fo sho!
love the sound of the twins...especially in lower rpms light load driving next to a barrier or another car..you can really hear the distinct sound of each turbo....sounds like a pair of jet engines at idle. then it kinda meshes into just hearing the 475 especially when its pushing 34-38psi.

I still need to tighten the gate on my secondary, but I need 110# springs and HD pushrods first before I do that...I'm already borderline at the boost pressures to float the valves. 5-10psi more and they will float.

 

That sounds like a CRAZY fun time! Hazing the rears at 60!!! Lol

 

Is that with a stock turbo or like a 64 mm

 

its awsome!!! well.... untill rains anyway, with rain, you go from one of the fastest things around to the slowest lol , rain + spooling turbo = instant unexpected dounuts



couldnt have described it better myself! i love the sound, and watching the 35 psi gauge in the cold pipe spin around and hit the needle stop, tighten the gate? dang i can barley get mine low enough, at one point i was running tripple wastegates and still couldnt do it, but now i got it with a lot of porting in a 3 piece manifold and in the turbine housing and internal WG, along with a 38mm external wg i finally got it down to 70 psi

you really dont have to have the push rods but its definatly not a bad idea, i love running the 4k tunes/govenors much better to drive and a wicked sound

 

Is that the stock turbo compounded with the S475?? Sounds friggin AMAZING!!!

 

that's what 4x4 is for!

and yes my gate needs tightened on the secondary.

I push 65psi now, but my primary is doing most of the work. soon as my primary takes over the secondary is only pushing a couple psi into the re-compression and holding its gate open. S300 is barely touching the start of its map once the S400 takes over.

here's the math formula to figure it out:

Primary PR
(primary psi + ATM)/ATM = PR

Secondary PR
(total psi + ATM)/(primary psi + ATM) = PR

PR = Pressure Ratio
ATM = Atmospheric pressure at your current altitude
Primary psi = boost pressure taken from a point in the plumbing before boost enters the secondary stage
total psi = pressure taken from the intake manifold.

Ideally you want the PR of each turbo within its map (google the map for the turbo you have to find out if you are within its efficiency range or not) and you also ideally want the PR numbers to be somewhat close to a 1:1 ratio to make sure the work is balanced between the twins.

it's not as simple as taking total boost and subtracting primary boost...the secondary is not really pushing much more, its re-compressing which is a whole different equation.

no, I blew up my stock turbo a few years ago when my head gasket went, as well as the replacement turbo after that (hx40/35 hybrid) when i put my 7x.010 injectors in. My top turbo is a super b single which is a 57/65/14cm² S300G. my primary or bottom turbo is a S475 or 75/96/1.32ar

 

so currently my pressures are call it 35 primary average and 65 total

plug that in and we have:
primary
(35 + 14.7)/14.7 = 3.38 PR
secondary
(65 + 14.7)/(35 + 14.7) = 1.60 PR

as you can see my secondary is not doing near as much as the primary so I can tighten my gate which will raise total pressure and force the secondary to take more of the compression load.

 

correct... i was just talking about dangerous boost spikes i was having and it took a lot to get under control, was breaking my manifold gauges and making my headgasket very nervous lol, but sounds like upgrading to a 60 or 62mm secondary comp wheel might be a better route for you? otherwise pinching the wg down is just raising manifold drive pressure further, im running a 62/68/13 with the ported housing and ported wg witch begins to open about 35 psi, then the external gate starts opening about 50-55, i run right at 1:1 with primary/secondary boost pressures, and 1:1 or less with boost/drive pressures

 

nah. too much lag. thought about smaller turbine housing on the secondary. my gate is loose though.

trying to reduce lag and smoke, so I'm going to have Chris from DFI (formerly from SDX) build me a set of 7x.011s which will run cooler EGTs and less smoke than my 7x.010 DDPs and should spool the twins quicker. get those springs in and tighten the gate, and possibly change my exhaust manifold to something like a steed speed and it should bring things closer together. going to check on my studs at the same time as doing the springs to make sure they are all still at 135lbs/ft.

my twin set should be running about 75psi but like I said I have the gate loose to limit boost, and I'm running the smallest set of injectors you can run with this twin combo. 7x.011 will be mid range, 7x.012 is top of the range before you want to go to a larger comp wheel.

 

ya i hear ya on the lag part, mine isnt horriable but definatly could be a lot better! im only running 5x12's right now, put 548/1091 on my last run but only hit 40psi, dang thing just wouldnt lite.... but i'm gona build a set of 5x14 0r 16 here soon and see what i can break lol, also been dreaming of a tripple turbo setup, something like two he/hy 35's fed by a 475, i even have a 475 vgt sitting on the bench i have been dreaming of installing, i wana try to lite it as a single first, but have my doubts, but ya never know, if it wont, im sure it will make a mean set of compounds