My car is in storage now for the next 6 winter months, and durring the storage season I would like to get a bigger turbo setup when the time is right. Right now my priority is getting a new wireing harness for my haltech, because my old one got burned, a wideband o2 kit, axles for my LSD diff, maybe an aftermarket LSD unit, and a lowered suspension (shocks and springs). I want this thread to be a future reference for me when I'm ready to get a bigger turbo.

Right now I have an S4 block, HBP on top of large street port, 9.4:1 rotors, RA seals, mazda oem springs, FD oil system, FD stationary gears, e-shaft oil mods, Mazda Racing Pulleys, HKS lightweight flywheel + HKS 6 puck twin clutch disks + HD pressure plate, HKS 3 inch silent hi-power exhaust (downpipe 2 a magnaflow hi-flow cat 2 a cat back exhaust), HKS air filter, Koyo S5 rad, Zirgo 3000cfm electric fan, braided SS lines for stock oil cooler, all emissions removed and block off plates installed, Walbro fuel pump, KG parts fuel rails, Denso 720 cc low imp primary injectors, venom 1000cc low imp secondary injectors, SX FPR, SS gas lines, Aeromotive 100micron gas filter (not installed yet), Haltech E6X brand new not tuned yet, 8mm spark plug wires, MSD 6T wired to leading coil pack, custom FMIC with 2.5 inch pipeing with Greddy TB elbow, APEXI twin chamber BOV, pipeing is mounted to route stock S5 turbo to TB, TB is a ported an modded S4 TB with secondary plates removed, stock S5 TPS sensor, mazda O2 sensor, GM water and Air temp sensors, HKS internal wastegate, solid aluminium motor and tranny mounts, Cusco front strut tower bar.

And a bunch of other aftermarket parts that I bought but not installed yet. (gauges, gaskets, polyurethane bushings, rear strut bar,etc) Basically I have everything I need to run a bigger turbo on my rotary. My goal is to have over 400rwhp, preferbly 450.

Can I obtain those numbers with 2.5 inch pipeing ?
Can I obtain such results with a turbo that can bolt up to the stock manifold and without having to switch to an external wastegate ?

If not, then what would I have to do obtain those numbers ?

 

You're kinda low on injector and I would get rid of the Venoms you have and buy the 160lb injectors from Keith (kgparts). You need a aftermarket manifold and external wastegate. GT35R, GT40R, To4r will get your numbers you want on pump gas.

 

for a half bridge I wouldn't go smaller than GT40/GT40R or T04R and its ball bearing equivalent, the T04Z. Your hotside A/R should be at least 1.15 divided

 

GT40/GT42R with a fully divided manifold,P trim exhaust wheel with at least a 1.15 A.R hotside,switch the 1000cc injectors to the primaries and get a set of 1680 for the secondaries,in order to control boost the right way with a bridgeport you need to run a big wastegate or a dual setup,if your taking about your exhaust size 2.5 inch wont do it you need at least 3 inch turbo back(i run a 4 inch on my setup,S5 TURBO HBP BLOCK)

 

Throw the Venoms in the garbage.

https://www.rx7club.com/showthread.php?t=728567

 

So what you guys are telling me here is I absolutely have to have the largetst a/r possible for a T4 ? And 1000cc injectors are not big enough ? And by the way I have a 3 inch exhaust, I have 2.5 inch Intercooler pipeing.

Let`s say my first ideas of a bigger turbo was a Turbonetics T70 with a 1.00 a/r on a t4 manifold, it`s not good enough ?

 

I'll tell you one thing. That is going to be lots of hp on an s4 block with tee-tiny dowl lands. What kind of power are you looking for? I wouldn't run much boost without strengthening the motor via oversized studs or dowl pins.

Back on topic I would say the t70 would be fine. My car hit 400 at 17psi at 5,900rpm. I am using a .96 hotside by the way. I'll let you know what the numbers are after the motor gets put back in with added dowl pins, higher rpms, and higher boost.

 

Large T4 turbo,1.15 turbine housing will do the trick.

 

No a 1000cc injectors are not enough for a turbo bridgeported motor and on top of that you are running high compression rotors so you need that extra fuel to be on the safe side,Get the divided 1.15 AR housing and at least a T70 and a big external wastegate(hks,tial,turbonetics)

 

If I absolutley have to get 1600cc injectors to be on the safe side, then that's what I'll do, but I'm still keeping the 720cc as primaries. Thanks joeylyrech.

Now can someone explain to me the differences between the different size a/r housings ? Why is it recommended to get a divided exhaust turbo housing compared to un-divided ? How big of a wastegate should I get if the manifold can fit only 1 ?

And does anyone with an S4 HBP motor use 2.5 inch intercooler pipeing ? If yes is it enough to obtain 400rwhp or more ?

 

you really need to start searching through the single turbo forum on here.

bigger a/r = less backpressure (but of course can be harder to spool). bridgeports have a lot of backpressure due to the overlap in the opening of the intake and exhaust ports. divided manifolds and flanges separate the exhaust from each rotor until it hits the turbine blade. keeping the exhaust pulses separate they hit the blade at greater velocity. Look at the s5 turbo and manifold and it will make sense.

You're going to need a big wastegate. Go for the Tial 44 (v-band one) or the 46 (4 bolt flange) or similar ones from Turbosmart etc. Or try the 50mm HKS or Greddy Wastegates. Do NOT use a Tial 38 or HKS 40mm wastegate. You will never get consistent boost control with a half bridge--in fact you'd have trouble on stock ports honestly depending on the manifold.

you need to budget at least 3 grand to do this right in terms of the piping and turbo. Contact Aspec and they can build you something for your setup.

 

No one has addressed the piping yet....

Yes, 2.5" is fine to make only 400HP.

I throw in the GT40R as a recommendation for 450HP. I'd recommend it over the "older" T series turbos. The GT series uses slightly better wheels. I have a GT40R 1.06 on my car. Just over 400 RWHP at 13 PSI. Last dyno I made 392 HP to the wheels at the same boost level on a hotter day.

 

Thanks for clearing that up for me Aaron Cake. I saw your videos on youtube btw. Do you have 2.5" or 3" intercooler piping ?

 

2.5"

 

Cool. And again for reference purposes, I've been looking at a T6 flanged BIG turbo like this one: https://www.rx7club.com/2nd-generation-rx-7-1986-1992-parts-194/fs-big-garrett-turbo-797840/.

To me it looks like a SSautochrome manifold. And i'm wondering is it considered smart or safe or cheap shortcut to have welded a T6 flange onto an originaly T4 flanged manifold and bolt up a big turbo like that ?

And also keeping my specs in mind, this turbo has 3.5" inlet and a 3" outlet (compressor) and a 3.25" turbine. And I have 2.5" IC piping and 3" exhaust. So if I were to get reducers for both it'll look like I went cheap shortcut all the way to make it fit. And will it be reliable ?

Or if I were to buy it, I would have no choice but to go all out ? (big intercooler, 3" piping, 3.5" exhaust, custom T6 manifold,etc...)

 

thread has been moved to Single turbo Rx-7 section