylinders...so no, I won´t jump the bandwagon saying twins are shit. For me both variants are cool and I´d leave it to personal preference for everone. While I live by "it came in twin form by factory so I´d stick to that" for most of my cars, I still choose a single on some of my projects to try it out as well. Hopefully this year I´ll be able to more or less compare an EFR9180 single vs. twin G25-550 on two similar built RB30s (forged bottom end, Poncams).

RB30 bottom end, RB26 head Forged rods / 86mm Wiseco RB26 pistons, CR about 8.7:1 HKS Step 1 cams 8.7 lift, 256in 264ex, exhaust mildly ported ID1000 RawBrokerage T4 twinscroll manifold with two Tial F44 WG (1 Bar spring presure) EFR8374 1.05AR twinscroll 3.5" exhaust 45mm screamer pipes Made over 600hp on wastegate pressure: 700 with manual bleed valve (unstable boost dropping to 1.45 bar at redline) 95 octane pump fuel (as setup will go to the states next year in a R32) Video:

*reminder*

I also used the anti surge housings with the GTX, with the stock cams Full boost was there around 4500, Same as the HKS GT2530s before. HKS GT-RS with their anti surge housings did take at least another 500rpm to spool. All on stock cams, with 100cpi cat and 3.5" exhaust. Didnt retune since the install of HKS 256 in 264ex cams but even with 2-3 degree less ignition now feels to push a lot harder.

Did you use the -5 before on the non-built engine? Or how do you come to the conclusion the GTX are laggier than the -5? I have used HKS GT2530, GT-RS and now GTX2860 (all in their genuine housings) on a RB30 with stock cams, and the GT-RS were the only one which were REALLY laggy. As they have been on the car inbetween I can´t really compare the 2530 to the GTX side-by-side, but my impression still is that the GTX are way better spooling etc. than the 2530...am I really that wrong? BTW all turbos were running with about 1.5 bar / 22psi.

What diameter is that? No middle or backbox? Surely no street car then

I have to measure again, I think I used 80mm pipes and bends, so 76mm inside diameter for each turbo until the cat converter, then 88.9x2mm to the back...as the cat is the biggest restriction anyways. That´s why I used two catalic converters on the GTR, and after the middle box there´s a 114.3x2mm pipe towards backbox + end, as this was the biggest possible diameter between rear axle and LSD

Are the tomei REAL 3 inch dumps? That´s the only one I could find where you can see the custom dump pipes...but it was before the GTX came in.

Instead of buying turbo elbows, just build your own - that way you can maximize size and still gain some space towards the rear turbo

It´s in the RB30 hybrid dyno thread ;-) 20 degree is not that much, taking into account that I use 102 octane pump fuel... If you compare that sheet to the last (disappointing) one I posted, you can clearly see how much later torque etc. is produced - as the dyno did not use it´s eddy-current brake. So I bet on the Superflow I´d see about 650hp and 550lbft...with 2 bar of boost (so fuel pump issue resolved), 700hp should be no problem! BTW the car drives absolutely fine on the road! Full throttle in 2nd gear, no traction issues using 265/35R18 Toyo R888 on the rear...in a GTR this would be a dream to drive from the starting line!

I was disappoint regarding absolute numbers, but not about the power delivery. Before the remap we / Steve from FC Tuning did now, there was no fair comparison possible between the HKS GT2530 we had before and the GTX2860R we use now - as the HKS´s were mapped "a bit", but the GTX were not. To be precisely: about 15 degree ignition timing at 1.35 bar got us more power with the HKS than with the GTX at 1.7 bar and 9 degree. But the GTX at about 21 degree ignition timing are a whole different story then ;-)

Can´t wait to see the graph when it´s done :-) We managed to get 604whp on a Mustang Dyno at 1.7 bar with more ignition timing (about 20 degree, last time on a Superflow we only managed to get around 415whp with 10 degree).

So, car finally got mapped but it looks like stock fuel lines give too much backpressure - so 1.7 bar was the save limit before mixture leaned out, which disappointed me a bit. We still could get much more power out of the car, by adding about 10 degree of ignition timing - no wonder we made such poor results the last time ;-)

It can be seen on the Dynosheets I posted above, although the boost pressure reading is wrong on the one with the GT2530´s it gives an indication when full boost was achieved (around 4800rpm), compared to around 4400 using the GTX.

The additional 50hp ain´t worth it - but 400rpm sooner RPM on a dyno and a much smoother power transition on the road are worth it. And your drivetrain won´t be f**ked as hard...