Need advice choosing the right turbo setup for my HBP motor.
 

I originaly posted this thread in the 2nd gen specific, https://www.rx7club.com/2nd-generation-specific-1986-1992-17/need-advice-choosing-right-turbo-setup-my-hbp-motor-799343/. Now it's here

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 ?
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I've learned that 2.5" piping is good enough to reach 400hp. And that 1000cc injectors are not big enough. So I bought 1680cc bosch injectors. And in terms of a bigger turbo I've been told that I have to get at least a 1.15 a/r, the largest a/r possible for a T4 flange. But I know people on this forum are running 0.96 a/r and 1.00a/r on their HBP motors. I'm a bit confused here.

Finally, 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 and get it done the right way ? (big intercooler, 3" piping, 3.5" exhaust, custom T6 manifold,etc...)

a t3 will get you in the 400-450 range easily and have awsome responce such as a gt35. a t4 will get you there with minimal lag with the smaller turbine A/R and have room to grow like a 60-1 or t66. a T6 is gonna have HUGE lag hit hard and be what we like to call a straight line turbo. ill be honest for what you want the link you posted is TOO BIG. save your money do like a gt35/40 setup more comenly gt3582r or t60-t66 to4 and be more than enough for what you want with room to grow.

z

infact i believe there are a couple in forsale section right now for pretty cheap although the ones i saw were in the FD section infact i bought one.

I'm not convinced a T3 will get me to what I'm aiming for. A HBP motor breathes more than a stock port and street ports. I haven't done any research on FD motors because I own an FC. But if someone else prove or at least clarify with details that I can get 400 to 450 rwhp with a T3 turbo, like you mentionned a gt3582r, then I will most likely buy one. If I'm not mistaken my stock hitachi turbo has a T3 flange.

Just because the manifold is T3 doesn't mean the turbo will fit if it is T3 if the overall dimensions are different. I wouldn't bother with a T3 on a SP let alone a HBP. There are better T4 options that cost less than the 35R. Everyone will be saying you need to run a large Turbine A/r, you wont. You are not interested in that T6 posted up either, no need for your power goals. You'll have a very quick spooling good power turbo with a T4 .96 or 1.0 divided and you'll hit your power level.

Thanks Zero R. My first idea for a bigger turbo would be a turbonetics T70. Any exhaust manifolds you would recommend ?

why not go with a bullseye s256? it'll outflow similarly sized turbos, and it's a T4.

never heard of it

This is how I usually set those up; 1.15/1.32 P trim To4Z; 4" exhaust...
https://www.rx7club.com/showthread.p...hlight=Railgun

I don't know why you did a half bridge for just 400whp. Either way though I wouldn't go bigger than a 35r. Going any bigger is just going to add onto the threshold. 400whp on a 35r is possible with a good tuner...

I didn`t do a half bridge, I bought a HBP motor from a forum member. Why, because he made me a deal I couldn`t refuse. And I love the fact that HBP have that lumpy idle and are loud.

You can make a SP have lumpy idle and be loud ;) I agree with above look at a smaller turbo if your power goals are that low I wouldn't go over a 67mm, run a 74mm or larger turbine wheel, stick it in a .96 undivided if you want power or 1.0 divided if your after response. Those should be pretty good and way more than is needed for 400whp.

I'm looking for response. And even if I'm able to get more power than what I asked for. I'm not gonna complain.
Here's the full setup that I'm looking at right now: I'm looking at a Turbonetics T-76 with a 1.00 divided. Neukin exhaust manifold and synapse 50mm wastegate.

And question out of curiosity, there's an exhaust manifold with a dual wastegate setup in the for sale thread, what's the reason for having a dual wastegate setup ?

A few reasons for dual gates, the largest being that you get to maintain *FULLY* divided runners. Even a true divided manifold will have exhaust pulses mixing in the wastegate runners where they collect - the true dual avoids that.

How beneficial? I have no idea.

If you're looking for response over power, but still want to get 400 hp you should go with a smaller turbo then the t76. A t76 is a big turbo. You can get 400 hp with a 60-1 and have faster spool. or you could go with a ball bearing turbo like the gt35 and have even faster spool. With the higher compression rotors and the HBP you will be making more power at a lower boost level and you need to keep it that way if you plan on running pump gas.Stick to 15 psi or less (on 93pump) unless you add aux injection or race fuel. A t76 wont even be awake at 15 psi. Also go with the t4 flange, while you could probably get close to 400 with a t3, rotaries are better suited with the t4 flange especially a half bridge, the t6 flange will be too sluggish for you.

I think you are falling into the bigger is better trap. you need to pick a turbo matched for your application. several people have all suggested very good sized turbos for your needs, and you come back talking about this monstrosity that you will probably never fully utilize with so much lag that you wont even get to enjoy the car.

t60-1, t62-1, t66, gt35, gt35/40 will all get you where you want to be, while having less lag. The ball bearing turbos will spool faster but are more $$

The single 50mm gate will work fine for you. And the 1.00 divided sounds like a good size a/r. I wouldnt go smaller then 1.00 considering your setup, unless you were going with an undivided manifold, then i might go .96, but with the half bridge you should be able to go a biy bigger a/r without sacrificing spool as much.

Alright would a T04R turbo with 1.00 a/r divided and .70 a/r compressor be a smarter choice ?

to4r is close to a t66 so it would spool quicker than the t-76 yes.

That turbo and A/R works VERY well on a 1/2 bridge. I ran that exact turbo before and loved it on my 1/2 bridge.

What size wastegate were you running on your T04R setup ?

45mm Greddy Type R