i was lookin to buy a S5 turbo and manifold for my S4 .

but i was wonder what r the differences between the 2 turbos?

Thanks for the help

 

s4 has a better internal waste gate

 

The compressor wheel, compressor housing, centre housing and turbine wheel are the same for both turbos. The turbine housing and exhaust manifold were redesigned to become a fully-independant twin-scroll arrangement, where the two scrolls in the housing are fed individually from each exhaust port. The S4 had a common manifold that fed both scrolls, so the strong exhaust pulses lost a bit of their energy in the manifold. Keeping the pulses divided allows them to hit the turbine wheel harder and so improve turbo response.

Another advantage is the higher-flowing dual wastegate, with each scroll having it's own port. Contrary to popular belief the dual wastegate ports were not there to make the wastegate flow better (in stock form the S4 had no boost control problems), but simply to keep the exhaust pulses completely seperated. This becomes a big advantage when you start modifying as the S4's small wastegate cannot control boost properly when the exhaust and intake system are improved.

 

im purchaseing the tubo and manifold.

so if i read what u have posted correctly the s5 manifold is better but the s5 turbo is aboutt he same as the s4?

 

Um, no...

 

No, like I said, the turbine housing is completely different.

You have to use the matching manifold, i.e. you can't put an S4 turbo on an S5 manifold and vice versa, as they're completely different.

 

I think he might mean that when on a modded car, you can maybe port the wastegate to a larger area than the s5? I have a ported S5 turbo, hopefully it will be ok.


-Justin

 

naw i meant to put s5 my bad.. just didnt catch it to edit it in time

 

s4 wastegate stock sucks donkey *****, s5 wastegate from factory is pretty good. theyre both good if you hog out the wastegates

s5 is divided manifold which is better, but they both have very short exhaust runners which sucks

I think I've seen someone mention s4 is 1.00 A/R on the hotside and s5 is somewhere in the .8's. I have no idea of how true this is though.

And s4 has twin scroll, which I've heard some people say hurts spoolup, and other people say it helps spoolup.

My turbo is a s4 h-trim compressor wheel hybrid (stock compressor housing) w/ a tial 38mm external wastegate welded onto the turbo manifold and routed to the downpipe. Twin scroll was completely eliminated as my engine is high compression and ported and will spool the **** out of them, so it was more of an impeding flow at topend issue than quick spoolup which I'll have reguardless
All of the downpipe/twinscroll/wastegate/turbo rebuild work was done by my buddy elliot at turblown.net and I bought it as a h-trim turbo w/ a blown oil seal from my friend.

Here are pictures of my wastegate
http://www.pbase.com/meanrex/externa...ybrid_s4_turbo

-Ben Martin

 

Why?

Nobody has ever said the twin-scroll system hurts spool, not anyone with half a clue anyway. Increased low-rpm lag without is well known. Why do you think Mazda put it there?

 

^----- don't worry, Node has no idea what he's talking about.

 

The twin scroll setup in an s4 turbo is designed to reduce turbo lag...thats all. They got rid of it in the s5 because...ummmm...hrmmmmm. And the answer to your q on why short exhaust runners are bad is because the longer the runner, within reason, the more low end power you will get(better exhaust scavenging), just like in headers with any other vehicle, the longer the headers, the more torque.

 

so the s5 turbo has more turbo lag because it dosnt have an twin scroll? but the exaust manifold for teh s5 is better then the s4?

so with would i get more power from the s5 turbo and manifold or the s4 turo and manifold?

 

I always thought Mazda's intention for the change of design from the S4 to S5 version was to reduce turbo lag. That is, the S5 stock turbo set up, in overall stock set up, has a more smooth transition to boosted power than the S4 version.

Does this sound right to you turbo experts?

Also, speaking of S4 vs. S5 designs, can anyone advise if the S4 and S5 front wheel spindles are interchangable or not? I know there is minor difference between the arms they mount too, but to the eye it really looks like the spindles mount exactly the same to the arms be it S4 or S5.

 

The combination of the fully divided twin-scroll set-up and new electronic boost control gave better results and made the old system unnecessary.

No, see above.

Both will give you about the same power, as the compressor section and turbine wheels are the same.

 

I have a s5 turbo torn down to rebuild it (as we speak) and it's a twin scroll....the difference between s4 and s5 is that the s4 had a solenoid-controlled actuator that opened a valve in the exh. manifold to direct gases to the second scroll to try to improve spool-up. The s5 uses a different manifold (not interchangeable) that doesn't use an actuator....each scroll is fed by gases from each exh. port. Go with the s5, it spools just grand. It's my understanding that you can also make it a "hybrid" by using a Garrett T-04 compressor housing....I'm looking for one so I can try it.

 

since the s4 turbo is selinode(sorry bout the spelling) controled is thee anything else then just the turbo and the maniofld i would need to change for the s5 setup to work right?

 

As long as you use an s5 exh. manifold with an s5 turbo it should bolt up just fine, and the solenoid for the s4 actuator can be discarded. Make sure you install all of the heat shields that go with the s5 turbo, especially the one that covers the manifold.

 

alight

how many heat sheilds is there only one? or is there more?

and i can just get rid of the solinode right?

 

how come this one is so important? i didnt get them with my turbo

 

The heat shields are used for 2 main reasons:

(1) The intake manifold is just above the turbo and we don't need an oven to cook the injectors and the air flowing thru the intake.

(2) Turbos work not only from exhaust gas flowing through it but from the heat energy that acts upon the turbine wheel blades. A lot of heat energy is lost to the cooler surfaces of the manifold until it gets really hot. If you have driven a turbo car with a cold engine you would notice the boost comes on more quickly when the engine and the turbo have warmed to normal temp. Look in salvage yards and ask someone in the "for sale" part of this forum and I bet someone will have them. There is one shield that bolts to the exh. manifold, another that bolts to the intake manifold, another that bolts to the turbo, and one more that bolts to the turbo outlet / downpipe elbow.