Everyone says the S5 turbo is a better stock unit for a few different reasons. Then reading all the BNR turbo posts it seems that the S4 has a better flowing exhaust manifold.

So out of curiousity, is it possible to use a S4 manifold, twin scroll removed, with a S5 turbo? Would there be any performance benefit?

What's everyone thoughts on this?

 

Ummm .... Pretty sure it's the other way around, the s5 manifold is better because the runs are equal. On the s4 one of the runs is slightly smaller. I would post a pic for you but can't find one at the moment.

 

s4 is open footprint , with a single asymmetric positioned stud in its foot flange
s5 is genuine split pulse ( divided footprint ) with a symmetrical pattern for its studs

they cannot swap about on the manifolds due to the different footprint stud patterns
you will need spacer plates to adapt the foot
( and all you will be doing is trading to a non split pulse design )

the s5 split pulse exhaust manifold is way better

incidentally i have a custom manifold and s4 high-flow turbo on my rx2
( very fast spooling rear design, that's restrictive at power levels above 1 bar )
and an FC with s5 mild port, s4 INLET manifolds, and s5 high-flow ( and LPG )

the s5 turbo will spool slower but produce more consistent boost than a s4 one above 1 bar without games
- mostly due to larger rear A/R , and a double internal waste-gate, and clean entry split pulse rear

 

if you didnt notice the S4 and S5 has a different mounts. and if i am correct, the s5 has a bigger waste gate letting it handle more boost than the S4. although when you port the S4, it becomes a bit better than the stock port. and lets you see boost levels as high or higher than the S5 turbo.

 

^ So your saying, all this talk i've heard on s5 manifolds being bolt on to the s4 turbo, isn't true? If you need a spacer technically that isn't bolt on.

 

i suppose... but i havent heard such a thing...

 

you need a spacer to fit the TURBO to the wrong manifold if its S4 to S5 or s5 to s4

if bolting a s5 turbo WITH its correct exhaust manifold and drain to the s4 and vichy versa
will be AOK , direct swapsy

 

AND
just to throw in the spanner ( and yes i have done this all multiple times )
the dump pipes swap, s5 and s4
the s4 dump gasket has a larger ID !

S5 turbos have tee and pill on waste-gate line, cause there ECU runs wastegate solenoid
( another reason s5 is more consistent )

and
if you have rx3 / rx4 / rx5/ early rx7 ( not rx2, but capella conversions OK )
you can fit the FC motor with 12a timing cover mod
and FLIP the s5 exhaust manifold upside down ( shifts turbine adjacent to front rotor )
oval two of the turbo foots holes
fit a 12mm spacer between turbo and exhaust manifold
( and / or grind back of LIM lightly, and or fit spacer between exhaust mani and block )

and it all fits in , almost factory look

( edit, most LHD ( US ) vehicles wont have the clash that RHD ones do that makes these mod necessary is aus and jap and nz and UK and SA )

 

The s5 has a better turbine housing design AND a better manifold period. I think your confusings things.... the S5 turbo BOLTS TO A s4 ENGINE, as in using the s5 turbo and manifold, not bolting a s5 turbo to a S4 manifold.

~Mike............

 

If we're talking strictly about the turbine housing, this is not true.
Both are twin scroll turbine housing designs.


-Ted

 

I believe ( or hope) hes talking strictly about the manifolds Ted.

~Mike............

 

yes, s5 manifold keeps both rotor runners independent of each other right up to the turbo
the s4 uses the twin scroll flap to make only one runner on the turbo receive low down exhaust flow , yet both rotors are unrestricted to it


s5 on the left



s5 twin flap gates



s4 single flap gate

sorry i dont think i have any stock manifolds for pics
( cause they make great crayfish ( lobster ) pot weights, just like cast flywheels )

 

I was aware the s5 turbo could be bolted to an s4 engine. I wasn't aware that you can't bolt an s5 exhaust manifold to an s4 turbo, without any modifications. I guess i've been getting wrong information from people on here, because from what I have read is you can just make the quick swap.

 

Travis,

The S5 turbo and Manifold will bolt onto an S4 TII motor, no problem.

The spacer/adapter is only needed if you want to mix and match S5 turbo with S4 manifold or S4 turbo with s5 mannifold.

But from the consensus it appears that the S5 turbo and manifold are the way to go, for a stock setup.

My original post was mainly a hypothetical one, taking into consideration the possibility of wanting to go with a hybrid turbo down the line.

Reading up on the BNR turbos it appears that the S4 turbo makes more peak power than the S5 unit, while the S5 turbo is more responsive in the mid-range.

If I undersdtood the BNR threads correctly, the higher horsepower of the S4 setup was due to a better flowing manifold. Hence my question about the S5 turbo with S4 manifold.

Now after posting this thread, it looks like I need to do some more research or talk to Brian at BNR directly.

 

I'm going to be swapping a S5 turbo and manifold in s4 TII. Since the S4 doesn't have a wastegate solenoid can i just run a vacuum directly to pressure nipple on coldside of turbo like S4? Also all i need to change is the oil line that goes to front cover as well right?

 

Basically, S5 turbo requires S5 manifold and same with S4. They aren't interchangeable. Both manifolds, however, bolt to either block with no issue. The compressor housing is basically identical, however, the turbine housing, wastegate and wheels are different. I run an S5 turbo on my Vert and it works very well, but I have a boost controller to keep things running as if it's an S4.

 

basically saying if you want a S5 Turbo, you must need a S5 Manifodl, S4 Manifold will not bolt up to S5 Turbo.

S4 Turbo, S4 Manifold
S5 Turbo, S5 Manifold

S4 Manifold and S5 Manifold will interchange with S4 TII and S5 TII

 

Just checking in, 4 ways to ID an S4 Turbo.
1. The S4 waste gate actuator rod is straight.
2. The S4 two exhaust ports are different sizes.
3. The S4 waste gate has 1 port.
4. The S4 manifold mounts the turbo at an angle, where the S5 mount is vertical.
Both the S4 and S5 have HT-18 Housings.
Photos below are of a S4.