TwinTurboM3

this is not a RB26. it is a BMW inline six 3.9L Cannot decide between Gt55 and Gt60. I know there are many big-boys here and your comments are appreciated. Use of this car is Highway rolls & drag racing as well. With the 3.9L displacement which turbo would you use? Compression ratio. 9,0 to 10.5:1 (C16 all time use, as this is not a daily cruiser. I have a E46 M3 with twin GT3076s for daily use) Arrow Precision Forged Titanium rods or Forged rods? How will Tit rods behave? Pistons: which brand would you opt? CP/ Arias? Main billet caps will be custom produced. There is no billet main cap for this engine. Cylinder head: I am leaning towards Headgames. Any other reputable head builder? Cams: Custom cams will be grind as per HKS 280 cam specs used on 2JZE. This is tough, need custom grinding. Exhaust manifold: not as perfect as a Full-Race. But I will do my best in fabrication, smooth curves, trying to keep the runners close to equal. Maximum engine speed will be 8800-9000 rpm Which turbocharger would you choose? GT55 or GT60? I personally dynoed a Supra with GT45-80 on my own Dyno Dynamics and saw full boost at around 5000 rpm on 3.0L. head was perfectly prepared with agressive Port & Polish and + 2 mm valves. I have talked to another supra owner, and his full spool is around 6k rpm. With 500 cc extra engine capacity, a GT 55 would spool at around 5300-5500 rpm (assuming the compression ratio is 10,0 and cylinder head is very well prepared) GT55 power band will be from 5500 to 8800 rpm. Acceptable and will put a smile on the face. On the other side, GT60 is an unknown application. Cannot get first-hand information about GT60. I only saw this video At which rpm will the Gt60 spool on this application with 3.9L engine? I fear of having full spool at around 6600-7000 rpm on the 3.9L with the GT60. Which turbocharger would you choose for this application? MD __________________

i have stock cams 260/260. And another set of 288/280 cams. The point is i am able to change overlap with the variable valve timing through oem ecu. I will start with the stock 260 cams, play with overlap and see on Dynamics. Then, I will change to 288/280 cams. Max engine speed is 9000 rpm, so i believe i need higher duration cams at those higher engine speeds. Thank you for the replies.

Thank you very much. Regards. mert

For the twin Gt3076s, i am building the intake manifold and I am stuck with the intake runner length. M3 3.2L engine has six individual throttle bodies, and I would like to know if I should stick to longer runners for improving the mid rpm power band. Gt3076s will be laggy and I am expecting to have full boost at around 5800 rpm. So, longer runners map improve spool up time? Your opinions are appreciated. Mert

Head is BMW M3 3.2L 2005 model. Head is ported and polished. Intake valves are 36,5 mm (this is the + 1 mm valve) Exhauts valves are 31,5 mm (this is the + 1 mm valve) Dual springs, titanium retainers are in place. 288/280 cams are installed. The engine has 3.2L capacity, and 2 x GT3076s. What I have seen is that, my friend has a Supra with GT55 turbo. This is a huge turbo with 91 mm compressor wheel. He has a full race brand exhaust manifold where all runners are 60 mm ,, So they make over 1000 whp on my Dyno Dynamics and I really would like to know if someone has a technical explanation for the runner size.

I started building the turbo exhaust manifolds for my 2 x GT3076. Have two options: 48 mm piping or 58 mm piping can be used for the exhaust manifolds. will 58 mm give more top end power and longer boost build up? Mert

yes, what is shuffling?

What is the advantage of using a balance tube for connecting the exhaust manifolds of a twin turbo system?

Gt42, was tested before. I will rebuild the bottom end and also the cylinder head and want to rev 9000 rpm. I could not find many BIG TWINS/ but saw on some forums, T04Z which is also big, and some RB30 owners put 2 of T04Z

Did anyone test twin Gt3076Rs on RB30? At which engine speed does full boost come on? Mert